O I was thine, and thou wert mine, and ours the boundless plain,
Where the winds of the North, my gallant steed, ruffled thy tawny mane …
William Henry Drummond, ‘Strathcona’s Horse’
Zorrita was my companion for just three days, and we were very close. We were thrown into each other’s company, but pretty much immediately we understood one another. For that short time, we looked after each other and I grew extremely fond of her. She became a firm friend. But when I said goodbye, I knew I was unlikely to ever see her again.
There was something of a language barrier on that first day, but I quickly learnt to communicate with Zorrita, and she understood exactly what I wanted. Together we trekked along valleys, through rivers and up mountains. She carried me all the way, taking my direction, but picking the best path herself through prickly bushes and up steep, rocky mountain ridges.
I first met Zorrita at the stables on the Cerro Guido ranch, in the Las Chinas Valley, near the Torres del Paine mountains in southern Chile. I was introduced to this horse by a gaucho named Luis. He was dressed in loose, black linen trousers, tall leather boots, a red shirt and a brown jerkin. He wore a black cap with a red cord around it, his tousled long black hair escaping at the back. His stubbled face and his hands were brown and weathered. I guessed he was around fifty, but he could have been younger. He’d clearly spent most of his life outside and around horses. He hardly spoke any English – and I hardly speak any Spanish – but somehow he asked me if I’d ridden before, and I said yes, a little. Zorrita, he told me, was a special horse. A champion. I was excited and daunted as I swung up into the saddle.
I’d grown up with the English way of riding, holding the reins in two hands, fitting feet securely into stirrups, and lifting out of the saddle to gallop. Western-style horse-riding is quite different – you hold the reins in one fist, with just your toes in the stirrups, and sit firmly into the deep saddle when galloping. I’d had a chance to experience this way of doing things before, but some years ago, and it still felt a little alien to begin with. But I settled in quite quickly – what was surely far more impressive was that Zorrita seemed to immediately understand her new rider. After a few minutes, she was perfectly attuned to what I wanted: where I wanted her to go, and how fast. We left the stables and made our way up into a long valley, with snow-covered mountains in the distance. After an hour of walking and trotting, Luis rode up alongside me.
‘Bien?’ he enquired. ‘Muy bien,’ I replied. ‘Gall-op?’ he asked, and before I had a chance to answer, he’d spurred his own horse into action, and I had little option but to do the same with Zorrita – she’d been wanting to run since we’d left the stables – and we were soon flying down the valley, hooves thundering on the turf. It was utterly exhilarating.
After three hours of riding, we reached our destination and set up camp, down by the river. I was hunting for dinosaur fossils with a Chilean palaeontologist called Marcelo Leppe. His site was high up in the mountains above us, and the following day we rode up to it. The first part of the ascent was steep, but over grassy, mossy terrain. As we climbed higher, the vegetation ended and we were riding up an even steeper, dusty and rocky mountainside. It rose up, practically at a 45-degree angle. I looked at Luis, above and in front of me. His horse was perched, seemingly precariously, on the sheer, stony slope. I followed him up on Zorrita. She seemed a little wary at first, testing her footing (her hoofing?) on the rocks. She picked out a narrow trail of her own devising. There were no real paths up here. Her hooves dislodged a couple of rocks and they went tumbling and skittering off down the hillside. I tried not to look down after them. We turned a corner and found ourselves on a more gentle incline – covered in vegetation again. It had been a false summit – we still had some way to go, to reach the fossil site near the top, but the most precipitous, dangerous-looking part was over. I breathed a sigh of relief. In fact, I think I’d been half-holding my breath for most of that tricky ascent.
We reached the fossil site and spent a fruitful few hours collecting surface finds – laid bare by the winter’s snow, now melted, and the wind, which still whipped sand into our faces as we searched for ancient relics. I found a piece of a vertebra of a hadrosaur, a 68-million-year-old duck-billed dinosaur, and several pieces of fossilised monkey puzzle tree – so well preserved that the grain of the wood and even the tree rings were still clear.
Then it was time to go back down to the camp, before darkness enveloped us. The descent was even more terrifying than the journey up the mountainside had been. Now it was impossible not to look down. I stood in the stirrups and leant right back in the saddle. If Zorrita had slipped, both of us would have ended up at the bottom of the slope. I could have dismounted and descended on foot, but I trusted her – and she got me down safely.
What an extraordinary partnership with another being. And it’s one that depends on centuries of humans and horses getting to know each other, working out how to communicate, and establishing trust. It also seems to depend on an innate predisposition of horses – something deep within them – that means, like dogs, they can enter into this inter-species partnership. They’re naturally gregarious creatures. Wherever we stopped en route or at the camp, Zorrita clearly wanted to be close to the other horses. When we were ready to set off, she would nudge the others, pushing her head against their flanks and shoulders, nuzzling their noses. They’d do the same to her. We’d left a couple of the horses tied up at the camp. As soon as Zorrita spotted them on our return down the mountain, she neighed excitedly. They neighed in reply. They were obviously very pleased to see each other.
The gauchos took the horses back to the stables each evening, and rode back up the valley to our camp each morning. On one of the evenings, we heard that they’d managed to catch one of the wild horses, los baguales, that roamed around the Las Chinas Valley. On our last day, we struck camp and rode the horses down the pass. I dismounted in the paddock and tied Zorrita to a fence post, whispering an affectionate farewell to her and patting her shoulder. She stood there calmly as the rest of the expedition arrived, and all the horses were tied up in a line along the fence.
The bagual was standing in a corner, tethered away from the others, with a basic rope bridle. His black mane and tail were splendidly long. He looked more curious than frightened, but his life as a creature of the wilderness was at an end. His feral nature would be tamed. He’d be a fine addition to the stables, I could see that. And there, he’d be protected from pumas, and fed plenty of hay. Still, I couldn’t help feeling a little sorry for him.
As I walked off and closed the gate behind me, Zorrita had a magnificent tantrum. I like to think it was because I was leaving. She reared up with such force that she pulled the stout fence post clear out of the ground. A raucous rumpus broke out, neighing and flying hooves, but the gauchos ran in and quickly held ropes and soothed the tired horses. Zorrita had been lucky not to injure herself, and she soon calmed down. She was tame enough, but still wild in her heart.
The wild horses of Chile seem to belong in that untamed landscape – as much a part of the wild, natural country as the guanacos, pumas, armadillos and condors. And yet the ancestors of the bagual that the gauchos caught in the Chinas Valley could only have been there for a few hundred years. For thousands of years before the Spanish and Portuguese arrived there had been no horses in the Americas. The ancestors of the baguales were domesticated – they are not truly wild horses, but feral.
And yet, going much further back in time, there were plenty of horses and earlier, horse-like creatures, roaming the Americas. In fact, the origin of this group, and many of its numerous branches, was in North America. The evolutionary history of horses and their ilk includes great proliferation of an ancient family tree, and diversification – as well as a harsh cutting back of many branches, until just a fraction of the splendid, ancient diversity exists today.
Horses are classified as odd-toed ungulates (hoofed animals). Now, it’s not that their toes are strange, just that they only have one of them, an odd number. Rhinos and tapirs are also odd-toed ungulates, or Perissodactyla – but with three toes. The fossil record of the Equidae, the family which includes modern horses, goes back some 55 million years – starting with the dog-sized Eohippus of North America. These early equids were still in possession of several toes on each foot – three-toed on their front feet; four-toed on their hind legs. Over time, they’d lose them all except one. With plenty of fossils to show the gradual loss of toes, this classic example of evolutionary change in anatomy is enshrined in biology textbooks.
At times of low sea level, early horse-like creatures could spill out of North America, across the Bering land bridge into Eurasia. There was an early expansion of small, leaf-eating equids out of America into Asia around 52 million years ago – but the descendants of those pioneers later died out. The family tree of horses goes crazy in the Miocene – the geological epoch that lasted from 23 to 5 million years ago. North America filled up with a huge range of horse-like animals of different shapes and sizes: some leaf-eating browsers, some grazers – all fleet of foot. By five million years ago, the fossil record of equids incorporates more than a dozen distinct genera – groups of species – of horse-like creatures, including the three-toed Merychippus, Pliohippus, the earliest one-toed horse, Astrohippus and Dinohippus (the ancestor of modern horses), to name just a few. Again, some – like Sinohippus and Hipparion – spilled out, across Beringia, into Asia.
At the beginning of the Miocene, North and South America were separated by a large body of water, called the Great American Seaway. In the middle of the Miocene, volcanoes at the bottom of the Seaway created a scatter of islands between the Americas. Sediment gradually accumulated around the islands, until eventually the Isthmus of Panama was created. The emergence of this land bridge allowed plants and animals to spread from North to South America, and vice versa. The migrations peaked around 3 million years ago in what has become known as the ‘great American interchange’. And as part of it, horses expanded down into South America. The first to arrive belonged to the genus Hippidion – a separate, now extinct lineage. They were funny-looking little horses with short legs. By a million years ago, Hippidion would be joined – in South America – by true horses, Equus caballus – essentially the same species as our domesticated horses today.
The tale of the equid family is one of severe pruning as well as burgeoning proliferation. Of all those diverse genera in the Miocene, only one lineage made it through to the present day: the genus – Equus – to which all the living horse-like animals belong, from actual horses (officially: caballines) to asses, donkeys (the domesticated descendants of the African wild ass) and zebras. Geneticists have been able to extract and sequence DNA from a horse bone preserved in permafrost in the Yukon, dating to 700,000 years ago – the oldest genome yet. Based on the differences between that ancient genome and those of modern equids, the geneticists have concluded that the Equus lineage originated around 4 to 4.5 million years ago. Then the caballine and the zebra–asses lineages diverge away from each other about 3 million years ago.
Some 2 million years ago, an expansion out of America saw the ancestors of modern asses and zebras arriving in Asia, spreading to Europe and down to Africa. Then, some time after 700,000 years ago, the ancestors of our modern horses also traversed the Bering land bridge from North America into north-east Asia. They quickly expanded across Eurasia. Fossils of two equine species, one an ass, the other an ancient horse, have been found at the early Middle Pleistocene site of Pakefield in Suffolk, dating to at least 450,000 years ago, and at Boxgrove in Sussex, dating to 500,000 years ago.
Having originated in North America, before spreading to South America and to the Old World, Equus would ultimately go extinct in its homeland. Some 30,000 years ago, as the ice sheets were descending over North America, the endemic, ‘stilt-legged’ horses disappeared from the landscape. In South America, Hippidion and caballine horses clung on longer, until after the last glacial maximum. If I’d been able to travel back to the Las Chinas Valley, perhaps 15,000 years ago, I may have seen truly wild horses – and perhaps species of both Equus and Hippidion – there. But they wouldn’t be around for much longer. And it wasn’t only the climate that was against them.
Around the peak of the last Ice Age, sea level was low and human hunters would have been able to cross Beringia into the northernmost reaches of North America. Butchered horse bones have been found in the Bluefish Caves in the Yukon, dating to around 24,000 years ago. But access to the land further south was blocked by vast ice sheets. By 17,000 years ago, the ice sheets were melting at the edges – enough to allow human colonisers to migrate from Beringia and the north-east tip of North America, down into the rest of the continent. By 14,000 years ago, there’s plenty of evidence for human occupation right across North America, and down into South America too. And these humans carried some formidable hunting weapons.
Horse bones turn up occasionally in North American archaeological sites, associated with human occupation or activity. At Wally’s Beach, above the St Mary River in south-western Alberta, Canada, wind erosion has helpfully exposed ancient sediments from the very end of the Ice Age. And pressed into the ancient mud are the preserved footprints and trackways of extinct American mammals – this was clearly a well-used game trail. But alongside the tracks of these long-gone animals, there were bones too – of horse, musk oxen, extinct bison and caribou or reindeer. Some of the horse and camel bones had clearly been butchered. The site has also yielded human artefacts, in the form of stone flakes, which were probably the tools used on the carcasses. The evidence at Wally’s Beach includes eight separate butchering localities.
Archaeologists have suggested that these localities were almost contemporaneous – it’s possible that animals were being butchered at these separate sites during the same year, the same season, possibly even during the same hunting trip. But are they really evidence of hunting, or could those ancient Paleoindians simply have been scavenging carcasses that had been killed by other predators? No hunting weapons were found at the butchering sites themselves, but a few stone points or spearheads were discovered nearby. And when archaeologists tested these points, they found two bearing traces of horse protein.
The stone points – which are beautiful, carefully flaked spearheads – are of the Clovis type. The oldest firm dates for Clovis culture in North America place its emergence around 13,000 years ago. The Wally’s Beach stone points were ‘out of context’ – it’s impossible to get a direct date on these spearheads. They were found some distance away from the bones at the butchering site, which were themselves dated to 13,300 years ago. So this leaves two possibilities: either the spearpoints, bearing horse protein, represent slightly later hunting of horses by Clovis people, after 13,000 years ago; or Clovis culture emerged a century or two earlier than previously thought. Whether the finds from Wally’s Beach represent at least two events, separated by a few centuries, or a single event, may be a question that remains impossible to resolve. Nevertheless, the points do provide unequivocal evidence – the Stone Age equivalent of a smoking gun – of the hunting of horses by ancient people in North America.
The last specimens of Hippidion – found in Patagonia – date to 11,000 years ago. Caballine horses in both North and South America may have clung on a little longer – but their days were numbered. The last trace of truly wild horses in North America comes not from bones, but from DNA preserved in sediment in Alaska – dating to 10,500 years ago. The debate rumbles on about whether it was climate or humans that finished off the indigenous American horses. There was an overlap of several thousand years between the arrival of humans in the Americas and the disappearance of the horses. So human hunters certainly weren’t rampaging across the land on some sort of violent, overkilling spree. On the other hand, we can be sure that they were hunting these animals, even if only occasionally, and that would have had some impact on the already dwindling population. Although climate and changing environments are probably mostly to blame, humans may have helped to speed the extinction of American horses.
By the nineteenth century, the memory of ancient horses in the Americas had completely faded. As far as everybody was concerned, horses were firmly Old World animals, introduced to the Americas by the Spanish. And then, on 10 October 1833, a ship’s naturalist from Britain was exploring the coast near Santa Fe, recording the geology and any fossils he came across. He was investigating a fossil of an extinct, giant armadillo, when he found what appeared to be a horse’s tooth in the same layer of reddish sediment. It looked a bit weird compared with modern horses’ teeth, but definitely horse-like, nonetheless.
The naturalist – none other than Charles Darwin – pondered in his field notebook as to whether the tooth might have washed down from a much later layer, but he concluded that this was unlikely. The tooth was extremely old. Darwin had found the first evidence of an indigenous, ancient horse in the Americas.
When he returned home, Darwin wrote up his discoveries in the Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle – the book which would later be rebranded as The Voyage of the Beagle. And he returned to that horse’s tooth in his Origin of Species, writing: ‘When I found … the tooth of a horse embedded with the remains of Mastodon, Megatherium, Toxodon, and other extinct monsters … I was filled with astonishment.’
The eminent nineteenth-century anatomist Richard Owen (who later became – I think it’s fair to say – the closest thing Darwin ever had to an arch-enemy) wrote up the fossil mammal remains collected during the voyage of the Beagle. He looked at the tooth from Argentina and had to admit that Darwin was right. He wrote that the tooth ‘… from the red argillaceous earth of the Pampas at Bajada de Santa Fe … agreed so closely in colour and condition with the remains of the Mastodon and Toxodon from the same locality, that I have no doubt respecting the contemporaneous existence of the individual horse, of which it once formed part.’ Then, he continued, begrudgingly: ‘This evidence of the former existence of a genus, which, as regards South America, had become extinct, and has a second time been introduced into that Continent, is not one of the least interesting fruits of Mr. Darwin’s palaeontological discoveries.’
It was an interesting fruit. No wonder Darwin had been ‘filled with astonishment’. It was a real revelation: when the Spanish brought horses with them to the Americas on the cusp of the sixteenth century, they were reintroducing a lineage which had existed for thousands of years in the New World – and which had in fact originated there. Darwin went on to use his fossil horse’s tooth from Santa Fe to illustrate his ideas about extinction in the Origin – proving that ancient horses had once galloped across South America, and then disappeared, long before Columbus made his voyage of discovery.
While horse populations were dwindling, eventually to disappear completely, in the Americas, their relatives – horses, asses and zebras – survived in the Old World. Large herds of wild horses continued to roam across northern Siberia and Europe while their American cousins were facing extinction.
It seems odd that horses went extinct in the Americas at the end of the Pleistocene, whilst surviving in Eurasia. They were facing similar pressures in both places – climate change and human predation. And horses had been feeling the sharp end of human hunting weapons for much longer in Eurasia than in the Americas. Our own species, Homo sapiens – originating in Africa some 300,000 years ago – had expanded into both Europe and Siberia by at least 40,000 years ago. But way before that, horses had been predated by earlier populations of humans, going back hundreds of thousands of years. At Boxgrove in Sussex, a 500,000-year-old horse scapula with spear damage shows that early humans – probably Homo heidelbergensis – were hunting horses. At the last glacial maximum, the horse population of north-west Europe would have plummeted, under attack from both the icy conditions and the lethal spears of the Palaeolithic hunters.
The Ice Age inhabitants of western Europe were very familiar with horses, and these animals formed the subjects for some cave paintings – images that would be discovered and wondered at millennia later. At the famous cave of Lascaux, near the town of Montignac in the Vézère Valley, in south-west France, small, pot-bellied horses run along the walls, alongside bulls and reindeer. They’re thought to have been painted around 17,000 years ago. My favourite Ice Age painting of horses comes from another cave, however, about 100 kilometres to the south of Lascaux – Pech Merle. The paintings inside this cave are believed to be even more ancient, perhaps around 25,000 years old. I was lucky enough to visit the cave in 2008, with just a few other people, and I wrote about what I saw there:
A flight of stone stairs led down … I passed [through a door] to emerge into a limestone cave deep within the hillside. I walked through magnificent chambers with huge flowstone creations, enormous stalagmites and stalactites, some of which had met between ceiling and floor to form massive pillars. The cave opened into a great chamber … there, on one rare, smooth part of the cave wall to my left, were two beautiful horses outlined in black, facing away from each other, their hindquarters partly superimposed. They were covered in black spots which also flowed on to the background around them, as though they were somehow camouflaged. There were red ochre spots, too, on the belly of the horse on the left, and on the flanks of the other. I noticed that the flat wall of rock had a strange contour where it ended on the left – almost like a horse’s head. It was as though the artist had taken this suggestion from the natural shape of the rocky canvas … The horses were stylised rather than naturalistic representations. They had great curving necks and small heads, rounded bodies and slender legs. Were they artistic representations of real horses or mythical beasts?
Whatever those images represented – imaginative riffs on real horses, or horse-spirits, or even horse-gods – we can be sure that the Palaeolithic hunter-gatherers of Europe not only knew what horses looked like, they knew what they tasted like, too. There are plenty of Ice Age archaeological sites with butchered horse bones. In fact, horse – together with bison – is the most common large mammal in archaeological assemblages. Around 60 per cent of late Ice Age archaeological sites in Europe and Siberia contain horse bones.
After the peak of the Ice Age, the climate began to improve and the potential range for horses increased, with plenty of pasture rolling out – but their numbers kept falling. The continued pressure on the Eurasian population of horses must surely have been exerted by human hunting. And by this time, of course, the hunters of Siberia and Europe were accompanied by dogs.
The world kept warming up, and the environment kept changing: grasslands were shrinking, as Europe became increasingly forested. The cold snap of the Younger Dryas interrupted the trend, with the forests of western Europe reverting briefly to glacial tundra – but then warmth returned. By 12,000 years ago, the open, Ice Age grasslands known as the ‘Mammoth steppe’ had all but disappeared from Europe – together with the mammoths themselves. Instead, there was now extensive woodland – mainly birch in the north, pine in the south. From around 10,000 years ago, the central European lowlands were colonised by much denser, mixed deciduous forest, with oak as the predominant species. Warm-loving, forest-dwelling animals such as deer and brown bears were suddenly in their element; they spread north from refugia in southern Europe. Horses, however, were facing habitat loss, and by 8,000 years ago they’d disappeared from central Europe. But there were other areas where much more widespread, suitable habitat existed, on into the middle of the Holocene. These were the grasslands of Iberia, and the Great Steppe or Eurasian Steppe, stretching from north of the Black Sea, as the Pontic-Caspian Steppe, through Russia and Kazakhstan to Mongolia and Manchuria. Plenty of grazing, then, in those grasslands – but also plenty of hunters.
Even in Europe, there appear to have been some refugia – pockets of suitable habitat – where small numbers of horses could cling on. There are over 200 archaeological sites, dating to between 12,000 and 6,000 years ago, ranging from Britain and Scandinavia to Poland, which preserve evidence of wild horses. This suggests that – although the new forests were too dense for animals like mammoths and giant deer, which then faced extinction – there were enough woodland groves for horses to graze in, even if their populations were now small and fragmented. Forest fires – common in pine forests – could have helped to create clearings. Along the course of large rivers, regular flooding could also have kept woodland at bay, creating river meadows suitable for large, grazing mammals.
And there was something else that helped to create habitat for wild horses. Around 7,500 years ago (5500 BCE), the frequency of horse remains found in archaeological sites across Europe increases. This upsurge in horses seems to coincide with the arrival of a new way of life in Europe: farming – and the beginning of the Neolithic. When early farmers began to fell trees to clear space for agriculture, cattle and sheep, they were inadvertently making room for wild horses too.
For species that became our allies, that teamed up with us, benefits could be even more direct and palpable. The end of the Ice Age was a time of great ecological upheaval. Many large-bodied mammals died out between 15,000 and 10,000 years ago – including enormous, iconic herbivores such as mammoths and mastodons. Predators were also hard-hit, as their prey dwindled away. The cave lion disappeared from Eurasia around 14,000 years ago; the American lion went extinct around 13,000 years ago. Sabre-toothed cats clung on in the New World until around 11,000 years ago. The wolf population survived but was still badly hit – though of course one lineage went on to become immensely successful: the wolves that took up hunting with humans, and became dogs. It’s estimated that there are well over 500 million dogs in the world and around 300,000 wolves. So today, dogs outnumber their surviving wild relatives by more than 1,500 to 1. No one seems to be willing to hazard a guess at how many red junglefowl there are in the world, but it’s bound to pale in comparison to the global chicken population of at least 20 billion – around three chickens to every person. And cattle – well, there are no surviving aurochsen and an estimated one and a half billion cattle on the planet.
Wild horses have led a similarly precarious existence. Loss of habitat and hunting by humans laid low their population. The forest-clearing of the Neolithic might have provided some pockets of habitat, and a temporary boost, but numbers would continue to fall. The population of Equus ferus – the close wild relatives of domestic horses – dwindled to nothing in the twentieth century. The last wild horse in Mongolia, belonging to another species, Equus przewalskii, was spotted in the 1960s. But then they were reintroduced, and now there are an estimated 300 living wild, with around 1,800 in captivity. In a curious twist of fate – and another unexpected and challenging example of the impact of human activity – it turns out that wild horses, along with moose, deer, boar and wolves, storks, swans and eagles, are doing very well in the exclusion zone around Chernobyl. The positive impact of removing humans from this area seems to be overshadowing the negative effects of the radiation itself.
But – not all horses stayed wild, of course. You’ve probably never seen a wild horse, but I imagine you’ve seen plenty of domesticated ones. You may even have ridden one. Did it stand there, meekly, as you swung your leg up and slid into the saddle? Probably.
I wouldn’t describe Zorrita as meek, but she was perfectly happy for me to jump up on to her back. She didn’t try to throw me off, at any rate. Can you imagine what would have happened had I tried to mount that feral horse, that bagual? He would have had none of it – and neither would his wild predecessors. However much we marvel at humans having become close to wolves, which meant trusting that they wouldn’t use their strength and their terrifyingly sharp, slicing teeth on us, it’s surely just as astonishing to trust yourself to a large, fleet-footed mammal – one which could easily rear up, or career away, and throw you off, doing some very serious damage.
Imagine catching a wild horse – for the very first time. No one you know has ever done this before. And you bring it home, biting and kicking. You tie it up. You feed it. Your family thinks you’re mad. They want you to kill it – after all, it would feed everyone for weeks. But you want to keep this young, wild thing alive. You like it. And you have an idea. Everyone thinks you’re crazy.
You wait until the wild horse gets used to you approaching. You get closer and closer. She lets you stroke her mane, her neck. And then – you grab the mane, and fling yourself up on to her back. She’s not happy. She pulls at the rope you’ve tied to a post. She bucks to get you off her back. You lie down and hold her neck. You cling on. As she calms down, you sit back, releasing your grip around her neck. You hold tight to her mane instead.
After a few moments, while she’s snorting and stamping, but not trying to buck you off, you move one hand down the rope around her neck. And you gently loosen the knot. She knows. As the rope drops to the ground, she knows that she’s free. You – are just a distraction. She swings around, plunging her hooves into the wet ground, and RUNS. Hooves flying, you hear her breath in rhythm with the footfalls. You are clinging on for dear life. This is like flying and dying and being born and feeling one with the wind and the wildness and the landscape and the heavens. You hold on. The cadence of the gallop knocks the breath out of you as you bounce up and down on her back. She pulls steep turns, trying to knock you off. But you stay on. She runs and runs and runs. You’re very far from home.
At long last, she tires. Snorting and throwing back her head, spraying you with horse snot. She’s cantering now, her flanks and neck damp with sweat. Your hands are knotted into her mane. She trots, walks, stands still. You both stay still and breathe for a while. The gallop was exhausting, terrifying … exhilarating.
Then you sit up a little. Pull gently on her mane. You’d like her to turn around. She does. Now you’re facing in the direction you’d like to go. The camp is somewhere that way – along this valley, to the left of that hill. Can you ask her to take you back?
You shift your weight forwards a little. She responds by stepping forward. You stroke her mane. You shift forwards again, pressing into her flanks with your feet. She breaks into a trot. You’re trying not to grip her neck too tightly. If you can sit back a little, you can pull her mane to one side or the other – you can guide her. You’ve made an astonishing connection with a wild animal. You splash down into the river and up the opposite bank, round the flank of hill – and you can see the camp, the tents, and the smoke from the fires snaking up into the sky. What are they going to say when they see you riding in on this magnificent creature? You’ve captured her spirit – felt her power – in a way you’d never do by hunting and killing and eating her. The potential of horses has been unlocked. You feel like a god among people. And they’re running out to greet you – your sisters and brothers, your parents, your uncles, aunts, cousins and friends.
You’re almost at the camp. Your horse is slowing – she would usually stay away from humans. You urge her on. She’s yours now.
One of the camp dogs runs out and sniffs at her legs. She rears up. You try to cling on to her mane. She’s rearing then kicking back and flinging herself from side to side. You are thrown off, flying up and then landing on your back. It knocks the air out of you. You lie on the ground, gasping and gasping. You’re all right. A pain in your ribs will last a while but will heal and disappear. As you get your breath back, you bring up your left hand, against your chest. Fingers uncurl to reveal a clump of black, wiry horsehairs in your hand. You travelled with her. Now she’s gone, but you’ll always remember that wild ride.
After that, all your friends want to try. It becomes like a game. Who will dare to catch and ride a horse? It’s exhilarating foolishness. The stuff of youth. But before long, there’s a small group of you who not only ride horses, you keep them. Together, you become a force to be reckoned with. Headstrong youngsters – but a rising elite.
Years later, when you’re an elder of the tribe, and horses are all around, you’ll tell the story. Once they were all wild, these beasts that now seem like our allies. And you were the first person to try the unthinkable, to try riding a wild horse. You broke the spell. Even though you lost that first horse, even though you cracked your ribs as you hit the ground, people saw what was possible. Things have changed so much during your lifetime. Horses have brought so much – meat and milk, but also transport, trading and raiding, and connections across a wider landscape: you started to make contact with faraway people you’ve only heard about in stories. All those things that seemed impossible when you were a child are now part of everyday life, as if it’s always been this way. You would think nothing of travelling thirty, forty miles in a day to see your cousins. You’d think nothing of travelling that far to raid other camps and steal their copper and their animals.
Your children have grown up riding horses as if this was an entirely natural state of affairs. And now, just a couple of decades after that first, exhilarating ride, it isn’t just your tribe that are horse people. The idea caught on like wildfire. You’ve given horses as gifts to three tribal leaders, securing their friendship and allegiance. As young women have left the tribe to marry into others, they’ve taken their horses with them. Across the steppe, the bond between people and horses has rippled out and taken hold. More wild horses have been caught and broken in, and every year new foals are born to tamed mares.
No one really knows exactly how or why horses were first domesticated – but archaeology provides us with clues. The geography of horse domestication maps on to the steppe – where these grazing animals could continue to thrive even while much of Europe had become blanketed in forest. Up on the Great Eurasian Steppe, humans and horses had shared the landscape for tens of thousands of years. Around five and half thousand years ago, the relationship – which had previously been that of hunter and hunted – was set to change, and the fate of Equus caballus and the trajectory of human history would become deeply intertwined.
The ‘kitchen waste’ of archaeological sites is hugely informative. We can find out from this waste exactly what people were eating. In Mesolithic and Neolithic sites in Europe, horse bones typically make up just a small percentage of animal bones. But on the steppe, such archaeological sites contain plenty of horse bones – around 40 per cent. Humans living there depended on these animals – and would have been very familiar with them – long before they ever caught and tamed them.
Horse domestication comes much later than cattle domestication. And by 7,000 years ago, cattle herding had reached the Pontic-Caspian Steppe. Foragers around the Dnieper River, running down to the northern coast of the Black Sea, were coming into contact with the farmers, who were spreading north and east, bringing their cattle, and also their pigs, sheep and goats with them.
Still, cattle herders could have carried on hunting wild horses rather than domesticating them. The anthropologist David Anthony has suggested that an icy climate could have been the driver. Cattle and sheep are fairly useless at digging through snow to get at forage, especially if that snow is crusted with ice. And they don’t tend to break ice to get to water, either. But horses use their hooves to do all of this. They are well-adapted creatures of the cold grasslands. Anthony suggests that a climatic downturn between 6,200 and 5,800 years ago could have seen herds of cattle struggling to make it through harsh winters – and perhaps this is what drove the cattle herders to catch the equine denizens of the steppe. Alternatively, it’s possible the domestication of horses emerged more naturally out of a horse-hunting culture. Maybe people who had been hunting horses for centuries, millennia – who understood them – started to catch and ride horses, in order to hunt other wild horses. But even that sounds too thoughtful, too strategic. Surely the first people who jumped up on to the backs of wild horses were teenagers, daring each other to do this unthinkable, foolish, brave thing.
In the early Neolithic, the people of north Kazakhstan were still mainly foragers, living in temporary camps. They hunted a variety of wild animals, from horses and short-horned bison to saiga antelope and red deer. But in the 1980s excavations at a site called Botai appeared to reveal a shift, happening around 5,700 years ago, to more specialised horse-hunting. At the same time, the people of the Botai culture, as it has become known, had also adopted a semi-sedentary lifestyle – they certainly don’t seem to have been nomads, following herds of wild horses. They were much more settled than that.
The vast majority of animal bones from Botai and similar sites dating to the fourth millennium BCE are all from horse. It’s clear that the Botai were eating a lot of horse meat. The evidence suggested that Botai people were not only able to trap entire herds of horses, they could also transport carcasses back home. This is a crucial piece of the puzzle: those horses were not killed and butchered in situ, like the horses at Wally’s Beach – they were brought back to the settlement. Archaeologists argued that the Botai must have been riding horses to hunt, and using horses as transport. But as more evidence emerged, the interpretation of the finds from Botai and related sites started to change. Amongst the archaeological remains at Botai sites, there are few spearheads, but plenty of what appear to be leather-working implements – bone tools showing characteristic patterns of microscopic wear. These clues suggest that the Botai were keeping horses – and riding them – not just hunting them. Archaeologists went further, probing the evidence, to test that suggestion.
Although there are only subtle differences in the shapes of bones between different equine species, and between wild and domestic horses, the metapodial or cannon bone, from the lower leg, has been shown to be a particularly informative part of the skeleton. So the archaeologists compared the shape of horse metapodials from Botai sites with those from other localities and periods. They found the Botai bones to be quite slender – and similar to those found at later sites, containing what were definitely domestic horses. They were also similar in their slenderness to metapodials from modern Mongolian horses.
Then they turned their attention to the teeth of the Botai horses, and found something quite extraordinary. They discovered a band of wear on the front edge of one premolar – the enamel of the tooth had worn right through, down to the dentine. If you’ve looked a horse in the mouth (it’s OK if it’s not a gift horse), you’ll have noticed that there’s a gap between its front teeth and its back teeth – it’s known as the ‘bars’ of the mouth, or the diastema. The only thing that could have caused this pattern of wear on the tooth was something which had been regularly placed in the bars of the mouth of that Botai horse – it had clearly worn a bit. Two other teeth showed more subtle signs of possible bit wear. The tooth with the very clear signs of wear was radiocarbon dated to 4,700 years ago. There were also bony growths on the surface of four other mandibles, in that gap between the teeth, just where the bit would sit in the horse’s mouth.
Finally, the archaeologists turned their attention to the pottery from Botai sites. They analysed the residues on the inner surface of sherds of cooking pots, and found evidence for not only horse fat but, in particular, lipids from horse milk. While hunters of wild horses would have undoubtedly tasted horse milk occasionally, when a lactating mare was killed, the milk on those cooking pots points to a more regular consumption. Far away from the centre of sheep, goat and cattle domestication and dairying in the Fertile Crescent, the people of the Eurasian Steppe independently came up with their own form of dairy farming. And it was a way of life, an economy, focused on horse meat and milk, that would continue for a very long time in Kazakhstan – right up to the present day. The herdsmen of the Altai Mountains are the inheritors of that ancient way of life, and fermented mares’ milk, in the form of kumis, is still a popular drink on the Eurasian Steppe.
This hat-trick of three separate strands of evidence – the leg bones, clear signs of bit wear, and use of mare’s milk – all point to the same thing. The Botai of ancient Kazakhstan were harnessing, milking and keeping domesticated horses by the fourth millennium BCE. But it doesn’t mark the start of something. It’s what archaeologists call a terminus ante quem – what it tells us is, by this point in time, domestication had happened.
The bit wear shows that the Botai horses were harnessed – bridles could have been used for driving them, but perhaps more likely, riding them. Beyond this specific evidence for keeping domesticated horses, the Botai culture itself goes back to 5,500 years ago. And it’s likely that horse-riding started even earlier than this. Burials in the Pontic-Caspian Steppe dating back to 6,500 years ago contain the skeletal remains of horses alongside bones of cattle and sheep. There’s clearly a symbolic association between these animals. It’s prompted archaeologists to suggest that horses may have been ridden this early, to herd the other animals.
Other clues turn up in the Danube Delta, in modern Romania and the Ukraine, with the appearance of horse-head stone maces and burial mounds, or kurgans – characteristic of steppe cultures – dating to 6,200 years ago. It strongly suggests that horse-riders from the steppe were moving south. Inside the kurgans, the dead were buried with necklaces of shell and tooth beads, as well as axes, twisted neck-rings and spiral bracelets made from a new material – that they’d acquired by trading with the people of the old European towns around the Danube – copper. They’d bought into the Aeneolithic, the Copper Age, and this shiny, malleable metal had become an emblem of prestige. This early expansion of steppe people may have carried something of its own, along with the horses: they may have been speaking a Proto-Indo-European language, a language which would evolve into Anatolian as they moved even further south.
So it seems likely that taming and riding horses could have started a thousand years before the Botai culture emerged – perhaps as early as the fifth millennium BCE. By the fourth millennium BCE – 5,500 to 5,000 years ago – horse bones were already becoming more frequent around the Caucasus, the mountainous region that stretches between the Black and Caspian Seas, south of the steppes. The same thing was happening in the Danube Delta, to the west of the Black Sea. By 5,000 years ago, the frequency of horse bones at some sites in central Germany had risen to account for 20 per cent of all animal bone. The connection is clear: horse-riding and domesticated horses were spreading – fast. Horses and horse-riding spread south of the Caucasus, too. After 5,300 years ago, horses are found more frequently in Mesopotamia – just as the Sumerian civilisation began to blossom.
Riding horses wouldn’t just have helped with horse husbandry – it would make herding other animals much more efficient as well. One person on foot, with a good dog to help, could herd 200 sheep. On horseback, with a dog, you could control 500 – and cover a much larger area. Expanding territories would surely have brought pastoralists into conflict with each other. Building alliances and gift-giving would have become important. The proliferation of copper and gold jewellery in the archaeological record suggests that people were seeking status and displaying wealth in a way they simply hadn’t before. But it all came at a cost: polished stone maces – some in the form of horses’ heads – also begin to turn up at this time. Riding and warfare seem to have been intimately linked, even at this early stage. Formal cavalry might not have emerged until the Iron Age, around 3,000 years ago, but mounted raids – stealing animals from other tribes – and the internecine strife that went with them probably go back to the very dawn of horseback riding.
Towards the end of the fourth millennium BCE, the herders of the steppe were becoming more mobile again. A climatic improvement in the early centuries of that millennium was followed by a downturn. Large herds now needed to roam more widely in order to take in sufficient pasture. This seems to have stimulated the emergence of a new way of life, and a new culture. The herders couldn’t afford to be semi-settled any more, as they had been at Botai; they needed to move with their herds and flocks. The solution: wagons. These wheeled vehicles first appeared on the steppe around 5,000 years ago. This sounds very precise. How on earth could archaeologists make such a claim, about vehicles which leave so little trace on the ground? Wheel ruts don’t tend to last for millennia (and where they are found, they’re impossible to tell apart from sled-ruts).
The answer lies inside the graves of these steppe people. They were still making kurgans, and under those mounds of earth, they buried their elite – mostly men – with their wagons. These extraordinary burials, with bodies and dismantled wagons placed in pits, appear across the Pontic-Caspian Steppe, dating to between 3000 and 2200 BCE. The burial rite gives this new culture its name, though it’s a name those people never knew – ‘Yamnaya’, after the Russian for ‘pit-grave’.
The wheel itself may not have been invented on the steppe. It’s thought that the idea of wheeled vehicles spread there, either from the west, from Europe, or from the south, from Mesopotamia. The earliest known image of a wheeled vehicle comes from a site in Poland, and dates to around 3500 BCE, while a clay model of a wagon from Turkey dates to about 3400 BCE. With covered, ox-drawn wagons as their mobile homes, the herders could migrate around the landscape, following huge flocks and herds. And they were still riding horses, of course. Archaeologists suggest that the cycle of the year would have taken the herders out on to the open steppe in spring and summer, while in winter they’d set up camp in river valleys. Crucially, those valleys would have contained trees – providing wood for fuel, and for mending the wagons. Although this horse-riding, wagon-camping, kurgan-building culture stretched right across the Pontic-Caspian Steppe, there were regional differences in livestock and the types of plant being eaten. In the east, beyond the River Don, people were mainly tending sheep and goats, with just a few cattle and horses – which provided essential mobility. Along with mutton and goat, they were eating foraged tubers and the seeds of goosefoot – a plant very closely related to quinoa. In the western steppe, people were more settled – and they were herding cattle and pigs, and growing some cereals.
But – like the earlier horse-riding nomads in the fifth millennium BCE – the Yamnaya didn’t stay on the steppe. By around 3000 BCE, they had begun a westward expansion, into the Lower Danube Valley, and on to the Great Hungarian Plain. The herders of the steppe were expanding eastwards as well, making contact with the early farmers of China. Crops and animals that had been domesticated in the west spread east. The idea of copper metallurgy may also have travelled to China from the west. After the Yamnaya, there seem to have been successive waves of steppe people expanding both east and west. Over five thousand years, this scenario played out again and again, with the last wave recorded in history – as the thirteenth-century Mongol invasion.
The prehistoric expansions of steppe nomads appear to have had very different impacts on existing societies in the east and west. In China, the nomads seem to have merged with settled societies, but in the west they encroached on lands occupied by other nomadic pastoralists – and they caused a knock-on effect, pushing those nomads even further west.
The Yamnaya expansion into Europe had a profound cultural impact, one that is still echoing today. Geneticists and comparative anatomists use patterns of similarity and difference between modern organisms, and ancient ones too, when they’re available, to construct phylogenies – family trees which represent evolutionary history. Linguists can do much the same thing with languages, using comparative grammar and vocabulary. Many ancient and modern languages, from English to Urdu, Sanskrit to ancient Greek, all group together, in the Indo-European language family. And linguists have traced the evolution of sounds back and back, until we have the closest thing to an original Indo-European language – in the form of about fifteen hundred distinct sounds. It’s very hard to test whether they really have found the traces of an ancient language, but archaeological discoveries have since revealed previously unknown words in Hittite and Mycenaean Greek – which were correctly predicted by the methods of the historical linguists, giving us some grounds to trust their reconstructions.
The fragments of the Proto-Indo-European language contain words for otter, wolf and red deer as well as for bee and honey, cattle, sheep, pig, dog and horse. In other words, it’s a language root that clearly emerged after the beginning of the Neolithic – its speakers had words for domesticated animals. Still, it’s not clear that the word for ‘horse’ refers to a domesticated horse. But there are other clues. The reconstructed Proto-Indo-European also contains words for wheel, axle and wagon. It seems that the Yamnaya people, the horse-riding, wagon-driving nomads of the steppe, were speaking a language which would form the basis for all the Indo-European languages that we continue to speak, across Europe and western and south Asia, today. How wonderful to think we’re still using words that contain a faint echo of that ancient culture on the steppes.
Unravelling the origins of domestic horses has proved – this is now a familiar theme – very difficult indeed. Just as with wolves and early dogs, aurochsen and early cattle, it’s difficult to discern any differences between the bones of wild and domestic horses. Those metapodials from the Botai sites were only subtly different to wild horse bones. In fact, there are very few differences in the skeletons of any species belonging to the genus Equus much more generally. If you compared the skeleton of a zebra with the skeleton of an ass, you’d be hardpushed to tell them apart. Once again, this is where genetics has ridden to the rescue. And before looking at the origin of domestic horses, we need to make sure that we really understand the differences between the various equine species that exist today. Some have recently turned out to be even less ‘different’ than we’d thought.
It seems that we’ve been taxonomically over-zealous in dividing up Equus in the past. Genetic analyses have prompted suggestions that some apparently discrete populations, traditionally seen as separate species, are actually much more closely related. For instance, the plains zebra and the extinct quagga are traditionally labelled as separate species, based largely on how they look. Modern genetics says: they are one and the same species. Similarly, the extinct ‘stilt-legged horses’ of America are, genetically, caballines – close cousins of modern domestic horses. But, as the family tree of horses collapses in on itself, with fewer branches and closer genetic relationships than previously suspected, one key part of the family tree is uncontested – and that’s the very close relationship between domestic horses, Equus caballus – together with their wild ancestors and relatives, Equus Ferus – and the surviving, truly wild horses of the central Asian steppe: Equus przewalskii – Przewalski’s horse. These small but robust horses have a sandy or reddish coat, pale muzzles and bellies, a bristly brown mane, and a stripe along the back.
Genetic analyses have made it possible to reconstruct the family history of the caballines, or true horses, and pin some dates on it. The wild ancestors of domesticated horses emerged as a separate lineage some 45,000 years ago, when they diverged away from the ancestors of Przewalski’s horse – long before domestication. Despite that divergence, however, a small amount of interbreeding continued – the reciprocal gene flow shows up quite clearly in genomes today. Most of that interbreeding happened long ago, before the last glacial maximum, twenty thousand years ago. After the Ice Age, there was still some genetic input from Przewalski’s horses into the ancestors of domestic horses, and it continued even after domestication. Later still, right at the start of the twentieth century, there’s evidence for gene flow in the other direction – from modern horses into Przewalski’s horses. This last injection of domestic horse genes into Przewalski’s horse was precisely at the time when Przewalski’s horses first started to be kept and bred in captivity.
The ability of these two horse populations to interbreed really is extraordinary. They’re distinct enough – morphologically and genetically – to be considered separate species. And they have different numbers of chromosomes – often considered to be a complete barrier to interbreeding. While domestic horses have sixty-four chromosomes (thirty-two pairs), Przewalski’s horse has sixty-six (thirty-three pairs). When a mammalian egg or sperm is made, it ends up with half the usual genetic complement found in other cells of the body. At fertilisation, the genetic material from the egg is combined with that from the sperm to create a full set once again. Each chromosome from the egg must pair up with its opposite number, from the sperm, before the fertilised egg can start to divide and make an embryo. If a domestic horse and a Przewalski’s horse mate – the resulting fertilised egg would have one set of thirty-two chromosomes and one set of thirty-three. But somehow (and even geneticists are astounded by this), the chromosomes manage to pair up – if they didn’t, there’d be no viable offspring. And the traces of interbreeding in the genomes of modern domestic horses and Przewalski’s horses shows that, not only were such offspring viable, they were fertile – they could reproduce.
Of course, hybrids between equine species are well known. A hinny is a cross between a male horse and a female donkey. A mule is a cross the other way – between a male donkey and a female horse. And although hinnies and mules are usually sterile, they can occasionally reproduce successfully. That’s again quite remarkable considering that donkeys have thirty-one pairs of chromosomes and horses have thirty-two. But the genomes of different equine species contain evidence of an even more astounding feat – interbreeding and gene flow between the Somali wild ass, with thirty-one chromosome pairs, and Grévy’s zebra, with twenty-three. Such findings challenge our stereotyped views about how biology should work. The species boundary is turning out to be much more permeable than we’d anticipated, before genomics came along. Even differences in chromosome number don’t seem to be quite the barrier to successful reproduction that we’d previously imagined.
As well as tackling questions of interbreeding, genetics provides an insight into fluctuations in the size of ancient populations over time. Both the ancestors of domestic horses, also known as Equus ferus, and Przewalski’s horse suffered a population crash in the late Pleistocene and early Holocene, around 10,000 to 20,000 years ago. Populations continued to dwindle – up until the point of domestication, some 5,000 years ago. Then, for Equus caballus, the domesticated horse, the future started to look decidedly rosy. But while this population of horses grew and grew, and spread around the world, their wild cousins would become endangered.
The close wild relative of domestic horses, Equus ferus, also known as the Tarpan – with a characteristic sandy-grey-coloured coat, pale belly, black legs and a short mane – finally went extinct in 1909. The Przewalski’s horse was also spiralling towards extinction. These rare, shy horses were spotted by a Russian explorer and geographer, Nikolai Mikhailovich Przewalski, who was making his way across the central Asian steppe in 1879. By this time, the range of these wild horses had contracted, and there were only small herds roaming the steppe in Mongolia and Inner Mongolia. When Przewalski was preparing to leave Mongolia, he was presented with the hide and skull of one of the horses, which had been shot, and which he duly took back to St Petersburg. These remains were studied by the zoologist I. S. Poliakov, who published his description of this unusual horse in 1881. Poliakov determined that the remains of the beast from Mongolia were sufficiently different from domesticated stock to be considered new to science, and he gave the wild horses of Mongolia a new species name, honouring its discoverer. The horses immediately became collectable, and expeditions set out to Mongolia to capture specimens for zoos – further depleting the wild population. The last Przewalski’s horse to be caught was a mare, named Orlitza, captured as a foal. The horses were getting rarer and rarer in the wild. Being recognised as a new species was in some ways their downfall. The expeditions that fed zoological collections inevitably killed some animals, and dispersed others.
In 1969, the last sighting of a wild Przewalski’s horse was reported, from the Dzungarian Gobi in south-western Mongolia. Extinct in the wild, a few Przewalski’s horses survived in zoos, long enough to breed. In the 1980s and 1990s, attempts were made to reintroduce these horses to the wild, using horses bred from a stock of just fourteen individuals – including Orlitza. And the attempts were successful. Between the 1960s and 1996, Przewalski’s horse was considered ‘extinct in the wild’, but by 2008 it was back in the game – though in such small numbers it was designated ‘critically endangered’. The numbers crept up – by 2011 it was considered to be merely ‘endangered’ – which meant that a population of more than fifty mature animals was living wild.
It’s now estimated that there are a few hundred Przewalski’s horses living outside of captivity. These small numbers mean that the population remains very vulnerable to adversity – to disease and severe winters – but they have some help. In the Kalamaili Nature Reserve in Xinjiang, China, where Przewalski’s horses were released into the wild in 2001, the horses are rounded up into a corral each winter to give them extra food and to protect them from competition with domestic horses. By 2014, there were 124 individuals in just this one group of rewilded Przewalski’s horses, which has been described as the most successful of the reintroduction efforts in China.
The population in captivity is looking healthy too – with around 1,800 horses in zoos worldwide, and growing. The reintroductions to the wild have mainly taken place in China and Mongolia, around the area where the horses were last seen living wild before going extinct. But some Przewalski’s horses have also been released into nature reserves and national parks – in Uzbekistan, Ukraine, Hungary and France.
The story of these wild horses provides us with an alternate history for their domesticated cousins, Equus caballus. What would have happened had these horses remained wild? There’s no doubt that the course of human history would have been altered, but the fate of horses would have been significantly affected as well. Wild horses formed an important source of meat for our Palaeolithic hunter-gatherer forebears, but they are surely very likely to have been hunted to extinction, or close to it, had they not proved useful to our ancestors in other ways – carrying riders across the vast steppes and knights into battle; pulling chariots, wagons and cannons; becoming emblems of status and prestige in human society. The reintroductions of Przewalski’s horses into the wild seem to be a success story – a triumph for rewilding – but the global population of these horses, out in the wild and in captivity, numbers just a few thousand at most. In comparison, there are around 60 million domestic horses on the planet. There are concerns about diminishing genetic diversity amongst them, and about loss of breeds, but Equus caballus is far from being an endangered species.
Perhaps it seems that we’ve already nailed the origin of this particular domesticate. Yet while the earliest archaeological evidence for domesticated horses undoubtedly comes from the Pontic-Caspian Steppe, this doesn’t mean that all our horses today must have come from a single origin. There could have been later, independent centres of domestication. After all, horses ranged widely across Eurasia – there were plenty of other places where horses and humans had been in contact for millennia. In a more diffuse, multiregional model, separate herds would later have merged into a single, diverse population of domesticated horses, which continued to reflect regional differences and local origins. Just as with dogs, the apparent diversity of modern horses could be taken to suggest that multiple origins were most likely. In the past, similarities between some domesticated breeds and local, wild ponies were taken to support such a model. Studies of morphological characteristics – the shape and size of bones – suggest a strong similarity between the Exmoor pony, the Pottok pony of the Basque country, and the extinct Tarpan. Some have argued that the beautiful, semi-wild horses of the Camargue represent the direct descendants of the ancient, truly wild Solutré horses which featured in Ice Age cave paintings. But the genes say something different, and more interesting.
In 2001, a piece of research was published, based on analysis of a particular stretch of mitochondrial DNA in samples taken from thirty-seven individual horses – and this bit of DNA was very variable indeed. But did this diversity represent lineages which had diverged from each other before or after domestication? If before, this would suggest multiple origins for modern horses. If after, that would support a single origin. In order to answer this question, the geneticists looked at the mitochondrial DNA of a donkey – which was 16 per cent different to that of horses. They assumed that donkeys and horses had split apart from each other some time between 2 million years ago (as the fossil record suggested) and 4 million years ago (according to the genetic estimates at the time). This gave them a form of calibration – over 1 million years, you’d expect to see genetic sequences diverging by 4 per cent (given a split 4 million years ago) to 8 per cent (for a 2 million-year-old split). They could then apply this rate to the differences they’d found within modern horse mitochondrial DNA, which amounted to about 2.6 per cent. The calibration suggested that the lineages found in those modern horses must have been diverging for somewhere between 320,000 to 630,000 years. Even the lower estimate places the origin of this genetic diversity well before the date of domestication around 6,000 years ago. The geneticists went on to suggest that wild horses had been captured over a huge area, and used for both meat and transport. Then later on, as wild populations began to disappear, domesticated herds became more important and were interbred, to form the genetic basis of modern horses. The researchers contrasted the domestication history of horses with that of dogs, cattle, sheep and goats. Firstly, those other species had been domesticated much earlier (still true), and they all came from a restricted origin, then spread out. The domestication of horses, on the other hand, seemed to have happened again and again, and in many places it represented the dissemination of an idea – a technology – rather than a spread of the animals themselves.
But that’s the mare’s tale. What about the stallion’s? It turns out they have a completely different story to tell. The anthropologist David Anthony describes horses as ‘genetically schizophrenic’. Maternally inherited mitochondrial DNA suggests that modern, domestic horses come from a great variety of wild female ancestors. The mitochondrial genetic diversity of horses is prodigious – and very unusual compared with other domesticates. But the paternally-inherited Y chromosome records only a very few wild, male antecessors.
The discrepancy between mitochondrial and Y chromosome data may – to some extent – reflect natural breeding patterns. Both Przewalski’s horses and feral horses operate in harems. This seems to be the natural state of things in horse society: polygyny is the norm, with one, dominant stallion presiding over a herd of mares and foals. Young males leave the herd and hang around in bachelor groups for a few years before they attempt to form their own harems – either by stealing mares from other stallions, or fighting to take over an existing harem. And so the genetics of modern horses may reflect social and reproductive patterns which are natural in horse populations.
But actually this isn’t enough to explain the stark contrast between the variation seen in mitochondrial lineages, compared with the Y chromosome. This pattern strongly suggests that many more mares were domesticated than stallions. To me, this makes so much sense. Stallions are, by their nature, feisty, independent, even dangerous. It would always have been difficult to find a young, male wild horse that wouldn’t go crazy, throw you off, kick you in the head. Mares are naturally more docile. If you’re a herder looking to catch and tame a wild horse, you’ve got a much better chance with a mare. So it’s not surprising that, historically, more wild mares than wild stallions were caught and tamed. But whilst mares were easier to tame, at least one stallion would have been needed for successful breeding. That’s basic biology.
Looking at the DNA of modern horses, however, there are missing parts to the puzzle. You don’t know where and when particular lineages were added to herds of domesticated horses, and you don’t know how much past diversity has been lost over time. Ancient DNA – extracted from age-old bones – provides much more depth to the story. Towards the end of the Ice Age, there was a large, genetically connected, population of wild horses ranging from Alaska to the Pyrenees. By 10,000 years ago, the North American horses had disappeared, and the population on the Eurasian Steppe had become separated from the one in Iberia. The latest genetic studies also reveal that Y chromosome diversity has been lost over time – giving us the mistaken impression that only a few stallions were ever domesticated.
While ancient and modern DNA is consistent with horse domestication starting in the western Eurasian Steppe, in the Copper Age, it also shows maternally inherited, mitochondrial DNA – from wild mares – entering domestic herds again and again, as domestic horses spread across Europe and Asia. More wild mares were caught and domesticated in the Iron Age, and again in the Middle Ages, adding their wild genes to the already domesticated herds.
A few maternal lineages found in ancient, pre-domestic Iberian horses – walled off from the rest of Europe by the Pyrenees – found their way into the domestic stock, and are still there in some Iberian breeds today, such as Marismeño, Lusitano and Caballo de Carro. As it was the Spanish who reintroduced the horse to South America, it’s not surprising that this ancient Iberian signature also turns up in South American breeds, such as the Argentinean Creole and Puerto Rican Paso Fino. But it’s also found in some French and Arabian horses, probably reflecting ancient trade between Iberia and France, and the close connections between Spain and North Africa. In China, most of the mitochondrial DNA lineages point to domestic horses spreading to East Asia from further west – but then with a few lineages being added from local, wild populations.
Rather than multiple, independent centres of domestication, the picture that’s now emerging is one of domesticated horses spreading from their original homeland in the steppes – but with plenty of wild mares being added to the existing domestic herds along the way, and through history. So it wasn’t just a spread of an idea and a new technology after all – it was a spread of horses, too.
Like other domestic species, the story doesn’t stop there. Selective breeding has promoted certain traits while suppressing others. Just as with dogs, cattle and chickens, strong artificial selection, brought about by strict breeding regimes, has operated over the last two centuries to create the range of modern breeds we know today. But selection was happening way back in the past, too. Small horses, built for speed and agility, were favoured for pulling light chariots – a Bronze Age invention – while the Iron Age Scythians bred larger horses, selecting for endurance in some, and speed in others. Medium-weight horses were pressed into battle service pulling wagons and, later, artillery. By the Middle Ages, draught horses had become massive, weighing up to 2,000 pounds.
Some traits which appear in our modern breeds were already there in pre-domestic horses. The horses running across the walls at Lascaux are brown and black – these could easily have been naturalistic coat colours. The spottiness of the horses at Pech Merle has been suggested to be rather imaginative, perhaps symbolic, even psychedelic – fitting in with the abstract spot patterns that appear around the horses. But on the other hand, the dappling of the Pech Merle horses looks very much like the ‘leopard’ pattern of coat seen in some modern breeds, such as Knabstrupper, Appaloosa and Noriker. The genetic basis of this ‘leopard’ pattern is well known – it’s down to a particular variant or allele of the LP gene on horse chromosome 1. Geneticists screened DNA from a range of thirty-one pre-domestic, ancient horses from Europe and Asia to see if they could pick up this variant. None of the Asian horses had the LP allele, but it was there in four out of the ten western European horses they looked at. There’s definitely some artistic licence at work in Pech Merle – the horses have particularly tiny heads and spindly legs – but the dappled pattern could easily represent the real-life appearance of Ice Age horses, copied straight from nature. It also seems to have been a characteristic which was particularly favoured by some early horse breeders – the LP gene turned up in six out of ten horses from a Bronze Age site in western Turkey, for instance.
Up in northern Siberia, it’s been suggested that Yakutian horses might have interbred with local, wild horses – imbuing them with key physiological and anatomical characteristics which allow them to survive in subarctic conditions. These horses are compact, with short legs, and they’re also incredibly hairy. But in this case, genetic studies of ancient and modern Yakutian horses have revealed no particular connection between them. The modern horses of Yakutia seem to have been introduced in the thirteenth century CE – and they’ve adapted extraordinarily quickly to a cold environment. Such rapid changes in genes related to hair growth, metabolism and blood-vessel constriction (to lessen heat loss at the surface of the body) must have been crucial to survival. Amongst domestic horses more generally, other genes that show evidence of having been positively selected for in the past appear to relate to changes in the skeleton, circulatory system, brain – and behaviour.
There are some fascinating elements of behaviour that horse owners may have known about, or at least suspected, for a very long time – and which scientific studies are just beginning to elucidate. Evidence suggests that cats and dogs are able to understand human emotions, expressed both physically and vocally. Dogs really do seem to understand what a happy human face looks like. It’s known that horses themselves make facial expressions, and that they can recognise emotions in another horse’s face. In a recent study, horses were shown pictures of men making angry, frowning faces and happy faces. The heart rate of the horses tended to increase more when they were looking at an angry face, compared with a smiling one. If this means that horses really do read human emotions, there are a few explanations for this ability. It could be that horses, having been able to interpret expressions on other horses’ faces for a very long time, started to be able to do the same with humans after they were domesticated. Or it could be something that horses learn to do during their lifetimes, associating other cues indicating angriness with an angry human face, for instance. This could still stem from an inbuilt predisposition to inferring emotion from physical appearances, inherited from their wild ancestors.
Another recent, carefully constructed study showed that not only are horses able to interpret our behaviour, they attempt to influence it as well: some gestures made by horses really do seem to be an intentional form of communication. Horses were seen to stretch their necks, pointing their heads towards a bucket full of food they liked, but could not reach. They’d look at the human experimenter, then ‘point’ at the bucket, then look at the experimenter again. If the experimenter walked away, they’d stop. When the experimenter walked towards them, they’d alternate their gaze more frequently. The horses also used nods and shakes of the head to get attention. It suggests that horses not only wish to communicate, they recognise humans as capable of receiving communication. It’s unlikely that horses have evolved to be able to do this over just a few thousand years of being domesticated, but it’s also unlikely that it’s innate. Instead, horses are probably predisposed to learn this sort of behaviour, through interacting with other horses – and now humans as well – in their social environment. So whilst the behaviour isn’t innate, the tendency to develop it is. Being naturally sociable animals, much like dogs, meant that horses were well suited to teaming up with another, sociable animal. They’ve made good allies, ever since the Copper Age, when the horse-hunters of the Pontic-Caspian Steppe became horse-riders. They became fellow-travellers – but it wasn’t only humans that they were carrying. The beginning of the diaspora of our next domesticated species started with the saddlebags of travellers along what would become the western end of the Silk Road. Stuffed into those saddlebags were fruits for the journey – apples.