12.5 to 12.6 billion years after the beginning of the Universe.

On Earth, biological organisms are getting more and more interesting as the years tick by. As the unbroken chain of life continues, the combined factors of inheritance, random mutations, and horizontal gene transfer serve to increase the total amount of genetic information found in the genomes of the most complex organisms. This results in them gaining more specialized features, and many new characteristics begin emerging.

Some organisms thrive together in colonies, with identical unicellular lifeforms binding to one another to ensure that the majority of them survive and thrive. Other organisms develop multicellularity: the ability for a single organism to produce multiple component parts — cells — that all remain bound together as part of the original, parent organism. And still other organisms become differentiated, where new subcomponents develop within an organism, conferring features and abilities onto it that it didn’t possess before. At this moment in time, the last of these effects leads to an entirely new kingdom of life on Earth: the fungi. 

Evolving well before plants or animals arise on our planet, these early fungi likely thrive in aquatic environments and possess flagella: tiny, thread-like tails that allow them to control their motion through water. The fungi are all eukaryotic organisms that reproduce through the creation of spores, which mature atop microscopic, soft-tissue structures known as fruiting bodies. In aquatic environments, flagella are required to transport spores away from the parent body, towards locations where they can gain nutrients, thrive, and survive until they reach reproductive age. 

The first complex organisms to colonize the
continental landmasses of Earth are neither
plant nor animal, neither of which has yet
emerged at this point, but fungi. Although
the first fungi arise in aquatic environments,
they swiftly develop symbiotic relationships
with algae, creating lichen-like structures
that can exist in sufficiently wet land-based
environments.
IMAGE BY MARK A. GARLICK

However, many species of fungus soon adapt to thrive on land as well. On land, fungi develop filament-like structures that connect member organisms with one another, where they then form a mycelium-like network. By radiating branches outward that have the potential to connect with the branches of neighboring fungi, they create a network through a process known as anastomosis, where splitting branches recombine. Due to their small sizes and soft, easily degradable bodies, fungi only rarely fossilize, leaving little trace of their presence from so long ago. While aquatic fungi are known to arise during approximately this epoch, substantial debate exists as to when terrestrial fungi first arose, with time estimates varying by more than half a billion years. 

Among the oxygen producers, cyanobacteria still dominate the biosphere. While oxygen-producing algae have already come into existence during this time, they produce only a tiny fraction of Earth’s oxygen and won’t rise to prominence for several hundred million years. However, small populations of terrestrial algae can — in concert with fungi — begin producing structures that resemble modern-day lichen, where algae and fungi enter into a symbiotic relationship in wet environments on land. The land itself continues to shift due to Earth’s tectonic activity, with the ancient supercontinent Rodinia beginning to assemble during this time. 

Although the most well-known form of fungus is the mushroom, containing the familiar cap-and-stem structure, they won’t arise for more than a billion years after the first fungi appear. Instead, these early fungi are mostly single-celled, aquatic-based forms of life with flagella and spores capable of traveling great distances through their watery environments. With mitochondria operating within their cells, the machinery is already in place for multicellular, sexually reproducing eukaryotes to arise. Over the next several hundred million years, these components pave the way for the first large, complex organisms.

The stage on Earth is set, at long last, for the appearance of plants and animals. 

This article Complex life started with fungi, not plants or animals is featured on Big Think.

For most of human history, we could only imagine what made us who we are. Then, just over two decades ago, the Human Genome Project — the international scientific effort to decode the three billion letters of human DNA — changed everything. 

Critics at the time called it too expensive, too ambitious, too abstract. And they weren’t wrong. It was the largest biology project ever proposed, and scientists hadn’t even managed to sequence the smallest bacterial genome yet. But the organizers knew that big plans — moonshots — inspire people and attract funding. 

Today, nearly every advance in modern medicine rests on its foundation. The project transformed biology into an information science, spawning ancestry testing, virus tracking, precision cancer therapies, the first personalized medicines, and more. 

Now, a new generation of scientists wants to take the next step: not just reading the code of life, but writing it. That’s the mission behind the Human Genome Project-write (HGP-write) and SynHG, the Synthetic Human Genome Initiative. 

HGP-write, a nonprofit I cofounded in 2016, is building the technological, ethical, and social infrastructure for large-scale genome writing. SynHG, a UK-led academic consortium announced in 2025, is focused on engineering, developing the pipelines and tools needed to construct chromosomes from scratch. Although different teams, they share the same audacious goal: to one day build a complete and functional human genome. Together, they’re helping to launch the next great revolution in biology, one that I believe will far surpass the impact of the original Human Genome Project (which I’ll call HGP-read from now on). 

Sequencing let us read the book of life, our instruction manual. Synthesis will allow us to write new chapters, if not entirely new books. 

Why write a human genome? 

When HGP-read finished in 2003, it had taken 13 years and more than $3 billion to sequence a single human genome (or sequence about 92% of one, since the technology to close all the gaps didn’t exist at the time — the whole genome wouldn’t come until April 2022). Today, sequencing a person’s DNA costs a few hundred dollars and takes a few hours. Few technologies have become so inexpensive and powerful so quickly. 

The advancement of sequencing technology has made Moore’s Law — the idea that computer processing power doubles while costs fall roughly every two years — seem like a slow crawl. This breathtaking drop in price and time has spawned entire industries, millions of jobs, and hundreds of billions in economic value. But the fact that sequencing is not yet a consumer technology, in every home, like TVs and phones, suggests we’re still nowhere close to the financial or technological bottom yet. 

Writing DNA holds even greater promise — the potential to cure any disease. DNA synthesis already underpins the engineering of new proteins, vaccines, and CRISPR-based therapies in the clinic. Writing the human genome in its entirety could enable correcting any genetic condition, regardless of its complexity. And writing small genomes could power a modern Cambrian explosion of new creatures of all shapes and sizes. 

Synthetic genomics is not new. In fact, the first synthetic genome was built over two decades ago. In 2002, scientists at Stony Brook University in New York, led by Eckard Wimmer, constructed the poliovirus genome entirely from digital sequence data. In 2010, J. Craig Venter’s team created the first synthetic cell — a living organism whose DNA contained hidden “watermarks,” including quotes from James Joyce and physicist Richard Feynman, a web address, and the researchers’ own names. By 2019, Jason Chin’s group at the MRC Laboratory of Molecular Biology re-engineered E. coli with a fully synthetic four-million-base genome. And in 2025, Jef Boeke and his international consortium of yeast scientists completed the ten-megabase yeast genome, a giant milestone on the path to writing larger, more complex genomes like our own. 

Whole genome synthesis is not speculative science; it’s a branch of genetic engineering that has been quietly simmering away under the radar, growing cheaper and more sophisticated in recent years.

Like AI systems before GPTs arrived in late 2022, most people remain entirely unaware that DNA writing can be done at all, let alone that thousands of labs and companies around the world are using it. 

While human genome-writing efforts won’t lead to designer babies or supersoldiers anytime soon, they do force society to confront an undeniable fact: Like amateur gods, we are beginning to author living organisms. We aren’t very good at it yet. The genomes that we’ve written are small and uncomplicated, and mostly lightly edited copies of what nature has produced. 

The bigger question is whether we’ll proactively organize as a species to do this engineering responsibly or wait on the sidelines until commercial, military, or geopolitical forces compel us to face reality and establish some rules of the road. 

Writing drives creation, understanding, and security 

Both HGP-write and SynHG are aiming to make genome-scale synthesis possible, affordable, and, importantly, safe. This is a grand challenge. Moving from short DNA fragments to entire chromosomes or genomes demands new instruments, enzymes, software, and standards — a completely new “synthetic biology stack.” It also requires that we create effective biosecurity systems, as some of the smallest genomes to engineer, those of viruses, are potentially the most dangerous. 

All this won’t be cheap to develop, but it will pay dividends long before a human genome is written. 

Every incremental advance in writing technology will accelerate progress across the entire spectrum of life science, from agriculture to pharmaceuticals, and from materials science to planetary defense; DNA synthesis is, after all, the foundational tool for engineering biology and biomanufacturing. Meanwhile, improved biodetection and biodefense technologies, accelerated by genome writing efforts, will enhance global health while better protecting us from the next outbreak or pandemic. 

Writing complete genomes is powerful. Editing existing DNA lets us tweak code, but changes must be verified by whole genome sequencing, considering that off-target changes are common. Building a genome from scratch means that software tools similar to word processors can be used to easily search and replace strings of letters, or cut and paste code blocks. Genetic engineering becomes a lot like software engineering. It empowers scientists to explore transformative questions like, “What happens if we remove ancient viral remnants from human DNA?” or “Can we program this cell so that it won’t age?”

Increasingly, it will be AI-based tools that do this coding, just as we’re seeing in computer software. This is already happening. Almost all protein engineering is now done with AI tools. And recently, the California-based Arc Institute combined its Evo AI tools with genome synthesis to make dozens of novel PhiX174 bacteriophages, the viruses that infect bacteria. The success of this experiment suggests that, in the near future, defeating a deadly superbug could be as simple as sending a document to an inkjet printer. 

As megabase-scale synthesis becomes available — a stepping stone to the gigabase synthesis needed for human genome synthesis — we’ll be able to design virtually any single-celled organism from scratch. All of microbiology becomes as much engineering as science. These “designer” microbes could transform biomanufacturing, producing medicines, fuels, and materials with unprecedented efficiency. 

Just as the transistor ignited the digital revolution, fast, inexpensive, and scalable genome design and synthesis will ignite a biological one. Life becomes a platform technology, a programmable medium for solving the world’s most challenging problems. 

The scientific dividends here will be profound. Cellular genomes are spaghetti code, with functions all intermingled and scattered through the chromosomes without rational organization, the only filter being that it works. Constructing complete synthetic organisms is the only way to untangle all the various functions evolution mixed together over billions of years. Starting fresh, scientists will be able to illuminate the mysteries of metabolism, development, and perhaps even consciousness in ways that editing genes cannot support. As the physicist Richard Feynman famously noted, you can’t truly understand what you can’t create. 

The world needs another biological moonshot 

But any project that aims to create life must confront serious ethical questions: What kinds of genomes should we build? Are any off limits? Who decides? How do we prevent biological weapons from being developed? 

Both HGP-write and SynHG recognize that the same tools that can cure or create life can also be misused to cause suffering and death. That’s why transparency, open science, and public dialogue are central to their missions. They want to ensure that the decisions about life’s code are a shared global responsibility, not the province of any single corporation or nation.

In this sense, genome writing is as much about governance as genetics. It’s about learning how to collaborate safely on planetary-scale, potentially planet-changing technology. And, in the short term, if history is any guide, a little friendly rivalry between teams will only accelerate progress. The US effort got an early start out of the gate, but the UK has quietly taken the lead with steady, consistent progress – and a “care-full” mandate that prizes responsibility as much as speed. But this is a race where, like sequencing, no matter who crosses the line first, all humanity wins. 

We could all use something big to cheer for — something that reminds us this planet is our home, not just a launchpad to the Moon or Mars. It’s been nearly 25 years since the world last united around a biology-based moonshot. The first Human Genome Project inspired a generation to see life as code that could be read and understood. Writing the human genome can inspire the next generation to see DNA as something that can be composed, unlocking possibilities that evolution has never explored. 

The question is no longer whether we can write a human genome, but whether we can do it wisely — and for everyone’s benefit.

This article The next revolution in biology isn’t reading life’s code — it’s writing it is featured on Big Think.

Have you ever seen a lek? Matt Ridley has. In fact, the prolific science writer somewhat bashfully admits to having viewed “umpteenth” leks in his lifetime.

After googling “lek” to make sure it’s not … what you think it is, you may be tempted to watch a video of one. If you do, you’ll witness something extraordinary. You’ll see dozens of beautifully ornamented male birds strutting their stuff in a field as the more modest females amble around. The ladies are sizing up the lads for potential suitorship, and only a select few will be chosen to receive the spoils: the opportunity to reproduce.

To the lay eye, a lek is a primitive mating game. But as Ridley vividly relates in his new book, Birds, Sex & Beauty: The Extraordinary Implications of Charles Darwin’s Strangest Idea, there’s majesty and mystery in the ritual. 

In its opening pages, Ridley transports readers to April’s picturesque Pennine Hills of Northern England to watch, feel, and hear a lek of the region’s black grouse. But a literary vacation is only one of Ridley’s aims. The other is to illustrate and explore, he writes, “an idea so powerful, so weird, so wonderful, that I still feel unsure whether I have gone far enough in accepting all its implications.”

That idea is sexual selection. You may already know of its more popular sibling: natural selection, the primary driving force of evolution. Natural selection is the idea that organisms more adapted to their environment will survive and reproduce; meanwhile, sexual selection contends that certain traits will evolve and endure simply because they help animals reproduce. The classic example is the male peacock’s flamboyant tail. Does it help the bird survive? Not really. But does it help it get laid? Absolutely.

In advance of Birds, Sex, and Beauty’s release, Ridley kindly chatted with Big Think about how sexual selection ties into beauty itself, the long and simmering scientific debate over the theory, and how sexual selection may have shaped the human mind. 

Big Think: What are some of the most memorable bird mating displays you’ve witnessed?

Ridley: The ones that blew me away most were the bowerbirds of Australia. They’ve outsourced the flamboyance from their feathers onto the decorations they put on their bowers. These birds build sophisticated structures with objects arranged by color and size, art installations basically. It’s truly amazing to find a bird doing that.

Big Think: How is it possible that we get these behaviors?

Ridley: I think it is sexual selection. One of the things I catalog in the book is the two centuries of explaining this [behavior] without sexual selection, without Darwin’s particular version of female choice. They said, “Well, it might be male competition,” or “It might be because the female needs to recognize the male of her species.” Brown birds seem to manage that perfectly well, so that doesn’t make sense. 

The key feature that we need to explain is how random it is. Species that get colorful use different colors, emphasize different parts of the plumage, and grow different shaped feathers. If it was all about saying, “Look, I’m strong,” you’d get a more consistent pattern. Instead, you get these unbelievably inventive ways of making an animal look beautiful and ridiculous. This force is so creative, and you don’t associate that with evolution. 

The whole point of “survival of the fittest” is that you’ve got to be tough and serious and boring and careful and cautious. Whereas, this process says, “No, let’s have fun. Let’s be bright red. Let’s make a bird disappear into a weird shape. Let’s make it collect art. Let’s grow a very long tail.” There’s something here finding new ways of doing things — which is why I think sexual selection is probably a hugely underestimated aspect of evolution.

I’ve started using two phrases to drive home the difference: “survival of the fittest” versus “seduction of the hottest.” Survival of the fittest gives you consistent, predictable, and to some extent directional results. Yes, the variation is random, but the selection is not. You end up with strong muscles or well-shaped wings or strong digestive systems. You can see why they’re designed the way they are. But sexual selection can come up with a peacock’s tail. You’re making a mistake if you say, “The precise pattern on the peacock’s tail has a reason, has a meaning, has a purpose.” Of course, that can’t be because it’s so random. It’s so arbitrary.

Big Think: The big theme in your book is sexual selection, but a supporting theme is beauty. How did birds become so keen on beauty compared to other animal groups?

Ridley: [When] Darwin wondered why birds have a taste for the beautiful, he was getting at something that many of his contemporaries just didn’t understand: What’s beautiful to them is also beautiful to us. Is that a coincidence or not? 

Birds and mammals are 400 million years apart in terms of evolution, and so it’s unlikely that the same taste for the beautiful existed in that common ancestor. You look at other mammals, and you don’t see the same taste for the beautiful. I was looking at pictures today of elephant seals mating. They’re truly hideous.

As Darwin wrote in a letter in 1860, “The sight of a feather in a peacock’s tail when I gaze at it makes me feel sick.” He’s referring to the fact that he’s cracked the problem of how you build an eye through natural selection to his own satisfaction. He hasn’t cracked the problem of how you come up with something useless but beautiful. His critics jumped on this. They asked why evolution decided that one hummingbird should have a red throat and one a blue throat. Show me the survival value of that. 

Darwin had to come up with another explanation, and he came up with the sexual selection argument, which I think is a good one.

Big Think: In the book, you describe how Alfred Russell Wallace, arguably the co-discoverer of evolution by means of natural selection, and Darwin got on pretty well. That friendliness didn’t extend to the idea of sexual selection, though. Why were Wallace and others so adamantly opposed to accepting beauty as a factor in evolution?

Ridley: To some extent, it must be a degree of jealousy on Wallace’s part that Darwin got all the credit for evolution. I think Wallace behaved beautifully throughout his life. He was the one who wrote [the theory] down and sent it for publication, but because he was off in the East Indies, Darwin got to choose how it was presented, and his paper was presented first. That’s quite good of Wallace to take that on the chin.

Big Think: So was challenging sexual selection his way of giving Darwin his comeuppance, then?

Ridley: A bit. But Darwin gets unreasonable at this point, too. Wallace does get the last word, however, because Darwin dies, and Wallace goes on writing. He wrote Darwinism (1889), and in it he basically trashes sexual selection by mate choice.

I’m not quite clear about what role Victorian sensibilities played in all this. Darwin doesn’t seem to have any problem saying that females will choose beautiful males. Other Victorians didn’t like saying things like that. Maybe they were nervous about what their wives would think. Maybe they genuinely believed that it’s men who choose wives and not wives who choose husbands. Maybe they were just worried that if they said this kind of thing it might lead to women becoming more sexually forward.

There’s undoubtedly a real problem that this science was being developed when culture had become very puritanical.

Big Think: After this saga, Wallace’s view of sexual selection dominated for almost a century. Then we get to Robert Trivers. Can you describe his simple, yet profound idea that ultimately helped cement sexual selection as a valid scientific theory?

Ridley: Robert Trivers is a truly brilliant man. Also a very eccentric man. The particular theory that he brought to the sexual selection argument — which is blindingly obvious really but nobody thought of it before — is parental investment. Whichever sex puts the most effort into bringing up the kids is going to be competed for by the opposite sex. You’ll get a flamboyant display and aggression in the sex that isn’t doing all the work. Another way of putting it is that they each put an equal amount of energy in; one puts it into fighting and the other into nurturing. 

That often occurs to me when I watch my black grouse because the males are spending months exhausting themselves displaying and fighting. The females are spending weeks exhausting themselves laying eggs and looking after chicks.

Big Think: Yale University Ornithologist Richard Prum told you that “The reason birds are so beautiful is because they don’t have penises.” Can you briefly explain what he meant by that simultaneously insightful, hilarious, and jaw-dropping assertion?

Ridley: About 97% of birds don’t have penises. The ones that do quite often engage in quite violent sex in which females can be harassed, raped, and even killed by ardent males. Ducks, in particular, do this, and they have large, explosive penises.

What most birds do for sex is something called “cloacal kissing.” Basically, two open-ended tubes are put next to each other, and sperm is shot through from one to the other. The point Richard Prum was making is that it is up to the female whether or not the male mates. She has to present her cloaca to him. If he had a penis, that wouldn’t be to the same degree. Therefore, what she can do with this newfound power is choose beauty as opposed to strength or fitness or something else. 

Big Think: On that note, what do a peacock’s tale and an Argentinian Lake Duck’s penis have in common? What can we learn from that?

Ridley: A peacock’s tail is a weirdly exaggerated sexual ornament designed to seduce a female. The bigger and better your tail display, the more likely you are to get a female to mate with you. An Argentinian lake duck was discovered to have a penis longer than its body, which nobody even suspected because, most of the time, it’s wrapped up inside. But during mating, it shoots out in a sort of hydraulic fashion. 

Clearly, there has been selection for a very long, very explosive penis in the Argentine lake duck — not because the females admire it, but because it leads to reproductive success. As does the peacock’s tail.

Big Think: What does this all mean for us? You write that sexual selection has been largely ignored by scientists studying human evolution, especially of the human mind. Why do you think this is?

Ridley: I think the starting point is to note that humans are quite a lot like birds. We sing a lot, which most other mammals don’t. We have a lot of color vision. We like dressing up. We seem to have an aesthetic sense. So Darwin was on to something when he said birds might be a better analogy for what we’re doing sexually than other mammals.

If that’s the case, then what’s the human version of the peacock’s tail? What is the flamboyant ornament that males or females are showing off? The obvious answer — one that Geoffrey Miller explored in a good book titled The Mating Mind — is that the human brain itself grew large as a seduction device rather than as a survival device. That is to say, the main thing that gave you an advantage is that you were able to impress members of the other sex.

When you think about things like wit and humor and song and poetry and art, none of these things seem to help you survive. They certainly wouldn’t have been much use in the African savannah for hunter-gatherers, but they help you get mates. 

Now, these traits may have another function which is more like natural selection in that they help you survive in a group and encourage others to like you. There’s a social brain hypothesis that is well-developed. But the sexual brain hypothesis has never really been explored adequately except by Miller.

I think he’s onto something. We shouldn’t neglect this because it’s the one evolutionary mechanism we know that produces sudden expansion in organs in quite surprising directions. And there is something very sudden about the human brain size getting bigger, which didn’t happen in other species. Why not? Why isn’t the world full of creatures with big brains? What was it about human society that made a big brain advantageous? Possibly, it was a mate-choice thing.

Big Think: So why do you think the idea has generally been thrown by the wayside?

Ridley: Well I think it’s partly because sexual selection was very out of fashion even in evolution until quite recently. It barely got mentioned in the great books about evolution in the 20th century. They’re all talking about natural selection.

Big Think: So not only has our understanding of birds been hampered by a puritanical hangover, but so has our understanding of ourselves in a way?

Ridley: That’s partly true. And you know you can sound a little prurient, frivolous, and odd if you start talking about the brain as a seduction device or the sexual role of the mind. It’s a slightly embarrassing way of joining the conversation. But why not have a go at it? I’m old enough that I don’t need to worry too much about what people think of me.

This article Seduction of the hottest: How sexual selection shaped birds and human brains is featured on Big Think.

If you’re lucky enough to live in a place with decent air quality, the surrounding medium might seem like empty space — a nothingness that deserves little attention beyond how hot or cold it feels. 

Carl Zimmer might change your mind about that. In his new book, Air-Borne, the celebrated science writer — who pens The New York Times “Origins” column and has authored 15 books over a 35-year career — tells the stories of the invisible organisms that inhabit our atmosphere and the intrepid scientists who discovered their existence.

As you read, you’ll fly with aerobiologists who risked asphyxiation to scour the stratosphere for floating life. You’ll serve as Dr. Watson to scientific Sherlocks investigating the microscopic purveyors of terrifying diseases, from tuberculosis to COVID-19. You’ll root for the researchers who sounded the alarm about airborne diseases yet were repeatedly and wrongly rebuffed. Above all, you’ll gain a new appreciation for each and every breath you take.

The air, Zimmer writes, is “a gaseous ocean in which we all live, which infiltrates our bodies, which our own bodies transform and then return to the great transparent sea….” In this interview with Zimmer, Big Think dives right in.

The following interview has been edited for length and clarity.

Big Think: Louis Pasteur takes a central role in your book. How much credit do you think he deserves for producing the far less deadly world we live in today?

Zimmer: Pasteur did so much that it’s easy to forget some of it. One of his earlier efforts was to destroy “spontaneous generation” — the idea, which lasted for centuries, that life could be spontaneously produced from decaying matter. By the mid-1800s, people knew a dead rat didn’t spontaneously produce maggots. Flies would lay eggs on them. But microbes were still a matter of debate. 

So, when Pasteur was looking at fermentation, how alcohol was produced, and how those batches could spoil, he decided the best explanation was that germs are floating in the air. If they happened to land in a vat, they could spoil it. No spontaneous generation needed. 

This [explanation] was controversial at the time. Pasteur got into a very public debate trying to persuade people that we’re surrounded by floating germs. A French journalist declared that he was attempting to bring us into a world that was too fantastic to believe, and Pasteur did some fantastic things to prove it. He climbed a glacier. He went all over France with these big flasks to collect bacteria from the air. 

Certainly, Pasteur is hugely important to modern public health. He has helped to save many millions of lives. He was also an aerobiologist. That part of his life and work has been forgotten.

Big Think: I loved your description of the aerobiologists. They were pushing the limits, not just to see how high they could go. They were looking for life. How did they push their field forward?

Zimmer: The modern age of aerobiology happened with the invention of airplanes. I write in the book about Fred Meier, a plant pathologist who hopped in airplanes to find out about these diseases that are wiping out wheat fields and other crops. He would go up and wave these Petri dishes on handles out of open cockpits. The pilots thought he was crazy, but he would actually collect stuff. He once collected fungi from 18,000 feet over Washington, D.C. 

But Meier kept pushing and pushing. When he found out that Charles and Ann Lindbergh were going to fly over the Atlantic, he talked them into helping him, and they found life over Greenland, which was amazing. He partnered with adventurers going up into the stratosphere with a giant balloon. They took along his equipment, and lo and behold, they showed that fungal spores could survive in the stratosphere despite the incredibly toxic conditions. They found that out in the mid-1930s. It blew peoples’ collective minds that life could get that high.

Big Think: There is a passage in your book where you described how hostile Earth’s upper atmosphere is, and yet there’s life up there! [However], I don’t notice much talk about looking for life in other planets’ atmospheres.

Zimmer: You’re absolutely right that the real focus of astrobiologists right now is either digging into the soil of Mars or drilling into one of these ice-covered moons in the outer solar system. There’s good scientific justification for going to those places. Who knows what we’ll find? 

But a small group of scientists would like us to think about Venus. You won’t find anything on the surface of Venus because you can melt lead there, but it’s not so bad in the clouds. 

We know that on Earth there are bacteria, lichen, all sorts of things in clouds. When you look at a cloud, you’re looking at a living thing. Trillions of organisms [representing] thousands of species are in each one. They’re alive and, in some cases, are growing because they’re eating the cloud. 

So, these scientists have said, “Maybe life arose on Venus’ surface, and it got into the atmosphere. Then maybe, just maybe, some of it survived there — cycling up and down through the layers of the atmosphere.” It’s a tantalizing idea, and it wouldn’t be that hard to test. Just shoot a probe through some of these clouds, and you should get a pretty good idea.

Big Think: Much of your book is about scientists stubbornly refusing to accept that diseases could be airborne, even into the mid-20th century. What were their motives here?

Zimmer: Infectious disease scientists [and] public health authorities saw an incredible shift in the understanding of diseases in the late 1800s. Before then, prominent medical authorities assured everyone that most infectious diseases were actually not infectious. They were caused by miasmas, disturbances of the air. Somehow, the air became corrupted, and if you inhaled it, you might get malaria, influenza, cholera, and on and on. 

Then the architects of the germ theory of disease worked long and hard to demonstrate disease by disease that they were actually caused by pathogens. Those pathogens, as they were identified, were not in the air. Cholera is caused by bacteria, and that bacteria is in water. Yellow fever is caused by a virus that’s in a mosquito. Syphilis is caused by a bacteria that’s spread through sex. So you have food-borne diseases, waterborne diseases, sexually transmitted diseases, and so on. These scientists were pulling diseases one by one out of the air. 

That led to the view that the air was basically harmless, and it would take a lot of evidence to persuade them otherwise. You have to wonder if they were ever going to be persuaded because they have taken this consensus as almost a law. Generations of medical students and public health experts were trained this way, and it’s still a widespread view.

Big Think: Fast forward to modern times: Why do you think many public health officials and scientists hesitated to declare COVID-19 airborne even into late 2021?

Zimmer: We were dealing with a new disease when the COVID pandemic hit. Scientists were trying to gather data on this disease to understand what we were dealing with. At the same time, they were also falling back on older paradigms. 

A default assumption was that this is a respiratory disease, so it’s probably spread by large, heavy droplets. But a few experts said, “This looks like it might be spreading like smoke in a room.” In other words, this is airborne. There was a lot of pushback against that — partly because many people didn’t understand the science of airborne disease as we understood it in 2020 already and partly because they were waiting for evidence. 

It did take time for a whole series of case studies to be published, for there to be outbreaks, and for scientists to figure out what made the most sense for how the virus spread. Finally, there was a consensus that COVID-19 is airborne.

Big Think: Between SARS, H1N1, and COVID-19, humanity has already faced three deadly bouts of infectious disease this century. How prepared are we for another when it inevitably arises?

Zimmer: We’re in a better position than we were before the SARS epidemic in 2003. You have to remember, in the early 2000s, the idea of entirely new diseases emerging and sweeping the planet was still unfamiliar. We understand the basics better. One way to prepare is to stockpile stuff that you may need and to make sure those stockpiles are still working. Developing better technologies for vaccines is important. Testing is important, too. Governments have made investments in all those things, but whether they’ve done enough is an open question. 

At the start of the COVID-19 pandemic, the United States had those stockpiles, but they were largely emptied out already. A lot of the stuff that hospitals were holding on to were old and decrepit. The rubber bands would literally snap off [masks]. Things were in a bad situation because we recognized the importance of stockpiles but we didn’t follow through. 

We now have Nobel-Prize-winning mRNA vaccines that can be made quickly. [However], in the United States, we have state legislators who want to ban mRNA vaccines altogether based on claims that have no scientific basis.

So, you can have all these great developments, but if you don’t use them in the right way, if you’re not organized, the next pandemic could just roll over us.

Big Think: What are the risks of a catastrophic outbreak in our staple crops? What steps are scientists and farmers taking to prevent them?

Zimmer: Diseases from the skies have been the bane of farmers’ existence for thousands of years. In the Bible, when God threatens to smite humanity, he will talk about things like stem rust. Of course, the Bible is not presenting these things as living organisms, but that’s what they are. Even as countries like the United States dramatically expanded their farm production in the 1800s and 1900s, they could never permanently escape these ancient diseases. 

In a way, we made it easier for airborne diseases because farmers often use the same variety [of crop] because it can resist the pathogen. If you have wheat that can resist black stem rust, then everybody plants it. Well, that stem rust evolves quickly, and there’s a good chance that a new stem rust variety will evolve that can attack the farms again. 

Right now, a bad stem rust is causing a lot of trouble in Africa. It has spread by the wind into Asia and is moving from country to country. Scientists have been trying to develop computer programs to try to predict where this stem rust will go next. It could eventually make it to the United States. We have been spared these huge stem rust outbreaks, but they could very well come back. 

Big Think: How have humans transformed the “aerobiome” in the last 50 years, and what are some of the ramifications?

Zimmer: The aerobiome is basically all the life in the air. Just like we have a microbiome inside our bodies — which is made up of thousands of different species — there are many, many more species floating around us. The aerobiome has existed pretty much since life began. When life emerged, cells would have been floating around on the ocean’s surface, and when there was a wave that crashed, tiny droplets would fly up into the air and take life with it. So the aerobiome is very old, but we humans have changed the planet in all sorts of ways, and one way is by changing the aerobiome itself.

For example, the kinds of microbes that live on huge industrial farms are different from what would have lived on the prairies that were there before. If you bring a bunch of pigs together on a gigantic farm, they will share viruses like foot-and-mouth disease, and those viruses will create airborne plumes that will travel for 40 miles or more. We have produced lots of antibiotic resistance here on ground level because we prescribe a lot to ourselves. 

We also feed farm animals huge amounts of antibiotics, so bacteria have evolved lots of resistance. Those bacteria then go up into the air. Those clouds will drift along, and they will rain down bacteria with those resistance genes. Trillions rain down every year. 

And we’re continuing to change the aerobiome with climate change. That changes the formula with the winners and losers in terms of who will get into the air and survive.

Big Think: I love your description of air “as a gaseous ocean in which we all live.” Did researching and writing the book change how you live within this ocean?

Zimmer: It has changed how I think about things. I take masks with me to be on the safe side. If I’m at a place where there are vulnerable people, I put on a mask in case I have something that I don’t know about. I don’t want to endanger them. So I am more mindful of how things in the air can make me sick.

At the same time, I have become keenly aware that I am probably breathing in thousands of living things with each breath. For the most part, I’m fine. It makes me more interested in research people are doing about the positive experiences we are having with the aerobiome. Maybe it’s good for us to have these living things floating around in our airways — sampling them, breathing them in and out. It may help to train our immune system. Some small studies on animals suggest they might even affect our mood. There’s a whole area of research about the aerobiome that has yet to be done.

This article Carl Zimmer explores the hidden world of the aerobiome is featured on Big Think.

“I want to change the way we think about the past altogether,” Dr. Betül Kaçar, an astrobiologist who studies the origin of life, told me. “We think of it as some failed state, as if it’s irrelevant. That’s just not true.”

At first, I wasn’t sure what she meant. We analyze history to learn from it — this is not a novel idea. But as we talked, I realized Kaçar wasn’t just arguing for the past’s importance. She was questioning how we frame it. Evolution is often seen as a binary: species either succeed and survive into the present, or they fail and vanish completely. Kaçar challenges that view. To her, the past isn’t just a record of failure and success, but a living force that still shapes how life works today and how we think about what comes next.

This line of thinking — the intersection of science and philosophy — has fueled Kaçar’s work for decades. At the University of Wisconsin, her lab studies the origins of life through enzyme evolution. These proteins, which catalyze biochemical processes, emerged and adapted over billions of years. By resurrecting ancient enzymes and tracing their evolution against environmental shifts, Kaçar and her team aren’t just looking back — they’re uncovering insights that could help us navigate an uncertain future.

Her groundbreaking research has earned her a distinguished reputation. But what struck me most about Kaçar wasn’t just the scale of her research or the boldness of her ideas — it was how she spoke about them. Many scientists focus on mechanisms: chemical reactions, evolutionary trees, molecular pathways. Kaçar does too. But she also elegantly talks about continuity, about life as an interconnected process shaped by time and adaptation. To her, ignoring the past is like ignoring the most impressive dataset in existence: organisms and molecules that have survived more than 3 billion years of change, a span no lab experiment could ever replicate.

It’s this mindset and perspective, combined with scientific rigor, that has led Kaçar to ask what she calls “big, bold, basic questions” — the ones that kept our ancestors staring at the stars, wondering how it all began and whether life exists elsewhere.  They’re also the types you need a new field for, so she made one. And some of the country’s most prestigious scientific institutions have noticed.

In January, Kaçar received a $1.3 million grant from the Keck Foundation, known for funding bold, high-risk, high-reward projects that transcend single disciplines. Her home institution, the University of Wisconsin–Madison, offered matching funds, giving her lab the freedom to pursue ideas that don’t fit neatly into existing research categories.

Big, bold, basic questions

Kaçar describes the Keck funding as a rare opportunity to “ask the big questions.” The project, “Past as Prelude: Preparing for an Uncertain Future Shaped by Nitrogen,” focuses on the evolution of nitrogenase — a crucial enzyme in bacteria that converts atmospheric nitrogen into a form that’s biologically available, sustaining life itself.

Kaçar, alongside colleagues from UW-Madison and a professor from Seoul National University, will use a variety of modern methods to reverse-engineer nitrogenase and map its evolution across key moments of environmental upheaval in Earth’s history. The goal is to understand whether and how the enzyme responded to these critical periods.

The implications are vast and interdisciplinary. This research could refine our understanding of the conditions necessary for life, while also addressing urgent challenges — such as how to sustain crop production in a rapidly changing climate.

Why nitrogen?

In biochemistry, carbon is the superstar — it literally puts the “organic” in “organic chemistry.” But when it comes to life, nitrogen is just as essential. It’s a key component of DNA, proteins, chlorophyll (key for photosynthesis), and countless other biological structures.

Yet for all its importance, nitrogen plays really hard to get. It makes up 78% of the atmosphere, but most living organisms can’t use it because it exists as inert nitrogen gas (N₂), held together by one of chemistry’s strongest glues: a triple bond. Breaking it requires immense energy — lightning can do it, but biologically, only one enzyme can: nitrogenase.

Nitrogenase is found in nitrogen-fixing bacteria, named for their ability to break nitrogen’s triple bond and convert N₂ into ammonia (NH₃), a form life can use. In other words, these bacteria “fix” nitrogen into a usable form. Without this process, life as we know it wouldn’t exist.

Kaçar and her team are particularly interested in nitrogenase because of its longevity and resilience. “At least seven or eight different enzymes can fix carbon from the atmosphere,” she explains. “For nitrogen, there’s only nitrogenase, and it evolved around 2.7 billion years ago. That kind of longevity suggests there’s something important about how life solved this problem early on.”

Creating Franken-zymes

For Kaçar and her colleagues, the singularity of nitrogenase raises a fundamental question: Has nitrogenase remained relatively stable because it was an optimal solution from the beginning, or has it subtly evolved in response to environmental pressures?

That’s the driving question behind her Keck Foundation grant, which funds her lab’s efforts to “reverse-engineer” nitrogenase. In simple terms, this means reconstructing ancient versions, and then testing how they functioned in different environmental conditions. By doing this, Kaçar and her team can determine whether and how nitrogenase evolved in response to changes on Earth.

To answer these questions, Kaçar and her team take a creative approach. Using bioinformatics, a field that applies computational tools to analyze genetic data, they compare the DNA and protein sequences of nitrogenase across different species. By tracing its evolutionary history through phylogenetics — which maps relationships between organisms like a family tree — they predict what nitrogenase looked like billions of years ago. Then, in the lab, they synthesize and test these ancient enzymes — essentially bringing molecular fossils back to life.

The next step? Using “molecular scissors,” as Kaçar calls the method, to place these reconstructed enzymes into modern bacteria. Then, they will take the modern bacteria and expose them to simulated ancient environments to see how the enzyme behaves

“Everyone always compares it to Jurassic Park,” Kaçar said with a slight laugh, perhaps fatigued by the very obvious but not entirely accurate analogy. “In a way, it’s like reconstructing a T. rex — except we don’t have a fossilized ‘bone’ to work with. All we have are the chemical imprints life left behind in the geologic record and clues hidden in modern enzymes — not just in their structure, but in how they’ve evolved and relate to one another. There are fingerprints there, and we’re playing Sherlock Holmes to piece them together.”

By placing these reconstructed enzymes within Earth’s geological timeline, Kaçar can test a key question: Did nitrogenase evolve in response to environmental changes, or has it always been a universal solution? The answer to that question will provide insights into nitrogenase itself, but it will also reveal deeper truths about resilience and evolution.

For example, one key event Kaçar is interested in is the Great Oxygenation Event, a period of time around 2.1 to 2.5 billion years ago when Earth’s atmospheric and oceanic oxygen levels increased dramatically. It was a time of massive environmental upheaval — many organisms died, ocean chemistry shifted dramatically, and life had to adapt to an entirely new atmosphere.

But nitrogenase made it through.

“We know nitrogen-fixing bacteria survived this event, but we don’t know whether nitrogenase changed along the way,” Kaçar says. “Did it subtly evolve to function in a different environment, or did life just work around it? That’s what we’re trying to find out.”

The origin of life

By studying how one of Earth’s most ancient and unchanging molecules has endured billions of years of planetary chaos, Kaçar’s work may reveal something deeper about life’s ability to persist — not just on Earth, but anywhere it might exist in the Universe.

This isn’t just theoretical. Beyond investigating the origin of life and how these insights could help us navigate an uncertain future, Kaçar is also working with NASA. 

“We look at two main questions,” she explained. “First, what conditions and chemistry are needed to sustain life? And if we find those conditions, should we expect life to respond the same way it did on Earth — or could it take entirely different paths? Another question is: If every necessary condition is met, does life always emerge, or is there something else we’re missing?”

Sometimes, the questions Kaçar is asking are so big, they’re hard to wrap my mind around. The origin of life, life beyond Earth — these ideas stretch our understanding of what’s possible and force us to literally think big. But her work also raises an equally urgent question:

What about life right now?

Unsurprisingly, Kaçar’s research is leading to major breakthroughs that don’t just help us understand the past or speculate about the future. They’re helping us innovate for the very near future.

One practical and immediate implication of her nitrogenase project is its potential to revolutionize sustainable agriculture — ensuring that crops can continue providing the yields we need while dramatically reducing their environmental impact.

In the natural world, plants get most of their nitrogen from bacteria that use nitrogenase — except for the occasional lightning strike that can fix nitrogen naturally. But this system isn’t enough to sustain the crops we need to feed a growing human population. Enter the Haber-Bosch process — a method that combines nitrogen gas (N₂) with hydrogen gas under extreme heat and pressure to create ammonia (NH₃), the foundation of synthetic fertilizers.

The world runs on synthetic nitrogen

Around 1913, the first industrial-scale applications of Haber Bosch began and dramatically increased crop yields. It’s largely responsible for intensifying crop yields to sustain a growing population. But it comes at a cost. The process is highly energy-intensive: It consumes nearly 2% of the world’s energy supply and contributes significantly to greenhouse gas emissions and water pollution. Scientists have long sought an alternative — one that mimics nature’s efficiency without the environmental downsides.

One promising approach? Harnessing bacteria that naturally fix nitrogen.

Some plants already form symbiotic relationships with nitrogen-fixing bacteria, which produce nitrogenase. Legumes, like pea plants, host these bacteria in their roots, and in exchange, the bacteria convert atmospheric nitrogen into a form the plants can use, freeing them from relying on nitrogen already present in the soil. But many other plants, including major crops like corn and rice, don’t form these relationships.

For years, researchers have explored ways to introduce nitrogen-fixing bacteria into crops to reduce reliance on synthetic fertilizers. This work is ongoing, but there is another problem: The environment is changing, and perhaps today’s nitrogenase isn’t the optimal solution for tomorrow’s world. Kaçar’s work may offer a new path forward.

“Ancient Earth is not that far from us,” Kaçar said. “In many ways, studying the past is also looking into Earth’s future.” 

She’s referring to the extreme heat, droughts, and heavy rains predicted with climate change — conditions that will challenge global agriculture in the decades to come.

“We are partnering with botanists and chemical engineers to see if we can recreate nitrogenases from ancient Earth environments and introduce them into nitrogen-fixing bacteria. The goal is to pair these microbes with crops so they can be more resilient to climate change while relying less on synthetic fertilizers.”

If successful, this research could offer a double benefit: a more sustainable way to fertilize crops while helping agriculture adapt to a rapidly changing climate. By looking billions of years into the past, Kaçar’s work could help solve one of the most pressing challenges of the future.

Curiosity over fear

Toward the end of our conversation, after I spoke with Dr. Kaçar about the origins of life, life on other planets, the catastrophic climate changes ahead, and even the scientific method, I admitted that these ideas — though ambitious and bold — felt overwhelming. For many people, myself included, even considering them was daunting. Thinking about our planet’s future as a coming catastrophe, a test of survival for all of us, was something I’d learned to push down over the years. Directly confronting it felt terrifying.

The moment I mentioned my fear, she cut me off, excited.

“I want to challenge that fear!” she said, practically giddy with enthusiasm.

I hadn’t heard anyone talk about the future with such excitement in a long time. She caught my attention.

“Humanity — and all living things — we always take leaps forward when we overcome fear. When we look at what’s coming and use our knowledge and curiosity to move through it. We have the tools now to study how organisms, over billions of years, found ways to persist. That’s what we should focus on.”

She paused, then continued, her words spilling out with conviction.

“There are questions we’ve asked for thousands of years, and our great-great-grandchildren will ask them too. Since humans gained consciousness, we’ve tried to understand our place in the Universe — and we always will. But nothing has been more powerful than the tool we created to seek truth: the scientific method. It allows us to systematically prove ourselves wrong, and in doing so, move forward. For the first time, we can tackle these questions in ways our ancestors never could. I want to tell young scientists — or anyone, really — that they shouldn’t be afraid to ask the big, bold questions. Technology will catch up to you.”

I sat there, uncharacteristically speechless, trying to absorb what she had just said. Then, in a very Betül Kaçar way, she turned to the past to make her point even clearer.

“It’s like what Marie Curie said: ‘Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.’”

This article The lab resurrecting ancient proteins to unlock life’s secrets is featured on Big Think.

Scientists stress out lab mice, a lot. Inducing chronic stress and anxiety in these furry critters is how scientists explore the bodily and cognitive effects of stress and discover anti-anxiety medications for humans.

There are two primary ways researchers stress out a lab mouse: immobilization and restraint. As described in the Encyclopedia of Stress (Second Edition), immobilization involves “taping the four limbs of a rat or mouse to mounts secured to a metal frame using hypoallergenic tape. A pair of metal loops attached to the frame limits the range of motion of the animal’s head…The duration of a single episode of immobilization usually varies from 5 to 120 min or more. In addition, animals in chronic stress protocols may be immobilized each day for many weeks even months.”

Psychologist Richard McCarty described the effects in the journal Psychoneuroendocrinology.

“The struggling that is typical of the first several minutes of an immobilization session places great pressure on the four limbs and animals are often physically exhausted at the end of an immobilization session.”

Other than immobilization, scientists might elect to stress out lab mice via restraint, in which critters are “secured in a plastic tube or a wire-mesh container that is small enough to prevent the animal from moving about or turning.” Mice are forced to endure this protocol for hours a day over weeks.

The bigger picture

Scientists are not bad people. For most, their overarching goal is to uncover new knowledge that betters the human condition and the broader world. But in that noble pursuit, they sometimes do things that fall into an ethical gray zone. Animal research is one of them. And 95% of all the animals involved are rats and mice.

Beyond psychological stress, scientists expose lab mice to starvation, pain, physical harm, and death. Blood is drawn in a variety of ways — sometimes deadly, sometimes not. Tails are snipped, holes are punched in ears, and toes are severed. Researchers and lab technicians carry out these activities all the time, for genotyping, identification, and data collection. This day-in and day-out doesn’t just take a toll on the animals, but also on their handlers.

Dr. Bernard E. Rollin, a professor of philosophy and animal sciences at Colorado State University, called attention to their mental health in a 2011 paper.

“Many research technicians… go into the field of animal research to help the animals, yet their day-to-day work ends up being the killing of animals or being complicit in creating pain, distress, disease, and other noxious states demanded by the research Enterprise.”

A good death?

Perhaps the most traumatizing part of the lives of lab mice, for both researcher and animal, is ending them. An estimated 192 million rodents, mostly mice, are studied and sacrificed each year in labs worldwide.

Lab mice meet their ends in a variety of ways, all of them regulated to be humane (though approved methods differ depending upon the country). Overdose of anesthetic, concussion by blunt force trauma, cervical dislocation, decapitation, exposure to carbon dioxide (CO2), and microwave irradiation are the most common. But if you’re of the opinion that “humane death” is an oxymoron, there’s a plethora of evidence to support you.

“The majority of rodents are conscious during handling and the application of killing methods and are therefore capable of experiencing negative states (e.g. pain and fear) until they lose consciousness,” a trio of UK-based animal researchers wrote in a thorough 2022 review of the practice of killing laboratory rodents.

They note that cervical dislocation, which involves “placing the finger or an instrument behind the base of the skull while pulling the tail firmly to achieve rapid separation of the high cervical vertebrae” is widely considered “to induce rapid unconsciousness due to concussion and damage to the brain.” But at the same time, there’s very little scientific evidence to actually support the view that the act produces a humane death — or even a reliable one.

“Work to date concurs that cervical dislocation is particularly susceptible to a high failure rate and that proper technique is crucial,” they wrote.

Then there’s decapitation, often carried out on conscious lab mice using small guillotines. Studies tracking the brain activity of mice indicate that the animals maintain consciousness for anywhere from three to 14 seconds after beheading, a disturbing notion.

Carbon dioxide exposure is by far the most commonly used technique to extinguish laboratory rodents.

“Some systems are fully automated and enable the animals to be killed in their home cage along with their cage mates, which offers several advantages over physical methods, such as its high-throughput and non-contact nature, elimination of stress associated with handling, isolation and restraint, as well as minimizing the impact of operator error,” the authors noted.

But this method has problems, too, which the reviewers say warrants discontinuing its use, unless lab researchers are “exploiting its high-throughput advantage”.

Chief among them, new evidence suggests that mice killed with carbon dioxide experience breathlessness — and worse — “air hunger,” the conscious appreciation of an urge to breathe, which humans find to be uniquely and primally uncomfortable.

Moreover, lab mice exposed to carbon dioxide have been observed running around, jumping, rearing, gasping, defecating, and urinating before death finally relieves them of their overt distress.

Mice lives matter

Is there anything that can be done to improve the welfare of lab mice? For starters, marking animals for identification doesn’t need to be a traumatic experience. Painless methods involving special dyes and markers are available. Second, antiquated methods of inducing stress, like the aforementioned immobilization technique, could be prohibited. Most importantly, lab mice can be granted quick, painless deaths. Current methods don’t do this reliably.

Novel techniques for sacrificing lab mice are rolling out now. Focused beam microwave irradiation is one of them. It involves rapidly heating the rodent brain with a high-energy beam. Mice reportedly lose consciousness in less than half a second. Unfortunately, the equipment for granting mice this swift end is costly, limiting wide adoption.

Hypobaric hypoxia, gradually decreasing the pressure in a chamber, causing death by lack of oxygen, is a cheaper alternative. In a study published last year, scientists compared it to carbon dioxide exposure. They found that while hypobaric hypoxia took longer to result in death — just over six minutes vs. under four minutes — the lab mice displayed fewer signs of pain and anxiety.

But while some researchers focus on bettering the lives of lab mice, others look to replace them entirely.

No more mice?

Professor Paul A. Locke is a Professor of Environmental Health and Engineering at Johns Hopkins Bloomberg School of Public Health, affiliated with the university’s Center for Alternatives to Animal Testing (CAAT). CAAT’s ultimate aim is to minimize the number of animals used in scientific research. Still, Locke thinks that animal models are useful and that the scientists who use them should not be vilified.

“We don’t always know as much as we would like to know about the underlying biology,” Locke told Big Think. “We’re shining a flashlight into a dark cave. While animal models don’t give us the information that we always need, unfortunately right now they’re one of the few tools we have.”

Scientists use lab mice to develop new human medicines, ensure that consumer products and environmental chemicals are safe, and uncover new biological knowledge that could lead to useful advances down the road. While those are all worthwhile aims, the general public isn’t convinced that animals should be used for them.

Polling firm Morning Consult surveyed 2,205 adults in September of this year. More than eight in ten respondents agreed with the statement: “Animal experimentation should be phased out in favor of more modern research methods.”

In step with public opinion, in 2022, President Biden signed a bill doing away with a longtime requirement that every new drug seeking FDA approval first be tested on animals. This year, the National Institutes of Health is launching a $300-million fund supporting the development, validation, and testing of alternatives to animal research.

And there are very promising alternatives. Models based on human cells and tissues grown outside the body attract a lot of attention. One researcher at Johns Hopkins University uses blood samples from Alzheimer’s patients to create stem cells. She then turns these into brain organoids, which eventually show signs of Alzheimer’s. Scientists can then test drug candidates on the organoids.

There are also microphysiological systems, so-called “organs-on-a-chip.” These contain engineered or natural miniature tissues grown inside microfluidic chips. Each emulates the physiology of a certain organ, like the liver or kidneys.

Computer simulations also show potential. In what’s been dubbed “in silico testing”, data scientists can task computers with analyzing the structures of drug candidates and predicting how they will affect living systems. Rapidly advancing artificial intelligence will surely speed up progress in this area.

We’re not there yet

To be clear, these novel approaches can’t replace lab mice yet. Locke noted that animal testing has been ended for a lot of consumer products, particularly cosmetics. Moreover, a Congressional rewrite of EPA’s Toxics law (TSCA) has put the agency on a path towards phasing out animal research for toxicology purposes in the next few decades. However, we’re nowhere near being able to remove lab mice from drug discovery and basic research.

That’s mostly because those two areas use the most lab mice, not necessarily because lab mice are better than animal-free alternatives. As Thomas Hartung, the Doerenkamp-Zbinden Chair Professor of Environmental Health and Engineering at Johns Hopkins and the Director at CAAT, noted in a review paper published earlier this year, animal studies are far from perfect, and often highly misleading. They frequently result in false negatives and false positives, and miss safety risks later discovered in human trials.

A host of factors limit the accuracy of animal studies, Hartung explained. These include biological differences, molecular differences altering drug effects, and the simple fact that what mice eat and how they live differ drastically from human lifestyles. Moreover, many mouse studies are small and short, and high dosing of tested substances can trigger irrelevant effects.

While animal research has in the past been considered essential to the drug discovery process, the reality is that roughly 90% of novel drugs that work in animal models fail in human clinical trials. That’s because rodents are not humans. Though mice and humans share 92% of their DNA and have identical genes, our bodies behave differently to the same substances. In one recent study, researchers compared the expression of individual genes within the same cell type in both mice and humans. They found that two-thirds of all genes shared between mice and humans are expressed differently.

The researchers working on alternatives are convinced that we can do better and that these alternatives will save time, money, and the lives of both humans and rodents. Emerging evidence is backing this rosy outlook, but Locke says that regulatory agencies at the federal level are currently not doing enough to accelerate change. The Food and Drug Administration has not yet accepted alternative data for drug discovery applications. And the National Institutes of Health needs to reform training grants so young scientists can be educated on animal alternatives.

“The federal government needs to take the lead here and they’re not exerting the leadership now that they should,” Locke said.

“Law and science are fellow travelers. You’re not going to have advances in science unless you have advances in law and policy. The scientists can’t do it alone. They need help. We have to put pressure on our federal agencies to be leaders in this area.”

This article Scientists kill 192 million lab mice each year. Is there a better way? is featured on Big Think.

Under the dry, piercing heat of the Utah sun, Sasha Reed is growing plots of plants — and bacteria, lichen and fungi, too. But Reed is no farmer, and at first glance, her fields look to be mostly dirt. She’s an ecologist, and what she is growing is cryptobiotic soil.

Also called biocrust, cryptobiotic soil is a community of tiny, dirt-dwelling organisms that form a distinct crust on the top of soil in arid landscapes. These crusts are vital across Earth’s dryland ecosystems, helping to hold loose soil together and prevent erosion. They retain water, provide nooks for other microbes to live in and add nitrogen to the soil.

Cryptobiotic soil often looks like a discolored patch of ground. Upon closer inspection, the stain becomes a mosaic of small, dark lumps, dotted with tiny beds of moss and inconspicuous patches of lichen. But it can also look very similar to regular, crusty soil. Although the crunchy earth might be tempting to trek over, like stomping through a pile of crisp autumn leaves, that’s a major faux pas: Biocrust can take decades to regenerate.

And these days, in addition to getting crushed by boots, biocrusts are threatened by another kind of human footprint: climate change. So researchers are diligently working to learn more about the crusts and how to restore them.

“It’s been a pretty busy but also exciting time, because we’re kind of inventing how to do this,” says Anita Antoninka, a plant and soil ecologist at Northern Arizona University in Flagstaff who studies the crusts.

The drylands where biocrusts reside are vital ecosystems, she says, but they are some of the most degraded around the globe. As biocrusts decline in these areas, soil fertility will drop and wind erosion will blow away the loose, unprotected dirt. Less water will soak into the ground. Even the carbon cycle could be affected, as there will be fewer tiny life forms absorbing carbon dioxide.

Itty-bitty communities

Biocrusts cover around 12 percent of Earth’s land surfaces and inhabit every continent in the world. A major component of these crusts is often photosynthesizing bacteria called cyanobacteria. The cyanobacteria form sticky filaments that act like glue in sandy desert soil, creating a clumpy, crusty surface where fungi and other bacteria take hold.

Depending on what environment a biocrust is in, it can also house itty-bitty mosses, lichens and microscopic algae. For example, in desert areas with more moisture, like Moab, Utah, biocrusts tend to feature mosses. In gypsum-rich soils, such as near Lake Mead, Nevada, lichens take center stage. Some crusts feature all components, and in other crusts, multiple components are missing. But regardless of their community lineup, the crusts all serve as a living skin for desert land.

“They provide this suit of armor to the soil,” says Ferran Garcia-Pichel, a microbiologist at Arizona State University in Tempe. When he first started working with biocrusts around two decades ago, very little was known about them. In the 2023 Annual Review of Microbiology, Garcia-Pichel outlines what researchers have learned about cryptobiotic soil over the last couple decades and what remains unknown.

“In these 25, 30 years, we’ve made so much progress,” he says.

One thing that several studies have shown is that increased warming and changes in rainfall pose a threat. Over the next 65 years, models suggest that climate change could slash 25 percent to 40 percent of biocrust cover. The crusts are sensitive to higher temperatures and to fluctuations in precipitation — both extended dry spells and unusual increases in rainfall can harm them, depending on their location.

Biocrusts are found worldwide, particularly in arid and semiarid regions. This map shows the current distribution of biocrusts, which cover a total of 12 percent of the globe’s land area. Localities where researchers have sampled biocrusts are marked with a black x. Many areas with the greatest cover of biocrusts, such as central Asia and the Sahel region of Africa, have yet to be extensively studied.

To combat those declines, ecologists like Reed, of the United States Geological Survey in Moab, and her colleagues are trying to figure out how to regrow crusts in the wild.

In what she calls possibly the largest outdoor biocrust nursery in the world, Reed is focusing on three main facets of biocrust restoration. The first ingredient is learning what environment the crusts will grow best in — and also, importantly, transfer well from. Initially, researchers had huge success growing communities of biocrusts in indoor greenhouses. But their life was too cushy, Reed says. When transplanted outside, the crusts struggled to take hold. Some of the crusts now grow directly outside: “We’re trying to give them a stricter upbringing,” she says. In the outdoors, they experience far more realistic environmental conditions, although they still get a leg up from the team through watering and shade.

A second arm of Reed’s work at the biocrust farm is seeing how much of an intact community biocrusts need to thrive. Biocrust is totipotent, which means just a small piece of it can eventually give rise to new crust. Thus, one way of growing biocrusts in new areas is to crumble some up and sprinkle it on the landscape, similar to scattering seeds.

But in the wild, crust components could work positively together in unknown ways, so Reed wonders if biocrusts might benefit from being grown as larger, more established communities. “We put them out in these harsh environments, kind of alone, and say, ‘Live, thrive,’” she says. “We’re not seeing them do that as much as we would hope.”

That led researchers to try a new restoration method inspired by sod. First, they sprinkled biocrust crumbles onto weed cloth — a thin fabric used by landscapers. After the crust grew, they rolled it up and unrolled it at its final destination. To Reed’s surprise, the strategy worked. Though she had feared the rolls of crust would crumble apart, they stayed intact and grew well in their new surroundings. The method could be used in small, strategic spots like next to trails, but probably not on a landscape-wide scale.

In the third facet of Reed’s restoration research at the biocrust farm, the scientists want to know if there are particular biocrust community members that are better suited for restoration in the face of climate change. To do that, Reed and Antoninka took biocrusts from hotter, drier locations — a stand-in for what the Southwest’s drylands could look like in the future — and grew them back on the farm. Now, they’re monitoring how the crusts continue to grow post-transplant in restoration sites. As the crust develops, researchers will look for species, or sources of biocrust communities, that seem to do particularly well.

Reed, Antoninka and others are now partnering with land managers — including national parks, the Bureau of Land Management and the US Forest Service — to apply what they’ve learned about biocrusts. “Partnerships are really, really important,” Antoninka says — the Moab nursery, for example, is a collaboration with Northern Arizona University, the Nature Conservancy and a local restoration nonprofit, Rim to Rim Restoration. And by working with land managers, Antoninka says, it’s possible to include biocrust restoration plans in future development projects that will disturb the soil.

People in arid regions can do the same in their own backyards. If property owners are planning a project that would tear up or build over soil that has a crust, they can simply salvage whatever crust is there then stick it in a bucket and keep it dry and cool, Antoninka says. Then they can sprinkle it back over the disturbed soil, or elsewhere on the property.

Other ways that the public can help to preserve biocrusts include staying on trails to avoid smashing them, and spreading the word about the crusts to raise awareness. If people don’t know biocrust is there, the tiny ecosystem beneath their feet is easy to overlook.

“Get down on hands and knees and just take a look,” Reed says. “We study them because of their importance, but their beauty and their coolness is also worth noting.”

This article The dirt on biocrusts: Why scientists are working to save Earth’s living skin is featured on Big Think.

Engineers assume that a mechanism designed by somebody for a purpose will betray that purpose by its nature. We can then “reverse engineer” it to discern the purpose that the designer had in mind.

Reverse engineering is the method by which scientific archaeologists reconstructed the purpose of the Antikythera mechanism, a mesh of cogwheels found in a sunken Greek ship dating from about 80 B.C. The intricate gearing was exposed by modern techniques such as X-ray tomography. Its original purpose has been reverse engineered as an ancient equivalent of an analogue computer, designed to simulate the movement of heavenly bodies according to the system of epicycles later associated with Ptolemy.

Reverse engineering assumes that the object facing us had a purpose in the mind of a competent designer, a purpose that can be guessed. The reverse engineer sets up a hypothesis as to what a sensible designer might have had in mind, then checks the mechanism to see if it fits the hypothesis. Reverse engineering works well for animal bodies as well as for man-made machines. The fact that the latter were deliberately designed by conscious engineers while the former were designed by unconscious natural selection makes surprisingly little difference: a potential for confusion readily exploited by creationists with their characteristically eager appetite for it. The grace of a tiger and of its prey could not easily, it would seem, be bettered:

What immortal hand or eye

Could frame thy fearful symmetry.

Darwin had a section of Origin of Species called “Organs of extreme perfection and complication.” It’s my belief that such organs are the end products of evolutionary arms races. The term “armament race” was introduced to the evolution literature by the zoologist Hugh Cott in his book on animal coloration published in 1940, during the Second World War. As a former officer in the regular army during the First World War, he was well placed to notice the analogy with evolutionary arms races. In 1979, John Krebs and I revived the idea of the evolutionary arms race in a presentation to the Royal Society. Whereas an individual predator and its prey run a race in real time, arm races are run in evolutionary time, between lineages of organisms. Each improvement on one side calls forth a counter-improvement on the other. And so the arms race escalates, until called to a halt, perhaps by overwhelming economic costs, just like military arms races.

Antelopes could always outrun lions, and vice versa, but only by counter-productive investment of too much “capital” in leg muscles at the expense of other calls on investment in, say, milk production. If the language of “investment” sounds too anthropomorphic, let me translate. Individuals who excel in running speed would be out-competed by slightly slower individuals who divert resources more usefully, from athletic legs into milk. Conversely, individuals who overdo milk production are out-competed by rivals who economize on milk production and put the energy saved into running speed. To quote the economists’ hackneyed saw, there’s no such thing as a free lunch. Trade-offs are ubiquitous in evolution.

I think arms races are responsible for every biological design impressive enough to, in the words of David Hume’s [fictionalized philosopher] Cleanthes, ravish “into admiration all men who have ever contemplated them.” Adaptations to ice ages or droughts, adaptations to climate change, are relatively simple, less prone to ravish into admiration because climate is not out to get you. Predators are. So are prey, in the indirect sense that, the more success prey achieve at evading capture, the closer their would-be predators come to starvation. Climate doesn’t menacingly change in response to biological evolution. Predators and prey do. So do parasites and hosts. It is the mutual escalation of arms races that drives evolution to Cleanthean heights, such as the feats of mimetic camouflage or the sinister wiles of Cuckoos. 

And now for a point that at first sight seems negative. Whereas animals look beautifully designed on the outside, as soon as we cut them open, we seem superficially to get a different impression. An untutored spectator of a mammal dissection might fancy it a mess. Intestines, blood vessels, mesenteries, nerves seem to spill out all over the place. An apparent contrast with the sinewy elegance of, say, a leopard or antelope when seen from outside. [But] the perfection typical of the outer layer must pervade every internal detail as well. Now compare your heart with the village pump, which seems neatly and simply fit for purpose. Admittedly, the heart is two pumps in one, serving the lungs on the one hand and the rest of the body on the other. But you could be forgiven for wondering whether a more minimally elegant pump might profitably have been designed.

The backwards wiring of the vertebrate retina is well compensated by post-hoc making good. You might think that “from such warped beginnings nothing debonair can come.” The great German scientist Hermann von Helmholtz is said to have remarked that if an engineer had produced the eye for him, he would have sent it back. Yet after tweaking, “in post” as movie-makers say, the vertebrate eye can become a fine piece of optical kit.

Why do animals look obviously well designed on the visible outside but apparently less so inside? Does the clue reside in that word visible? In the case of camouflage, and also ornamental extravaganzas like the peacock’s fan, (human) eyes are admiring the external appearance of the animal, and (peahen or predator) eyes are doing the natural selection of external appearance: similar vertebrate eyes in both cases. No wonder external appearance looks more perfectly “designed” than internal details. Internal details are every bit as subject to natural selection, but they don’t obviously look that way because it is not selection by eyes.

That explanation won’t do for the streamlined flair of a sprinting cheetah or its equally graceful Tommy prey. Those beauties did not evolve for the delectation of eyes but to satisfy the lifesaving requirements of speed. Here it would seem to be the laws of physics that impose what we perceive as elegance: as it is for the aerodynamic grace of a fast jet plane. Aesthetics and functionality converge on the same stylish elegance.

I confess that I find the interior of the body bewilderingly complex. I might even go so heretically far as to dismiss it as a mess. But I am a naive amateur where internal anatomy is concerned. A consultant surgeon whom I have consulted (what else should one do with a consultant?) assures me in no uncertain terms that, to his trained eye, internal anatomy has a beautiful elegance, everything neatly stowed away in its proper place, all shipshape and Bristol fashion. And I suspect that “trained eye” is exactly the point. My eye sees elegance on the outside. Then when I cut an animal open, my amateur eye contemplates only a mess. The trained surgeon sees stylish perfection of design, inside as well as out. Yet there is more to be said. Something about embryology.

The skeptic vocally doubts whether it can really matter whether this vein in the arm passes over or under that nerve. Maybe it doesn’t in the sense that, if their relationship could be reversed with a magic wand, the person’s life might not suffer, and might even improve. But I think it does matter in another sense. Every nerve, blood vessel, ligament, and bone got that way because of processes of embryology during the development of the individual. Exactly which passes over or under what may or may not make a difference to their efficient working, once their final routing is achieved. But the embryological upheaval necessary to effect a change, I conjecture, would raise problems, or costs, sufficient to outweigh other considerations. Especially if the embryological upheaval strikes early. The intricate origami of embryonic tissue-folding and invagination follows a strict sequence, each stage triggering its successor. Who can say what catastrophic downstream consequences might flow from a change in the sequence — the kind of change necessary to re-route a blood vessel, say.

Moreover, perhaps Darwinian forces have worked on human perception to sharpen our appreciation of external appearances as opposed to internal details. It is entirely unreasonable to suppose that the chisels of natural selection, so delicately adept at perfecting external and visible appearance, should suddenly stop at the animal’s skin rather than working their artistry inside. The same standards of perfection must pervade the interior of living bodies, even if less obviously to our eyes. To dissect the non-obvious and make it plain will be the business of future zoological reverse engineers, and it is to them that I appeal.

This article Richard Dawkins on reverse engineering evolution’s optimal beauty is featured on Big Think.

“Come!” “Sit.” “Speak.” “Down.” “Shake.” “Heel!” “Roll over!”

These words are well-known among dog owners. We teach them to our faithful companions so they will learn to understand rudimentary commands and do our bidding. It’s a task dogs are evolutionarily primed for. They keenly observe humans’ hand gestures, body movements, facial expressions, and especially our eyes to try to interpret what we want and how we feel.

The result of this culturally and biologically evolved status quo is that the human-dog relationship is often one-sided. Dogs focus on the wants and whims of humans far more than people consider the emotional needs of dogs. As a result, dogs are better at understanding humans than we are at understanding them.

In her recently published book, Dog Smart: Life-Changing Lessons in Canine Intelligence, science journalist Jennifer S. Holland aimed to help rectify that imbalance. She showcases numerous heartwarming stories of dogs’ devotion to humans and provides fascinating glimpses of — and insights into — their unique intelligence.

A doggy dog world

Pet dog ownership continues to rise in the United States. The American Veterinary Medical Association estimates that 44.6% of households have a dog, up from 38.4% in 2016. These dogs aren’t merely restricted to homes, of course. They share our streets, parks, outdoor festivals, breweries, restaurants, and airports, among many other places. Today, dogs go almost everywhere we do.

This constant contact leads to interspecific misunderstandings that can result in conflict. Altercations are rising in step with pet dog populations. According to the U.S. Centers for Disease Control, over 4.5 million people are bitten by dogs every year in the U.S. These unfortunate incidents send humans to the hospital about 800,000 times per year and contribute to the euthanizing of 390,000 dogs.

Aggressive, poorly-trained pooches are often at fault for bites, but in many cases, humans share the blame. Perhaps an owner brings their dog to a loud, crowded place. Feeling scared and cornered, the anxious animal lashes out at an unsuspecting stranger out of fear for its safety. Maybe an overexcited human hankering for a soft, furry pet rushes a dog and, reaching for its fluffy head, prompts the pup to nip at the outstretched fingers to prevent a perceived attack. These are just two examples where a misunderstanding, not innate aggression, triggers an altercation. To prevent situations like these, and to help humans and canines live more harmoniously together, Holland, along with a great many dog behaviorists, are imploring people to learn to speak basic “Doggish.”

“The better we are at reading … emotions, the more appropriate our responses can be. And that can mean avoiding a bad situation such as a bite, and it can help grow the trust our dogs have in us to be their advocates and protectors,” Holland tells Big Think in an interview.

A crash course in Doggish

Completely mastering Doggish isn’t necessary to mitigate most human-canine misunderstandings. A passing grasp of the canine “language” goes a long way.

“Probably most important is to learn how a dog says, ‘I’m stressed,’ in Doggish,” Holland notes. “You can see stress in their eyes, in their dipped, sometimes-rapidly wagging tails, in their general ‘get small’ body language, but there are other signs.”

While humans and other primates are generally touchy-feely species, dogs are not. A pup approaching to sniff you is rarely an invitation to pet its head or stroke its back. To say ‘hello’ to a cautious but curious pup, it’s best to stand up straight and slightly turn away with your hand down at your side. With this motion, you’re letting them know you’re not a threat or interested in confrontation. Never directly approach an unfamiliar dog and reach down to pet them. In Doggish, you’re essentially issuing a challenge.

Most humans also get petting wrong, massaging our dogs longer and more frequently than they prefer. Pups generally dislike having the top of their head, paws, and hind legs touched, sometimes interpreting pets to these regions as aggressive signals. Instead, research finds that they prefer pets under the chin or slight pats to the sides of the chest.

A major part of learning Doggish is reading a dog’s emotions.

“There are still people who think animals, including dogs, are just instinct machines that don’t experience the full complement of emotions we do,” Holland said. “I don’t agree with that, obviously. While some emotions might manifest differently in dogs than in us, there’s no reason to think they don’t exist. Dogs, and other mammals, have the same brain structures we have [and] that we know are tied to emotions. Scientists can even zoom in and see those emotions lighting up a dog’s brain.”

Dogs reveal their feelings through sounds, smells, and, most prominently, body postures.

“Control by voluntary muscles allows dogs to display a wide range of postures and body part positions that convey different information about the signaler’s inner state and intentions,” a team of animal scientists at the University of Bari in Italy wrote in a widely cited 2018 review on dog communication.

And the tail is a dog’s most visible tool. As the researchers explained:

“The tail is held high to communicate confidence, arousal, or the dog’s willingness to positively approach another individual, for example greeting and playing, while it is held stiff to express a threat or the individual’s anxiety. On the contrary, a tail held low or tucked between the limbs signals fear, anxiety, or appeasement as it contributes to decreasing the individual’s body size. Dogs wag their tails loosely from side to side to communicate friendliness or their excitability. Fast movements of the tail, instead, express different inner states according to its position; dogs communicate confidence if they hold their tail high, while a low wagging is generally associated with anxiousness, nervousness, or internal conflict.”

Meanwhile, dogs broadcast their intentions with their eyes. A hard stare is threatening and says, “Back off!” Avoiding eye contact signals appeasement and a desire to decrease tension. The mouth showcases valuable information, too. A relaxed visage, with the mouth slightly open, displays friendliness while drawing the lips forward to show the front teeth is a warning to steer clear.

Humans can also glean a lot of information from dogs’ ears. According to the researchers:

“Ears can vary from simply ‘back’, to communicate an appeasement intention, to ‘flattened’ or ‘pressed back’, in frightened individuals or as an agonistic response. In extremely fearful individuals, ears can be pressed back so far on the head that they completely disappear (‘seal ears’). On the contrary, ears kept forward are associated with interest, attention, and approach-oriented intentions, while sideward position indicates a conflicting inner state (‘airplane ears’).”

Dogs tend to outwardly display their emotions. They want us and their conspecifics to know what they’re thinking and feeling. 

“It’s important to look at the whole dog, the combination of behaviors and sounds and postures, when assessing what the animal is feeling,” Holland said.

Beyond learning the basics of dog “language,” she recommends that dog owners adjust their expectations of their furry, four-legged companions.

“They are not ‘little humans.’ They experience and navigate the world differently from us,” Holland tells Big Think. “When possible, let them choose — for example, which way to walk and what snack to eat — [or] let them play their way — rough in some cases! Give them a break from manners. A roll in the mud might require a bath later, but your dog will enjoy living in that messy moment so much. And what’s more wonderful than seeing dogs loving life, tongues lolling over big smiles, regardless of what comes next? Their joy is good for us, too.”

Do we really need to learn Doggish?

But is learning Doggish really necessary? Case in point, the internet is frequently amazed by dogs using “talking” buttons to communicate with their owners via audible language. Pups can apparently learn to press buttons with their paws to communicate their feelings and make various requests. Some can seemingly even string together basic sentences!

In reality, these machines, which anyone can purchase, likely rely on operant conditioning. A dog learns that by pressing a certain button, they can get a reward — perhaps a treat, pet, or walk. 

But what about instances where dogs use the buttons to form brief sentences?

“They’re likely just responding to their owner’s body language. And they probably wouldn’t be able to replicate the behavior if a new pet-sitter was making the command,” animal behaviorists Susan Hazel and Eduardo Fernandez explain at The Conversation.

So these buttons and other human language-focused methods of communication aren’t perfect.

“There’s nothing wrong with our pets learning our words and using them to get what they need — but I hope we won’t rely on them instead of being close observers who attend to our dogs’ “Doggish” requests effectively,” Holland tells Big Think. “I’m not aware of any great new technology coming down the pike that would replace this kind of natural communication. Of course, there may be technologies akin to MRI that are poised to open new windows onto dogs’ minds; that kind of advance can help us be better conversationalists with our pets, on their terms.”

This article More humans should learn to speak “Doggish” is featured on Big Think.

Have you ever wondered what makes you alive? What makes anything alive? 

At the 2012 meeting of the American Chemical Society, in a session on the origin of life, Andrew Ellington proposed a radical theory: “Life does not exist.” Andy is a chemistry professor from the University of Texas at Austin, and this was the first slide of his presentation on RNA chemistry and the origin of life. His idea left me incredibly perplexed.

I was perplexed because I probably should have agreed with Andy. But I don’t. When I attended Andy’s lecture I was pretty sure I was alive, as I am now. You’re probably confident you are alive too. Haven’t you spent your whole life, well, living? Being alive matters. It’s very different from not being alive.

Yet despite our natural confidence in our own existence, some scientists challenge it and argue that life may be just an illusion or epiphenomenon, explainable by known physics and chemistry.

Physicist and public intellectual Sean Carroll is one such individual. In a crowded evening lecture on the Arizona State University campus where I work, I was aghast in my seat as Sean stated how the equations of particle physics are sufficient to explain the existence of all matter—including you and me. Jack Szostak, a Nobel Prize winner, holds a similar view, arguing that the focus on defining life is holding us back from understanding life’s origin. According to Jack, the closer you look at any of the “defining” properties of life, the more the boundary between life and nonlife blurs.

As a child, I remember trying to take an insect apart and then failing to restore it to its original state. I was too surprised at the time to even feel upset. We are all familiar with how life cannot be reduced to its parts, be they elementary particles, atoms, or even molecules. Perhaps it is easiest to take the view, as Andy, Jack, and Sean do, that life is not a property of its parts, and that therefore we don’t need to worry about defining it. If true, it follows that all we need to understand what life does and how it emerges is to understand those parts.

In my training as a theoretical physicist, I was taught to believe that life was not a conceptually deep scientific problem. Instead, the most fundamental concepts regarding the nature of reality were what other physicists had studied—things like space, time, light, energy, and matter. Indeed, the successes of physics have been nothing short of profound: over the short span of the last four hundred years, we have gained a deep understanding of how our universe works. We have even defined what we mean by “universe.” At the very small scales, we understand much about the elementary constituents of all matter. At the very largest scales, we can take photos of distant galaxies whose light took more than 13.5 billion years to reach our telescopes.

Yet the origin of life remains one of the greatest puzzles in science. Physics, as we collectively understand it at this moment in history, provides a fundamental description of a universe devoid of life. It’s not the universe I live in, and I bet you don’t live there either.

But if life does exist, what is it?

What are we?

If Vitalism Is Dead, Maybe You Are Too

In stark contrast to the views of modern physicists and chemists, scientists used to believe life exists as a separate category from matter.

Animated matter was believed to be imbued with a “vital” force, sometimes referred to as the élan vital. Aristotle called it entelechy; Gottfried Wilhelm Leibniz called it monads. They were both describing, as many have, a unique quality found only in living entities that directs living behaviors, such as the development of an embryo, regeneration of a lost limb, or any of the other purposeful activities that seem uniquely characteristic of life. This concept of being alive is somewhat akin to the religious concept of a soul, and some have even called it that. Whatever you call it, we think these features are unique to life because we do not observe them in nonliving things. A rock does not restore its original shape when cut in two, but a planarian worm can and does. Vitalism, as the scientific movement came to be called, was driven by the idea that what makes matter come alive cannot be described mechanically and is therefore not material. 

While modern materialists like Andy, Sean, and Jack regard the known properties of matter as sufficient for explaining life, the vitalists had quite the opposite view. They believed that life does, in fact, exist, but it cannot be explained in terms of the properties of matter. Often, the idea of a vital principle was discussed in terms of a life energy or vital spark that could animate even dead matter. If this sounds a bit Frankensteinian, that’s because it is. Mary Shelley was just twenty-one when her famous novel Frankenstein was published in 1818. When she penned the book, she was reflecting on the leading science of her day, particularly theories on the soul, what makes us alive, and how we might reanimate the dead with electricity. Mary was influenced by the contemporary work of Luigi Galvani, work later carried on by his nephew Giovanni Aldini. These two attempted to animate body parts through electrostimulation; they would stimulate dead frogs’ legs with electric shocks to make them “dance.” Mary was also reportedly inspired by Erasmus Darwin, grandfather of the more famous Darwin, Charles. The elder Darwin wrote on the topic of spontaneous generation, citing how inanimate materials could spontaneously become animated in water warmed by sunlight.

In Mary’s novel, the body parts of the recently deceased could be reanimated by electrocution if they were properly wired together. This is how her lead character, Dr. Victor Frankenstein, made his “living” monster from dead bodies. If we were to try to write down laws of physics that could explain Dr. Frankenstein’s unique insight in animating the monster, we might conjecture he had discovered a life “force” that dissipated slowly after death, and that whatever substance this force was made of was strongly coupled to electromagnetism. It’s a bit of an odd set of properties Dr. Frankenstein discovered in his fictional universe, but matter in our real universe has many strange properties too. Our universe is weird when you start to understand it (in fact, it gets odder the more you think you understand it).

We might imagine a consistent physics that Dr. Frankenstein tapped into that explains life. It just so happens that whatever physics he was onto is not the physics that describes our real universe. The real physics underlying life might be even stranger still. While right now we do not understand what principles govern life, they may one day be as obvious to subsequent generations as the curvature of space-time or the existence of particles of light (photons) are to us now.

Many of the vitalists thought life could not be produced by things that were not already themselves alive. Living matter was special because its parts were special, carrying some of that requisite élan vital. Thus, living things were necessary to make more living things; even Dr. Frankenstein had to make his monster from once living parts that were only recently deceased.

Around the time of the publication of Frankenstein, the idea that life is necessary to produce the stuff of life was already beginning to lose popular support within the scientific community. In 1828, Friedrich Wöhler synthesized urea, an organic molecule found in urine, from two other simple molecules, cyanic acid and ammonium. Friedrich’s experiment showed that biologically derived molecules do not carry any sort of life force. The component parts of living matter are no different from those of nonliving matter. In experiments like these, scientists have repeatedly demonstrated that there is nothing that separates the properties of nonliving chemistry from living chemistry: the former can easily be transformed to the latter under appropriate conditions. The sharp boundary between nonlife and life started to blur as humanity began to understand more about chemistry and the physics underlying it. Sean, Jack, Andy, and many others who hold similar views are right . . . to a degree.

In fact, as much as we have looked, we have found the transformation from a nonliving to a living substance is not excluded by any known law of physics or chemistry. There is no life conservation law that says life cannot be created or destroyed. Of course, this is obvious, because we know organisms are born and die— but sometimes it is the most obvious observations that are the hardest to explain scientifically, and harder still to turn into mathematical law. 

What modern science has taught us is that life is not a property of matter. 

Physicists and chemists see very intimately what the rest of us who think life exists cannot: there is no magic transition point where a molecule or collection of molecules is suddenly “living.”

Life is the vaporware of chemistry: a property so obvious in our day-to-day experience—that we are living—is nonexistent when you look at our parts. 

If life is not a property of matter, and material things are what exist, then life does not exist. This is probably the logic Andy was going for. 

Yet here we are.

This article “Life does not exist”: The deceptively tricky task of defining life is featured on Big Think.

In early August 2023, a beekeeper near the port of Savannah, Georgia, noticed some odd activity around his hives. Something was hunting his honeybees. It was a flying insect bigger than a yellowjacket, mostly black with bright yellow legs. The creature would hover at the hive entrance, capture a honeybee in flight and butcher it before darting off with the bee’s thorax, the meatiest bit.

“He’d only been keeping bees since March … but he knew enough to know that something wasn’t right with this thing,” says Lewis Bartlett, an evolutionary ecologist and honeybee expert at the University of Georgia, who helped to investigate. Bartlett had seen these honeybee hunters before, during his PhD studies in England a decade earlier. The dreaded yellow-legged hornet had arrived in North America.

With origins in Afghanistan, eastern China and Indonesia, the yellow-legged hornet, Vespa velutina, has expanded during the last two decades into South Korea, Japan and Europe. When the hornet invades new territory, it preys on honeybees, bumblebees and other vulnerable insects. One yellow-legged hornet can kill up to dozens of honeybees in a single day. It can decimate colonies through intimidation by deterring honeybees from foraging. “They’re not to be messed with,” says honeybee researcher Gard Otis, professor emeritus at the University of Guelph in Canada.

The yellow-legged hornet is so destructive that it was the first insect to land on the European Union’s blacklist of invasive species. In Portugal, honey production in some regions of the country has slumped by more than 35 percent since the hornet’s arrival. French beekeepers have reported 30 percent to 80 percent of honeybee colonies exterminated in some locales, costing the French economy an estimated $33 million annually.

The yellow-legged hornet’s nests can be quite large and house as many as 6,000 workers. (Francis ITHURBURU / CC BY-SA 3.0)

All that destruction may be linked to a single, multi-mated queen that arrived at the port of Bordeaux, France, in a shipment of bonsai pots from China before 2004. During her first spring, she established a nest, reared workers and laid eggs. By fall, hundreds of new mated queens likely exited and found overwintering sites, restarting the cycle in the spring. The hornet’s fortitude — it is the Diana Nyad of invasive social wasps — allowed it to surge across France’s borders into Spain, Portugal, Italy, Belgium, Germany, the Netherlands, the United Kingdom and Switzerland in only two decades, hurtling onward by as much as 100 kilometers a year.

Suspected stowaway

As the hornet fanned out across Europe, scientists in North America wondered when it might arrive on their side of the Atlantic. Queens sometimes overwinter in crates and containers, allowing them to stow away on ships and be transported long distances. In 2013, researchers cautioned that a yellow-legged hornet invasion at any one point along the US East Coast would have the potential to spread across the country.

After the first sighting last summer, Georgia’s agricultural commissioner urged people to report hornets and nests, and warned that the yellow-legged hornet could threaten the state’s $73-billion agriculture industry. American farmers grow more than 100 different crops, including apples, blueberries and watermelons, that depend on pollinators. Georgia mass-produces honeybees and ships them north to jumpstart spring crops, like Maine blueberries, before local pollinators have awakened.

In response to the arrival of the yellow-legged hornet, the Georgia Department of Agriculture has placed hundreds of traps to monitor the insects’ spread near Savannah. This map shows the locations of those traps (gray dots), sightings of the hornet (pink dots) and five nests (red squares) as of December 15, 2023. (GEORGIA DEPARTMENT OF AGRICULTURE)

Less than two weeks after the first hornet was spotted, scientists found a nest in a tree, 25 meters off the ground. In a night operation, while the hornets idled, a tree surgeon climbed to the nest, sprayed it with insecticide, and cut it down. Just a quarter of the full nest was the size of a human torso, and the Georgia Department of Agriculture displayed a chunk, still wrapped around the branch, at a press conference — warning that this was larger than those seen in Europe.

“Savannah, Georgia, is primo climate for these guys,” says Otis. It’s a lush, subtropical paradise, giving the insect a long growing season — and a rich hunting ground.

For the next several months, Bartlett helped the state agricultural researchers set traps and follow individual hornets to find other nests. By the end of 2023, they’d removed four more. “We think we’ve discovered them at a very early stage, which is why pursuing eradication is very, very plausible,” Bartlett said in November. If not, Georgia and its neighbors could get caught in an endless — and costly — game of whack-a-mole.

Social wasps: Invasive global predators

The yellow-legged hornet and other social wasps, like the common yellowjacket, the German yellowjacket and the western yellowjacket, have successfully invaded every continent except Antarctica. They’ve been introduced to new areas by global trade, sometimes more than once over several decades.

The hornets live in colonies of individuals organized into groups that divvy up the labor of reproduction, foraging and caregiving. These behaviors, and the insects’ nearly omnivorous appetites, make them among the most successful invaders of new habitats and fiercest aggressors of native fauna. In their endemic ranges, these wasps are eaten by skunks, squirrels or bears, or snagged in flight by kingbirds and tanagers, or attacked by other predatory wasps. But in the absence of predators, their toll can be enormous.

In New Zealand’s Nelson Lakes National Park, the beech forests are thick with invasive yellowjackets by early autumn. They sip the sugary secretions of scale insects living on the trees, and will fight the bellbirds, tui, silvereyes and other birds for it, even slaughtering nest-bound chicks. The densities of the yellowjacket nests — up to 40 nests per hectare and 370 wasps per square-meter of tree trunk — are among the world’s highest.

“When you walk through the forest, you should smell the sweetness of the honeydew and hear the birds,” says invasive species biologist Phil Lester of Te Herenga Waka—Victoria University of Wellington, coauthor of a review of management strategies for invasive social wasps in the 2019 Annual Review of Entomology. “But with the wasp, you don’t hear the birdsong, you don’t smell the honeydew.”

In Hawaii, the western yellowjacket has had dramatic impacts on the island ecosystem. Genetic studies show that the original population came from the Pacific Northwest or Northern California, possibly in a shipment of Christmas trees. It hunts native bees and drains the nectar from the wispy red flowers of the ‘ōhi’a lehua tree, stealing food from other pollinators and curtailing seed production.

“They eat everything,” says ecologist Erin Wilson-Rankin of the University of California, Riverside, who has been studying invasive social wasps for nearly 20 years. “They don’t specialize. They’ll eat caterpillars, aphids, flies, the whole gamut of arthropods.”

Controversial tools

People have tried just about everything to get rid of wasps: fire, boiling water, electricity, traps, poison and brute force. While many poisons do work, they can also harm native insects and other animals. New Zealand has suppressed yellowjacket populations in highly trafficked areas with a selective poison bait called Vespex, but they reinvade elsewhere.

Nest destruction can kill hundreds of wasps at once, but it’s dangerous: Yellowjackets can squirt venom into an attacker’s eyes, and stings can be painful or life-threatening. Reiner Jahn, a hornet-buster and research assistant for a local landscape conservation association in Germany, describes the pain of a yellow-legged hornet sting as “digging a hot rusty knife into your flesh.”

Another approach to managing invasive species is biological control: A different species, often a natural enemy, is transplanted into the ecosystem to take on the role of contract killer. It can do the trick, but the long history of this strategy going awry (think harlequin ladybirds, cannibal snails, small Asian mongoose, cane toads) gives pause.

Cajoling foreign predators to take root in new places is another bother. In New Zealand, for example, the government recently approved the release of a non-native hoverfly and beetle to target invasive wasps. In Europe, both species hitch a ride into the hornet nests, feasting on the juvenile hornet grubs and decimating the next generation. But the imported insect predators had to have their seasonal cycles flipped before they could be released in the Southern Hemisphere. After some setbacks, scientists released about 20 hoverflies into the wild on the northern end of the South Island in mid-May.

Lester has other ideas: Silencing some of the wasps’ essential genes could reverse their spread. A handful of genetic control technologies are being tested globally to target invasive or harmful insects. For example, the biotechnology company Oxitec aims to combat the spread of dengue and other mosquito-borne diseases by releasing gene-edited male mosquitoes that produce female offspring that die young. (It’s the females that bite and spread disease.) Other researchers are using CRISPR gene editing on a range of agricultural pests to reduce pesticide use and save crops.

In 2020, an international group of researchers, including Lester and Wilson-Rankin, sequenced the genomes of three invasive social wasps: the common yellowjacket, the German yellowjacket and the western yellowjacket. Lester then zeroed in on a gene called ocnus that’s involved in sperm development, with the goal of making sterile males.

Like many insect pests, common yellowjackets are haplodiploid, which means that fertilized eggs become female wasps (with two copies of each chromosome) and unfertilized eggs produce males (with only one copy of each chromosome). If a queen mates with a sterile male, the eggs laid would produce only male wasps. Without female worker wasps, the nest would fail. But Lester’s modeling has shown that it would take decades for the mutation to spread across the South Island wasp population. So he continues to look for new genetic targets that might snuff out New Zealand’s invasive wasps more quickly.

Many people are unsettled by the idea of releasing genetically modified organisms into the wild, even if it’s to save native species, but the approach carries advantages. The impact would be precise; it wouldn’t poison other animals or insects. It would disperse over large distances and into remote areas. It would also be self-perpetuating, so people wouldn’t have to climb long ladders in protective suits to cut down enormous nests full of angry wasps.

Nest busting

On a hot afternoon in mid-September, Jahn, the German hornet-buster, pulls up to the Metropolitan International School in Viernheim, an industrial town east of the Rhine River. Kids run and jump in the playground, until a teacher ushers them away. High in a tree overhanging the soccer field is a caramel-colored, beach-ball-sized yellow-legged hornet’s nest.

“The kids can’t play soccer. I had to close the field because it is too dangerous,” says Oliver Wagner, the school’s facility manager.

A whiff of revenge hangs in the air as Jahn and his crew set up. Each is a beekeeper who has lost colonies to yellow-legged hornets, or knows someone who has. Jahn extends a telescopic pole fitted with a spray nozzle into the branches. He jabs the nest and blows in a fine powder called diatomaceous earth as chunks of the nest tumble to the ground. Hornets stream out like the air escaping from a punctured balloon.

Dusted with the white powder and unable to fly, the inch-long yellow-legged hornets wander through the grass and across the tarp. The crew picks through the nest debris and they tweeze the larger hornets into specimen bottles. When a nest is attacked — whether by a predator or a human — the queen may try to escape, Jahn explains. Find her, and the work is done. This time, she’s unaccounted for.

The trick to stopping a yellow-legged hornet invasion is to find the nests and destroy them before hundreds of new queens fly out in the fall to establish their own nests. EU member states must, by law, control the hornet’s spread, but Germany has strict rules that protect pollinator and native insects and limit what beekeepers and hornet-busters can do. Diatomaceous earth, often used in homes to kill cockroaches and centipedes, has become Jahn’s go-to solution. It sticks to the hornet’s exoskeletons and dries them out but doesn’t spread to other insects.

In all of 2023, Jahn destroyed 160 yellow-legged hornet’s nests in his home state of Hesse and 80 in a neighboring state, most brought to his attention by beekeepers. After a few years of nest-busting, he’s given up beekeeping (there’s no more time) and he no longer believes that the yellow-legged hornet can be eradicated in Germany — the country may have waited too long to start removing nests. Still, he says, “it’s easier to do something now than wait until next year.” But by mid-May this year, he’d already fielded calls for 19 new nests, compared with only two by late May last year.

Back in Georgia, Bartlett has tracked down the source of the captured yellow-legged hornets. His genetic analysis shows that a single queen arrived from southern China, the Korean peninsula or Japan in late 2022. He believes the hornets captured last year were the first American-born generation founded by the stowaway queen. Now, the second-generation has emerged. “We have been finding queens a little further out than we had hoped. But nothing near the distances they see in Europe,” says Bartlett. As of the end of April, the state had trapped and destroyed 21 queens.

Bartlett sees the work as his duty to protect the beekeeping industry, but his hope is that the hornet won’t define his scientific career. Still, he knows he can’t relent. “If we don’t get rid of them, there is very little chance that I’m not going to become the yellow-legged hornet expert in the US.”

This article The hornet has landed: Scientists combat new honeybee killer in US is featured on Big Think.

A hammerhead shark less than one meter long swims frantically in a plastic container aboard a boat in the Sanquianga National Natural Park, off Colombia’s Pacific coast. It is a delicate female Sphyrna corona, the world’s smallest hammerhead species, and goes by the local name cornuda amarilla — yellow hammerhead — because of the color of its fins and the edges of its splendid curved head, which is full of sensors to perceive the movement of its prey.

Marine biologist Diego Cardeñosa of Florida International University, along with local fishermen, has just captured the shark and implanted it with an acoustic marker before quickly returning it to the murky waters. A series of receivers will help to track its movements for a year, to map the coordinates of its habitat — valuable information for its protection.

That hammerhead is far from the only shark species that keeps the Colombian biologist busy. Cardeñosa’s mission is to build scientific knowledge to support shark conservation, either by locating the areas where the creatures live or by identifying, with genetic tests, the species that are traded in the world’s main shark markets.

Sharks are under threat for several reasons. The demand for their fins to supply the mainly Asian market (see box) is a very lucrative business: Between 2012 and 2019, it generated $1.5 billion. This, plus their inclusion in bycatch — fish caught unintentionally in the fishing industry — as well as the growing market for shark meat, leads to the death of millions every year. In 2019 alone the estimated total killed was at least 80 million sharks, 25 million of which were endangered species. In fact, in the Hong Kong market alone, a major trading spot for shark fins, two-thirds of the shark species sold there are at risk of extinction, according to a 2022 study led by Cardeñosa and molecular ecologist Demian Chapman, director of the shark and ray conservation program at Mote Marine Laboratory in Sarasota, Florida.

Sharks continue to face a complicated future despite decades of legislation designed to protect them. In 2000, the US Congress passed the Shark Finning Prohibition Act, and in 2011 the Shark Conservation Act. These laws require that sharks brought ashore by fishermen have all their fins naturally attached and aim to end the practice of stripping the creatures of their fins and returning them, mutilated, to the water to die on the seafloor. Ninety-four other countries have implemented similar regulations.

Perhaps the main political and diplomatic tool for shark conservation is in the hands of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), composed of 183 member countries plus the European Union. The treaty offers three degrees of protection, or appendices, to more than 40,000 species of animals and plants, imposing prohibitions and restrictions on their trade according to their threat status.

Sharks were included in CITES Appendix II — which includes species that are not endangered but could become so if trade is not controlled — in February 2003, with the addition of two species: the basking shark (Cetorhinus maximus) and the whale shark (Rhincodon typus). Following that, the list of protected species grew to 12 and then increased significantly in November 2023 with the inclusion of 60 more species of sharks in CITES Appendix II.

But do these tools actually protect sharks? To seek out answers, over the past decade researchers have worked to develop tests that can easily identify which species of sharks are being traded — and determine whether protected species continue to be exploited. They have also focused on studying shark populations around the world in order to provide information for the establishment of protected areas that can help safeguard these animals.

Which shark does that fin belong to?

The port of Hong Kong, along with the Chinese city of Guangzhou, is one of the world’s major centers for the trade in shark fins, considered by many Chinese communities to be a delicacy, often served in soup. Hong Kong serves as a legal importer, re-exporter and consumer of these cartilages, both fresh and packaged in bags of trimmings. A decade ago, Cardeñosa, Chapman and other members of their team began an investigation there, with the goal of answering a question: Are protected shark species being exploited?

Many fins look the same, making it difficult to know whether they belong to CITES Appendix II-listed sharks. But the scientists were confident that, with the use of genetic analysis tools, their question could be answered.

Bags of dried shark fins. (Wikimedia Commons)

After scouring a market that stretches for several blocks of storefronts cluttered with bags and jars of yellowed shark fin clippings, Cardeñosa returned to his lab in Florida with several randomly chosen bundles. The challenge, then, was to develop the analysis for molecular identification in the dead material. “The problem is that processed fins have degraded DNA, preventing their identification with established protocols,” Cardeñosa explains. “Genetic approaches to identify shark products exist, but they typically rely on sequencing large regions of DNA, which can fail when working with highly processed products.”

So Cardeñosa, Chapman and other colleagues developed a new test, using a technique known as DNA barcoding, that reads short pieces of DNA sequences to detect what species of shark is in a sample. It works not only on fin pieces but also on cooked shark fin soup and cosmetic products made of shark liver oil.

DNA barcoding technology uses small segments of the cytochrome c oxidase I gene, COI, as molecular tags. Each animal species has its own label or barcode of those DNA segments, and forensic geneticists compare the DNA sequences of the sample with a database of genomic sequences from living animals.

The method designed by Cardeñosa and colleagues is more effective than the original barcoding technology because, instead of having to use all 650 DNA base pairs of the COI  gene to serve as a species barcode, the test can identify a species with just 150 base pairs — in effect, a mini-barcode. The test also simultaneously analyzes several mini-barcodes or the COI  gene for each species, instead of just one. This makes it easier to identify the species in highly processed products, even in a bowl of soup.

During four years of using that protocol on 9,200 fin clippings purchased in Hong Kong, Cardeñosa and colleagues showed that the species most traded for their fins included sharks listed on CITES Appendix II — specifically, several species of the family Sphyrnidae, which includes hammerhead sharks, as well as the blue shark (Prionace glauca).

To make it simpler to identify shark species being traded, Cardeñosa and Chapman decided to bring the lab to port. In 2018, they published in Nature  the design of a portable lab for rapid, on-site DNA analysis: In a single reaction that takes less than four hours, it can detect nine of the 12 shark species that were listed on CITES Appendix II at that time. “It’s a PCR or polymerase chain reaction test, just like a Covid test,” Chapman explains, but instead of detecting fragments of viral genetic material, it detects fragments of the COI  gene, which are different in DNA sequence for each of the nine shark species. It is easy to use, and therefore suitable for port officials, and costs 94 cents per sample, making it affordable even for low-income countries.

Now that there are more than 70 species of sharks under CITES protection, more powerful tools will be needed to identify protected species among the materials being traded. Chapman is working with the company Ecologenix, which has developed a modification to the PCR test that allows it to identify many species at once.

Ecologenix’s development is based on a technology called FastFish-ID, which was created to identify bony fish. A small-scale study in Indonesia showed that the technology can be adapted for use in cartilaginous fish like sharks. The identification technique also makes use of the COI  gene but incorporates fluorescent dyes and machine learning into the PCR procedure to help recognize species. Although it is more expensive — at $10 per test — it is more powerful because it can identify many more species at once.

Protecting sharks’ homes

Genetic analysis not only allows scientists to know what type of shark the fin or meat being traded belongs to, it can also tell them where the animal comes from geographically. Hammerheads are especially suited to these studies, not only because the DNA database that exists on them is so extensive, but also because they tend to return to breed in the place where they were born.

In 2009, Mahmood Shivji, director of the Save Our Seas Foundation at Nova Southeastern University in Fort Lauderdale, Florida, co-led with Chapman a study that demonstrated that the use of a forensic method called genetic stock identification, or GSI, could be used to determine the provenance of fins traded in the Hong Kong market.

The researchers used GSI to examine the DNA in fins from 62 hammerhead sharks (Sphyrna lewini) obtained from the market. GSI looks at DNA contained in the mitochondria, an organelle of the cell that is transmitted by the mother and is therefore traceable to the creature’s regional birthplace. The study found that the sharks came from the Indo-Pacific, Eastern Atlantic and Western Atlantic basins, and that fully 21 percent of them came from the Western Atlantic where they are listed as a species at risk of extinction. In other words, the international trade in shark fins continues to threaten endangered populations in this region.

A subsequent study in 2020 by Chapman and colleagues revealed that 75 percent of hammerhead shark fin clippings found in Hong Kong markets came from two populations originating in the Pacific Ocean, but mostly from the Eastern Pacific — 61.4 percent of all clippings — where this species is listed as endangered under the US Endangered Species Act.

Identifying which shark species are being traded and tracking their geographic origin is only part of the conservation effort. Knowing the movements and population structure of different shark species is also important in determining which marine areas should be under protection.

“Sharks are quite large, by marine fish standards, and have the ability to make long-range movements. The perception that they tend to be highly mobile has led many nations to wait for international management policies,” Chapman and coauthors wrote in an article in the Annual Review of Marine Science. But in fact, some populations of sharks would benefit from protective legislation at smaller scales, the authors say.

After analyzing the results of over 80 studies on shark tracking and population genetics, the scientists identified at least 31 shark species that show coastal behaviors, either by exhibiting residency (remaining in a defined geographic area for an extended period), fidelity (returning after long absences) or philopatry (returning to their birthplaces to reproduce). These shark populations would probably respond well to effectively designed protected areas and protective legislation at the national level, the authors conclude.

Monitoring such coastal sharks, including those living among coral reefs, is therefore key, Cardeñosa says — hence the importance of the Global FinPrint project, of which Chapman is scientific director. It is the largest global survey of sharks that inhabit the coral reefs, achieved by attaching cameras to underwater structures and deploying bait to attract sharks. The first phase of the project, which ended in 2018, was conducted in 58 countries and more than 400 reefs, comparing protected and unprotected marine areas.

During that first phase of Global FinPrint, Cardeñosa was in charge of monitoring the UNESCO Seaflower Biosphere Reserve, a huge oceanic archipelago in the Colombian Caribbean. The results were unexpected. Even though the corals in large parts of Seaflower are not doing well, the project found a high abundance of sharks of all sizes and at least seven species. Cardeñosa suggests that this could be because the sharks are feeding in an area of the reef that still has abundant food because it is difficult for fishing boats to access it. Another reason, he says, is that local communities are complying with protection regulations.

The second phase of Global FinPrint began in December 2023, with plans to return to 26 countries to assess the status of sharks within marine protected areas: regions within the ocean where government agencies have imposed limits on human activity. The data should assist nations in determining which areas nurture healthy populations of reef sharks, and in designing new protected areas that do so.

Chapman and Cardeñosa both say they are moderately optimistic about the future of sharks on a global scale, as long as science, public opinion and legislation — and that legislation’s enforcement — work together.

“There are definitely serious problems,” Chapman says. “But the good news is that we’re starting to get things right. In the United States, we’ve seen a recovery in sharks” — he points, for example, to increased shark sightings in Florida after new legislation. “We simply stopped killing too many and allowed them to reproduce,” he says. “My career goal is to help as many countries as I can to do similar things to improve the situation. That’s a long way of saying I’m hopeful.”

Cardeñosa hopes that his research will help ensure that laws and agreements on shark protection are actually enforced. “The idea is that with our research, CITES can start to tighten the screws on countries and say, ‘Are you saying this is sustainable? Show us where you got it from,’” he says.

Conserving sharks is not just a nice-to-have, Cardeñosa adds. These fish are primordial beings that have been navigating through underwater landscapes for 400 million years, guided by senses we are only beginning to understand. Sharks help maintain the carbon cycle in the water by feeding on dead organisms, and may indirectly contribute to the ongoing balance of photosynthesis in plant life by controlling species that feed on seagrasses. Keeping them in our oceans, Cardeñosa says, is critical.

This article A scientific mission to save the sharks is featured on Big Think.

Antechinus, a mouse-like marsupial found in Australia, is a rarity among mammals. At the end of each mating season, the males all die at once. This fate means they only get to breed once in their lifetimes, while the females may survive a couple of additional mating seasons. Naturally, the males make the most of their mortal Mardi Gras.

In a paper published in Current Biology, researchers found that male antechinuses will sacrifice sleep to out-mate each other. On average, they stayed awake an extra three hours a day compared to their pre-breeding habits. One frisky fellow cut his sleep schedule in half to keep the party going.

It’s not the weeks of sleep deprivation that kill either. In the study, two of the ten males who died synchronously didn’t lose the most sleep, and in captivity, some males survived longer but became sterile. What causes them to die remains a mystery — though the researchers suggest it could be an environmental trigger.

But while male antechinuses trade sleep in a reproductive gamble, it doesn’t seem to impact their performance. In fact, antechinuses aren’t the only animals that manage some extreme feats despite a lack of sleep.

Sleep deprivation across the animal kingdom

African elephant matriarchs have been observed sleeping as little as two hours a day — some even going sleepless for as long as 46 hours a stretch. That is because elephants need to graze often, while the matriarchs keep a watchful eye for predators. On the other hand, captive elephants are known to enjoy six hours of restful Z’s a day from the safety of their enclosures.

As steep as elephant sleep deprivation can be, they have nothing on dolphins. Mother dolphins and their newborn calves won’t sleep for a month after the birth. Once again, this serves as a defense mechanism against predators, but the constant movement has a beneficial side effect, as well. It helps the calves maintain their body temperature until they can build up the layer of fatty blubber that will insulate their adult bodies.

But it is certain bird species that have arguably the most extreme of sleep variability. For instance, frigatebirds soar over oceans for weeks on end. While airborne, they will slumber less than an hour a night to maintain the vigilance necessary to ride updrafts and spot prey on the ocean surface. When back on land, they pay off their sleep debt by snoozing for up to 12 hours at a time.

What’s the secret to their sleepy success?

There are several explanations for how animals manage to, well, manage without sleep. They may be paying a physiological cost that biologists have yet to identify, or they may sleep more than scientists think. Chinstrap penguins, for instance, sleep for 11 hours, but it’s difficult to notice because they spread their rest across four-second micro-naps. That’s 10,000 sneaky siestas a day!

More recently, adaptive plasticity has emerged as an explanation for how animals can function at lower-than-usual amounts of sleep. An animal can change its traits in response to changes in its environment. Hibernation is one example of such adaptive plasticity.

Hormones could also enable high activity with little or no sleep. Among antechinuses, males sport high blood steroid levels during the breeding season. This has been suggested as a possible cause of their deaths, but it could also be adaptive plasticity at work. High blood steroid levels could unlock the virile energy that the antechinus males need to go about their sex frenzy.

Do people really need all 40 winks?

From less than an hour a night for frigatebirds to 20 hours per day for koalas, animals display a wide range of sleep diversity. The differences in the amount stem from the differences in their ecological niches. Now, there is growing evidence that individuals of the same species can survive on a wide range of sleep.

Generally, health professionals recommend that adult humans sleep a minimum of seven hours a night and limit interruptions. But could both the duration and timing be flexible? Elephant sleep ranges from two interrupted hours of standing sleep in the wild to six hours lying down in a zoo. And even though sleep is considered vital for creating memories, elephants have the most remarkable memories.

Many night owls — the people, not the birds — report heightened focus around midnight and, if they get sufficient sleep, no drowsiness during their waking hours.  If humans can also thrive on varied amounts of sleep, could the ill effects of not sleeping a fixed number of hours or staying awake at night be down to other factors? For instance, multiple studies attribute low sleep and midnight wakefulness to mental and metabolic diseases (though few of these have established any causal links).

The examples from the wild ask for a rethink of the links between sleep and human health and longevity. In animal studies, researchers hope to find clues about the physiological adaptations that animals make to compensate for loss of sleep.

This article How sleep deprivation helps some animals outperform the competition is featured on Big Think.

In Aug. 19, 2021, a humpback whale named Twain whupped back. Specifically, Twain made a series of humpback whale calls known as “whups” in response to playback recordings of whups from a boat of researchers off the coast of Alaska. The whale and the playback exchanged calls 36 times.

On the boat was naturalist Fred Sharpe of the Alaska Whale Foundation, who has been studying humpbacks for over two decades, and animal behavior researcher Brenda McCowan, a professor at the University of California, Davis. The exchange was groundbreaking, Sharpe says, because it brought two linguistic beings—humans and humpback whales—together. “You start getting the sense that there’s this mutual sense of being heard.”

In their 2023 published results, McGowan, Sharpe, and their coauthors are careful not to characterize their exchange with Twain as a conversation. They write, “Twain was actively engaged in a type of vocal coordination” with the playback recordings. To the paper’s authors, the interspecies exchange could be a model for perhaps something even more remarkable: an exchange with an extraterrestrial intelligence.

Sharpe and McGowan are members of Whale SETI, a team of scientists at the SETI Institute, which has been scanning the skies for decades, listening for signals that may be indicative of extraterrestrial life. The Whale SETI team seeks to show that animal communication, and particularly, complex animal vocalizations like those of humpback whales, can provide scientists with a model to help detect and decipher a message from an extraterrestrial intelligence. And, while they’ve been trying to communicate with whales for years, this latest reported encounter was the first time the whales talked back.

It all might sound far-fetched. But then again, Laurance Doyle, an astrophysicist who founded the Whale SETI team and has been part of the SETI Institute since 1987, is accustomed to being doubted by the mainstream science community.

For years, Doyle sought out other worlds beyond our solar system. When he and others started looking for these worlds, they were rejected by the prevailing astronomy community. Now, we know there are thousands of exoplanets, some of which appear to be in the habitable zone around their stars—not too hot, not too cold, and a bit wet; they could harbor life, some perhaps even life complex enough to communicate across the cosmos.

Doyle and his peers use radio observatories to try to detect narrowband radio signals from outer space. SETI was founded on the idea that if extraterrestrial intelligences reached out to worlds beyond them, they would do so through radio signals, which travel at the speed of light and slice through space “noise” unimpeded. As SETI points out, the universe is full of “cosmic noisemakers,” including pulsars, quasars, and the interstellar gas of our own Milky Way. SETI focuses on narrowband radio signals because they can be distinguished from the cosmic noise, and, importantly, can only be produced by transmitters, meaning some intelligence must have designed them, and they must contain some form of information. Their nickname is “technosignatures.”

How much information does a humpback call carry at any one time?

Of course, after more than 50 years of radio astronomy, we haven’t detected a single technosignature. Even if we did, how might we interpret it? Are scientists even prepared for that question?

Doyle recounted a talk he gave to other SETI scientists. He had only five minutes and decided to spend one of them playing a humpback whale song. “I played a humpback whale song that lasted for maybe a minute. And then I said, ‘What if that had come from space? Is that intelligent?’ And everybody got it almost right away. They’re like, ‘Wow, we are not prepared, are we?’”

A big part of the problem is that scientists don’t have a way to tell whether an alien signal contains complex information or is even designed to be understood. They need to know both these things before they get anywhere near the hard work of assigning meaning to the information. The only way to start working on that problem, Doyle says, is to start practicing. And the only things to practice with are non-human species on Earth.

Doyle started this work back in 1999, when he proposed studying the clicks and whistles of bottlenose dolphins to try and find markers of complexity and intelligence in their linguistic repertoire. The idea, based on an earlier concept supported by Carl Sagan, was that studying—and ultimately, talking to—dolphins could help inform the search for signals coming from an extraterrestrial intelligence. In 2016, Nautilus spoke with Doyle about how dolphin communication revealed linguistic hallmarks that could, in turn, help separate a signal from the noise of the cosmos.

Since then, Doyle has turned his attention to humpback whales, which have even more complex communication. These creatures are the ideal practice partners, he says. They are highly intelligent, their calls are often extremely long, repetitive, and broadcast across vast swathes of ocean—and those calls contain complex information. 

Like humans yelling at one another over a distance, some of what one whale is saying to another will be lost to the environment because of how far it must travel and the interference it meets along the way. Yet the whales still get the gist of what’s being said. That means some parts of the signal may carry more information than others, or perhaps some parts of the signal carry key pieces of information that let the whales fill in the blanks. The better scientists understand the nature of whale signals, the better they may be ready to understand the nature of alien ones.

Much of Doyle’s theories rest on information theory and, particularly, Zipf’s law, a principle in quantitative linguistics used to plot the frequency of a word or letter in a language against its frequency in any given text. For most human languages, word frequencies tend to follow a pattern of word distribution, where the most common word in the language is twice as frequent as the next most common. It’s not entirely clear why most languages appear to follow Zipf’s law.

One idea proposed by American linguist George Kingsley Zipf himself—and Doyle agrees—is that language is designed to be used and understood with minimal effort on both the speaker and listener’s part. For example, if a friend calls to you from far away and all you hear is “going … beach … Wednesday,” you can infer that someone is going to the beach on Wednesday. Zipf’s law is an expression of this.

Plotting linguistic data according to Zipf’s law can, in turn, reveal a language’s rules and syntax. If animal communication—or an extraterrestrial signal—follows Zipf’s law, scientists can assume it is a language, and then make inferences about the information carried within the signal. “We discovered syntax in humpback whales, so they have structure in their communication system,” Doyle says.

“Looking at the way other organisms communicate is a useful way of saying, ‘OK, is there a language fingerprint? Is there not a language fingerprint?’” says Arik Kershenbaum, a zoologist at Cambridge University, who studies animal communication and is a board member of the thinktank Messaging Extraterrestrial Intelligence, focused in part on designing messages to be received by an extraterrestrial intelligence. Kershenbaum is not part of the Whale SETI team.

“Do whales have a language? My guess is no,” Kershenbaum says. “I think they probably don’t. But I think the communication is complex enough that we can use it to build physical models of what complex communication is.” In turn, Kershenbaum says, that could help SETI scientists tell how much information is in a signal from outer space.

“That’s where the real advantage of this approach is: Can we quantify the amount of information in a signal?” Kershenbaum says. “Whereas it’s not very helpful when you start thinking about translating.”

Kershebaum hits on the fact that once scientists have a snippet of complex communication, whether from a humpback whale or an alien intelligence, they are still largely unable to assign meaning beyond making broad assumptions based on the context of the communication. 

“We can use things like AI and other machine learning-type systems to find patterns in the data,” animal behavior expert McCowan explains. “But the patterns alone are not going to be enough. We’re going to need to understand what those patterns mean. And that’s the hard work animal behaviorists and animal communication researchers focus on.”

What if that had come from space? Is that intelligent?

Doyle describes this as a search for carrying capacity—in other words, how much information does a humpback call carry at any one time? And, in turn, how much uncertainty is there in their calls? Humans, for example, can still get the gist of a message even if chunks of it are missing, and it’s possible the whales do something similar.

The next step for Whale SETI is to use AI to refine the whale playback calls in the hope that a future encounter might lead to a more dynamic “conversation,” whereby the whale and the researchers could exchange vocalizations in a more natural way. Ultimately, they want to better understand how much information is carried in the whales’ different calls and, perhaps, get a sense of what they mean.

Kershebaum makes the analogy of the 2016 sci-fi movie Arrival, when linguist Louise Banks (played by Amy Adams) manages to translate a complex alien language she has never come across fast enough to save the world.

“It’s not going to be like that because we haven’t started” decoding non-human communication on Earth, Kershebaum said. “And the place to start is with that complex animal communication. It is the only thing we’ve got.”

One particular aspect of humpback communication, over most other animal communication, that could help SETI, Doyle says, is their ability to transmit messages across vast distances and have them be understood. If SETI scientists can work out what pieces of information are crucial to humpback understanding, it could in turn help them pinpoint where relevant information might lie in a technosignature that has been broadcast over a vast distance in space and time.

In fact, Doyle says, the whales have already answered at least one big question for SETI scientists.

“A big assumption of SETI right now,” Doyle says, “is that ET will be curious and will want to be contacting us. And that’s something we can investigate like the encounter with Twain. Twain heard ‘hello’ in humpback and came over!”

This article How whales could help us speak to aliens is featured on Big Think.

In an attempt to study the spine, scientists in Portugal accidentally created a mouse embryo with an extra pair of hind legs, where its genitals should be — and the strange turn of events could improve our understanding of human embryo development, metastatic cancer, and more. 

What’s new? There’s a lot we still don’t understand about what goes on in the womb — how a single cell becomes an entirely new organism.

In an attempt to clear up some of this mystery, scientists at the Gulbenkian Science Institute in Portugal decided to study the gene Tgfbr1, which codes for a protein already known to play a role in embryo development. 

For their study, published in Nature Communications, the team inactivated the Tgfbr1 gene in mouse embryos that were halfway through development.

They expected that this might have some effect on the rodents’ spines. What they weren’t expecting was for one of their embryos to grow an extra pair of hind limbs where its external genitalia should have been.

“[We were] very surprised,” lead researcher Moisés Mallo told Newsweek.

But… how? Prior to this, scientists knew that, in most four-legged animals, external genitalia and hind limbs emerge from the same basic structures during embryo development.

Upon further study, the Portuguese team discovered that the Tgfbr1 protein affects the cells that make up these structures, altering the way the DNA in them folds. By inactivating the Tgfbr1 gene, they affected the expression of other genes in the cells, leading to the structural abnormality.

“I would actually expect the same would happen in humans, but of course, this cannot be experimentally tested,” said Mallo.

Looking ahead: The researchers are hopeful that their study will improve our understanding of abnormalities that occur during human embryo development, given that mammals share many of the same early developmental pathways.

They plan to continue studying Tgfbr1 to see how it might affect the development of other body parts, including the immune system, as well as explore its potential impact on the structure of DNA in cancer cells and their ability to spread. 

This article How turning off one gene causes mice to grow 6 legs is featured on Big Think.

On a brisk September morning, Brian Palik’s footfalls land quietly on a path in flickering light, beneath a red pine canopy in Minnesota’s iconic Northwoods. A mature red pine, also called Norway pine, is a tall, straight overstory tree that thrives in cold winters and cool summers. It’s the official Minnesota state tree and a valued target of its timber industry.

But red pine’s days of dominance here could fade. In coming decades, climate change will make red pine and other Northwoods trees increasingly vulnerable to destructive combinations of longer, warmer summers and less extremely cold winters, as well as droughts, windstorms, wildfires and insect infestations. Climate change is altering ecological conditions in cold regions faster than trees can adapt or migrate.

Palik, a forest ecologist with the US Department of Agriculture’s Forest Service Northern Research Station, stops and points to a newcomer under the red-pine canopy: a broadleaf deciduous tree, bitternut hickory, as high as an elephant’s eye at about 10 feet tall and eight years old. “It’s doing really well,” he says.

This bitternut hickory probably shouldn’t be thriving in the Cutfoot Experimental Forest in north-central Minnesota, near Grand Rapids. It likely began as a seedling in a nursery in Illinois, to the south, where deep freezes are less extreme. Normally, if a southern-adapted seedling is planted in an unsuitably cold climate like this one, it can risk frost damage and its survival is threatened. But the newcomer’s lush, green foliage exudes good health.

It is a promising sign in a project that aims to keep forests growing in a warming world.

In the Cutfoot Experimental Forest in 2016, the Forest Service planted seedlings of eight tree species from seeds, collected from woods up to several hundred miles farther south, as part of an experiment that Palik manages. Four species are native to this northern region: eastern white pine, northern red oak, bur oak and red maple. Four species are uncommon or nonnative: white oak, bitternut hickory, black cherry and ponderosa pine.

Two decades back, these southern seedlings likely would have struggled to flourish here. Today, Palik and his team can see the success of almost all the southern trees they planted. “They are going like gangbusters,” he says, “which is indicative that the climate is right for them,” although the researchers don’t know about the seedlings’ long-term health yet. In seven of the eight species, the survival rate has been 85 to 90 percent.

“The climate typical of southern Minnesota from 20 years ago is now in northern Minnesota,” Palik says. Climatic conditions have moved about 200 miles north in just two decades.

Palik’s project is an experiment in forest assisted migration, the relocation of trees to help woodlands adapt and flourish despite the heating of their habitats from climate change. Foresters advocating assisted migration are typically not aiming to save specific species — instead, by moving trees, they want to help sustain productive forests for multiple benefits such as carbon storage, water filtration, wildlife habitat, recreational beauty and timber.

Experimenting with assisted migration calls for a different way of thinking about nature. Whereas ecological restoration typically looks to the past for cues on repairing degraded places, foresters exploring assisted migration are planting warmer-climate trees that could have a better chance of thriving under warmer future conditions.

Forestry companies have long moved trees around to improve timber production on privately held land. But forest managers have so far been cautious about assisted migration projects for conservation aims on public land. Most of their projects have been experimental and small in scale, typically moving tree populations relatively short distances to the northern parts of their native ranges.

Now, though, assisted migration research for conservation is getting bolder with growing concerns about future forest disruption from climate change. And the movement is growing internationally, with research happening in Spain, Canada and Mexico. Today, Palik’s study is one of 14 research projects in a network named Adaptive Silviculture for Climate Change (ASCC). Most foresters who are experimenting with assisted migration are planting trees farther north or planting trees from lower elevations at higher elevations.

Sites across North America include western larch-mixed-conifer forests in the Flathead National Forest in Montana; diverse pine-hardwood woodlands at the Jones Center at Ichauway in Georgia; spruce-fir forests of the Colorado State Forest; and mixed-pine-hardwood forests of the Petawawa Research Forest in Ontario, Canada. Some Forest Service scientists, including Palik, expect that assisted migration will transition from a subject of research to a standard management strategy.

In line with the trend, the Forest Service and many other federal and state agencies are looking at revising their policies to accommodate this strategy. The US Fish and Wildlife Service, for instance, is considering allowing forestry managers to relocate species beyond their historical range.

Artificially moving a forest, some biologists say, has risks. Relocated species might become invasive or disrupt the ecological balance of the forest. But, says Palik, “the risk of not trying to move species for climate change is larger.”

Diversify or decline

Assisted migration was first proposed in the 1980s when some biologists anticipated that habitat conditions could change too fast for species to keep pace. Recent proposals have called for relocating endangered species to new habitats where they would have a better chance of thriving: Mexican gray wolves to northern Arizona or to New Mexico or Texas, for example, or Karner blue butterflies farther north from southern Michigan.

Palik and other forest scientists, though, are working on a different conservation solution. They want to save stressed forests from further decline or even disappearance by planting large numbers of more southern-climate-adapted trees, thereby diversifying woodlands so their canopies can survive.

“Forests die fast and grow slowly,” says Lee E. Frelich, a forest ecologist with the University of Minnesota Center for Forest Ecology. As climate change continues, he says, some forests could vanish, replaced by encroaching grasslands that do not provide the types of wildlife habitat and other benefits that healthy forests do. “Your only option in that case,” he says, “is to bring in new species or live with whatever nature does,” which — in cases of extreme climate change — “is likely to be brushy vegetation and not be a forest for quite some time.”

Climate change has already contributed to rapid forest losses. In recent decades, forests on every forested continent have suffered intense heat waves and drought exacerbated by climate change, says Henrik Hartmann, an ecophysiologist at the Julius Kühn-Institute for Forest Protection in Germany and lead author of an overview of forest die-offs in the 2022 Annual Review of Plant Biology.

Extremes are a natural part of a forest’s life history, and trees typically adapt to them — but this time is different. “These extremes were enough to bring trees to the edge or beyond the edge of functioning,” Hartmann says.

Cold-winter lands like the Minnesota Northwoods are disproportionately affected by climate change, which is causing shorter winters, drier summers and longer fire seasons.

Minnesota has one of the coldest climates in the Lower 48 United States because it is strongly influenced by the Arctic. But the Arctic has warmed four times faster than the rest of the Earth since 1979, and the state now has the Lower 48’s fastest-warming winters. Since 1970, average winter temperatures in Minnesota have increased by nearly 5 degrees Fahrenheit.

Over the past 50 years, Minnesota has heated up faster than any other state in the Lower 48, with the strongest warming in winter.

Minnesota is also unusual for having four major plant boundaries within its borders: mostly cold-climate conifers in the Northwoods; temperate deciduous trees such as oaks and maples in the state’s middle and southeast; and former prairie grasslands and aspen parklands, these days predominantly farmland, to the west and southwest.

Now these boundaries are blurring. Temperate deciduous trees have begun invading the understory of conifers in the Northwoods because the warming climate has begun favoring them. Many Northwoods tree species, including red pine, are likely to lose more and more of their livable southern range as warming continues. When Northwoods trees fade from the scene in the southern range, researchers worry that the migration of deciduous trees to replace them will happen far too slowly for healthy, continuous forest canopies to survive.

At the same time, the ecology of the Northwoods is becoming more tenuous. As climate change continues, giant swaths of northern conifers are increasingly likely to collapse suddenly — over just a few years — from combinations of climate-driven drought, insect infestations and other stresses. Many northern native tree species might not grow back there because they would no longer be suited to the region’s changed climate.

Recently, Frelich and his colleagues studied a range of possible impacts from rising temperatures — largely dependent on carbon dioxide emission scenarios — on Minnesota forests by 2070. A rise of 1 degree Celsius above 1979-to-2013 average temperatures would allow broadleaf forests to further invade the Northwoods. With a 6 degree C rise, prairie would cover most of Minnesota, with only broadleaf forests surviving in the northeast corner.

Speeding up nature’s pace

Worldwide, trees move north and south and up and down mountains in long-term response to changing climate, their seeds dispersed by winds and carried by animals.

It can take a millennium for many forests to reach equilibrium in a new location, according to Hartmann. That’s not really a problem for the forests, which eventually migrate; instead, it’s a problem for people. On weekends in Germany, people walk in the hills and mountains and through the forests, which is very popular as recreation, says Hartmann. But now, “They’re all shocked — it looks like the moon, and the forest is dead.”

Waiting for new trees could take a while: Some tree species reach an age of 25 years before making their first seeds. “If we want all of the services [of forests], similar to what we had only a decade ago, then we may want to think about getting a few more options,” Hartmann says. “We should think about conserving a forest and not the forest that we know.”

That’s what Julie Etterson, an evolutionary geneticist at the University of Minnesota Duluth, had in mind when she cofounded the Forest Assisted Migration Project with Meredith Cornett, then of the Nature Conservancy, and David Abazs of the University of Minnesota Extension. Etterson was worried that native tree decline would create openings for invasive plant species and sought a way to preserve forests by gradually moving in southern trees. The Forest Assisted Migration Project aims to build a regional market for climate-adapted tree seedlings grown by local farms and nurseries based on principles of Etterson’s and Cornett’s research.

For one study, Etterson and colleagues acquired seedlings of red oak and bur oak grown from seeds collected in two climatic zones: one in northern Minnesota and one nearer the center of the state. Workers planted the seedlings on 16 sites in two northern seed zones as part of a Nature Conservancy reforestation project, and the trees were measured for three years. Red oak sourced from southern seeds — adapted to a slightly warmer climate — had higher survival, faster growth and other advantages compared with the northern type. Results for the southern bur oak, while more mixed, were also generally better than the northern bur oak.

Etterson’s experiments in assisted migration, done in collaboration with the Nature Conservancy and public and tribal agencies, provide a scientific foundation for including climate-adapted trees in reforesting efforts underway in the state: In 2023, for example, the Nature Conservancy planted 1.4 million seedlings across northern Minnesota as part of a multi-partner goal to have 10 million seedlings planted on public lands by the end of 2024. As they plant, workers select about three-quarters of seedlings in the traditional way — seeds are collected from a climate zone, grown to seedlings in that zone, and planted in that zone, too. The rest of the seedlings come from parent seeds collected in forests farther south.

“We are using the ones that science tells us are in the best position to be climate adaptation winners,” says Chris Dunham, associate director of forest resilience with the Nature Conservancy in Duluth. But they are turning the dial slowly, he says, “because there’s also plenty of unknowns dealing with natural systems.”

The dial is turning slowly for another reason: Nurseries in the state can’t provide enough local seedlings to meet growing demand for “climate-smart” trees. And so Abasz started organizing a broader supply chain of seed collectors, seedling growers and buyers, and set a five-year goal of expanding the Farm & Forest Growers Cooperative to a network of 100 farmers and nurseries to each grow 10,000 southern-adapted, locally grown tree seedlings per year. The program would then expand the number of purchase agreements with restoration agencies such as county forestry departments.

Through all of this, the Forest Assisted Migration Project would recommend which young trees to plant where, designating them as green, yellow or red. The designations are based on Etterson’s research findings, input from experts and different kinds of assisted migration.

Seedlings designated as green are considered safe to plant in northern Minnesota because they already thrive there. Southern seedlings of native species would be planted farther north but within their historical range. This is called assisted population migration.

Trees designated as yellow require more caution. This is assisted range migration — moving species beyond their current historical range to keep up with climate change. This process also mimics what natural seed dispersal might do. “These are species that may be just creeping in our area or have very small populations in our area,” says Abazs, such as Eastern hemlock and American beech.

These southern seedlings are more likely to become resilient trees. Among other things, the climate-adapted trees may bloom earlier in the year and end growth later in the fall, capturing longer periods of photosynthesis.

Finally, trees designated as red by the Forest Assisted Migration Project would be ones that could not naturally disperse seeds to northern Minnesota because the distance is too great. Relocating that category of tree would be considered assisted species migration. Seedlings from southernmost Minnesota or northern Iowa, for example, would be designated as red. “Those are ones that we are not entertaining at this point,” says Abazs.

A lesson from the ponderosa

One of Palik’s relocated species over at the Cutfoot Experimental Forest would have gotten a red rating by those guidelines. But Palik is placing bets on the tree as a future invaluable conifer for northern Minnesota.

Palik took ponderosa pine seedlings from seeds collected in northwest Nebraska, hundreds of miles to the south and west, and planted them in experimental plots for research purposes. Though only a fifth of them lived, the ones that survived have flourished. His experiment suggests that ponderosa pine — a tall, long-needled tree used for timber but adapted to warmer, dryer summers and more moderate winters — could someday thrive in northern Minnesota if red pine falls away.

Temperate broadleaf trees will continue to edge into the Northwoods, but they can’t replace the characteristic pinelands that define how many Minnesotans experience the region, Palik says.

Many forest managers could eventually face a choice: Consider moving southern trees into northern areas, or eventually wind up with fewer productive woodlands for timber and other uses.

It’s imperative, Palik says, that we work to maintain useful woodlands. “The forests at the end of the century are not going to be your grandfather’s forests,” he says. “But they’re going to be the forest your grandchildren inherit.”

This article Moving trees north to save the forests is featured on Big Think.

Earth, a little over four billion years ago: The planet was still in its infancy, coming together just 500 million years prior. There was little to no oxygen. The surface — what little there was — was barren, scorching, and volcanic. Instead of land, there was water, lots of it. Earth was an ocean world. And it was in this global ocean that life formed for the very first time.

To be fair, nobody can say with certainty when, where, or how life first came into being. Separated from the momentous event by billions of years, scientists can only speculate how a self-sustaining chemical system became capable of transmitting genetic information from parents to progeny. But that speculation is not blind. Researchers have spent more than a half-century probing basic biological systems, poking around for primitive fossils, and searching for the places that could have roiled life into existence. In light of this extensive hunt, two biologists with over 75 years of collective experience think they have enough information to outline how life began. In a paper recently published in the journal Life, they shared their educated vision of life’s origins.

The two authors are Clifford Brunk, a professor of cell and molecular biology at the University of California, Los Angeles, and Charles Marshall, a professor of paleontology at the University of California, Berkeley. They started with a humble caveat: their story is just that — a story.

“We undertake this effort in full recognition of the fact that we do not yet have a comprehensive understanding of all steps in this path, and that many will disagree with aspects of our narrative,” they wrote.

But it’s a tale that’s guided by the scientific literature, so it has a strong spine. It unfolds in three parts.

Part I: The vent of life

Long ago, deep in the ocean, there was a vast system of alkaline hydrothermal vents. At these locations, seawater that had seeped down into the earth through fissures in the ocean crust erupted back into the ocean after being heated to hundreds of degrees by underground magma. Within this constant, cacophonous flow of energy and raw materials, simple organic molecules formed from the hydrogen and carbon dioxide spewing outward. Over time, the reactions that made these molecules transformed into new ones called autocatalytic food-generated networks, or RAFs.

“Each reaction in the network is catalyzed by a molecule within the network and all molecules are produced from a small set of food molecules,” the authors explained.

You can think of RAFs like life but without instructions or direction.

“Lacking a genetic core, they remained solely the product of their environment, unable to evolve,” Brunk and Marshall wrote.

Yet in these RAFs, protein-like substances formed — as did the precursors of energy-carrying molecules. For the most part, however, RAFs just went on reacting, over and over and over again. Nothing changed…

Part II: Biomolecular magic

A unique feature of hydrothermal vents is that they form structures composed of billions of minuscule microchambers, each contained and exposed to different conditions and reactants. They constitute a “vast array of simultaneously running semi-independent experiments,” Brunk and Marshall described.

Eventually, in one of them, biomolecular magic occurred: ribonucleic acid (RNA) appeared. Suddenly, genetic information could be stored, replicated, and transmitted. Non-life had become life.

These RNA molecules then formed enzymes called ribozymes, which catalyze biochemical reactions. At this point, things really got cooking.

“Proteinoids, polysaccharides, lipids, and other macromolecules combine with the replication of RNAs to produce quasi-cells, vent creatures, within the microchambers,” the authors wrote.

These creatures subsequently started making specific proteins, one of which was ATP synthase. ATP synthase is very important because it makes ATP, the nucleotide that provides energy to drive and support processes in living cells. Vent creatures could thus make energy on the go, not just within their cozy microchambers. And so, they ventured out…

Part III: Breaking free and changing Earth

Occasionally, hydrothermal vents break apart, thus spilling the contents of their microchambers. Initially, when this happened the vent creatures inside would simply die. But eventually, some may have persisted. Though these explorers at first remained very close or even attached to the hydrothermal vents, sustained by the warm, material-rich waters, they started to move farther and farther, until one day, they left home altogether.

Out in the ocean, the vent creatures might have moved up the water column, eventually rising to the photic zone, where the Sun’s light is strong enough to provide energy. They evolved the ability to photosynthesize, producing oxygen as a byproduct. At this point, oxygen was essentially a foreign element, unknown to Earth. Over millions of years, the vent creatures produced so much that they oxidized the oceans and the atmosphere.

“This was the most profound change on Earth ever produced by living systems,” Brunk and Marshall commented.

Basic life now had crafted elemental fuel that would permit it to grow in complexity. Microscopic life that emerged around a scalding crack in Earth’s surface had now irrevocably changed the entire planet. Life as we know it would never be the same.

This article The ocean vents where life on Earth likely began is featured on Big Think.

Stanford University scientists have discovered what appears to be a brand-new class of virus-like organisms in the human gut microbiome. If confirmed, the next step will be figuring out whether the strange creatures are helpful or harmful to human health.

“It’s insane,” Mark Peifer, a cell and developmental biologist at the University of North Carolina at Chapel Hill, who wasn’t involved in the research, told Science. “The more we look, the more crazy things we see.”

The background: You have trillions of microbes living in your digestive tract, and usually, that’s a good thing — some of these tiny hitchhikers help you stay healthy by producing vitamins, aiding in food digestion, and keeping bad bacteria in check.

If the balance of those microbes, known collectively as your “gut microbiome,” is thrown off, though, it could make you sick — scientists have found correlations between an imbalanced microbiome and a higher risk of diabetes, cancer, mood disorders, and more.

What’s new? The more we can learn about the gut microbiome, the better our ability to change it to improve our health. A Stanford-led team has just made a potentially major discovery, uncovering a brand new class of gut-dwelling organisms.

They call these creatures “obelisks,” and they found them inside bacteria taken from human guts and mouths. They appear to be fairly common, too, turning up in 7% of the gut bacteria samples and 50% of the oral bacteria samples the researchers analyzed.

“It’s not really something sporadic or isolated in the population — it’s really affecting a considerable amount of the sample,” Joan Marquez-Molins, a molecular biologist at the Swedish University of Agricultural Sciences, Uppsala, who was not involved in the work, told Nature. 

The details: According to the researchers’ paper, which has been shared on the preprint server bioRXiv, obelisks are similar to “viroids.” These tiny loops of RNA can infect other organisms, like viruses can, but because they lack coding for proteins, they don’t have viruses’ characteristic protein shell.

Viroids were discovered in plants, but newer research suggested they might be able to infect bacteria and other organisms, too, so the Stanford team developed a tool that could search through databases of RNA sequences for ones likely to form loops, hoping to find more viroids.

This led to the discovery of nearly 30,000 sequences with too few bases to be RNA viruses. Like viroids, they lacked the coding to create a protein shell, but unlike viroids, the sequences included coding for other proteins. The team named them “obelisks.”

“I am really impressed by the approach,” Simon Roux, a computational biologist at the Department of Energy’s Joint Genome Institute, who wasn’t involved in the study, told Science. “The authors were really creative.”

Looking ahead: The research still needs to be confirmed through peer-review, but if the Stanford team has discovered something new and yet so common in the human gut, the next step will be figuring out what, if any, impact it has on human health. 

“I think this [work] is one more clear indication that we are still exploring the frontiers of this viral universe,” said Roux.

This article “Insane” new type of virus-like organisms found in human gut is featured on Big Think.

The first time Dr. Maoyan Zhu saw the fossil that would change how he thought about early life on Earth, he was visiting his friend, Shixin Zhu, in his home in North China.

“Next to Shixin’s sofa were several beautiful fossils,” Dr. Zhu, a paleobiologist from the Nanjing Institute of Geology and Paleontology, told Big Think. “One was exceptionally large—it reminded me of modern seaweed fossils. When Shixin told me that the rock was 1.56 billion years old, I instantly realized that this was something special.”

Along with a team of researchers, the pair formally analyzed the fossil and published their findings in 2016. They described it as the oldest known multicellular eukaryote, related to all animals, plants, and fungi. Initially, the team did not name the fossil, choosing instead to focus on describing its important physical features rather than its taxonomic relationship with other species.

This chance find would lead Dr. Zhu and his colleagues to a series of discoveries that culminated in this January’s publication of another ground-breaking finding: a 1.63 billion-year-old multicellular eukaryote. The article, published in Science Advances, shows that early life on Earth was far more complex than scientists had thought.

Revising life’s timeline

Biologists group life into two major categories: eukaryotes and prokaryotes. Eukaryotes, which include all animals, plants, and fungi, have cells with DNA enclosed in a nucleus, while prokaryotes have free-floating DNA. Prokaryotes evolved approximately 4 billion years ago. The first single-celled eukaryote joined nearly 2 billion years later. 

Prior to the 2016 publication by Dr. Zhu and his colleagues about the large, seaweed-like fossil, the oldest known multicellular eukaryote dated back to 600 million years ago. That means that their 2016 finding of the large, 1.56-billion-year-old fossil, pushed the evolution of multicellularity back by a staggering 1 billion years. 

This discovery rippled through the scientific community and motivated Dr. Zhu and his team to keep studying the Yanshan region of North China, where Shixin Zhu had discovered the fossil. This time, the researchers sought out smaller specimens that had more well-preserved cell structures.

Dr. Zhu and another paleobiologist from the Nanjing Institute, Dr. Lanyun Miao, had already been collecting and studying 1.63-billion-year-old shale rocks from the Chuanlinggou Formation in the Yanshan region. Now, they looked at their samples with a renewed interest and perspective, hoping to find more evidence of ancient multicellularity.

Eventually, they found what they were looking for: Within the shale samples were exceptionally well-preserved microfossils of Qingshania magnifica. With modern techniques, the team was able to conclusively demonstrate that these specimens were multicellular eukaryotes.

This discovery further extends the timeline for the evolution of multicellularity by an additional 700 million years and challenges fundamental assumptions about the pace of evolution and what life looked like billions of years ago.

Q. magnifica: the first multicellular organism?

The team of researchers described Q. magnifica as having cylindrical cells joined together with cell walls, like modern plants. Some had spheroid structures in the cells, which suggests that they reproduced with spores. The team hypothesized that Q. magnifica was photosynthetic and, though they can’t prove it, suggested that they might be an extinct group related to today’s modern green algae. 

For Dr. Zhu, the most interesting aspect of the finding was that Q. magnifica is not significantly younger than the earliest known single-celled eukaryote. The fact that they co-existed so closely together suggests that multicellularity evolved incredibly early in Eukarya.

“The oldest single-celled eukaryote is around the same age as these multicellular specimens. That’s an interesting finding because it suggests that multicellularity evolved relatively early on in the Eukarya domain. It might make people think differently about whether it’s difficult to evolve multicellularity from a single-celled ancestor.” 

Dr. Zhu also noted another potential explanation: Scientists haven’t yet found the oldest single-celled eukaryote.

“There might be a prehistory of eukaryotes still unknown to us, potentially pushing the timeline of Eukarya evolution even further back into the past.” 

This underscores the inherent challenges of relying solely on fossil evidence, as numerous factors must converge perfectly for biological material to be preserved over millions of years. “Finding specimens in these ancient layers is particularly difficult, especially before 1.8 billion years ago, when extensive tectonic activity would have made it even more challenging to find those perfect conditions,” Dr. Zhu said.

Revisiting the “Boring Billion”

Dr. Zhu and his team’s discoveries — the large fossil and Q. magnifica — mean that these specimens lived in Earth’s oceans during the “boring billion,” a period between 1.8 billion and 800 million years ago. As the name suggests, this era is characterized by minimal evolutionary and ecological change.

However, Q. magnifica might make scientists rethink this era. As Dr. Zhu puts it, the “Boring Billion might not have been so boring after all.”

“The perceived lack of evolutionary change might have been an issue of preservation — we just don’t have the fossils — not of biology. The truth is, it’s harder to study older samples, and many people assume they won’t find much, anyways. I hope our findings spur the Earth Science community as a whole — paleobiologists, chemists, geologists — to pay more attention to these older rocks and shed more light on what happened in the so-called Boring Billion.”

Still, the first complex multicellular organisms, with more advanced and diverse cells, did not appear for another billion years after Q. magnifica, after the boring billion and close to the well-documented Cambrian explosion around 539 million years ago.

“The step from single-celled eukaryotes to multicellular ones apparently didn’t take as long as we thought,” Dr. Zhu said. “But it makes sense that the evolution of highly complex multicellularity, which would lead to the world we see today, required a much longer timeframe.”

Rediscovering Q. magnifica

As for the name, Qingshania magnifica, Dr. Zhu said that his team was batting around ideas for a name, assuming that they were the first to formally discover the species. That was until they stumbled upon a 1989 paper in an obscure Chinese journal, where they saw sections and an official description that matched their specimen. The authors of this early paper formally named the species “Qingshania magnifica.” 

“It shows what new methods and a renewed vision and context can do,” Dr. Zhu said. “There are so many of these lost papers in obscure journals whose significance wasn’t appreciated at the time. In many cases, the early researchers just didn’t have the technology or tools to fully understand what they had found.”

This article 1.63-billion-year-old fossil may rewrite the history of multicellular life is featured on Big Think.

A new electrically conductive “eSoil” could make hydroponic farming even more productive — and help ensure a sustainable new source for the human food supply.

“[W]e can get seedlings to grow faster with less resources,” said Eleni Stavrinidou, leader of the Linköping University team that developed the new substrate.

The challenge: Much of the world is perpetually in a food crisis. An estimated 735 million people experienced chronic undernourishment in 2022, a number that has increased by 122 million since 2019, a major setback after decades of progress. The struggle to expand food supply is likely to face new stresses in the future. 

“The world population is increasing, and we also have climate change,” said Stavrinidou. “So it’s clear that we won’t be able to cover the food demands of the planet with only the already existing agricultural methods.”

The idea: Hydroponic farming — a technique where plants are grown in water rather than soil — could help the world meet some of its future food needs. 

Not only does it enable farming in places that lack arable land, hydroponic systems can also be paired with lights to grow plants indoors. Trays of crops can then be layered vertically, allowing more food to be grown in an area than would be possible with traditional farming.

​​“We can’t say that hydroponics will solve the problem of food security, but it can definitely help, particularly in areas with little arable land and with harsh environmental conditions,” said Stavrinidou.

The biggest challenge with indoor hydroponic farming is the cost — it’s far cheaper to let the sun provide light than it is to power LEDs — so finding ways to make the process more efficient is key to helping it meet its potential.

What’s new? Stavrinidou’s team has now developed a new substrate for hydroponic farming. This is the material the plants’ roots attach to in a hydroponic system, instead of soil, and the standard option is mineral wool, which is made through an energy-intensive process.

The new substrate, called “eSoil,” is made out of cellulose, a material found in plant walls, and PEDOT, an electrically conductive polymer.

This conductivity made it possible to apply a small voltage to the roots of barley plants growing in the substrate. That electrical stimulation made the plants grow 50% larger (by dry weight) than control seedlings grown in eSoil with no stimulation during a 15-day study.

The cold water: This isn’t the first study to show that electrical stimulation can help plants grow. However, the Linköping team says previous studies have used higher voltages, while their eSoil requires a low voltage and has a very low energy consumption, which could make it more practical.

Because the controls were also grown in eSoil without electrical stimulation, though, it’s not clear how this approach compares to barley grown in a traditional substrate. The study also ended while the plants were still seedlings, so more research is needed to test the longer term impact of the eSoil and stimulation.

Looking ahead: The next step for the Swedish scientists will be figuring out how their approach works so that they can further optimize it for use during hydroponic farming.

“We don’t yet know how it actually works [or] which biological mechanisms that are involved,” said Starvrinidou. “What we have found is that seedlings process nitrogen more effectively, but it’s not clear yet how the electrical stimulation impacts this process.”

This article Zapping plants in “eSoil” makes them grow 50% larger is featured on Big Think.

For the first time, scientists have mapped the process of limb development in human embryos down to the individual cell — and the stunning result could help prevent a common type of birth defect in the future.

The challenge: At four weeks old, the parts of a human embryo that will eventually be arms and legs are essentially buds of undifferentiated cells. By week 8, though, the limbs are well-defined, with visible fingers and toes, and we’ve never really understood how we get from point A to B. 

In part, that’s because researchers have traditionally only been allowed to grow human embryos in the lab until about day 14. While that restriction is loosening, we don’t know if it’s even possible to get an embryo to develop to week 4, let alone week 8, outside a womb.

Studying young embryos inside a womb, meanwhile, is logistically tricky — at 8 weeks, an embryo is only about an inch long. Studies of animal limb development, meanwhile, might be telling us what’s going on, but we don’t know for sure since we can’t validate them.

Because we don’t fully understand the limb development process, we also don’t understand much about why it goes wrong so frequently — 1 in 500 babies is born with some significant limb abnormality, such as shortened fingers or extra toes — or how to prevent it.

What’s new? An international team of researchers, led by scientists at the Human Cell Atlas initiative, has now traced the expression of genes and differentiation of individual cells in donated fetal tissue to create the first map of human limb development.

“For the first time, we have been able to capture the remarkable process of limb development down to single cell resolution in space and time,” said senior author Sarah Teichmann.

This work led to the discovery that our fingers and toes actually don’t grow out from the clumps of limb cells we have at week 4. Instead, they form inside the buds — extra cells around them then die off to reveal the digits.

“What we reveal is a highly complex and precisely regulated process,” said senior author Hongbo Zhang. “It is like watching a sculptor at work, chiseling away at a block of marble to reveal a masterpiece. In this case, nature is the sculptor, and the result is the incredible complexity of our fingers and toes.”

Aside from exposing this remarkable process for the first time, the researchers also identified connections between common limb abnormalities and disturbances in specific genes through their study, which could be the key to preventing those abnormalities in the future.

“Our work in the Human Cell Atlas is deepening our understanding of how anatomically complex structures form, helping us uncover the genetic and cellular processes behind healthy human development, with many implications for research and healthcare,” said Teichmann.

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Thirty-five years ago, the waters of Lake Colden in New York’s Adirondack Mountains were found to be too acidic to support fish, making the picturesque, high-altitude body of water one of the signature casualties of acid rain. Red spruce trees in New England were also showing signs of strain as the rain leached vital calcium from the soil, severely stunting the trees’ growth. Today, Lake Colden’s trout have returned and the spruce trees are flourishing, tangible signs that the decades-long effort to mitigate acid rain has worked.

Now that sulfur dioxide and nitrogen oxide emissions — the causes of acid rain — are greatly reduced in Europe and North America, a success based on capstone environmental legislation, it’s easy to look back on the panicked news stories from the 1980s and 1990s and wonder if acid rain was really more of a “nuisance, not a catastrophe,” as William Reville, an emeritus professor of Biochemistry, wrote for the Irish Times. Seeing as how we dealt with the problem, we may never conclusively know the answer.

What we do know is that scientists in the U.S. and Scandinavia originally discovered acid rain in the 1960s and chose to gather evidence for years — more than a decade in some cases — before sounding the alarm in the 1970s and 1980s. American ecologist Gene Likens and his colleagues found that while rainwater was often slightly acidic, with a pH of 5.6, by 1980 the average rainfall in the U.S. was at a pH level of 4.6, about ten times more acidic! And it was getting worse.

In areas downwind of coal power plants — the primary sources of sulfur dioxide emissions — the problem was even more acute. The pH of individual rainstorms sometimes dropped to 3 or below, similar to that of grapefruit juice or soda. These sorts of downpours weathered buildings, dissolved nutrients in the ground that trees need to survive, and caused aluminum to be released in the soil.

Across the Atlantic Ocean in Sweden, scientists warned that half of the country’s lakes and rivers would reach a critical pH level by the early-mid 21st century and cause mass fish die-offs if actions weren’t taken to stop acid rain.

Whether these scenarios constitute “hype,” a “nuisance,” or a “catastrophe” might depend on one’s feelings towards scientific predictions, the environment, and wildlife, but there was no question that acid rain was a growing problem, and one that humans were responsible for.

That’s why, after years of public debate and amendments to the Clean Air Act in 1990, legislators in the U.S. instituted a bipartisan cap and trade program that capped sulfur dioxide emissions in the power industry at a drastically lower level compared to 1980 and allowed companies to either lower their emissions or buy and trade credits from companies that did. Limits were also placed on nitrogen oxide emissions.

The free-market program was a resounding success. The national average of sulfur dioxide annual ambient concentrations in the U.S. decreased a whopping 93% between 1980 and 2018.

But while the cloud of acid rain has all but vanished from much of Europe, North America, Australia, and Japan, it is a surging problem in places like India and China, where coal power is still widely used. Urbanizing areas of Latin America and Africa are also seeing precipitation grow increasingly acidified.

For these places, reducing noxious emissions that fuel acid rain is a tandem goal with lowering air pollution as a whole. Four million people die prematurely due to outdoor air pollution globally. Making air more breathable and rain less acidic benefits everyone, regardless of whether or not acid rain is a hyped problem or a genuine one.

This article Acid rain: Real danger or overhyped doomsaying? is featured on Big Think.

“Anthropogenic” is a key word of our time. It means caused by, and/or originating with, humans. It’s generally used to refer to climate change. But anthropogenic warming isn’t the only thing we’re collectively causing here on earth. Humans have become a major evolutionary force. In fact, we may be the most powerful evolutionary force going. We are driving rapid evolution—contemporary evolutionary change—in other species at rates that seem to be faster than anything else in history, barring the five great mass extinctions of earth history.

In their introduction to a special issue of Philosophical Transactions: Biological Sciences on human influences on evolution and the ecological and societal consequences thereof, Andrew P. Hendry, Kiyoko M. Gotanda, and Erik I. Svensson list some of the anthropogenic factors influencing evolution today, which include

[p]ollution, eutrophication, urbanization, habitat fragmentation, climate change, domestication/agriculture, hunting/harvesting (including fishing), invasion/extinction, medicine and emerging/disappearing diseases.

It’s a lot. And, of course, these factors aren’t necessarily separate and distinct. Consider fish, for instance, beset by hotter, more acid waters; many different kinds of pollution; and eutrophication, among other things.

Antibiotic resistance is the best known of our evolutionary forcings. With too-liberal use of antibiotics in both human and domestic animal populations, we’ve channeled pathogens into evolving super-resistance against antibiotics.

There any many other examples. The peppered moth is a now classic one, but it’s only the most famous of more than 100 other species of moth affected by industrial melanism. Formerly rare dark (melanic) versions of peppered moths began to predominate as the Industrial Revolution coated England’s Midlands with dark industrial filth. The dark ones blended in, so they were less likely to be picked off by predators and more likely to pass on their genes. Once the air got cleaner, the lighter ones returned to their former prominence.

Killifish are another example. These small fish are now able to survive in polluted environments that would normally kill most species. Populations in places like Newark Bay have evolved enormous resistant to industrial pollutants.

Rapid evolution has also been seen and studied in such animals as wolves (Chernobyl Exclusion Zone), Crested Anoles (Puerto Rico), Fairy-wrens (Australia), Spotted Hyenas (Tanzania), Red Deer (Scotland), and Red Squirrels (Canada). Fish have gotten smaller because we’ve removed the large ones out of the gene pool and smaller ones get through nets easier. Female elephants are losing their tusks in response to slaughter by ivory poachers.

Hendry et al. draw distinctions between “how humans interact with their ‘enemies’ (or ‘adversaries’) versus their ‘friends.’” Enemies are things like “weeds, pests, and pathogens” which we want to decrease. Efforts to do so can favor resistance/tolerance to our control efforts. Friends are things like crops, natural resources, and biodiversity, which we strive to increase. Here we can facilitate adaptive evolution that benefits the target species. In the case of both enemies and friends, there can be “spillover to influence non-target species.”

The authors also write that some species may be “frenemies,” that is, good or bad at different times and places. Meanwhile, many species (“neighbors”) are just there, living besides us, neither “good” nor “bad” for us, but just just as likely to be driven to evolve because of the multi-pronged pressures we put on them, often quite unintentionally.

Without even realizing it, we’ve actually become pretty god-like in our powers. We’re controlling what lives and dies; what evolves and what becomes extinct. Our domesticated species dominate the biosphere: 34.4 billion chickens, 1 billion cattle, 784 million pigs. Our stuff—roads, buildings, phones, daily coffee cups—may now outweigh all the life on earth.

Welcome to Anthropogenic Earth.

“From our increasing knowledge of how humans influence evolution comes the opportunity, perhaps even the responsibility, for humans to do something about it,” conclude Hendry, Gotanda, and Svensson, noting numerous ways we already do so. “The future affords even greater opportunities to influence evolution in informed, effective, restrained and safe directions.”

This article Humans may be the most powerful evolutionary force on Earth is featured on Big Think.

Could a jellyfish tell you why the ocean is near the shore, or think of things never thunk before — if it only had a brain? Maybe, but jellyfish don’t have brains. They instead have simple nervous systems dispersed throughout their transparent bodies. For this reason, it has been long thought that they are incapable of learning beyond a basic level, and research seems to back up this notion.

In 2021, biologist Ken Cheng wrote a systematic review of learning in cnidarians — the phylum that consists of jellyfish, hydras, and sea anemones. He found substantial evidence of habituation among these animals, meaning they can grow accustomed to a stimulus. In other words, super basic learning.

Only a few studies showed the potential for associative learning in sea anemones. In these, the anemones were shocked while also being shown a light. In time, the animals would retract their bodies when the light was shown, even without a concurrent shock. It’s classic conditioning and does suggest that the anemones formed a memory and adapted their behavior accordingly.

But there’s a concern. Because anemones rarely encounter shock-happy scientists in the wild, it’s not entirely clear whether these studies demonstrated learning that aids survival or simply induced an unnatural behavior in the creatures.

To see if and how cnidarians learn, researchers at the University of Kiel and the University of Copenhagen created a more natural school for Caribbean box jellyfish. Their results challenge the belief that advanced learning requires a brain.

A school for jellyfish

For brainless, spineless, blueberry-sized predators, Caribbean box jellyfish have it pretty good. They spend their days swimming in sunlit tropical waters among the prop roots of mangrove trees. These roots provide protection as the jellies hunt their prey of choice, tiny crustaceans called copepods.

It all sounds idyllic, but as always in nature, dangers abound. One such danger is the roots themselves. Should a box jellyfish’s fraile body collide with a root, it could injure the creature. The weather also poses risks. It can churn up silt and other particles to make the water murky, inhibiting a box jelly’s ability to see the prop roots and navigate them safely. (Caribbean box jellyfish are unique among jellies for having eyes on their bells. Most other jellyfish can only sense light and dark.)

The researchers wanted to determine if box jellyfish learn to avoid the prop roots or have to mindlessly take their licks. To test this, they brought the jellies into the lab and created three experimental conditions using round tanks.

The first tank sported high-contrasting black-and-white stripes. This condition was meant to simulate clear-water days where the prop roots are easily visible. The second tank also contained stripes but with low-contrast colors to simulate murky days. The final tank had uniformly gray walls.

The researcher’s aim was to create conditions analogous to those the box jellyfish actually encounter in the wild — and not the cnidarian equivalent of a close encounter with the third kind.

“Learning is the pinnacle of performance for nervous systems,” Jan Bielecki, the study’s first author and a postdoctoral researcher at Kiel University, said. “It’s best to leverage its natural behaviors, something that makes sense to the animal, so it reaches its full potential.”

Learning is a no-brainer

Turns out, these “brainless” creatures are quick studies. In the low-contrast bucket, the jellies initially collided with the wall, but in less than 8 minutes, they began swimming an average of 50% farther away. They also quadrupled their number of quick turn maneuvers to avoid collisions.

In the high-contrast bucket, the jellyfish managed to avoid the walls altogether by sticking to the center. Conversely, in the gray bucket, they continuously bonked their bells. Taken together, these results suggest that the box jellyfish began associating the murky stripes with collisions and adjusted their behavior accordingly.

In short, they learned.

“We can see that as each new day of hunting begins, box jellyfish learn from the current contrasts by combining visual impressions and sensations during evasive maneuvers that fail,” Anders Garam, one of the study’s lead authors and an associate professor of marine biology at the University of Copenhagen, told Genetic Engineering & Biotechnology News.

He added: “So, despite having a mere one thousand nerve cells [per eye-bearing structure] — our brains have roughly 100 billion — they can connect temporal convergences of various impressions and learn a connection — or what we call associative learning.”

Specifically, this is a type of associative learning known as operant conditioning. This advanced learning occurs when an organism learns to associate a voluntary behavior with a stimulus or result. The classic example is the lab mouse taught to push a blue button for a treat and avoid the red button that gives it a zap.

As the researchers note in their study: “[This] suggests the intriguing possibility that advanced neuronal processes, like operant conditioning, are a fundamental property of all nervous systems.” And not just those based on a centralized brain.

In the 24 eyes of the beholder

To tease out how the box jellyfish learn without a brain, the researchers tested the creature’s rhopalia — sensory structures located on a box jellyfish’s bell. An adult box jelly will have four such structures, each one housing six eyes. These structures also generate “pacemaker signals” that control the jelly’s pulsing movement and spike in frequency when avoiding obstacles.

The researchers positioned isolated rhopalium in a Petri dish to face a screen. The screen projected images showing moving bars of different contrasts — similar to the tank experiment. During the pre-trial runs, the rhopalium did not respond to the gray or light gray bars, seemingly because it interpreted them as distant. It did, however, generate pacemaker signals for the dark gray bars.

During the trials, the researchers trained the rhopalium by giving it a small electric shock when any colored bar appeared on the screen. Within five minutes of testing, the rhopalium began generating pacemaker signals in response to the gray bars and even the light gray ones. These results suggest that the rhopalial nervous system is the learning center of the Caribbean box jellyfish and that the species combines visual and mechanical stimuli to learn.

“Our behavioral experiments demonstrate that three to five failed evasive maneuvers are enough to change the jellyfish’s behavior so that they no longer hit the roots. It is interesting that this is roughly the same repetition rate that a fruit fly or mouse needs to learn,” Garm said. 

The researchers published their results in the peer-reviewed journal Current Biology.

Relearning our understanding of learning

In future research, the team hopes to identify which cells precisely control the box jellyfish’s ability to learn, and how those cells translate that information into behavior. There is also the question of how the jellyfish form memories and how long they retain them. 

The research also opens the question of whether more natural studies will demonstrate similar results among other cnidarians.

“This is only the third time that associative learning has been convincingly demonstrated in cnidarians,” Cheng, who was not involved with the study, told The New York Times. “And this is the coolest demonstration, replete with physiological data.”

The findings have implications for our understanding of the evolution of learning, too. They suggest that associative learning may be a property of all nervous systems, not just those centralized around a brain. That has the potential to shake up how much and how far back learning may have shaped our shared evolutionary history.

This article Jellyfish surprise scientists by learning without a brain is featured on Big Think.

A herd of wooly mammoths march across the snowy tundra steppe. Close by, human hunters scavenge meat from a dead elk with stone-flint tools while their compatriots scanned the horizon, wary that their kill might attract neighboring steppe lions. Against this ancient backdrop, something historic happened: A group of nematodes (also known as roundworms) became trapped and frozen in an arctic gopher burrow.

Granted, it didn’t seem all that historic at the moment. The nematodes are only about one millimeter long, so it’s unlikely even the gophers took notice. But one Ice Age later, Anastasia Shatilovich, a scientist working at the the Institute of Physicochemical and Biological Problems in Soil Science RAS, would unearth the burrow in the Siberian permafrost near the Kolyma River and discover something quite amazing. The nematodes were still alive.

Just add water for life

Radiocarbon dating of plant material found alongside the nematodes showed the specimens were frozen around the end of the Pleistocene epoch — sometime between 45,839 and 47,769 years ago. They managed to survive the intervening millennia thanks to a survival strategy known as cryptobiosis.

Cryptobiosis is a state some plant and animal species can undergo in response to overly harsh environmental conditions, such as freezing or extreme dryness. Essentially, the organism slows down biological functions to nearly undetectable levels to preserve itself. When environmental conditions return to livable, the organism revs up its metabolism and starts “living” again.

Perhaps the best-known cryptobiotic species is the tardigrade (also known as the water bear). This most extreme of extremo-tolerant animals can use cryptobiosis to survive freezing, high temperatures, and even exposure to outer space. For a more everyday example, you need only look to your cupboard. The fungal cells in active dry yeast have been desiccated to the point of entering cryptobiosis. When yeast and water combine as part of a recipe, the yeast returns to life (albeit shortly before being baked).

Even for cryptobiosis, the nematodes’ 46,000-year stint on ice is impressive. They handily beat the previous nematode record of 39 years and even the rotifer record of 24,000 years. It may ultimately prove to be the longest cryptobiotic hibernation — for an animal, that is. But it’s nowhere near the longest. Scientists were able to revive a bacterial spore from an extinct bee’s abdomen. The bee had been preserved in amber for 25 to 40 million years.

So, how did Shatilovich revive a pair of the prehistoric nematodes? Like all good bakers, she just added water and waited for life to rise.

Ancestor or contemporary?

The ancient nematodes would die several days later, as part of their natural life cycle, but not before spawning more than 100 generations of descendants. Shatilovich then took her discovery to researchers in Dresden and Cologne to have its DNA sequenced and morphology analyzed.

The researchers discovered that the nematodes belonged to the genus Panagrolaimus, a genus of nematodes that survives to this day. In fact, the Antarctic nematode Panagrolaimus davidi is known for its ability to survive in sub-zero temperatures. However, genome analysis showed that these nematodes belonged to a previously unknown species. The researchers named them Panagrolaimus kolymaensis, after the Kolyma River where they were discovered.

They also compared the genome to another contemporary species of nematode, Caenorhabditis elegans. Their analysis shows that both species prepare their bodies for cryptobiosis by upregulating a sugar, trehalose, which makes them more tolerant by protecting cellular membranes. They also discovered similar genes present in each species’ genomes.

However, they could not determine if those similar genes functioned the same way in both species or if P. kolymaensis had other biochemical pathways that helped it survive. In future studies, they hope to use RNA experiments to determine the species’ cryptobiosis mechanisms and determine if they are the result of convergence (the independent evolution of a similar trait in two unrelated organisms) or parallelism (the evolution of such a trait in a common ancestor).

“Our experimental findings also show that Caenorhabditis elegans can remain viable for longer periods in a suspended state than previously documented. Overall, our research demonstrates that nematodes have developed mechanisms that allow them to preserve life for geological time periods,” Temo Kurzhchalia, professor emeritus at the Max Planck Institute of Molecular Cell Biology and Genetics and one of the study’s authors, and Vamshidhar Gade, another study author, said in a news release.

The researchers published their findings in a study in the peer-reviewed journal PLOS Genetics.

Reconsidering the road of evolution

That life can be preserved across such periods of time further challenges a simplistic conception of evolution as a successive series of species, one progressing into the next. Consider, for example, the famous Road to Homo Sapians illustration: A chimp progresses into a bipedal primate into an upright primate into a tool-wielding primate into a modern human.

Cryptobiosis on a geologic scale complicates this simple idea of evolutionary processes. Prehistoric species — particularly microscopic ones like nematodes, bacteria, and viruses — may be out there alive and, well, not well but ready to reemerge. Ancestors might one day become contemporaries with their progeny, and as environments alter from climate change, previously unknown species may reappear. This makes the road to nematodes — and potentially other species — less a straight path and more an evolutionary highway system.

“Our findings are essential for understanding evolutionary processes because generation times can range from days to millennia and because the long-term survival of a species’ individuals can result in the re-emergence of lineages that would otherwise have gone extinct,” Philipp Schiffer, another study author and the co-lead of the Biodiversity Genomics Center at the University of Cologne, said in the same release.

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The scale of humanity’s meat consumption is enormous. 360 million tonnes of meat every year.

This number is so large that I find it impossible to comprehend. What helps me to make these numbers more relatable is to turn them from the weight of meat to the number of animals and from the yearly total to the daily number. This is what I have done in the graphic below. It shows how many animals are slaughtered on any average day.

About 900,000 cows are slaughtered every day. If every cow was 2 meters long, and they all walked right behind each other, this line of cows would stretch for 1800 kilometers.¹ This represents the number of cows slaughtered every day.

For chickens, the daily count is extremely large – 202 million chickens every day. To comprehend the scale, it is better to bring it down to the average minute: 140,000 chickens are slaughtered every minute.

The number of fish killed every day is very uncertain. I discuss this in some detail at the end of this article. But while the uncertainties are large, it is clear that the number of fish killed is large: certainly, hundreds of millions of fish are killed every day.

If you believe that the slaughter of animals causes them to suffer and attribute even a small measure of ethical significance to their suffering, then the moral scale of this reality is immense.

From the perspective of animal suffering, it is the absolute numbers of animals that matter, but if you want to explore this data in per capita terms, you can do so in our Animal Welfare Explorer.

It’s not just about how many farm animals are killed but also the suffering they endured while they were raised. The majority of the world’s farm animals are raised in dismal conditions. Pigs are held in cramped, stressful conditions, living a life in chronic discomfort and distress. Cows get their calves taken away to produce milk for human consumption, a practice under which both the mother and the calf suffer. Many animals are castrated without anesthetic. Chickens are often debeaked to stop them from fighting with other chickens out of discomfort and pain; many cannot turn around their entire lives.

What would be the benefits of reducing our meat consumption?

Meat production has a number of large negative impacts on the environment, wildlife, and our health.

Viewed from the other side, this means that the benefits of reducing meat consumption are large. What would some of these benefits be?

Less land use for agriculture and more biodiversity: The use of land for agriculture is the main driver of biodiversity loss.³ Today, almost half of the world’s ice- and desert-free land is used for agriculture, and most of this land is used by livestock. The total global land use for meat and dairy production sums up to 37 million square kilometers, an area as large as the entirety of the Americas — from Alaska in the North to Cape Horn in the South.For the data, see our page on land use.

As my colleague Hannah Ritchie showed, if we didn’t eat meat, it would be possible to reduce agricultural land from 4 to 1 billion hectares. Changes towards less meat consumption would have large benefits for animals around the world as wilderness could regrow to provide habitats for wildlife.⁴

Benefits for the world’s climate: Reducing global meat consumption would also help to address climate change: it would reduce direct emissions from burping cows and nitrous oxide from manure, but also reduce emissions from deforestation and land use change.

Less antibiotic resistance: Reducing the world’s meat consumption would decrease the use of antibiotics in livestock farming, a practice that contributesto the rise of antibiotic-resistant bacteria. This reduction could preserve the efficacy of existing antibiotics and the health of people around the world.

Lower risk of pandemics: Many infectious diseases originate in other animals. The high-density conditions in many meat production facilities create ideal environments for the mutation and spread of pathogens. Reducing global meat consumption would reduce the risk of zoonotic diseases and the risks of suffering another pandemic.

Less animal suffering: Coming back to the starting point of this short text, less meat consumption would mean less suffering for animals.

I think this future is possible. I can imagine a future in which our grandchildren look back at our time and find it hard to believe that we today are living in a world in which we kill hundreds of millions of fish, 900,000 cows, 1.4 million goats, 1.7 million sheep, 3.8 million pigs, 11.8 million ducks, and more than 200 million chicken every day.

This article How many animals get slaughtered every day? is featured on Big Think.

So what’s their cutest feature? Is it their squashy little faces? Their grunting pants? Their double-curled tails?

That coiled tail is possibly less endearing when you know it’s a purpose-bred genetic defect, which in its most serious forms leads to paralysis. And their squished noses? That’s been selectively bred to become ever shorter and smaller, making it difficult for the dogs to breathe and eat, causing trickle down effects like cardiovascular stress, eye prolapses, overheating (dogs don’t sweat, so they need to pant to expel heat through evaporation), weight gain because of that sedentary overheated lifestyle, dental crowding, soft palate collapse, and skinfold dermatitis. More of an “anatomical disaster” than the patron saint of cuteness.

Despite performing corrective surgeries and designing pain treatment plans for these dogs, veterinarians don’t often speak up about the unethical nature of buying and creating demand for genetically impaired dogs for one simple reason: It’s bad for business. “If I stood up and told the truth about these breeds,” says an anonymous vet to The Guardian, “I would immediately alienate [their owners] and they would up sticks and move to the neighboring practice where the vet was not as outspoken. Vets in general practice simply cannot afford to be honest and to speak out.”

Perturbed by pugs

The British Veterinary Association (BVA), which represents vets across the UK, is in a better position to do so. It has made several statements this year on the breeding and buying practices of brachycephalic dogs, expressing the trend as a concern in dog health and welfare. “The surge in popularity of these dogs has increased animal suffering and resulted in unwell pets for owners, so we strongly encourage people to think about choosing a healthier breed or crossbreed instead,” Sean Wensley, president of the BVA, says to The Guardian.

Mixed breed dogs are said to be much healthier than pure bred dogs, a claim that is contested by dog breeders, but a study from 2013 inserts some much-needed data into an argument that is skewed by passion and profit. Using medical records from more than 27,000 dogs and comparing the incidence of 24 genetic disorders in mixed versus pure bred dogs, the researchers found that 10 of those genetic disorders had a significantly higher incidence among pure bred dogs, and just one was greater among mixed breeds. For the remaining disorders, the incidence was fairly even in both groups.

Funny looks, serious problems

Why has this peculiar set of physical traits become so popular in dogs — and for that matter, in cats? While dogs are America’s #1 pet, cats are arguably more famous in the digital world. Two of the most viral cat celebrities with millions of fans were Lil Bub (who died at age 8) and Grumpy Cat (who died at age 7).

Why were they so cute and famous? Because they had health problems. Lil Bub was the runt of her litter and had a tongue that always hung out of her mouth because of her abnormally short lower jaw and toothlessness. She also had serious osteoporosis and was medicated for it. Lil Bub eventually died from a bone infection. Grumpy Cat had feline dwarfism and an underbite, which caused her famous frown. She succumbed to complications of a urinary tract infection.

If you look at Bored Panda’s list of the most famous internet cats, many of them have disabilities or genetic mutations such as vision impairment (Honey Bee), a missing nasal bridge (Monty the Cat), and a cleft palate (Lazarus the Vampire Cat). There is a big ethical difference, however, in loving an animal with a debilitating genetic mutation and intentionally breeding animals to have more of them.

Among domesticated pets, there is an increasing fetishization of the weird. Ugly is cute, and deformed is unique. This is the new Victorian freak show — and we love them so.

This article Top vets urge dog lovers to stop buying pugs and bulldogs is featured on Big Think.

One of humans’ key characteristics, and a major reason we’ve been so successful, is that we can adapt to a huge range of environments and lifestyles. For instance, while modern changes in our diet may have caused an increase in certain inflammatory bowel conditions, we can now consume a wide range of calorie-dense, complex foods previously unimaginable to our hunter-gatherer forebears.

Humans have not evolved alone. In our settled agricultural wake, we brought along a whole host of animals. We domesticated the wild. We tamed the beast. One of the first examples of this is the dog. While it might be hard to imagine in some cases, modern dogs do share a common ancestry with the wild gray wolf.

This has been a pretty good deal for the dogs, on the whole, but even pampered dogs are known to suffer from gastrointestinal conditions that their wolf cousins generally do not. One plausible reason is that we give them our processed foods, but they lack an accompanying effective and adaptive gut microbiome to help them deal with them.

Knowing this, a recent study from a team of researchers at Oregon State University-Cascades explored an interesting way to improve dogs’ gut health.

Trouble in the dog bowl

A gray wolf eats predominantly raw meat, hunted or scavenged. So, a wolf’s gut will contain certain microbiota that are specifically designed to aid in digesting carcass meat. The Paenibacillus species of bacteria is the main ally here. This stomach bacteria will produce certain advantageous antimicrobials, antibacterials, and antifungals that improve the overall health of the wolf. For instance, Paenibacillus reduces E. coli in the lower intestine and strengthens the immune system more broadly. In short, Paenibacillus is a good thing for a wolf.

The problem is that when you stop eating only raw meat, your gut biome will adapt. Modern dogs eat a different and more varied diet than gray wolves or their ancestors ever had. Most importantly, domesticated dogs have been eating more food high in carbohydrates made up of cereal grains — in the past, scraps and food waste from humans, and more recently, commercial dog foods.

So, over time, dogs have developed GI tracts suitable for this polysaccharide metabolism. In some ways, our pet companions are better for this diversification of diet because they are exposed to more nutrients, vitamins, and calorific foods. Diets only made up of meat can place strain on the kidneys and cause renal failure.

In one very important way, however, the move from a meat diet to a carbohydrate one exaggerates and multiplies the incidence of inflammatory bowel conditions in modern dogs, by changing their microbiome.

A difficult resolution

If the inflammatory bowel conditions are caused by a deficit in Paenibacillus, and if that in turn caused by eating less meat and more other foods, surely giving your dog more meat would resolve the issue? Sometimes, yes. But as McCabe et al reveal, “even when switched to a raw meat diet, a dog’s fecal microbiota only partially resembles that of a wolf.” You cannot change millennia of canine stomach adaptation with a bit more offal.

You generally cannot currently cure IBCs. Diet changes can and do help, but most cases in dogs are treated with antibiotics or anti-inflammatory medications from the vet. These can be expensive and might have other knock-on effects on a dog’s gut microbiome and general health.

Now, we have a different solution. What the team from Oregan State University-Cascades has discovered is a strain of Paenibacillus that could be turned into an effective prebiotic or probiotic. Up until now, it’s been hard to isolate and locate a suitable microbe to make such a formula, and this novel strain, which the team calls ClWae2A, makes for an optimistic change in fortune. This strain, collected from a freshly killed wolf hit by a car, is able to “encode enzymes that would be of value in digesting carbohydrates and could contribute to energy metabolism for a monogastric animal.”

If you don’t have a dog or you take only passing interest in canine intestinal microbiota, this all might seem a touch irrelevant to you. It’s the parochial esoterica of dog-lovers and biologists. But Americans spend $36 billion on veterinary care, and it can cost around $850 a year to treat IBCs. The pet food industry is estimated to be worth $170 billion by the end of the decade. That’s a lot of money, and it’s just possible that this new discovery, and ones like it, could one day help pet owners treat or prevent this condition. That will make for a lot of happy dogs and happy owners, too.

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After investigating the origin of the species, Charles Darwin lunged into an exploration of something that seemed, by comparison, terribly minute: orchids. By 1862, he’d traveled the world wide and far, encountering incredible organisms like giant tortoises, seafaring iguanas, and fossils of giant ground sloths. But he couldn’t stop thinking about a delicate, white star-shaped flower he’d been sent as a gift by his acquaintance James Bateman, an English horticulturalist with a penchant for rare flora from Madagascar. The flower’s odd shape—with an extremely long nectar pouch hanging under its crown—stirred in him a deep, almost inexplicable fascination.

“Orchids have interested me as much as almost anything in my life,” Darwin wrote. In their forms, he saw a vast landscape of the forces of selective evolution, a dance they played with their environment and their pollinators. “My little darlings,” as he sometimes referred to orchids, became his model for further exploring the forces he so broadly described in The Origin of Species. Just three years after the publication of that shattering work, he had produced his tome puzzling over the multitudinous, striking habits of orchids: On the Various Contrivances by Which British and Foreign Orchids Are Fertilised by Insects, and On the Good Effects of Intercrossing.

How a single family of flowers could vary so widely—from small and frilly, almost invisible to see, to large, gaudy and with a front pouch—left Darwin baffled. He called this, and flower diversity as a whole, an “abominable mystery.” Indeed, there are upward of 28,000 species of orchids worldwide and new ones cropping up every so often—sometimes even right under our noses. They have made their homes on all contemporary continents save for Antarctica—from the Arctic north, across the equator, and reaching south through all but the tip of South America.

“I think the reason people become obsessed with them is because of that mystery: Why are there so many?” says Jamie Thompson, a life sciences researcher at the University of Bath, in the United Kingdom. Yet the scientific jury is still out—and fervently debating—how many species there are exactly, what secret makes them so brilliant at diversifying, and when and where orchids evolved in the first place. Getting to the bottom of these mysteries could help us better understand the evolutionary dynamism of this massive group of alluring plants, and how we might help them fend off upcoming decimation.

Phallaenopsis orchid in bloom. (John Wiesenfeld / Unsplash)

To search for answers, researchers have spent decades digging into the orchid’s past. For plants, fossil records are often hard to come by because soft organic matter is less likely to be preserved than, say, bones. To track when a plant first appeared on this planet, experts now tend to rely on phylogenetic profiling: They use DNA from different species to plot them onto a tree of life, and then use a statistical model to pull them back into the past and recreate their history. 

When, in 2015, researchers used this technique to sequence 39 species from all major orchid groups, as well as data from some fossils, their findings suggested that orchids originated between 102 and 120 million years ago, most likely in Australia.¹ Ancient orchids then spread to the tropics by making their way through Antarctica—which was then connected and flourishing with vegetation. And since then, Southeast Asia is where most of their speciation has taken place.

Darwin couldn’t stop thinking about a delicate, white star-shaped flower.

Or at least, this is currently the leading theory about orchid origins. It may soon be upended, though, according to new preliminary findings.² An international team of researchers has drafted a study using DNA from more than 1,900 species of orchids and pinpointed their origin north, in Laurasia, modern-day Europe, Asia, and North America. The majority of diversification happened just over the past 5 million years, their work suggests, and southern Mesoamerica, such as the lush Costa Rica and Panama, actually hosts the fastest speciation of orchids.

This paper, posted to a preprint site in September, hasn’t yet been peer-reviewed, and some outside experts don’t think this new hypothesis is any good. But Oscar Pérez-Escobar, the lead author of the study and a researcher at the Royal Botanic Gardens, Kew in the United Kingdom, doesn’t think his findings are controversial at all. “Understanding where things come from can help us understand why we have X or Y species, and why there are so many,” Pérez-Escobar says.

Today, it takes a long logbook to account for orchids’ present diversity of appearances and habits. “There’s quite a number of innovations that orchids can do that other plants can’t, or not so well,” says Katharina Nargar, an orchid researcher at James Cook University, in Australia who contributed to the new study.

The neatest and most helpful of these tricks, according to Nargar, is that more than 70 percent of orchids have developed the ability to grow out of tree trunks and branches instead of soil—a capability known as epiphytism. This allows them to exploit new territories other plants cannot use, giving them “free rein,” says Nargar. Studies suggest that epiphytism evolved independently at least 14 times throughout the orchid family tree, and epiphytic orchids are “significantly richer in species” than terrestrial ones, write the authors of one study of their diversity.³ To successfully live in trees, orchids have developed the ability to absorb moisture from the air via a succulent spongy outer coating on their stem and leaves, as well as to use their roots directly to photosynthesize. The Taeniophyllum orchid, for instance, doesn’t even have any leaves: it just uses its roots for all energy production from the sun.

For the species that haven’t evolved to live in trees, the other main running theory for their inexplicable ability to diversify lies in how specialized their flowers are at getting pollinated. For one, some orchid species are the ultimate swingers—they’re very lenient in their sex lives and can produce fertile offspring with orchids from some other species, making them more likely to reproduce and more likely to often birth unique, new hybrid species, according to Nargar.

Marsh helleborine, a species of orchid native to Europe and Asia. (Hans-Juergen Roessler / Unsplash)

To ensure pollination, some orchids also strike up an evolutionary deal with local fauna: The plant evolves a flower so intricate it’s only accessible to a couple types of insects, and those insects are sure to only really ever pollinate other orchids. One of these striking examples is the Angraecum sesquipedale, the orchid Darwin had grown obsessed with, which has evolved a 12-inch long and narrow satchel for its nectar so that only the Hawk moth, with an exceptionally long proboscis, can access it. Although Darwin had already mused on this possibility, the moth hadn’t yet been discovered, so his theory was only confirmed almost four decades later, in 1903.

Some orchids are very lenient in their sex lives. 

In order to fine-tune their ability to accommodate just certain pollinators, orchids have also grown very meticulous about how they deliver their pollen gifts. Some orchids bundle their pollen in tailor-made, measured, sticky packages and fling them onto their preferred pollinators with precision so that no grains are wasted and lost along the way once they fly off, and they can only be dislodged once they reach their destination. This push to specialize pollen packaging according to available pollinators—maybe a moth, maybe a bee—has also pushed diversification. And it allows one mutant orchid to have a higher chance of having loads of offspring because less pollen goes to waste than with traditionally dispersed grains. The branch of the orchid family tree that has evolved this trick called “pollinia” has a higher speciation rate than orchids that have stuck with traditional pollen grains.⁴

To take their specialization a step further, some orchids have evolved to mimic the mate of their preferred pollinator, or their favorite snack through looks, scent, and the release of special chemicals.⁵Unknowing insects show up on their flower crown hoping to get lucky, and get duped into picking up the flower’s pollen instead. Ophrys apifera orchids look and smell like female bees. The Hammer orchid eerily resembles a female wasp. The Satyrium pumilum orchid, in South Africa, imitates the scent of dead animals to attract fruit flies, while Disa pulchra orchids pretend to be other nectar-offering flowers, like the pink iris, to fool insects into coming looking for a sweet reward. Since bees, wasps, and butterflies alike would clock the ploy if it were too common, it’s possible this has led orchids to vary in their mimetics as much as possible, spurring the birth of so many different species and tactics.

These unique flower morphology strategies are “fundamental,” to diversification according to Dewi Pramanik, an orchid morphology researcher at the Naturalis Biodiversity Center, in the Netherlands. One of her favorites is the Serapias cordigera orchid, which has evolved to shape its hairy, burgundy flower like a comfortable resting place for the Hoplitis adunca male bee, which will conveniently stop to rest there in between bouts of foraging, accidentally pollinating the flower.

Dust-like seeds are also likely among the orchid’s arsenal for rapid diversification. A single orchid seed packet can contain up to 4 million seeds, sometimes as tiny as 0.05 mm in length—the smallest in the plant kingdom—meaning plenty can easily disperse with a single gust of wind. Although most of the dust seeds won’t ever germinate, this tiny seed technique does increase the odds for diversification compared to a plant with a heartier seed bulk because new plants can crop up quickly in new locations without too much energy expenditure, and rapidly adapt accordingly.

Though orchid excellence might not all be down to just tricks pulled by the plants themselves, according to Thompson—there are external factors at play, too. When Thompson ran another phylogenetic statistical analysis on nearly 1,500 species of terrestrial orchids, his data suggested that their diversification “exploded” specifically when temperatures started dropping across the globe, somewhere around 10 million years ago.⁶ Global cooling is 700 times more likely to have influenced the rate at which orchids speciated than just time alone, Thompson says, making orchids “the best example of climate-driven speciation.”

Unfortunately, this also suggests extra trouble for the challenges orchids will face as the world warms. “I think extinction will increase, because a lot of them are cold-adapted, and we’ve seen in Europe, how hot it’s been this year,” says Thompson. Climate changes also put orchids at additional risk due to their hyper-specializing for one pollinator that might die off or be forced out of their habitat.

Going by their evolutionary history, orchids should continue to proliferate, and we should continue to discover new ones. “If you look at the number of orchid species described against time, it’s not really showing any evidence of leveling off,” according to Thomas Givnish, a professor of botany and environmental studies at the University of Wisconsin-Madison, who penned that seminal Australia-orchid-origin research. But human-caused climate change and other habitat destruction are spelling out a different future for many of these species of flower.

Some calculations suggest that plant species are dying out at least 500 times faster than before 1900, with orchids high on the threat list. Bangladesh has lost 32 of its 188 identified orchid species since 1996; in the Czech Republic, the suitable habitat for endemic orchids has declined up to 92 percent; in Florida, the number of famed ghost orchid (the sought-after subject of The Orchid Thief) has declined by half; orchids in India are blooming earlier than they should, potentially disrupting pollination. And according to a study published earlier this year, almost 280 known orchid species are in need of “immediate conservation action” but most of these still lack adequate protection.

If most of the diversity arose in the past 10 to 5 million years, the rapid loss of species we’re experiencing now might be too late to counteract, according to Pérez-Escobar. “We are kind of stuck,” he says. “If we don’t protect the orchids that we have left, the time it will take for that orchid diversity to bounce back is millions of years.” He’s on a mission to gather additional international collaboration to sample the DNA of all existing orchid species—however many they may be—because he thinks that will help him definitively plot out the plant’s evolutionary history.

The one thing experts seem to all agree on is that perhaps the best way to come up with strategies to effectively stop orchids’ decline⁷—whether it’s going to be saving the habitats they reside in, focusing on the pollinators they rely on, cutting down on their illegal trade, or all of the above—is to somehow answer the big questions of the “abominable mystery”: What are the secrets to their success in speciation? Further parsing these details about orchid diversity can help conservationists home in on their rapid and wild evolutionary plasticity to, hopefully, give them a fighting chance at adapting to a rapidly changing world.

After all, Darwin, himself noted that orchids had been “eminently useful” for him to learn how every little element, “even most trifling details of structure,” are somehow a result of natural selection.⁸ As he writes in a letter replete with exclamation points to a fellow botanist: “The beauty of the adaptations of parts seems to me unparalleled.”

References

1. Givnish, T.J., et al. Orchid historical biogeography, diversification, Antarctica, and the paradox of orchid dispersal. Journal of Biogeography 43, 1905-1916 (2016).

2. Perez-Escobar, O.A., et al. The origin and speciation of orchids. BioRxiv (2023).

3. Gravendeel, B., Smithson, A., Slik, G.J.W., & Schuiteman, A. Epiphytism and pollinator specialization: Drivers for orchid diversity? Philosophical Transactions of the Royal Society B 359, 1523-1535 (2004).

4. Givnish, T.J., et al. Orchid phylogenomics and multiple drivers of their extraordinary diversification. Proceedings of the Royal Society B 282, 20151553 (2015).

5. Ackerman, J.D., et al. Beyond the various contrivances by which orchids are pollinated: Global patterns in orchid pollination biology. Botanical Journal of the Linnean Society 202, 295-324 (2023).

6. Thompson, J.B., Davis, K.E., Dodd, H.O., Wills, M.A., & Priest, N.K. Speciation across the Earth driven by global cooling in terrestrial orchids. Proceedings of the National Academy of Sciences 120, e2102408120 (2023).

7. Fay, M.F. Orchid conservation: How can we meet the challenges in the twenty-first century? Botanical Studies 59, 16 (2018).

8. Darwin, C. Letter to J.D. Hooker. Darwin Correspondence Project. University of Cambridge (1862).

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More than 1.5 billion years ago, a momentous thing happened: Two small, primitive cells became one. Perhaps more than any event — barring the origin of life itself — this merger radically changed the course of evolution on our planet.

One cell ended up inside the other and evolved into a structure that schoolkids learn to refer to as the “powerhouse of the cell”: the mitochondrion. This new structure provided a tremendous energetic advantage to its host — a precondition for the later evolution of complex, multicellular life.

But that’s only part of the story. The mitochondrion is not the only important structure within complex, eukaryotic cells. There’s the membrane-bound nucleus, safekeeper of the genome. There’s a whole system of internal membranes: the endoplasmic reticulum, the Golgi apparatus, lysosomes, peroxisomes and vacuoles — essential for making, transporting and recycling proteins and other cargo in and around the cell.

Where did all these structures come from? With events lost in the deep past and few traces to serve as evolutionary clues, it’s a very tough question to tackle. Researchers have proposed various hypotheses, but it is only recently, with some new tools and techniques, that cell biologists have been able to investigate the beginnings of this intricate architecture and shed some light on its possible origins.

A microbial merger

The idea that eukaryotes originated from two cells merging dates back more than 100 years but did not become accepted or well known until the 1960s, when the late evolutionary biologist Lynn Margulis articulated her theory of endosymbiosis. The mitochondrion, Margulis said, likely originated from a class of microbes known as alphaproteobacteria, a diverse group that today includes the bacterium responsible for typhus and another one important for the genetic engineering of plants, among many others.

Nothing was known about the nature of the original host cell. Scientists proposed that it already was fairly complicated, with a variety of membrane structures inside it. Such a cell would have been capable of engulfing and ingesting things — a complicated and energetically expensive eukaryotic feature called phagocytosis. That might be how the mitochondrion first got into the host.

But this idea, called the “mitochondria late” hypothesis, doesn’t explain how or why the host cell had become complex to begin with.

In 2016, evolutionary biologist Bill Martin, cell biologist Sven Gould and bioinformatician Sriram Garg, at the University of Dusseldorf in Germany, proposed a very different model known as the “mitochondria early” hypothesis. They argued that since no primitive cells today have any internal membrane structures, it seems very unlikely that a cell would have had these over 1.5 billion years ago.

Instead, the scientists reasoned, the endomembrane system — the whole hodgepodge of parts found inside complex cells today — could have evolved soon after the alphaproteobacterium took up residence inside a relatively simple host cell, of a kind from a class called archaea. The membrane structures would have arisen from bubbles, or vesicles, released by the mitochondrial ancestor.

Free-living bacteria shed vesicles all the time, for all sorts of reasons, Gould, Garg and Martin note, so it seems reasonable to think they’d continue to do that when enclosed inside a host.

Eventually, these vesicles would have become specialized for the functions that membrane structures perform today inside eukaryotic cells. They would even fuse with the host cell’s membrane, helping to explain why the eukaryote plasma membrane contains lipids with bacterial features.

Vesicles could have served an important initial function, says biochemist Dave Speijer of the University of Amsterdam. The new endosymbiont would have generated plenty of poisonous chemicals called reactive oxygen species, by oxidizing fatty acids and burning them for energy. “These destroy everything, they are toxic, especially on the inside of a cell,” Speijer says. Sequestering them inside vesicles would have helped keep the cell safe from harm, he says.

Another problem created by the new guest could also have been helped by making membranes barriers, Gould, Garg and Martin add. After the alphaproteobacterium arrived, bits of its DNA would have mixed with the genome of the archaeal host, interrupting important genes. Fixing this would mean evolving machinery to splice out these foreign pieces — today they’re known as introns — from the messenger RNA copies of genes, so those protein-making instructions wouldn’t be garbled.

But that created yet another problem. The protein-making machinery — the ribosome — works extremely fast, joining several amino acids together per second. In contrast, the intron-removing system of the cell is slow, snipping out about one intron per minute. So unless the cell could keep the mRNA away from ribosomes until the mRNA was properly processed, the cell would produce many nonsensical, useless proteins.

The membrane surrounding the nucleus provided an answer. Serving as a spatial barrier, it allows mRNA splicing to finish up in the nucleus before the intron-free mRNA is translated in the cell’s internal fluid, the cytosol. “This is the selective pressure behind the origin of the nucleus,” Martin says. To form it, vesicles secreted by the endosymbiont would have flattened and wrapped around the genome, creating a barrier to keep ribosomes out but still allowing small molecules to pass freely.

An inside-out explanation

In short, Gould, Garg and Martin’s hypothesis explains why endomembrane compartments evolved: to solve problems created by the new guest. But it doesn’t fully explain how the alphaproteobacterium got inside the host to begin with, says cell biologist Gautam Dey at EMBL in Heidelberg, Germany; it assumes the endosymbiont is already inside. “This is a massive problem,” Dey says.

An alternative idea, proposed in 2014 by cell biologist Buzz Baum of University College London (with whom Dey once worked) and his cousin, University of Wisconsin evolutionary biologist David Baum, is the “inside-out” model. In this scenario, the alphaproteobacterium and the archaeal cell destined to be its eventual host would have lived side by side for millions of years in an intimate symbiosis, each depending on the other’s metabolic products.

The archaeal cell would have had long protrusions, as seen on some modern-day archaea that live in close association with other microbes. The alphaproteobacterium would have nestled up against these slender extensions.

Eventually, the protrusions would have wrapped around the alphaproteobacterium and enclosed it completely. But during the long stretch of time before that happened, the archaeal cell would have begun some spatial division of labor: It would keep information-processing jobs in its center, where the genome was, while functions like protein building would take place in the cytosol within the protrusions.

The power of the inside-out model, Buzz Baum says, is that it gives the cell eons of time, before the alphaproteobacterium becomes fully enclosed, to evolve ways to regulate the number and size of the mitochondrion and other membrane compartments that would eventually become fully internal. “Until you can regulate them, you’re dead,” Buzz Baum says.

The model also explains why the nucleus has the shape that it does; in particular, it provides an explanation for its unusually large pores. Viewed from inside the center of an archaeal cell, the long protrusions would be openings that could naturally become big pores like those, Baum says.

Most important, the inside-out model explains how the alphaproteobacterium would have gotten inside the archaeal host in the first place.

Still, the inside-out model has features it needs to explain. For example, the mitochondrion would end up in the wrong place — inside the endoplasmic reticulum, the network of tubes on which sit the cell’s protein-making ribosomes, as the archaeal protrusions wrapped around it. And so an additional step would be required to get the alphaproteobacterium into the cytoplasm.

But Martin’s main objection is that the inside-out model does not provide an evolutionary pressure that would have caused the nucleus or other membrane-bound compartments to arise in the first place. The inside-out model “is upside-down and backwards,” Martin says.

The nucleus: A riddle in the middle

Though the models agree that the mitochondrion evolved from an alphaproteobacterium, they have very different ideas about the origin of the nucleus and other organelles.

In the Gould, Garg and Martin model, the source for all of the structures would have been vesicles released by the evolving mitochondrion. Vesicles to contain reactive chemicals or cellular cargo, and the ability to move this cargo around, would have evolved very early. The nucleus would have come later.

In the inside-out model, the nucleus was, essentially, the remains of the archaeal cell after it wrapped its membranes around the alphaproteobacterium. So it would have appeared immediately. The endoplasmic reticulum also would have formed early, created from those squished-together protrusions. Other organelles would have come later — arising, Buzz Baum says, from buds of archaeal membrane.

Thus the models also make different predictions about the chemical nature of the membranes of cell organelles — at least originally — and how today’s complex cells came to have membrane lipids that are all chemically like the ones in bacteria, not archaea.

In the Gould, Garg and Martin model, in the beginning all the membranes except for the host cell’s outermost one would have been bacterial, like the membranes of the new resident. Then, as bacterial vesicles fused with this archaeal outer membrane, the bacterial lipids would slowly replace the archaeal ones.

In the inside-out model, the membranes of the nucleus and endoplasmic reticulum — and probably others — would have been archaeal, like the host, to start. Only later on, after genes from the bacterial genome moved over to the archaeal genome, would the lipids become bacterial in nature, Baum suggests.

How to test these ideas? Through experiments, cell biologists are starting to glimpse ways in which simple vesicles could have diversified into different organelles with distinct jobs — by taking on different shapes, like the layered membrane stacks of the modern endoplasmic reticulum or the Golgi body, or by ending up with different proteins inside them or on their membranes.

They are also highlighting the dynamism of the modern-day mitochondrion — and its potential to spawn new membrane structures.

Take, for example, the compartment that Speijer thinks evolved early in order to deal with reactive oxygen species: the peroxisome.

In 2017, cell biologist Heidi McBride of McGill University in Montreal reported that cells lacking peroxisomes could generate them from scratch. Working with mutant human fibroblast cells without peroxisomes, her team found that these cells put proteins that are essential for peroxisome function into mitochondria instead. Then the mitochondrial membrane released them as little bubbles, or vesicles.

These vesicles, or proto-peroxisomes, matured into true peroxisomes when they fused with another type of vesicle derived from endoplasmic reticulum, which carry a third necessary peroxisome protein. “It’s a hybrid organelle,” McBride says.

For McBride, this is an indication that peroxisomes — and probably other organelles — originally came from mitochondria (not exclusively from the endoplasmic reticulum, as previously believed). “The presence of mitochondria launched the biogenesis of new organelles,” she says. “In the case of peroxisomes, it’s quite direct.”

Other mitochondrion antics have also been noted.

First, a 2021 report from the lab of biochemist Adam Hughes at the University of Utah found that when yeast cells are fed toxic amounts of amino acids, their mitochondria will shed vesicles that are loaded with transporter molecules. The transporters move amino acids into the vesicles, where they won’t poison the mitochondria.

Hughes also discovered that the vesicles shed by the mitochondria can form long, tubule-like extensions with multiple layers, reminiscent of the layered stacks of the endoplasmic reticulum and the Golgi body. The structures persist in the cell for a long time. “They’re definitely their own unique structure,” Hughes says. 

And in 2022, immunologist Lena Pernas, now at UCLA, showed that multilayered, mitochondria-derived structures can form in other contexts, too. When a cell is infected by the parasite Toxoplasma, her team found, the mitochondria surround the parasite and change shape. The parasite responds, and the upshot is that the mitochondrion ends up shedding large bits of outer membrane.

Pernas, who wrote about mitochondrial remodeling in the Annual Review of Physiology in 2016, recently discovered that these structures, which initially look like simple vesicles, also can grow and take on more complex shapes, such as stacks of sheet-like layers. What’s more, the stress of infection changes what sorts of proteins are placed on these shed bits of mitochondrial membrane. Such changes open the door for the stacked sheets to behave in different ways than they normally would, presenting the opportunity to take on new jobs, Pernas says.

The more Pernas and Hughes study these structures — found in quite different cells and conditions — the more similar they look. It’s tantalizing, says Hughes, to imagine how a structure like this, forming in the early days of eukaryote evolution, could have evolved over eons of natural selection into some of the endomembrane compartments existing in cells today.

It may never be possible to know for sure what happened such a very long time ago. But by exploring what can happen in today’s living bacterial, archaeal and eukaryotic cells, scientists can get more clarity on what was possible — and even probable. A cell moves into another cell, bringing benefits but also problems, setting off a complex cascade. And then, McBride says, “all this stuff blooms and blossoms.”

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