Around 30,000 years ago, deep within a cave in France, ancient humans drew a series of animals in charcoal. A group of elegant, fearsome cave lions. A herd of woolly rhinos with giant horns, some locked in battle.
A long-eared owl engraved in clay, with its head swiveled 180 degrees, perched and watching. And perhaps most striking of all, a panel of majestic horses in profile, all painted by the same artist. These are the oldest known paintings of horses ever discovered. They're first of many that show up again and again in cave art from Europe, from around 30,000 to 12,000 years ago. In fact, according to some estimates, horses are the most frequently represented animal in the art of this period.
Back when those paintings were made in France, in the cave now known as Chauvet, horses would have been a source of food for people, as well as artistic inspiration. But over time, our relationship with horses would shift. They would become our companions, and the literal workhorses behind the rise of many cultures and civilizations.
But do these ancient artworks depict horses? the same wild horses that we eventually domesticated? And do our modern horses descend from just one domesticated population?
Or did it happen many times in many places? Answering these questions has been tricky, as we've needed to bring together evidence from art, archaeology, and ancient DNA. Because as it turns out, the history of humans and horses has been a pretty wild ride. At its heart, the story of horse domestication has been so mysterious for so long because good evidence has been really hard to come by.
For one thing, the wild horses depicted in ancient artwork, the potential ancestors of modern horses, no longer exist. Which might sound weird, because there are plenty of horses that live in wild herds across the world today. But these are all descendants of domestic horses, the subspecies Equus ferris cabalis, that were released or escaped. We call these feral horses, as opposed to lineages of horses that were never domesticated, which we call wild horses.
And at the genetic level, feral horses are still indistinguishable from domestic horses. The only potential wild horse that's still around is an endangered subspecies, Jowalski's horse, also known as the Taki or Mongolian wild horse. And I'm pronouncing it that way because that's how Sir David Attenborough pronounces it, and he gets the final word with me.
Although also I have heard it called the Peahorse, which, for what it's worth, Smithsonian calls it the Peahorse. What was I talking about? Okay, so today there are only a few thousand of them spread across several populations in Europe and Asia.
And we're still debating whether or not these horses were ever domesticated, at any point in time, by anyone. If not, then they're the only living horses that could truly be described as wild. They're the last living insight into what the ancient wild horse populations of Eurasia might have been like.
And they bear a striking resemblance to the most ancient depictions of horses, with their short, stocky necks and rigid, bristly manes. You gotta hand it to those ancient artists, they just really nailed it. But, Zywalski's horses don't bridge the gap between those ancient artworks and our modern horses.
Because the genetics are pretty clear, they're not the ancestors of modern domestic horses. They don't even have the same number of chromosomes. So where did modern horses come from?
Well, for a while we thought that they might trace back to a 5,500-year-old settlement in Kazakhstan called Botai. And in one of our earlier episodes about horse evolution, we even said that that place was the origin of modern domesticated horses. But the science has changed a lot since then.
Starting in 1993, archaeologists began finding a huge number of horse remains around Botai. And in 2009, They reported the discovery of pottery that contained chemical residues from horse meat and milk fat. They even found horse teeth with wear patterns that suggested that the horses had been bridled and maybe even ridden.
But then, in 2018, the connection between Bowtie's horses and our modern horses was challenged by geneticists, who took another look at the remains. They concluded that the horses from Bowtie had little to no genetic connection with modern horses. In fact, they were indistinguishable from Zhevolsky's horses.
And then, in 2021, researchers re-evaluated the teeth. and argued that those wear patterns could have happened naturally. They even found similar patterns on the teeth of ancient wild horses that had never come into contact with humans.
They proposed that the people of Botai hadn't domesticated horses at all, but instead were just harvesting them from the wild for food. So we still don't know for sure when the first domestication of horses took place, or how many times it happened. After all, it might be that many different cultures domesticated horses independently and just didn't leave behind any evidence, either archaeological or genetic. But thanks to a huge study of ancient DNA, we finally have a good understanding of the domestication event that really matters to us, the one that gave rise to all of our modern horses.
In a paper published in 2021, a team of over 160 researchers sequenced the genomes of 273 ancient horses from across Eurasia, covering the last 50,000 years. And they found that, up until around 4,000 years ago, Eurasia had a diverse community of wild horses with a lot of genetically distinct lineages spread across the region. Then, pretty suddenly, one lineage of horses just disappeared.
exploded, spreading rapidly across the continent and replacing other horses as it went. This sudden shift marked the rise of the domestic lineage that all of our modern horses descend from. And the researchers were able to pin ...point the origin of this lineage to the region of what's now Russia, around the Volga and Don rivers. There, around 4,200 years ago, people began domesticating and breeding those horses in huge numbers. Okay, but so what made these particular horses, the direct ancestors of our modern ones, so successful?
Well, it seems that they had some key genetic variants that breeders probably selected for. One of the variants changed the function of a gene called GSDMC, which seems to be involved with the spine, potentially giving these horses a stronger back. making them ideal for carrying the heavy weights of people, chariots, and goods.
Another one affected a gene called ZFPM1, which is actually involved in the brain chemistry that affects mood regulation, possibly making the horses less anxious and skittish, and more docile, so they were easier to handle and breed. By around 3500 years ago, the modern domestic horse had spread far and wide across Eurasia and replaced the other populations of horses. And today, their descendants all over the world come in many different shapes and sizes. From small ponies to massive draft horses, who can all trace their homeland back to the grassy steppe of Russia over 4,000 years ago.
Without these horses, human history would probably be unrecognizable to us. Nearly everywhere they went, they transformed the way we traveled, farmed, and waged war, almost overnight in evolutionary terms. And we still find horses just as fascinating and beautiful and mesmerizing as those ancient artists in France did 30,000 years ago.
We're not horsing around when we thank this month's Eontologists. Chase Archambault, Colton, Mikhail Afridi, Annie and Eric Higgins, John Davison Ng, Jake Hart, and Melanie Lamb Carnevale. By becoming an Eonite at patreon.com slash eons, you can get fun perks like submitting a joke for us to read, like this one from Philip. What kind of candy do paleontologists like? Popping rocks.
I mean, yeah, okay. And as always, thank you for joining me in the Konstantin Haase studio. Subscribe at youtube.com slash eons for more journeys in deep time.