I have always thought of horses as telling me something about my own origins.

My grandfather, the most instinctive and natural horseman I have ever known, taught me to ride. Our time on horseback was filled with stories about his father and grandfather on horseback, stories set in locales both familiar and exotic to me: the Rocky Mountain trails I knew by heart, the Cretan paths I dreamed about, and the Congolese jungles and Argentine plains I could not even imagine. Horses, I knew intuitively, were in my blood, ancestral friends.

DNA sampling suggests that the horses found at the Botai sites are not ancestors of modern domestic horses but of the Przewalski’s horses of present-day Mongolia, believed to be the world’s last wild horses. iStock Photo

Horses and dogs are the only two animals that humanity has not only managed to domesticate but also befriend. And those friendships have changed history. Despite the historical—and personal—importance of our relationships with our two closest animal companions, we know very little about the beginning of these relationships. The origins of their domestication have left very little evidence in the archaeological record and confusing, often contradictory evidence, in the genetic one.

Dogs were likely domesticated between 20,000 and 40,000 years ago, while people still lived in small hunter-gather bands, a period lost in the mist of time. Horses were domesticated much later, likely after the beginning of settled agriculture and after the domestication of goats, pigs, cows and chickens. Nonetheless, how, when and where horses were domesticated has been the subject of much debate.

That debate is heating up once again with a recent article in the journal Nature challenging what has been, for the past decade, the accepted understanding of horse domestication. An old debate centering around whether horses were domesticated once and in one place or multiple times in a number of places has been put largely to rest by genetic evidence demonstrating that both theories are partially correct. Stallions probably were domesticated on only a few occasions; most modern horses likely descend from a very small number of foundation studs. Conversely, bands of mares likely were domesticated in a number of places over a fairly long period of time. It is a theory borne out not only in the genetic evidence, but one that makes sense to anyone who has spent any time around horses and knows the relative ease of keeping a band of mares together versus a group of stallions.

The question of where this all happened likewise had seemed resolved. Since the late 2000s, it generally has been accepted that horses were first domesticated by the Botai people in what is today northern Kazakhstan around 4,000 B.C. This consensus was based in large part on evidence of apparent “bit wear” on horse teeth found at Botai sites. But new research, detailed in the Nature article, questions whether the damage seen on the horses’ teeth is from the use of bits. Instead, the article suggests this is simply common wear that can be found on the teeth of wild horses from the same era as well.

The age and gender distribution of equine skeletal remains found at the Botai site also calls into question whether the horses came from a domesticated, human-managed herd. Skeletal remains of such herds typically show a pattern of young male horses, as those would be culled early for meat and other uses, and older females, as those would be maintained to breed. However, further examination of Botai remains shows a markedly different pattern: predominantly breeding-age skeletons, relatively equally divided between mares and stallions, indicating the horses likely were wild and hunted for meat rather than members of a herd raised and managed by humans.

In addition, DNA sampling suggests that the horses found at the Botai sites are ancestors, not of modern domestic horses, but of the Przewalski’s horses of present-day Mongolia (believed to be the world’s last truly wild horses). Taken together—the evidence casting doubt on the bit wear theory, the patterns of skeletal remains and DNA suggesting the animals thought to be the first domesticated horses are, instead, ancestors of the last wild horses—the Botai origin theory starts to run into some real trouble.

One way archaeologists could know if the dental damage truly was from a bit would be to find a bit. But that is not likely to happen. The first bits probably were made before metallurgy, from materials like rope, horn and hardwoods, that do not hold up well across millennia. Besides, it is possible that the first people to domesticate horses, to drive and ride them, did not use bits to do so. It is, after all, quite possible to drive or ride a horse without one and is done so even today. That this fact is not a bigger part of the conversation (and rather often treated as a separate debate) may indicate that many of the people arguing about how horses were domesticated have not spent much time around domesticated horses.

One thing is for certain: There is a kind of “time limit” on when horses were domesticated. By the 4th millennium B.C., human beings were moving around. They were moving at such speeds and such distances that it stands to reason they were moving on horses. That is clear in the archaeological record and in our DNA, which has provided perhaps the best evidence to date regarding how and when humans migrated around the globe. And so, as with so many things about horses, we are left understanding very little about them and very much about how they changed us.

Katherine Kelaidis is the Resident Scholar at the National Hellenic Museum in Chicago. She holds a bachelor’s degree in classics from the University of California, Berkeley, and a Ph.D. in classics from the University of London. A lifelong horse lover, she recently has returned to more serious riding after a decade-long break, discovering that three-day eventing is the perfect counterbalance to the life of a professional historian.