Why Prey Animals Got Weirder the Longer They Lived Alongside Human

[00:00:00]There is a photograph from a suburb outside Cleveland that has been quietly making the rounds among ecologists. It shows a white-tailed deer standing in someone's driveway at 3:00 in the afternoon, calmly chewing on the tips of a rose bush, while a male truck idles about 10 ft away with its door open. The deer does not look up. The male carrier does not look up. Nothing about this scene is unusual to either of them.

[00:00:23]Rewind that image 30,000 years and it would have been unthinkable. A prey animal that ignored an upright tool using predator at 10 feet did not have descendants.

[00:00:34]That deer in that driveway is the descendant of a very long line of animals whose ancestors ran the moment they saw us and whose ancestors before them ran the moment they smelled us. For most of that species evolutionary history, the presence of a human being was as close to a guarantee of death as the natural world could provide. And yet here we are. A deer that would rather chew than flee. A red fox in Bristol that treats a crowded pub garden the way its ancestors treated a hedro. A tuskless elephant in a Mosamb beek national park. A cod in the Baltic Sea that will never grow to the size its great grandparents did. What has been happening to prey animals over the last few thousand years is not the story we were told in school. It is stranger and it is measurable and it is still going on. There is a pattern hidden underneath all of this and once you see it you cannot unsee it. It is a pattern that shows up in Mosmb beek in the Florida Keys in Nova in Siberia in the fallow deer of a Dublin park in the raccoons of Little Rock and in Ram Mountain in Alberta. It is showing up on every continent where there are humans, which is now every continent. And it says something uncomfortable about the world we are living in and about the animals we share it with. This is a story about what happens to a prey animal when the biggest predator on the landscape stops being a wolf or a tiger or a short-faced bear and starts being us. It is also, it will turn out, a story about ourselves.

[00:02:11]For most of the history of vertebrate life on land, the rules for staying alive were simple. If you were a prey animal, you avoided predators. Your senses evolved for that. Your muscles evolved for that. Your brain evolved for that. Your entire behavioral repertoire was in one way or another a system for detecting threats and either fleeing them, hiding from them, or fighting them off if you had the mask to try. The deer in the driveway is running a piece of software that was written for a landscape of wolves and mountain lions.

[00:02:46]And that software has been under continuous revision for tens of millions of years. Then something happened that had never happened before. A single primate species working in groups spread across the entire land surface of the planet and became the most efficient large prey killer that Earth had ever produced. We did not just hunt animals.

[00:03:08]We hunted them with strategy, with weapons that increased their range every few thousand years, and eventually with rifles that could kill from 400 meters.

[00:03:16]If you were a big horn ram or a bison or a mammoth, we were an evolutionary catastrophe.

[00:03:23]But we also did something else, and this is the piece that gets missed in the usual telling. We built settlements, then we built villages, then we built towns, then we built cities. And with those settlements came something that had never existed at that scale before, which was a permanent highdensity concentration of food waste, of shelter, and of protection from other predators.

[00:03:46]Where humans lived, wolves and lyns and pumas mostly did not because we killed them. Where humans lived, food came out of holes in the wall in the form of grain and later in the form of garbage bags in an alley. That set up a fork. A prey animal in the wild that stumbled into a human settlement had two options.

[00:04:06]It could keep running from us the way it always had, which meant giving up the food and the shelter and the freedom from wolves that the settlement offered.

[00:04:14]Or it could hesitate just a little, just long enough to eat. Almost no animals took the second option at first. The ones who did tended to die. But over enough generations in a few species, the arithmetic began to shift. A single fraction of a percent of the population had essentially by accident an inheritable trait that made them slightly less anxious around humans than their neighbors. Their neighbors starved in a hard winter. They did not. They had descendants. Their descendants had descendants. And after a couple of thousand years, they were something different. That process has a name. It is called self-domemestication.

[00:04:52]And until very recently, most biologists did not really believe it was possible on that scale.

[00:04:58]Then a Russian geneticist changed everyone's mind. His name was Dimmitri Belellay. And in 1959 at a research station near Novosk in Siberia, he started an experiment that his own government considered ideologically dangerous. Soviet biology at the time was still under the shadow of lysencoism which rejected mainstream genetics.

[00:05:19]Belellayv was pretending to run a project on fur quality and silver foxes because a project on evolution would have gotten him fired or worse. What he was actually doing was testing an idea that had been quietly gnawing at biologists for more than a century. The idea was this. When Charles Darwin looked at domestic animals, he noticed something odd. Dogs, pigs, cattle, sheep, horses, rabbits, and goats all seem to share a suite of traits that none of their wild ancestors had. Floppy or shortened ears, curly tails, patches of white on the coat, especially on the face and chest, smaller teeth, smaller brains, shorter snouts, extended breeding seasons rather than a single yearly rut. retained juvenile behaviors well into adulthood. Nobody had bred for any of those traits directly. They just showed up over and over in species that had been living with humans for a long time. Darwin called it a puzzle. Later biologists called it domestication syndrome. Blev's theory was that all of these traits, wildly different as they looked, were somehow linked. And the thing that linked them, he suspected, was tameness.

[00:06:32]If you selected only for animals that were calmer around humans, and you did it for enough generations, you would eventually get all the other weirdness as a package deal. Nobody knew if this was true, so he started breeding silver foxes. The rules were simple. Every generation, he tested each fox as a young cub. A human being approached the cage. The cub either recoiled, snapped, and hissed, or it approached and let itself be touched. Only the calmst foxes in the whole population were allowed to breed. Every other fox went to the fur farm. Believe was ruthless about it because the experiment demanded ruthlessness. He was breeding for a single trait, willingness to be near a person, and he was breeding for it in isolation from every other consideration. Within about eight generations, the foxes at the research station were already visibly different from wild silver foxes. Within 20 generations, the change was undeniable.

[00:07:29]The tame foxes wagged their tails at researchers when they walked past the cages. They whed when the researchers left. They approached, they licked, they climbed onto laps like puppies. But that was only the part everyone had expected.

[00:07:43]The part nobody had expected was the rest of it. Their ears started drooping.

[00:07:47]Their coats developed white patches, especially on the face and belly. Their skulls got shorter and rounder. Their tails curled up over their backs like a huskys. Their breeding season, which is once a year in wild silver foxes, spread out and became less predictable. They started barking, which wild silver foxes basically do not do. Some of them had piebal splotches that looked from a distance like a border collie's markings. By had bred in fewer than 50 years, an animal that looked and behaved like a dog from a starting population of foxes. He had also unintentionally produced the clearest demonstration in modern biology that domestication syndrome is real, that it can appear in a few generations of selection, and that the thing driving it is not human aesthetic preference, but tameness itself. Something about selecting for calmness around humans was pulling the entire developmental program of the animal sideways. That something is still being argued about. And the leading hypothesis put forward in 2014 by Adam Wilkins, Richard Rangham, and Tecumsa Fitch is elegant enough to be worth pausing on. It has to do with a group of embryionic cells called the neural crest. If you have ever looked at a diagram of an early vertebrate embryo, the neural crest is a strip of cells that runs along the top of the developing nervous system. Those cells do something extraordinary.

[00:09:11]They migrate. They travel outward across the entire body of the developing animal and they turn into an astonishing variety of tissues once they get to their destination. Neural crest cells become the pigment cells in the skin and fur. They become the cartilage of the face and jaw. They become part of the adrenal glands which govern the fight orflight response. They become part of the ears. They shape the front of the brain. If you have ever wondered why a single glitch in embryionic development can cause a suite of traits that seem to have nothing to do with each other, the neural crest is often the answer.

[00:09:48]Wilkins and his colleagues proposed something that once you hear it is difficult to unhear. What if selecting for tameness is really selecting for a slightly reduced migration of neural crest cells during embryionic development? A mildly underdeveloped adrenal system would give you a calmer animal. It would also coincidentally give you less pigment in patches where the cells did not fully arrive, hence the white spots. It would give you slightly less cartilage in the ears, hence the floppiness.

[00:10:17]Slightly less bone in the muzzle, hence the shorter snout, slightly smaller teeth, a slightly smaller brain case.

[00:10:25]Every symptom of domestication syndrome, in other words, could be a downstream consequence of a single tweak to the neural crest. This is still a hypothesis and it is still being tested. But it explains in a way nothing else does why this syndrome keeps showing up across such a bewildering variety of species.

[00:10:45]It explains why BIV's foxes without a single human ever selecting them for floppy ears or piebal coats ended up with both. And it means that any prey animal anywhere on Earth that is selected across enough generations for calmness around humans will start looking ever so slightly like a domestic animal, whether we meant to breed them or not. Which brings us to what is actually happening right now in a lot more species than the average nature documentary tends to mention. The first domesticated animal was not a project.

[00:11:16]It was probably an accident. The best current evidence for how dogs became dogs and how cats became cats does not involve some ancient hunter gatherer capturing a wolf cub and taming it by hand. The evidence involves garbage.

[00:11:29]Around 15 to 40,000 years ago, depending on which line of evidence you trust, humans in Eurasia were living in semi-permanent camps large enough to produce a reliable mound of food waste.

[00:11:40]Bones endrails and scraps piled up at the edges of those camps. That pile was a magnet for any scavenger tolerant enough to hang around it. Wolves are opportunistic scavengers and greywolves in particular sit on a spectrum of individual boldness. Some wolves in any given pack are shy than others. Some are by wolf standards unusually mellow. The wolves that could tolerate the presence of humans at say 30 m had access to a food source that their shy packmates could not exploit.

[00:12:12]Over generations, this created a subpopul of wolves that self- selected for reduced human flight distance. That subop was doing something none of their ancestors had done. They were living essentially on the edge of the human niche, feeding out of what we discarded and slowly getting used to the sight and sound and smell of us. This is what biologists call the commensal pathway to domestication. And it looks like it happened at least twice with wolves and at least once with cats. For cats, the story runs through the grain silo. Once agricultural civilizations in the Near East started storing surplus grain about 10,000 years ago, they created another new ecological niche, one full of mice.

[00:12:56]Wild cats followed the mice into the villages. The wild cats that could tolerate humans lived very well. The ones that could not did not. Cats never fully domesticated in the way dogs did, and they still have not. Which is why a modern house cat is on almost every genetic measure closer to a wild cat than a golden retriever is to a wolf.

[00:13:19]Cats domesticated themselves halfway and then stopped because halfway was the sweet spot. Neither of those species was ever intentionally selected for calmness by early humans. They selected themselves. They passed themselves through the tameness civ generation by generation because on the other side of the civ was food. And here is the point that gets skipped in most tellings. That process did not stop. It never stopped.

[00:13:45]The wolves and the wild cats were only the beginning. The same evolutionary pressure has been running quietly on many species for as long as humans have had settlements. And it is still running today. It is running in your neighborhood right now. Look at what has been happening to red foxes. Red foxes have lived alongside humans in some parts of the world for a very long time.

[00:14:07]Archaeological evidence from the Kodiak Archipelago in Alaska puts red foxes in contact with people for at least 7,500 years. In London, in Bristol, in Zurich, and in Melbourne, red foxes moved into cities during the last century and never really left.

[00:14:25]Modern urban red fox populations across Europe have been quietly diverging from their rural relatives in ways that a Belv would recognize immediately.

[00:14:34]Urban foxes, according to studies coming out of the University of Glasgow and others, have shorter and wider muscles than rural foxes. Their brain cases are on average slightly smaller. The muscle attachment sites on their skulls are subtly reshaped, apparently to give them a stronger bite for cracking open discarded bones from human food waste.

[00:14:55]They show reduced sexual dimmorphism, meaning the difference in skull shape between male and female urban foxes is less than the difference between males and females in the countryside. If you laid the skull of a country fox next to the skull of a Bristol back alley fox on a table and did not label them, a mamologist could tell them apart. Every one of those changes is a classic component of domestication syndrome. Not a single one of them is what you would expect from a wild predator. If you visited a London street corner at 3:00 in the morning and watched the foxes come out of the shrubbery to work the bins, what you would be watching is Belellv's experiment running at a scale of a whole city without a cage, without a researcher, and without a plan. These foxes were not deliberately bred. Nobody is running a Belellv experiment on the streets of Bristol. The city itself is the experiment. The environment selects generation by generation for the fox that can tolerate humans without panicking. That fox eats better. That fox breeds. Its descendants inherit whatever combination of physiology and psychology allowed the parent to stay calm at a distance of 10 m from a passer by. And over enough generations, the population starts looking like the beginning of a domesticated animal. The same thing is happening to raccoons. A recent study led by Rafael Allesh at the University of Arkansas at Little Rock analyzed nearly 20,000 images of raccoons from across the continental United States. The researchers looked at snout length, one of the classic domestication syndrome markers.

[00:16:28]What they found was that raccoons in cities and suburbs had on average measurably shorter snouts than raccoons in rural areas. It was not a huge difference. It did not need to be. It was the direction of the difference that mattered. Urban raccoons were beginning to move down the same road that Belaidav's foxes had traveled in the lab. The explanation Leesh gave for the pattern was almost blunt. Raccoons love our trash. It is a rich, reliable, loweffort food source. All they have to do is put up with our presence long enough to raid the can. The raccoons that can put up with us feed better.

[00:17:04]Their kits inherit whatever made mom calm enough to hop the fence. Over time, the population slides toward tameness, and the developmental package that comes bundled with tameness slides in alongside it. This has been going on so long in some places that it has produced strange side effects that are only now being cataloged.

[00:17:26]In the Florida Keys, there is a subspecies of white-tailed deer called key deer that has lived in close contact with people for generations.

[00:17:36]Key deer are compared to their mainland cousins less afraid, more social, more fertile, and unusually large for their body plan. In other parts of the United States, urban white-tailed deer have been documented showing splotchy or piebal coats and even albinism at rates well above what you see in remote populations.

[00:17:58]Wildlife biologists have started collecting anecdotes of what they politely call deformities, including short legs, unusually long tails, and asymmetric jaws in the urban and pybal populations.

[00:18:11]If you have read this far in the video, you already know how those deformities sound. They sound like the neural crest hypothesis in the wild without a laboratory. They sound like a landscape doing to a wild deer what Bellev did to a silver fox. The deer that live inside Phoenix Park on the north side of Dublin are one of the best documented cases of this in the world because the same herd has been studied continuously for years.

[00:18:38]The park is home to a freeranging population of fow deer and researchers who have followed them notably Simon Chi and his collaborators have found that the herd sorts itself into two distinct behavioral types. There are the deer that scientists have labeled acceptors.

[00:18:55]These are the bold individuals, roughly one in five in the population that will walk up to a visitor, sniff at an outstretched hand, and take a piece of bread if it is offered. And there are the avoiders, the shy ones, who keep their distance from anyone on two legs.

[00:19:11]The avoiders behave the way a wild fellow deer is supposed to behave. The acptors do not. What the more recent work on that herd has shown is more startling than the boldness itself.

[00:19:23]Boulder mother deer. The acceptor mothers choose to give birth in less concealed sights, closer to the paths where humans walk, closer to the picnic areas, closer to the roads. They are in effect trading the ancient predator avoidance strategy of concealment for a new one. They are hiding their fawns in plain sight near the humans because being near the humans is now safer than being far from them.

[00:19:52]Which brings us to the strangest twist in this whole story and the one that changes what domestication means. There is a concept in wildlife ecology called the landscape of fear. It says that prey animals do not just perceive predators, they perceive risk. They form a mental map of where the danger is and they adjust their behavior according to that map. In a normal forest, the safe places are the ones without wolves. The scary places are the ones with wolves. The prey animals move accordingly. But when a new predator arrives on the landscape, a bigger one, the map changes. The prey animals over time learn that the biggest predator scares off the smaller ones.

[00:20:33]And if they can find the sweet spot near the biggest predator, where they are just tolerated enough not to be eaten, they can use that predator as a shield.

[00:20:43]That is what modern prey animals have started doing with us. Unulate.

[00:20:47]Researchers have documented white-tailed deer and moose in North America giving birth close to houses and villages, apparently deliberately because black bears and wolves and mountain lions do not want to come that close to a human structure. Bear cubs in some parts of Yellowstone hang around the edges of visitor areas because larger male bears, which are dangerous to cubs, avoid people.

[00:21:09]California pumas that live near the suburban edge kill more deer per capita than pumas in remote areas. Apparently, because they are so anxious about being interrupted by a human that they abandon carcasses early and have to hunt again sooner. The whole system is now rearranged around the human presence at the top of it. For a prey animal that is willing to tolerate humans, this creates a startlingly positive feedback loop.

[00:21:35]The calmer you are near people, the more you can exploit the safe zone they create. The more you can exploit that safe zone, the better fed you are and the more likely you are to reproduce.

[00:21:46]The more you reproduce, the more calm around humans genes you spread into the next generation. And the calmer that generation is, the more they benefit from the shield. Round and round it goes for as many generations as the pattern holds. And this is not just deer.

[00:22:03]Coyotes in North American cities show more exploratory behavior and less fear-driven caution than their rural counterparts. And the difference is not just learned. It is measurable across individuals raised in similar conditions. Urban rats behave differently than rural rats in subtle heritable ways. Even pigeons, which we barely think of as a species anymore because they are so ubiquitous, are the descendants of rock doves that self- selected for calmness around humans about 5,000 years ago. The animals that are still afraid of us are statistically the ones that live in the shrinking places where we are still absent.

[00:22:40]Everywhere else, we are running a very slow, very quiet, very unintentional version of the silver fox experiment on the entire vertebrate class. But that is only one of the ways we have been shaping other animals evolution. And it might not even be the biggest one. The second way is subtractive. It is the version of the story that happens whenever we start systematically taking a particular kind of animal out of the population. Fishing does this. Hunting does this. Poaching does this. And in every case what we take is not random.

[00:23:15]It is size. It is horns. It is tusks. It is antlers. It is whatever we consider a trophy or a catch. The Atlantic cod is one of the clearest cases in the world.

[00:23:27]For most of the 20th century, industrial trwers off the coast of Newfoundland and in the Baltic Sea hauled up cod by the hundreds of thousands of tons. The nets they used were sized to catch large fish. The small fish, by law and by mesh size, slipped through. That meant that any cod that reached breeding age at a smaller size than its neighbors had a very significant advantage. It was not caught. It reproduced. Its offspring inherited the slower growth rate over about three decades. According to the researchers who have measured this, the average size of a 4-year-old cod in the Gulf of St. Lawrence dropped by roughly 20%. This is not a change in nutrition.

[00:24:07]It is not a change in habitat. It is a change in the genes of the cod population driven by the fact that anything above a certain size class was for practical purposes sentenced to death by trwler. Fishing did not just remove big cod, it bred them out. The Baltic cod tells the same story and a genetic study published in 2025 documented shifts in genetic markers consistent with smaller body size becoming the norm in the population.

[00:24:32]Something similar has been reported for Atlantic salmon. Prehistoric salmon vertebrae recovered from upper paleolithic sites on the Iberian Peninsula show larger fish at every age than modern Iberian salmon reach today.

[00:24:46]We have been taking the big ones for so long that the fish have started to be smaller before we ever get to them. The same principle applies on dry land and one of the best studied examples in the world lives on a piece of high country in Alberta called Ram Mountain. Ram Mountain is home to an isolated population of big horn sheep. And starting in the 1970s, it was also home to one of the most intensive trophy hunts for large horned rams anywhere in North America. A trophy hunter looking for big horn wants one specific thing.

[00:25:16]They want a ram with horns large enough to be called four fifths or full curl.

[00:25:21]Those are the rams that get their heads mounted. Those are the rams that hunting permits are written for. Those are the rams that Ram Mountain used to produce reliably generation after generation.

[00:25:32]Then the horn started shrinking.

[00:25:34]Researchers led by David Colman and later Fonnie Pelier and Marco Fesa Biance monitored the population for more than four decades. The average size of a set of horns on Ram Mountain declined by more than 20% across that span. Body mass declined too, apparently because the genes for large body size and the genes for large horns are correlated.

[00:25:56]When intensive trophy harvests were finally reduced, the decline stopped. It did not reverse. The genes for large horns had at least partly been shot off the mountain. This is not because the rams had learned anything. This is because trophy hunting is by its nature an inverted natural selection. In the wild, rams with the biggest horns win the most fights and mate with the most use. In a hunted population, rams with the biggest horns are removed before they finish breeding. The rams that live longest and therefore breed longest are the ones whose horns never got big enough to attract a rifle. Their sons inherit smaller horns. Their grandsons inherit smaller horns still. And within about five generations, you have a herd of animals that look meaningfully different from the herd their great great-grandparents belong to. Which brings us finally to the most extraordinary case of this happening in a modern large mammal. It happened in Mosamb beek and it involved elephants.

[00:26:53]For 15 years from 1977 to 1992, Mosambique was gripped by a civil war.

[00:27:00]Armed forces on both sides financed their operations partly by killing elephants and selling the ivory. In the region that would later become Gorangosa National Park, the elephant population collapsed. Before the war, there were somewhere around 2,200 elephants there.

[00:27:17]When the war ended, there were fewer than 200. 90% of the population had been shot for their tusks. Under any other circumstances, that would be the end of the story. A 90% population collapse, a slow recovery, a conservation tragedy.

[00:27:34]But something strange was going on in the survivors. Before the war, tuskless female elephants had been a genetic oddity in the Gorangosa population.

[00:27:43]Fewer than one in five females were born without tusks. It was a rare trait produced by a specific mutation and it did not confer any particular advantage in a normal environment.

[00:27:55]Tusks are useful. Elephants use them to strip bark from trees, to dig for water and dry river beds, to leverage each other during dominance disputes, and to defend their calves. A tusked elephant is in every practical sense a better equipped elephant than a tuskless one.

[00:28:13]But during the war, a tuskless elephant was from a poacher's perspective invisible. No ivory meant no bullet. And so generation by generation, as the tusked elephants were killed and the tuskless ones survived to breed, the frequency of tusklessness in the surviving population shot upward. Among the mature female elephants who lived through the war, more than half were tuskless. Among the daughters those females had after the war, about a third were being born without tusks. A 2021 paper by Shane Campbell Staten and colleagues published in the journal Science worked out the genetics. The trait for tusklessness in these elephants turned out to be linked to a gene called AML X which sits on the X chromosome and is involved in tooth enamel development. Because it is on the X chromosome and because the mutation is dominant in females but lethal in males, the entire genetic legacy of the war has been rewritten into the female half of the population. Male elephants that inherit the mutation die before they are born. Female elephants that inherit it live and grow up without tusks and pass the trait to about half their daughters.

[00:29:23]within a single elephant generation. In other words, the population of Gorangosa National Park was permanently reshaped by a genetic bottleneck imposed by human beings with rifles. That is a rate of evolution that biologists 100 years ago would have said was impossible in a species with an elephant's lifespan. And this is where the story turns from being merely interesting to being genuinely uneasy. Because those tuskless elephants are still elephants and they still have to survive and they cannot do the things that tusks are for. They cannot dig for water as well. They cannot strip bark.

[00:29:57]They cannot spar. The females who inherit tusklessness live but they live differently. They eat differently. They occupy different microhabitats.

[00:30:05]Some early research suggests they even socialize slightly differently. Their whole ecological role in the savannah has been quietly rewritten by a war they never saw. Elephants are what ecologists call ecosystem engineers. They knock down trees. They clear under brush. They dig water holes that other animals then use. They shape the physical structure of the landscapes they live in. When you take away their tusks, you do not just change what an elephant looks like. You change what the savannah looks like over centuries. You change the plant communities. You change the animals that depend on the plant communities. You change everything downstream.

[00:30:44]We do not fully understand what those downstream effects will look like yet because the tuskless generation of Gorangosa is only now reaching adulthood. But the researchers who work there have started using a phrase that captures the situation. They call it evolutionary rescue with an ecological cost. The trait that saved the population from extinction may end up remaking the entire system the population lives in. Step back for a moment and put those three lines of evidence next to each other because they are the same story told three ways. The urban foxes, the raccoons, the key deer, and the Phoenix Parkow deer are being selected generation after generation for tolerance of humans. They are becoming functionally what Blev's foxes became in a laboratory. Not tame exactly, not domesticated in the full sense, but sliding measurably down the same neural crest slope, getting weirder in the same set of ways. The cod, the salmon, the ram mountain rams, and the gorangosa elephants are being selected in a different way, but in the same direction. They are being sifted generation after generation for whatever traits happen to make them invisible or uninteresting to us. smaller bodies, smaller horns, missing tusks. The bigness, the ornament, the projection that used to signal fitness has become a liability.

[00:32:06]The animals that survive are the ones that fail to signal. And then there is a third layer running underneath both of these, which is that the old predators of these prey animals, the wolves and the pumas and the bears are being pushed to the margins by us. The landscape of fear has been redrawn with human beings at the top and the safe zones now radiate outward from the places we live.

[00:32:27]Prey animals that can tolerate our presence get to use those safe zones.

[00:32:31]Prey animals that cannot do not. Every one of these forces pushes in the same direction. They push toward a prey animal that is smaller, less ornamented, less afraid of people, more able to raid our food waste, more willing to raise its young near us, and more likely to display the physical signatures of domestication syndrome as a side effect.

[00:32:54]All three forces select for the same phenotype. All three forces are being applied by us. And all three forces have been applied at increasing intensity for the last few centuries with no sign of easing anywhere on the planet. You could reasonably ask at this point whether that is a bad thing. And the honest answer is that biologists are still arguing about it. In some cases, the changes seem to help the animal. A tuskless elephant that lives is better than a tusked elephant that dies. A calm fox that eats is better than an anxious fox that starves. But in every case, something is being lost. A trait that took millions of years to build is being erased in decades. And once the genes for a big horn or a large tusk are gone, they do not come back on their own. The Ram Mountain researchers, when they wrote about their big horn sheep, used a phrase that has stuck with a lot of the people who work in this field. They called what was happening to the sheep an undesirable evolutionary consequence that would be extremely difficult to reverse. Even after the hunting pressure eased, the genes for large horns did not come back. Evolution is not symmetric.

[00:34:09]It is much easier to lose a phenotype than to rebuild one. There is one more thing worth saying about this whole pattern, and it is the part that turns the entire video essay in on itself.

[00:34:20]Modern humans compared to our ancient ancestors of even 50,000 years ago show physical traits that look suspiciously like domestication syndrome. Our skulls are more delicate. Our faces are shorter. Our brow ridges are reduced.

[00:34:34]Our teeth are smaller. Our brains are on average slightly smaller than they were during the peak of the plea scene. Our reproductive cycles are extended. Our behavioral repertoire compared to a chimpanzee or a Neanderthal is dramatically more tolerant of strangers, more prone to cooperation, more patient with novelty. A genomic analysis published in 2017 by researchers including Cedric Boex compared selective sweeps in modern humans with those in domesticated species and found statistically significant overlap in genes involved in the neural crest. The strongest version of this idea put forward most forcefully by the primatologist Richard Rangham is that our species self-domemesticated.

[00:35:20]Rangum's argument is that early human groups executed the individuals in their communities who were violent, aggressive or unmanageable.

[00:35:28]The calmer, more cooperative individuals bred. Over enough generations, humans became the animal we are today, which is startlingly gentle by primate standards, capable of sitting shoulder-to-shoulder with total strangers on an airplane, capable of forming societies of millions of unrelated individuals without immediate violence. Every one of those traits in Rangom's argument is a symptom of the same syndrome we are watching appear in the foxes of Bristol and the deer of Dublin. Which means that we are not just observers of this process. We are part of it. We are the animal that domesticated the wolf and the wild cat and the cow and the sheep. And we are also apparently the animal that domesticated itself first. The changes we are now imposing on the prey animals of the modern world are in a strange sense the same changes we long ago imposed on ourselves. And the mirror runs in both directions. When you watch a deer walk through a suburban driveway without looking up, you are watching something that is beginning to look like us in the specific evolutionary sense that it is beginning to be shaped by the environment humans create rather than the one nature built. There is one open question left and biologists do not have a firm answer to it yet. The question is what happens if the pressure lifts? If humans hypothetically stopped hunting elephants for ivory, stopped trollling for large cod, stopped occupying the urban and suburban environments where foxes and raccoons now live, would the animals evolve back? Would the tusks return to the elephants? Would the horns grow back on Ram Mountain? Would the deer of Phoenix Park stop begging for bread? The best evidence we have suggests the answer is no, or at least not quickly. The Ram Mountain rams, once the hunting pressure was reduced, stopped losing horn size, but they did not regain it. The genes were simply gone from the population.

[00:37:25]The Gorangosa elephants in the two decades since the war ended are still producing daughters at a higher rate of tusklessness than the pre-war population ever showed because the mutation is now baked into the surviving mothers.

[00:37:38]Evolution moves in one direction very readily and in the other direction very reluctantly.

[00:37:43]What we have selected for in the animals of the modern world is going to be with the biosphere for a very long time, probably longer than any of us will be alive to see. Which leaves us with the driveway in Cleveland and the deer at 3:00 in the afternoon and the mail truck. That deer is not an accident.

[00:38:01]That deer is not a curiosity. That deer is what a prey animal looks like at the end of a very long, very quiet experiment that has been running on the entire biosphere for a few thousand years. And that has now become the dominant evolutionary pressure on most large vertebrates on Earth. That deer is what happens when the biggest predator on the landscape decides on purpose or by accident to reshape the animals below it. And if you want to know what a modern prey animal looks like on a planet ruled by a hyper social tool using citybuilding, garbage producing primate that is itself in the middle of a self-domemestication event that started before recorded history. Look at that deer. Look at the fox in the pub garden. Look at the raccoon on the balcony. Look at the tuskless elephant in Mozambique. Look at the cod that will never grow as long as its great grandmother. They are not the animals their ancestors were. They will not be the animals their descendants are. And the reason for that in every case is that we are here. The strange thing when you sit with it long enough is realizing that we are no longer separate from natural history. We are the part that is bending it. And every animal that manages to live near us. From the fox on the tube platform to the elephant on the Mosamb beek savannah is being quietly rewritten in our image at the level of the skull, the coat, the tooth, and the temperament whether we ever notice or not.