Why are there no wild cows?

Think about it. The domestication of the dog didn’t  lead to the extinction of the wolf.

The ancestors of most domesticated  mammals – goats, sheep, dogs, cats, pigs –   they're still out there. And horses are a whole situation. But most of them are still around.

So why not cows? The ancestor of domestic  cattle, the aurochs, is extinct. Recently, though.

It has the dubious honor of being the  first historically documented extinction. It went the way of the dodo in 1627,  shortly before the dodo itself in 1662. So the question is: Why was it  able to hang on for so long?

But also, paradoxically: Why  did it go extinct at all? And also… Is it gone for good? See, there are plans in the  works to bring the aurochs back,   by piecing together its DNA from modern cattle.

This is more than a simple scientific curiosity. And it’s more than guilt about being the reason  the animal went extinct in the first place. The proponents of this de-extinction program  have the future of all of Europe in their sights.

They say they need the aurochs to  save the continent’s entire ecosystem. It’s ambitious. It’s controversial.

And it’s already happening. My name is Michelle Barboza-Ramirez, and  I usually host SciShow’s sister channel, Eons,  where we talk about all things deep time. I’m here today to talk about  extinctions … and new beginnings.

We’re going to take a deep dive into  humanity’s long relationship with the aurochs.  A relationship that might not be over. [♪ INTRO] Ok, first, a quick linguistic note. We’re going to be talking about the aurochs,   and yes, that word ends with an  s in the plural and singular. The English word aurochs comes from  German, and has been used to refer   both to the animal we now know as the  aurochs, and to the European bison.

In older Germanic languages, it was called  the ur, which the Romans changed to urus. We’re not totally sure what it means,   but it might refer to either the color  red or to the animal’s masculine power. Anyway, that s does belong there.

Think of it like the word  “ox” but with extra steps. But why are we talking about cows at all? Humanity has an ancient  relationship with the aurochs.

If you mainly think about  cows as the adorably round,   placid critters from the Harvest Moon  games, first of all, I love that for you. But second, let me adjust your  expectations a little bit. [Wright] Humans have been long  fascinated with this animal,   I think because of its huge size  and its really distinctive horns. That’s Lizzie Wright, an archaeozoologist who  studies humanity’s relationship to cattle.

And we have admired their ancestor the aurochs   for at least as long as we’ve had  the ability to make art about it. The cave paintings at Lascaux in France,   which might be about 17,000 years old, feature  beautiful and lifelike renderings of aurochs. A Proto-Indo-European myth from  about 6,000 years ago suggests   a cow was present at the creation of the universe.

But even as cattle were domesticated, we  continued to revere their wild cousins. The Hebrew Bible mentions aurochs when it says,   “God, who brings them out of Egypt, is  like the horns of a wild ox for them.” Julius Caesar described aurochs this way: “Those animals [are] called uri. These are a little below the elephant in size,  and of the appearance, color, and shape of a bull.

Their strength and speed are extraordinary;   they spare neither man nor wild  beast which they have espied. [...] But not even when taken very young can  they be rendered familiar to men and tamed. The size, shape, and appearance of their  horns differ much from the horns of our oxen.” An Anglo-Saxon runic poem from  the ninth century CE reads: “The aurochs is fearless and large-horned; a fierce animal – it fights with its horns – the famous marsh walker; it is a brave animal.” And even now that aurochs are gone,   we still name our sports teams after cows  to demonstrate the athletes’ prowess. Think of the Chicago Bulls or the Texas Longhorns.

We even pit ourselves against  them in feats of strength,   as our ancestors have done for  generations, at bullfights and rodeos. So the idea I want you to have in  your head is that cows mean power. That very association is what doomed  the last population of aurochs.

But I’m getting ahead of myself. Let’s talk about what an aurochs was, and how  they’re different from the cattle we know today. [Wright] The aurochs was the extinct  ancestor of domesticated cattle,   and they were similar to domesticated  cattle, but they were large. And they had these kind of horns that  came out kind of pointing forward like this.

The aurochs, scientific name Bos primigenius,   first shows up in the fossil record about  700,000 years ago in what is now Tunisia. And if you want to know what they looked like,   you actually can’t go wrong  looking at those cave paintings. Though it’s a bit harder to render the  shape of the horns in two dimensions.

We know that the bulls were much larger  than the female cows, and they were huge. Caesar was probably exaggerating a bit when  he said they were the size of an elephant,   but some bulls could reach 180 centimeters  at the shoulder, or nearly six feet. The bulls would also have  been dark brown or black,   while the females were a lighter reddish color.

They would have had powerful builds and  cute little curls on the top of their heads. Most importantly, they had very distinctive horns. In contrast to most modern cattle breeds,   the horns of aurochs pointed forwards  and curved in toward each other.

They would have been light  in color with darker tips. At their peak, aurochs would have occupied most of Europe, all of North Africa and the Middle East,   India, and parts of Asia, possibly  extending all the way to China. That wasn’t always the case, since  they weren’t big fans of the cold.

During periods of glaciation, they would have  been pushed into refuges in southern Europe. At some point, though, something began to change. Humans didn’t necessarily stop hunting them,   but they did start keeping them confined  for their meat, milk, and leather.

This domestication happened twice: once in the  Fertile Crescent more than 8,000 years ago,   and once only a little more  recently in the Indus Valley. This led to the two kinds of cattle we have today:   taurine cattle, the ones that include  that cute black and white dairy cow you’re   probably thinking of, and the humped  zebu cattle that originated in India. This development was great for  folks who enjoy cheeseburgers.

But for the aurochs, it wasn’t so hot. [Wright] Wherever farming was adopted, humans   had a larger impact on their  local landscape than ever before. And so that's also where a massive impact  would have been had on the aurochs. This opening up the landscape for  growing crops and for livestock grazing,   their habitat would have become more restricted.

They would have had less space to roam around. All around the world, aurochs  populations began to decline. We know very little about  what became of them in Asia.

They must have survived in India  long enough to be domesticated,   but we don’t know much more than that. In Africa, very early Egyptian  depictions of cattle have horns   with the distinct aurochs shape,  while later ones point upward. However, fossil evidence seems  to suggest that wild aurochs in   North Africa didn’t make it past 6,000 years ago.

In Mesopotamia, they survived  into historical times,   with aurochs hunts documented  in the first millennium BCE. However, by the start of the medieval period,   aurochs were gone everywhere but Europe –  central and eastern Europe specifically. The question is why.

Although overhunting has been  blamed, Wright is skeptical. [Wright] In terms of the overhunting thing,  I think it's unlikely to be this primarily. We don't have evidence that they were  being hunted in very large numbers,   not from archaeological sites anyway. So it would be a bit strange if that was  the main reason why they went extinct.

It just seems like hunting pressure  wasn’t the number one thing. After all, if you need a side of beef,   why go hunting for it when there’s already  one munching grass in your backyard? Instead, it seems to be more related  to the indirect pressure of humans   and their cows taking up all the best space. [Wright] Their extinction correlates  with changes in the landscape related   to the introduction of agriculture  and other domesticated livestock.

In the areas where they survived the  longest, and so Central and Eastern Europe,   Poland and Germany, primarily, the areas did seem  to be those with less human disturbance,   and these areas actually became their favoured  area from the Neolithic period onwards,   to be honest, and when they became  a lot scarcer in Western Europe. The very last group of aurochs – that we know  of – was managed in Poland’s Jaktorów Forest. And they were managed.

The king’s men maintained them as his property  for the purposes of hunting them for sport. [Wright] In some places, they were  maintained in areas so that the elite   could go and hunt them on a kind of more  staged basis rather than for subsistence. So that's the kind of context in which  they go extinct, is where that population   was being kept alive so that royals  could essentially go and hunt them,   more than them just surviving  in their favoured bit of forest. In other words, in an ironic twist,   the aurochs only survived for as long  as it did because of human management.

Not out of compassion for their welfare,   but for the prestige of hunting  these powerful trophy animals. The very last aurochs bull was killed in 1620. We still have one of his horns.

It was taken as a trophy and turned into a hunting  horn, and now resides at a museum in Sweden. That horn reveals a secret about  the decline of the aurochs. In 2018, a genetic study revealed that he  had domestic cattle among his ancestors.

It seems that aurochs survived as long as  they did in part by interbreeding with cattle. With no remaining males, the species was doomed. The last remaining cow, the very last  aurochs, is believed to have died in 1627.

So that’s it. The end of the line for the aurochs. We valued it.

We admired it. We tamed it. And in the end, we killed it.

Story’s over. Go home. Unless… No, it can’t end like this!

There has to be more to the story. And there is. We’ve talked about what an aurochs  looked like and where it lived.

But we haven’t talked about its ecology – what  it ate, what kind of habitat it preferred. And that’s going to be the most  important part of our story by far. So important, it could shape the  future of an entire continent.

But to understand why, we need to  stop talking about cows for a minute. Instead, we’re going to talk about a very  controversial approach to conservation. When an animal goes extinct, it  doesn’t simply vanish without a trace.

The aurochs left a cow-shaped  hole in their ecosystem. A hole that had previously  interacted with predators,   with plants, with the flow of  energy through the entire food web. That loss of energy flow can be profound.

Big herbivores like aurochs eat a lot of plants. They also trample, and wallow, and poop. Their daily lives change the shape of  their habitat, sometimes in massive ways.

If big cows trample and eat all the  seedlings, a forest will never grow. To understand how the loss of the  aurochs affected the landscape,   we first need to know what that landscape was. So, remember the poem that called  the aurochs a “marsh walker”?

And that forest in Poland,  Jaktorów, was pretty swampy. From the historical information like this,   you might infer that aurochs  preferred to live in wetlands. However, scientists now doubt that conclusion. [Wright] I think it's a bit misleading to look  at that last population of aurochs in Poland   as an example of, you know, that's the kind of  habitat that they would have wanted to live in.

That was a kind of marshy area with  some deciduous woodland and the kind   of wild isolation of this environment is often  cited as the reason that they survived there. Wright is not the only person who thinks  so, which brings me to our next guest. [Goderie] Well, that that's the  story of domesticating the animal   and then pushing the animals back  into forests, back into marshes. They can survive there, but  it's not the optimal habitat.

The optimal habitat is drier grassland, the  mix of drier grassland and open forests, et cetera. That’s Ronald Goderie, an  ecologist and director of   the Grazelands Rewilding Foundation,  and we’ll come back to him later. The point is that aurochs probably preferred  open grasslands, maybe mixed with forests,   but were pushed into more marginal  habitats by human activities.

Open grassland, mixed with forests. There’s a problem with that conclusion, though. See, for a long time, there was a broad  consensus that for most of its history,   Europe was heavily forested with a dense  canopy, until humans cut the trees down.

There’s plenty of historical  evidence to support this notion. Let’s ask our friends the Romans again. Caesar wrote frequently about how much trouble the   dense forests gave him in his  campaign against the Gauls.

And other writers, like Tacitus, also  described dense forests and marshes. That makes it seem like at least by  2,000 years ago, Europe was a forest. Other lines of evidence support  a forested Europe as well.

But in recent years, that  consensus has been challenged. [Goderie] And it must have been what I always say,   a kind of cooler version of what we now  still know of, what Africa looks like. A mix of woodlands, but also open  areas, savannah and steppe-like. And not so much a closed, the European  landscape was not so much a closed forest   before we had a big influence on the landscape.

And there's quite some circumstantial  evidence that it must have been this way,   because we've still got a lot of species  that are adapted to open landscapes. So how would they have survived in the  evolutionary sense without open landscapes? There must have been open landscapes.

Goderie also cites other evidence,   like plants that are adapted to regrowing  after being trampled by herbivores. In general, there’s a growing movement  of people who support the idea that   Europe was not a closed-in forest, but a  park-like mix of forests and grasslands. And the reason that closed forest  never grew was because herbivores   like the aurochs ate or trampled the seedlings. [Wright] They were grazers  and maintaining open habitats   that support a wide range of plants and  animals, and thus increasing biodiversity.

So they would have been part of a process where   kind of a rich mosaic of open  landscapes was maintained. But they would have been doing it alongside other large herbivores as well,   red deer, bison and and some others. The idea is that some trees would  establish themselves eventually,   in areas defended by thorny plants  that those animals didn’t want to eat.

So patches of forest would grow up, only to  eventually die to fire and disease, maintaining   mixed open landscapes that could support  more biodiversity than closed forest alone. Now, where am I going with this? Well, a lot of European land  has been converted to farms.

But a lot of that farmland has  subsequently been abandoned. And people would like to  restore it to its natural state. But to do that, they need to know what the natural  state was: dense forest or mixed grassland.

And if it was grassland, it’s because big  grazing animals maintained it that way. No grazers, no grassland. Maybe you can guess the conclusion some people  reached: What if… grazing animals again?

Then… grassland? This is going to take a second to explain. So, stick with me.

This approach to conservation is called rewilding. Rewilding seeks to restore  the function of ecosystems. Now, that doesn’t necessarily mean reverting  them to a pristine state from the past,   but rather, putting all the parts back  together to create a functional whole.

Usually, what they mean is putting  big animals back where they belong. Rewilding is often described as being “top-down.” Some conservation strategies are “bottom-up,”   focusing on how things like climate  or vegetation affect the ecosystem. Rewilding instead proposes that big animals,   especially carnivores but also big  herbivores, have such profound effects   on their environment that replacing them  will have ripple effects all the way down.

In this example, you’d be replacing large grazing   animals to support the return of  a mixed forest-grass landscape. Rewilding was originally proposed around “the  three Cs”: cores, corridors, and carnivores. Meaning core wilderness areas connected by  corridors that animals could travel along,   all managed from the top by  the presence of carnivores.

Rewilding also tends to envision  limited human management,   at least once things reach a stable state. It calls for rebuilding functioning  nature, and then leaving it the heck alone. It’s not as simple as tossing  an animal into an environment   and asking it to sort things out for  us, but it’s a little bit like that.

Although I should probably note there’s  a lot of discussion in the field of   what rewilding really is, and what it should do. I’ve only sketched out the broad strokes. Indeed, some rewilding approaches and  strategies can get downright kooky.

Imagine driving down the freeway in North America   and seeing a cheetah or an  elephant out your window. That’s the vision proposed  by Pleistocene rewilding. Some restoration efforts in North America try to  reset things back to right before the year 1492,   when some guy named Chris set  off with a couple of boats.

The people who proposed Pleistocene  rewilding say: That ain’t good enough. After all, humans were managing the  environment in North America long before that. Just not European humans.

Instead, Pleistocene rewilding says: A lot  of big animals went extinct beginning with   the end of the Pleistocene epoch,  right around 13,000 years ago. Even though that seems like a long time to  us, in evolutionary time that is a blip. That means the animals and plants we have  today evolved alongside those extinct animals.

They’re supposed to be here. They should be present in the ecosystem,   providing all of the functionality that  carnivores and big herbivores normally would. And so, what do you do?

You introduce the closest equivalents. If you can’t make your own woolly  mammoths, store bought is fine! Throw in some lions and cheetahs to replace the  extinct North American lions or saber-toothed   cats, maybe a camel or two, and you’ve  got your very own Pleistocene menagerie.

Now of course, this is the  point where I should note   that no one is actually serious about doing this. Well… almost no one. And even the people discussing this  strategy can see obvious flaws,   like the need to keep large and potentially  dangerous animals contained, or the fact that   African elephants would have a rough time  surviving winter in the Rocky Mountains.

Rather, this is a thought experiment. An inquiry into what North America would  look like with its ecosystem fully intact,   the way it was thousands of years ago. Now, the conclusion of that thought experiment  is that we can’t truly turn back the clock.

But we should be willing to entertain radical  strategies to try to ensure the future. Which brings me to the kinder, gentler cousin  of Pleistocene rewilding: trophic rewilding. It’s still focused on restoring  the flow of energy through food   webs – that’s what trophic means –  but with slightly fewer elephants.

The goal of trophic rewilding  isn’t exactly to restore an   ecosystem to what it was like in the past. After all, things change, and especially  with climate change going on, it’s more   important to promote biodiversity  and the capacity for biodiversity. It’s pretty open-ended, but  that’s kind of the point.

Humans aren’t deciding what the final state is. They’re just giving it the ability to get better. And unlike Pleistocene rewilding, this  one has been tried in quite a few places.

Some initiatives have introduced  non-native species, but in less   dramatic fashion than the Pleistocene approach. Think tortoises, not elephants and lions. Other times, a species has been returned to  its native range where it had been absent,   or domesticated animals are used  in place of their wild equivalents.

And we’re going to get into both of those. The first one is a place in the  Netherlands called Oostvardersplassen. Oostvardersplassen, or OVP for short,  began in 1968 when a section of land   was reclaimed from Lake IJssel in the Netherlands.

A 6,000 hectare slice of this reclaimed land was   left undeveloped and was eventually  converted into a nature reserve. The area proved irresistible to rare  native birds and quickly became a   flourishing pocket of nature tucked  in amongst otherwise developed areas. An ecologist named Frans Vera saw an opportunity   to test the hypothesis that Europe  had once been grassy, not forested.

And in the rewilding fashion, he decided  to use large herbivores to prove his point. He introduced horses and cattle to take the  place of extinct wild horses and aurochs. The horses he used were Konik horses, a breed that   at the time was thought to resemble the  extinct wild horse called the tarpan.

The cattle were… well, he chose a very specific kind  of cattle for a very specific reason. But we’re going to come back to those. And at first, this was a screaming success.

It’s fair to say we learned a lot about how  herbivores can maintain open landscapes from OVP. For example, one paper from 2014  shows how the establishment of   woody species first increased at OVP, then  decreased as herbivore populations grew. And a 2015 study likewise suggests herbivores   prevent trees from establishing, well, a little too well, and that two of rewilding’s   three C’s – corridors and carnivores  – might help the trees get a toehold.

But in 2018, everything came crashing down. There had been public outcries for many years  over the treatment of the animals in the reserve. The place was totally fenced in,   and during harsh winters the animals had no  way to leave for literal greener pastures.

And human management? It was minimal, merely culling  animals who got too weak. There was no supplemental food,  and shelter was only added later.

As a result, during harsh winters, hundreds or  thousands of cattle, deer, and horses could die. And the public hated it. They didn’t see a self-regulating  wilderness at work.

What they saw was downright animal cruelty. Eventually, the pressure proved too much and  the rewilding experiment at OVP was shut down,   and the area is now a game reserve. And there does seem to be agreement in  the literature that OVP was mismanaged,   however, that doesn’t mean OVP proves the  concept of rewilding itself is invalid.

Mostly because it… kinda did rewilding wrong? I mean, the definition of  rewilding has changed over time,   but as a starting point let’s look at  how the three C’s worked at OVP anyway.

Cores: The “cores” proposed by  rewilding should be as big as possible,   and at 6,000 hectares, OVP just isn’t very big. Corridors: The animals  literally had nowhere to go. There was supposed to be a corridor connecting  OVP to the outside, but it was never completed. And Carnivores: There weren’t any of those either!

If carnivores had been keeping herbivore  populations in check in the first place,   maybe they wouldn’t have crashed so badly. Now, combine that with the management decisions  that led to the culling or starvation of   thousands of animals, and yeah, this is more of  an administrative problem than a science problem. The science could still work, and  other reserves based on OVP do exist.

But researchers warn that  we risk a repeat of history,   and that a fourth C – compassion – should  guide our approach to animal welfare. Thanks for watching SciShow! You help our non-profit bring more  educational videos to more people   every time you watch, comment, share,  and tell people about a SciShow video.

And now you can get something beautiful too. We made a very nice t-shirt to go along  with this wild story about wild cows. So you can support SciShow and our  work spreading aurochs knowledge,   and other knowledge, while  you liven up your wardrobe.

The original art designed by our very own Elliott  Zheng was inspired by the Lascaux cave paintings. And you can get it cave colored or vintage  white to fit whatever vibe you’re feeling. The shirts are on sale now  at Complexly.store/aurochs.

And it's spelled differently than how it's pronounced It's at Complexly.store/a-u-r-o-c-h-s. See you there! So that’s the very mixed success of OVP.

But what happens when a native predator  is reintroduced to its historic range? Now some of you, like me,  might have been thinking,   “Where’s the bit where they get  to the wolves in Yellowstone?”. Well, this is the bit where we  get to the wolves in Yellowstone.

If you’re familiar with this project,  you might know it as a huge success. As the story goes, elk populations  were out of control in Yellowstone,   but wolves cut them down to size. And of course, carnivores being one of the  three C’s, reintroducing a top carnivore   and inducing changes in the food web is  absolutely textbook rewilding— [MacNulty] In the— In the context of Yellowstone,  the wolf reintroduction in Yellowstone,   that actually came before the whole  concept of rewilding was even coined.

The reason why wolves were  reintroduced to Yellowstone   and to central Idaho back in the  mid 1990s was because the wolf,   the northern Rocky Mountain wolf population was  a listed entity under the Endangered Species Act. It was motivated purely by the legal  requirements of the Endangered Species Act. …Oh. Huh.

That’s Dan MacNulty, a professor  of ecology at Utah State University   and kind of the guy you want  to talk to about this stuff. Not only was the wolf reintroduction in  Yellowstone National Park not a rewilding   exercise, but the managers actually  worried that the wolves would kill too   many of the elk and have a negative  economic impact on local hunters. But even though rewilding wasn’t the motivation,  wolf reintroduction still provides an   opportunity to test another of rewilding’s  hypotheses: that of the trophic cascade.

Recall that the word “trophic” refers to  the movement of energy through food webs. So a trophic cascade is when you make  a change at the top of the food web,   and that change cascades all the way down. [MacNulty] It's the idea that a predator has  indirect effects on the resource that a prey uses. So if we're talking about carnivores,  herbivores, and plants, a trophic cascade   is an indirect effect of the carnivore  on the plant that the herbivore eats.

Here’s what’s supposed to happen: The wolves  introduce pressure on herbivores, mostly elk,   who were putting too much pressure  on plants like aspen and willow. If wolves eat the elk, or even just scare  them away from where plants are growing,   they ease the pressure on those  plants and the plants can recover. And this does appear to have happened.

But the extent of it is unclear. [MacNulty] And so that's one of the questions  that's being debated still, quarter century later. And then we're also debating  the strength of that cascade. it shows up in some places. Some plants in some places are recovering.

But not all plants in all places,   and the question is why and we really don't  have a rock solid answer to that question. Let me give you an example. In 2025, a paper came out called  “The strength of the Yellowstone   trophic cascade after wolf reintroduction.” This paper claimed to find a 1500% increase in the   crown volume of willow trees – a  way of measuring their recovery.

MacNulty and others dogpiled on this  paper for exaggerating its findings,   claiming flawed methodology and conflicts  with other published literature. I mean, according to a different paper from 2024,   the effect of the trophic cascade on  willow trees is actually fairly minor. In other words, this is an  active, even ferocious debate.

And it concerns two related questions:   How much has elk predation by  wolves affected the vegetation? But also, to what extent is the decline  of elk actually the wolves’ doing? After all, there are other  carnivores in Yellowstone. [MacNulty] The expectation though is that  wolves have that power to restore vegetation.

But what we're seeing in  Yellowstone is like, well,   the bit of change that we are seeing  can't be attributable all to wolves. Other players are involved  like these other predators. And we're trying to work out what the  contributions of all those other predators are.

That's probably one of the biggest myths  we've I think been reasonably successful   at challenging over the last, say, 10 years or  so is that this isn't just a wolf system, folks. This is a cougar system, you know mountain lions. It's a grizzly bear system.

It's a black bear system. Maybe it shouldn’t surprise anybody to  learn that food webs are complicated. And the thing is, there’s more than just  food webs making up a given ecosystem.

A trophic cascade can only do so much. [MacNulty] This is kind of humbling to say  this, but based on the measurements we've made,   the total land area covered by Aspen  in Northern Yellowstone National Park,   has actually shrunk since wolf reintroduction. And overall, that the study area is  predicted and has been shown to become more   warm over the last 30 years, warmer, drier,  less hospitable to a plant like an Aspen. So it's this notion that, you know,  wolves can't fight climate change, right?

I mean, that's really something that's  on us as human beings to deal with. You know, wolves are not the ecological  silver bullet if you're looking to,   you know, bring back your aspen forest  or bring back your willow forest. You need to do other things  in order to bring that back.

Once again, none of this totally invalidates  the hypotheses proposed by trophic rewilding. There is more than likely some sort  of trophic cascade in Yellowstone. And I think having wolves there, as  opposed to not having wolves there,   is a good thing for biodiversity!

But what this story does tell us is there  is a lot we need to pay attention to beyond   introducing an animal to a system and  hoping it will clean up our messes. And before we move on, I want to point to one  or two other slight problems with rewilding. One is the risk of human-animal conflict.

Rewilding seeks to create relatively autonomous   landscapes with large carnivores  operating in a natural state. But people have always feared wolves for a reason. Safety is an important concern  with any rewilding project.

Also, every project has to account  for different stakeholders, not all of   whom are going to be crazy about turning  large animals loose in their backyards. [Wright] Another thing around rewilding is that  it doesn't take place in a political vacuum. You know, it needs backers, it needs  support, both politically and financially. And there are people for and against it.

For example, in Britain, this issue with the lynx   is because sheep farmers don't want  to lose their sheep, essentially. But at the same time, we have a  massive red deer issue and they   have to go out and like physically  cull them because there's too many. So it would be good to have a carnivore  around to do some of that work for us.

But the farming lobby is very strong. So you always have to have in mind that there's  all of these different players in the process. There are also just some straight  up issues with the idea that large   herbivores always naturally maintain grasslands.

African forest elephants, for example,  live in – you will never guess – forests,   in places like the Ivory Coast. Even rewilding advocates say  they’d like more evidence. Still, it’s pretty clear at least that  herbivores do shape the landscape around them. [MacNulty] Yeah, herbivores have  a tremendous ecological effect.

There's all kinds of examples of this  from Africa with things like elephants,   et cetera, hippo, massive  effects on the environment. And the aurochs, well, it is gone. See, I told you we’d come back to cows.

Let’s go ahead and say we’re at least willing  to test the hypotheses of trophic rewilding. That we’re willing to see what aurochs  used to do for the environment,   and what they would do if they were still around. People have tried to use domestic cattle in  their place, at OVP as well as elsewhere.

But what if we didn’t have to compromise? What if we could bring the aurochs back? Back from the dead, and back to its  rightful place in the ecosystem,   where it could – theoretically –  restore the wilderness of Europe?

Let’s talk de-extinction. So, you know how I said we were gonna  come back to the cattle used at OVP? As it turns out, those cattle represent an attempt   from the first half of the twentieth  century to de-extinct the aurochs.

It’s not a very good attempt, and…   Ok look, the number of Nazis in a story  about cows should be zero. Unfortunately, the number of Nazis in this   story about cows is more than  zero, and in fact, it is two. It’s not gonna be that heavy,  but if you’d rather just skip it,   we’ll provide a timestamp on the  screen that you can jump ahead to.

Ok. It’s time to talk about the  brothers Heinz and Lutz Heck. The two of them each started a breeding program  where they chose domestic cattle and bred them to   try and produce something that would recapture  their view of what the aurochs had once been.

They did it separately from each other,  which is weird, but I guess we shouldn’t   assume that just because they’re brothers,  they’d also be research collaborators. [Wright] So, my understanding of it is that  the original motivation was pre-war,   it was pre-Nazi Party, and they wanted to  show people what the aurochs looked like and   essentially create a spectacle for the public. And then of course the Nazi party came along   and one of the brothers was quite  good mates with Hermann Göring,   and helped him in this vision to recreate  the kind of Nazi ideology around ancient,   pure German landscapes and with all of these  large animals roaming around to be hunted. In addition to their garbage politics,  though, their science was… iffy.

Let’s call it iffy. [Wright] One of the things that they've been  criticized for is that there's not a clear,   they weren't very clear about  why they were choosing the species— the breeds of cattle that they chose. And there wasn't really any sensible scientific   reason that they gave as to why  they chose these specific breeds. And that’s an understatement.

Seriously, for this piece we read a book called  “Retracing the Aurochs” by Cis van Vuure. It’s out of print, but if you can get  your hands on it, he spends like 40 pages just dragging these two losers for  their bad science and it’s pretty funny. Here’s the short version.

Their criteria for what an aurochs  was, and therefore the goals of   their respective breeding programs,  appear to have been partially made up. They didn’t even agree with each other  on what their cow should look like. They chose breeds to cross with one another,   but they didn’t provide much of a rationale  for why they picked those ones over others.

And then they didn’t even take good  notes on who got bred with whom! Folks, as a wise man once said,   the only difference between screwing  around and science is writing it down! What that means is that we don’t even really  know what went into the Heck brothers’ cows.

We kind of just know they’re cows. Lutz’s cattle don’t seem to have  survived WWII, but Heinz’s did. In fact, they survive to this very day.

They’re at OVP, among other places,  and they’re now known as Heck cattle. They were chosen for OVP because of  their supposed resemblance to aurochs. But that resemblance is dubious at best.

There have been more credible attempts  at de-extinction in recent years. And that’s why we wanted to talk to Goderie. He’s the guy.

He’s that guy! [Goderie] When you're in the Netherlands and you  see one of our herds, you might get the feeling,   especially if you're not very specialized  in cattle breeds, that you're back in time. You see herds high on the legs, large  horns, performing natural behavior. Yeah, those animals really  look like Aurochs already.

They might be a bit higher on the legs still. Maybe the horn shape is not exactly yet what  Aurochs was, but then again, we don't want,   and we aren't able even, to copy exactly what  Aurochs was, because too much has gone lost. But we use Aurochs as a reference, you might say,  to breed the best Aurochs-like population that's   well adapted for the wild circumstances  that European rewilding landscapes ask.

Goderie is responsible for the Tauros Programme:  a breeding project designed to reproduce,   as best as possible, the appearance, ecology,  and behavior of the aurochs… for real this time. Strictly speaking, because this is a breeding  project using cattle, the animals it produces are   also cattle, but they’re cattle designed  to reproduce the aurochs as closely as possible. [Goderie] We chose a name  that's similar, but not aurochs,   because there must have been maybe a  million of those animals, if not more. And of course, the domestication process  went through a very narrow bottleneck.

So you lost that much information  that—no, well—the chance that   you will really get a copy of aurochs are  zero, at least on the techniques we use. So that's why we call it Tauros. Do you remember how I told you the  last aurochs bull had some cow DNA?

Well, the reverse is also true. Wild aurochs DNA snuck into our domestic  cows, especially early on in domestication. There are relatively ancient cattle  breeds kicking around Europe that have   changed fairly little since their domestication.

What this means is that the aurochs may  be extinct, but their genes still exist. And if you can identify those  genes out there in the wild,   you can use an approach called back-breeding,  where you breed together individuals to maximize   the concentration of those genes, until you have  something that has an awful lot of aurochs DNA. In theory, anyway.

At the time, in the mid-2010s,   Goderie and his team had only a  single aurochs genome to work with. They compared this genome to  around 50 modern cattle breeds,   and picked out ten of them with the  most similarity to that one genome. But if we really wanted to rebuild the  aurochs, with those special horns and   all the other characteristics, we’d  need to know what all those genes do. [Goderie] We would really like to know  where, for example, the genes for big horns,   or for a kind of coat color, or for  specific adaptation and behavior to   wild landscapes are located, and  that's still not very well known.

For all kinds of commercial breeds and commercial  traits it is known that we know quite good. If you want to have a cow that produces,  say 15,000 kilo of of milk a year,   we know exactly where those genes  are located and the fat content, et cetera, But we don't know this for the traits  that were very characteristic for aurochs. Unlike some prominent de-exctinction efforts,   these Tauros animals are  not genetically engineered.

The team used genetic tools to identify portions of ancestral aurochs  DNA, but not to put them into the cows. That’s being done by back-breeding. At most, they’re using techniques like  artificial insemination to speed things along.

We asked Goderie how close he  thinks he is to the genuine article,   and how close he thinks he can get. [Goderie] Well, I think we go for 99. X%, because  as I already mentioned, genetically spoken, well,   there's hardly any difference even between  maybe a dairy cow and a former aurochs. But of course, the way the animal  looks, the way the animal behaves,   that's a completely different story.

And that's where we try to get us as close  as can be with the knowledge we have. And of course, the reason he’s doing  this is because the aurochs should   be great at engineering the environment around it. [Goderie] Yeah, that has to do with the  fact that the European landscape, of course,   has dramatically changed the last centuries,  but now again it's changed dramatically. Large areas of Europe are being left by farmers.

So that would mean that  a lot of biodiversity linked   to those open landscapes, you  would lose this biodiversity. Natural grazing is one of  the forces that can change this. Oh, yeah.

It’s rewilding. And while there’s a robust debate to be  had about the ethics of de-extinction,   Tauros cattle are already out there – in several  places in the Netherlands and across Europe. They’re not running around in the wild, mind you.

European law requires them to be managed  as captive cattle, complete with ear tags. They’re in protected conservation areas,  and Goderie’s team works together with   whoever manages that particular nature  reserve to accomplish their goals. When we asked why ordinary domesticated cattle  weren’t good enough, Goderie matter-of-factly   told us that they needed to be able  to defend themselves from wolves.

He’s picturing spaces not just with herbivores,   but with totally rewilded assemblages  of carnivores and everybody else. Gang’s all here. It’s a daring, long-term vision  that’s already in progress. [Goderie] And because those landscapes are  wild landscapes, including big predators,   wolves, bears, you would need animals that  are completely self-defended, self-reliable.

So that's why we think that you need an  animal that should come as close as can   be to what aurochs once was because, well,  it co-evolved with all the big predators,   including lions and tigers and then you name it. Now… are these really aurochs? Even Goderie says we just don’t have access to  enough DNA to put the whole thing back together.

But at the same time, if they’re filling the same  ecological niche, performing the same behaviors,   shaping the landscape around them in  the same way… how much does it matter? It’s rewilding at its finest: Restoring  a functional piece to the ecosystem,   without worrying so much about whether  it’s the same as the old piece used to be. As long as it works, that’s the goal.

Goderie seems very confident that these  Tauros cattle are the way forward. They’ll munch, trample, and poop  their way to a wilder Europe. He sees nowhere to go but up. [Goderie] We aim at scaling up.

We need to scale up in terms of  landscapes and herds and in the end,   in connecting the landscape so that even  migrating patterns might be possible again. And that's easily said, but not easily  done, because of course every square   meter in Europe has an owner and to be  able to get this going is not so easy. Not everyone is as convinced.

Do we really need this one specific  animal – this one admittedly charismatic,   majestic animal, when others might do? [Wright] There is a bit of a question  mark over whether it's worth bringing   back the aurochs because there are these other  breeds that are doing quite a similar job,   as part of a wider network, a wider ecosystem,   and the loss of this one specific large herbivore  could potentially be compensated by other things. And are we bringing back these animals... Is it really going to make a difference?

Is it worth the resource  that we're putting in essentially? The motivations behind what the Heck  brothers were doing wouldn't cut it today. And the biodiversity and rewilding argument  is a lot stronger in my view, of course.

But there is something about the  Aurochs where there's always a bit   of a feeling that people are just  really excited about this big cow. I have to admit… I am! I am excited about the big cow.

But we’re asking the big cow to do a lot. And it’s just a cow, you know? Rewilding seeks self-regulating natural  spaces with limited human involvement.

And look, humans have made a mess. It makes a lot of sense to picture a state of  nature where we undo all the stuff we’ve done,   from soda bottles littering  the ground to microplastics   in the water to carbon in the atmosphere. But if you look at it differently… if  we leave humans out of the equation…   we’re actually leaving the most  powerful tool we have on the table. [MacNulty] Human beings have vast  potential to be ecosystem service   providers to all the animals and plants  on our planet if we put our minds to it.

So I'd say that the most powerful  species by far, we all know this, are humans. To me, what—I see untapped potential  for humans to work together with these   reintroduced species whether it's an  auroch or a wolf or what have you,   it's sort of a team effort to make  ecological restoration happen. So… we can work together with the big cow.

The cow can do what the cow does…  and we can do what we can do. We and the aurochs were  together for thousands of years. It might be nice to be reunited. [♪ OUTRO]