The domestication of horses was a major moment in human history. Suddenly, it allowed us to travel vast distances, farm larger areas, and resolutely crush enemies in battle. However, much of what we thought we knew about the domestication of the horse is wrong, a surprising new study has revealed. Even what we thought were the last remaining wild horses on the steppes of central Asia have turned out to be feral animals.

It has long been believed that the first people to tame the wild ancestor of the horse was the Botai people from the grasslands of northern Kazakhstan, with multiple groups domesticating the animals from different stocks. Once nomadic hunter-gatherers, it seems that as soon as the wild horses were brought under rein around 5,500 years ago, their entire culture and way of life shifted towards the animals.

Communities stopped moving and settled down, keeping up to 150 horses, used for meat and milk. Ancient corrals have even been unearthed, including leather thongs that were likely used as bridles, as well the seemingly ritualistic burial of horse heads.

It was thought that the wild horse species that is native to Mongolia, Przewalski’s horse (Equus ferus przewalskii), was a remnant sub-population of the original animals that the Botai were capturing from the wild and domesticating in Kazakhstan (Equus ferus ferus, the now extinct tarpan). A new genetic study, however, has thrown all this into doubt.  

Published in the journal Science, the researchers analyzed the genetics of the horse bones excavated from Botai settlements, and then compared the results with the genetics of ancient horse remains found across Europe, modern domestic horses, and Przewalski’s horse. From this, they then built a new family tree of the horse, and the results shocked everyone involved. 

 

Firstly, it turns out that all modern horses are on a completely separate branch of the tree to the remains found in Botai settlements. This suggests that despite popular belief, the domestic horse we know today did not originate in Kazakhstan as we thought, and that actually we now don’t know where they came from.

The second – and arguably most surprising – discovery was that the Przewalski’s horse is not truly wild at all. It turns out that the “wild” horse is actually descended from the ones domesticated by the Botai over 5,000 years ago, which then escaped and became feral on the steppes of central Asia.

“They started developing a semi-wild lifestyle like our [American] mustangs, but they still have a wild appearance,” explained co-author Sandra Olsen. “This is partly why biologists assumed they were genuinely wild animals. They have an upright mane, something associated with wild equids.”

“They also have a dun coat, like the ones you see in the Ice Age cave paintings in France and Spain made when horses were wild,” Olsen continued. “Their size, however, is very similar to what you see at Botai and other sites.”

It means that there are no living wild horses on Earth anymore. While the Przewalski’s horse likely looks the same as their wild descendants, and probably still fills the same ecological role, they may also have subtle changes in their genes that are thought to occur when a species is domesticated. It means that the horse will join the likes of the dromedary camel in Africa, which similarly comes not from wild ancestors but feral domesticates.

This is obviously quite sobering news, particularly to those who have been studying Przewalski’s horse thinking they were wild. But it also raises many more fascinating questions, such as why the horses the Botai domesticated only persisted to modern day through feral animals, and not least where modern-day horses can trace their ancestry to.