Transcript:

[0:04]

[Music] I want to read you a story — one I read as a young man in the mountains of Northern California, mining gold with my dad. That was his summer hobby, and we didn’t have the internet; we didn’t even have cell phones back then. But we had books. And this book series left such an impression on me that, when it comes to the domestication of the horse, this story has always stuck with me.

[0:29]

Now, to set the scene — we talked about equus, all the different species. So this is the last recent Ice Age, the height of it — maybe 30,000 years ago. At the base of these ice sheets were valleys. The valleys were fruitful; they were full of animals, full of life, full of plants, full of trees — but also plains. Lots of grasslands. Horses — equus ferus, the wild horse at the time — were doing extremely well. And humans were living next to Neanderthals.

[1:10]

Ayla was a young woman surviving by herself with her equid companion that she had raised since she was a little foal. Here we pick up the story:

[1:23]

She drew in her breath, pursed her lips, and, concentrating on it, let out a long, solid whistle. Winnie tossed her head, whinnied, and pranced to her. Ayla stood up and hugged the horse’s neck, suddenly realizing how much she had grown.

“You’re so big, Winnie. Horses grow so fast. You’re almost a grown woman horse. How fast can you run now?”

Ayla gave her a sharp slap on the rump. “Come on, Winnie, run with me!” she motioned, starting across the field as fast as she could. The horse outdistanced her in a few paces and raced ahead, stretching out as she galloped. Ayla followed her, running just because it felt good. She pushed herself until she could go no further. Panting to a breathless halt, she watched the horse gallop down the long valley, then veer around in a wide circle and come cantering back.

[2:22]

“I wish I could run like you,” she thought. “Then we could both run together, wherever we wanted. I wonder if I’d be happier if I were a horse instead of a human. I wouldn’t be alone then. I’m not alone — Winnie’s good company, even if she isn’t human. She’s all I have, and I’m all she has. But wouldn’t it be wonderful if I could run like her?”

[2:45]

The filly was lathered when she returned, and Ayla laughed when she rolled in the meadow, kicking her legs in the air and making little noises of pleasure. When she got up, she shook herself and went back to grazing. Ayla kept watching her, thinking how exciting it would be to run like a horse. Then she fell to practicing her whistle again. The next time, she managed a shrill, piercing sound. Winnie looked up and cantered to her again. Ayla hugged the young horse, pleased that she’d come at the whistle, but she couldn’t get the thought of running with the horse out of her mind.

[3:19]

Then an idea struck her. Such an idea would not have occurred to her if she hadn’t lived with the animal all winter, thinking of her as a friend and companion. And certainly, she would not have acted on such a thought if she were still living with the clan. But Ayla had become more used to following her impulses.

“Would she mind?” Ayla thought. “Would she let me?”

She led the horse to a log and climbed up on it, then put her arms around the horse’s neck and lifted a leg. “Run with me, Winnie. Run and take me with you,” she thought, then straddled the horse. The young mare was unaccustomed to weight on her back, and she flattened her ears and pranced nervously. But though the weight was unfamiliar, the woman was not, and Ayla’s arms around her neck had a calming influence. Winnie almost reared to throw the weight off, then tried to run away from it instead. Breaking into a gallop, she raced down the field with Ayla clinging to her back.

[4:14]

But the young horse had already had a good run, and life for her in the cave was more sedentary than usual. Though she had grazed the standing hay of the valley, she hadn’t had a herd to keep up with or predators to run from — and she was still young. It wasn’t long before she slowed, then stopped, her sides heaving and her head drooping. The woman slid off the horse’s back.

“Winnie, that was wonderful!” Ayla’s eyes sparkled with excitement. She lifted the droopy muzzle with both hands and laid her cheek on the animal’s nose, then tucked the mare’s head under her arm in a gesture of affection she hadn’t used since the horse was small. It was a special embrace, saved for special occasions. The ride was a thrill she could hardly contain. The very idea of going along with a horse when it galloped filled Ayla with a sense of wonder. She had never dreamed such a thing was possible — no one had.

[5:19]

That was a passage from The Valley of Horses by Jean M. Auel. Some of you might have recognized that, or recognized the story. The first book, The Clan of the Cave Bear, is part of the Earth’s Children series — one that made a huge impact on me as a young adult. I just go back to that scene when I think of the first human to jump on the back of a horse, and it makes me think it had to be something similar to that — possibly where the horse was raised by humans from a young age, where there was some sort of trust. Or it could have been that the animal was more tame and somebody decided to hop on the back to see what would happen, how long they could hold on, or how far they went.

[6:15]

At some point in history, somebody was the first to do that. And I really believe that book passage brings that out. As we mentioned in the first episode, when we domesticated the horse, everything changed for us. Humanity changed. It changed your life — even if you’ve never worked with horses or touched a horse in your life — it did. It changed everything.

[6:46]

It’s interesting to study the process of how this happened and when it happened. That’s what this episode is going to tell us. It also goes into why we should care about this topic — because understanding their history and the process of domestication makes your connection to the horse that much stronger. You can look at your horse and go, “Wow. I know your history. I see you. I know you.” Or you can look at your donkey, or if you have a hybrid — a mule — you can connect with them and think, “Wow, I get it now.”

[7:31]

That’s why we talk about it — because their history is so tied up in their behaviors, their physiology, their identity as domestic horses, donkeys, or mules. Another important aspect — and I’ve read this quote in a previous podcast — is where the author said the domestication of the horse about 5,500 years ago represents one of the most important technological innovations in the ancient world. And they argued there’s really nothing since that can trump it.

[8:01]

Now, maybe fire — humans discovering fire — probably trumps horses by a nudge. I’ll give it a nudge, okay. But I would still argue that once horses were domesticated, it changed everything. It changed the game. It changed our trajectory.

[8:30]

Another reason to care — and something I found particularly interesting when doing the research, reading recent papers and scientific publications — is an aspect I’d never really thought about. For many of you listening, speaking English, not only our genetics but our languages can be traced to the spread of horses, in spreading the Indo-European languages around the planet. And this dates back thousands of years, shaping individual cultures — whether European, Asian, African, or Pacific.

[9:16]

Here I am, living in New Zealand — all have been directly impacted by the domestication of horses. So, telling their story also tells us a little bit about ourselves.

[9:28]

Before we get going, I just have a couple of terms I want to explain. We use the term “wild” and then we use the term “feral.” When it comes to horses, wild animals — or true wild horses — are animals that, in their natural state, have been without human interference or selective breeding. Of all the horses left, Przewalski’s horses are considered wild. Now, there is a little debate on that, and we’re going to get into it in this podcast, because some of the evidence of early domestication talks about Przewalski’s horses — and it’s really interesting. I’ll get there in a minute.

[10:11]

Outside of horses, if we go into the non-cabaline equids, we have the wild asses and the zebras. Zebras are obviously wild — they have been tamed, but they were not domesticated.

[10:29]

Now, the “wild” horses in the western United States, or the massive herds in Australia, or in other parts of the world — the ones we call wild horses — are not truly wild. They have been domesticated for thousands of years, selectively bred to be domestic and tame. What that means — what domestication means — I’ll touch on in a minute. But really, they’re feral. Feral animals are ones that were domesticated but have reverted to their “wild” state. You could call it semantics, but when you really dig into it, it makes sense.

[11:19]

In the United States today, you can adopt Mustangs — wild horses — and they can be trained and ridden relatively easily because, generation after generation, they still carry that domesticated genetic background. The true Equus ferus wild horse no longer exists.

[11:44]

The final piece of this is “tame” — what it means to tame an animal. These are wild animals that are habituated to humans, or trained to be habituated to humans, or tolerant of us. They don’t flee like any wild animal normally would. But they are still wild and can revert to their wild state relatively easily. For example, zebras have been tamed; Asian elephants are not domestic, but they have been tamed to work with humans in parts of Asia.

[12:25]

Now, the process of domestication — I’ll try to make this as tangible and digestible as possible, because it is very complex. It’s a long process, taking many generations to domesticate any species. The specific definition is: “To adapt an animal or plant — because plants can be domesticated too — over time from a wild or natural state, especially by selective breeding, to life in close association with and to the benefit of humans.”

[13:11]

Anthropologists have said that the domestication of animals and plants is one of the most important advancements of our species. They rank it up there with fire, tool use, and language. It has been that important to us and has changed our history so deeply. This is especially true with our relationship with the horse.

[13:41]

Domestication is complex. There’s a study some scientists have called one of the most important scientific studies of the 20th century — the classical study of the silver fox. The reason I bring up the silver fox in a horse podcast is because this study demonstrates how wild animals have been domesticated, and it helps explain why our horses and donkeys look and behave the way they do. This study has given us so much insight into the process of domestication that we can infer what it might have looked like for the horse.

[14:37]

For over 60 years, a team of Russian geneticists have been running this experiment — from the 20th century into the 21st. The experiments are still going, and with genetics, we’re learning even more. The project began in the Soviet Union in 1959. It was the brainchild of Dmitry Belyaev, but the lead researcher — still working today in her 80s — is Lyudmila Trut. She’s an incredible scientist and one of my idols. Reading about her research and persistence — especially when the project was nearly shut down in the ’60s — is inspiring.

[15:45]

They started with wild silver foxes and hypothesized that in the early stages of all animal domestication, early humans — with horses, for example — must have chosen the calmest and most pro-social animals toward humans. They called this “tameness.” If you had ten silver foxes, they’d select the ones least aggressive, least stressed, and most tolerant of people. You can imagine with wild horses — the ones chosen to domesticate were probably less flighty and less aggressive.

[16:51]

The silver fox was a good subject because its generation interval is only one year — they reproduce quickly. In contrast, for horses, it’s about 10 years; for humans today, it’s about 30 years (historically about 25). So with horses, six generations to achieve noticeable tameness would take about 60 years. That’s already two to three human generations — meaning the knowledge of breeding and selection had to be passed orally from parents to children to grandchildren.

[19:00]

In the fox study, within six generations — just six years — the foxes were still not domesticated, but they would lick handlers’ hands, allow petting, whine when humans left, and wag their tails when approached. Within 10 generations (a decade), physical changes appeared — floppy ears, curly tails. In horses, that would take 100 years.

[20:09]

By 15 generations — 150 years in horses — the foxes had lower stress hormones and smaller adrenal glands, meaning a reduced stress response. Even their nervous systems were changing. By generation 40 — which would be 400 years for horses — the foxes were considered fully domesticated. They also had changes in coat color and markings.

[21:08]

So for horses, this suggests it took at least 10 human generations — and probably longer — to fully domesticate them. And remember, this was in a controlled, modern scientific study. Thousands of years ago, the process may have been slower, but it gives us valuable insight: domestication wasn’t something that happened in just two or three breeding cycles — it was a long, multi-generational endeavor.

[21:55]

You have a domestic horse — it took hundreds and hundreds of years for this to happen. Again, that’s why this story is so fascinating. So where do we start with today’s horses? I know last week, with the rise of Equus, we were talking about Hagerman’s horse giving way to all of the horses we have today. All domestic horses trace their lineage back to Equus ferus — the wild horse. Scientists think it looked somewhat like the Przewalski’s horse, but with a darker coat pattern — maybe brown or black, not the dun color we see in Przewalski’s today. They went extinct in the wild because we took them out and domesticated them.

[22:43]

There are other wild types — the Mongolian Przewalski’s horse is still around, and then there was the tarpan, which went extinct in 1909. That was another wild horse, a separate species.

[22:57]

Science is detective work — it takes a lot to do these studies. What I love about science is it’s full of debate; things are constantly evolving and changing. One study — and I used to teach this to my students — is not the truth. You need to repeat it, and repeat it, and repeat it. For example, here in New Zealand, let’s say I find a plant, feed it to someone with cancer, and they get cured. If I say, “I’ve cured cancer, and it’s this plant,” other scientists would need to take that plant extract, run multiple studies, and confirm my results. If they can’t, my study is dismissed. One study does not make a truth.

[23:48]

The study of horse domestication has fascinated people because of its importance to human history. The general consensus about a decade ago was that domestication began with the Botai people of northern Kazakhstan — in Central Asia, just south of central Russia. The Botai were hunter-gatherers who became sedentary. They had settlements, horse meat was a major part of their diet, and 5,500 years ago they were surrounded by horses. Evidence suggested they domesticated them — structures that may have been pens, large numbers of horse bones, and other signs.

[24:57]

In 2009, a major multi-agency study (US, UK, France, Russia) concluded this was the site of the earliest horse harnessing and milking. One key piece of evidence was bit wear on a stallion’s tooth — the lower second premolar had a band of wear in the cementum and enamel consistent with a bit, likely made of hard leather. They also found degraded animal fats on pottery, identified through analytical chemistry as likely horse milk fats. And you can’t milk a wild horse — having milk fats suggested some level of tameness or domestication.

[28:01]

But about ten years later, genetics turned that idea upside down. In 2018, a huge study with over 46 authors, published in Science, analyzed ancient genomes from Botai horses. They found these were actually Przewalski’s horses — not Equus ferus. This meant the Botai may have tamed Przewalski’s horses, then those animals went feral, which would mean today’s Przewalski’s horses are not truly wild, but feral descendants. However, Przewalski’s behavior — highly reactive, difficult to tame — suggests they retain strong wild traits. Modern domestic horses only have about 2.7% of their DNA from Botai/Przewalski stock, so the Botai were not the primary source of today’s domestic horse.

[30:16]

This raises the question: are Przewalski’s horses truly wild? I lean toward “somewhat wild.” All 2,000 alive today were once under human care; 50 years ago they were extinct in the wild. They’ve been selectively bred, but not for tameness — rather, for genetic diversity from what was left. Their wild genes are likely still strong.

[31:08]

A recent paper titled Rethinking the Evidence for Early Horse Domestication at Botai casts further doubt. One sign of domestication in herbivores is a skewed sex ratio — many females to few males, as in modern breeding. But Botai sites show a 1:1 sex ratio, suggesting hunting rather than controlled breeding. The bit wear evidence could be natural wear; one tooth from one horse is not conclusive. The vertebrae show no signs of load-bearing (riding or pulling). Many horse bones have arrowhead damage, again pointing to hunting.

[33:38]

I kept thinking — what about the milk fats? You can’t milk a wild mare, can you? But human remains from Botai show no dietary milk proteins in their dental calculus. So those “milk fats” could have been other animal fats with similar chemical profiles.

[34:17]

So, were the horses domesticated in Botai? Probably not. It probably wasn’t. That means we still don’t have a completely clear picture — but we do have a good idea of where horses were first domesticated. Now that Botai has been largely eliminated as a strong contender, scientists are looking elsewhere.

[34:46]

One promising lead comes from studying human history and migration patterns. The culture they look at is the Yamnaya — pastoral people who kept herds of animals on the Pontic-Caspian Steppe, in modern-day Ukraine. About 5,000 years ago, there was a massive migration of these people, along with the spread of Indo-European languages. This expansion reached into Andalusia, southwestern Asia, Europe, Africa (including Egypt), southeastern Asia, China, Mongolia, and Siberia.

[35:37]

Linguistics is one way to trace human migration. I’m not a linguistics expert, but it’s fascinating — here I am in New Zealand, speaking English because Britain settled here. We also have Te Reo Māori, which is making a comeback, but English remains part of everyday life — just as it has spread worldwide.

[36:21]

Archaeological evidence is also important — sex ratios in horse remains (more females, fewer males), settlements with pens that could hold horses, bit wear in teeth, vertebral wear from carrying loads, evidence of horse milk in human diets, and even skeletal changes in human hips and backs from riding. Riding changes our physiology, and those changes can be seen in skeletal remains.

[37:21]

Genetics is the big one. Evidence from around 2200 BC — about 4,200 years ago — strongly indicates that horses domesticated in this region were the forerunners of most domestic horses today. We can trace the spread of their genetics outward from here. A study in Nature titled “The Origins and Spread of Domestic Horses from the Western Eurasian Steppe” shows how their genes expanded across Eurasia.

[38:08]

It’s like ancestry.com — but for horses. Based on DNA, domestication is estimated between 4,600 and 5,500 years ago. By 2200 BC, there was a massive expansion across the Eurasian steppe, spreading domestic horse genetics into Europe, Asia, and possibly Egypt. It took hundreds of years to create truly domestic horses, so they must have been in use locally long before spreading globally.

[39:55]

Another part of the story that’s often overlooked: donkeys. They were being domesticated almost simultaneously — but in a different part of the world. About 7,000 years ago, the wild asses of East Africa (Kenya, the Horn of Africa, the Somali wild ass) began to be tamed. By 5,500 years ago, donkeys were fully domesticated and traded into Egypt and other parts of Africa. Within 2,500 years, they had spread through Europe and Asia, developing into many breeds. Archaeological remains of donkeys dating back nearly 7,000 years have been found in Egypt and Southwest Asia. Mules — donkey-horse crosses — also appear thousands of years ago.

[41:42]

To finish this up — bridles were important early on, but for thousands of years, most people rode horses bareback or with a simple blanket. Saddles didn’t appear until about 2,700 years ago, first with the Assyrian cavalry in 700 BCE, giving them a huge advantage in warfare. Even then, there were no stirrups. Riders had to be exceptional horsemen, using legs and seat for control. Stirrups — a massive aid — didn’t appear until around 200 BCE in India, and even then, they were crude toe supports. The first modern-style stirrups appeared around 200 AD in China and Mongolia, allowing riders like Mongolian archers to stand and shoot from horseback.

[44:19]

One last fun detail — people were selecting coat colors thousands of years ago. About 4,000 years ago, chestnut, black, and silver coats were being bred for deliberately. My personal favorite is blue roan — but that’s for another day.

[45:02]

To summarize: the domestication of Equus ferus gave rise to Equus caballus — our modern horses. And I always like to imagine that first human — maybe 30,000 years ago, maybe longer — in the cold wind, taking a leap of faith, jumping onto a horse’s back, holding the mane, and feeling that exhilaration. That moment happened, and every day we’re getting closer to knowing exactly where and when.

[46:13]

I’ve been diving deep into research papers to update my knowledge on this, and it’s such a fascinating topic. I hope you enjoyed this podcast on the history of domestication. Next week, we’ll start exploring who our horses are today, then move into what it’s like to be a horse. We’ll return to history from time to time — breeds, coat colors, and anything else fascinating that crosses my desk.

[47:16]

You can find us on Instagram and Facebook at Mad Barn, or email us at podcast@madbarn.com. At madbarn.com, you can read over 400 science-based articles written by our PhDs, DVMs, and graduate students. We’re working to get this information out to as many people as possible. Thanks for listening, and stay tuned for the next episode.