Przewalski's Horse: The Last 'Wild' Horses On Earth

In the magnificent Mongolian landscape, where the large prairies meet the unlimited dunes, flocks of horses rove. Neither fastened nor compelled by fencing, they run and graze on the arid, windswept steppes.

The very sight of wild horses symbolizes freedom, however, these Mongol horses are not really wild. They are descended from domesticated horses, possibly from the same ones tamed by the armies of Genghis Khan in the thirteenth century.

Unlike the equids we're accustomed to seeing on farms or roaming over hillsides, the Przewalski's horse was believed to be a truly wild horse breed, having never been tamed by humans.

And for good reason: Przewalski's horse is a "prehistoric" horse, the last known descendant of these wild equids that roamed the plains of Eurasia before their domestication by humans. Although genetically very close to Equus caballus (the common domestic horse), it is actually considered a subspecies - even outright as a separate species, according to classifications.

This original horse was therefore considered to be the "last wild horse". Was, because recent genome analyzes published in the journal 'Science' show that these horses were well tamed by humans, 5,000 years ago, before returning to the wild, upsetting the conception that scientists had of the evolutionary history of this animal!

Przewalski's horse survives today in a few regions, where it has been reintroduced into the wild. It is found in Mongolia, China, Spain, but also in France on the plateau of Causse Méjean, in Lozère, a UNESCO World Heritage site. He was therefore considered to be the "last wild horse", a kind of species-fossil of non-domesticated horse that had escaped all domestication.

Except that the paper published by Science, supported by a solid comparative study of the genome of the bones of domesticated horses by the Botai and Prjevalski horses, has demonstrated two things: the first is that Przewalski's horse is not really "wild" And that it was already domesticated by humans a very long time ago. The second is that domestic horses, as we know them today, come from an unknown strain, undiscovered to this day and probably extinct.

A cave painting showing a Przewalski's horse

Credit: Robert Harding/Alamy Stock Photo

Ludovic Orlando, a CNRS researcher from Toulouse, has teamed up with Alan Outram, a zooarchaeologist at the British University of Exeter. Together, they discovered the remains of a former prehistoric "ranch" of the Botai people. They collected the bones of about twenty Botaï horses, in order to identify DNA sequences. They also recorded the DNA sequences of different horse species that populated the region over the past 5,000 years - including of course the Prjevalski horse - to compare them.

They expected to find that Przewalski's horses were close to a strain at the origin of the other species, and that the Botai horse was a kind of semi-domesticated version. But the result surprised them enormously.

Not only were Prjevalski and Botai horses from the same family ... but in view of their genetic heritage, it became clear to the researchers that these "wild" Prjevalski horses were in fact simply Botaï horses escaped and returned to nature !

"We discovered that there were no more real wild horses on Earth," Alan Outram told Science.

Like the Mustang in the United States, Przewalski's horse is therefore a "brown" animal, that is to say, an old domestic species returned to the wild, creating a new population. In 5,000 years, Przewalski's horses had time to "domesticate" and regain their natural instinct, so that we took them for a purely wild species.