An international team has drawn on surprising genetic and archeological evidence to show that Przewalski's horse, previously believed to be the last wild equine in the world, actually descends from horses once domesticated by humans.
A study published on Thursday in the journal Science has signified that there are no surviving purely wild horse left but only "feral" ones that descend from domesticated Botai horses from Kazakhstan.
Ludovic Orlando from the French National Center for Scientific Research, who led the study, said: "What we used to understand as the last wild horse on earth is in fact the descendant of the earliest domestic horses, which simply escaped human pressure and became feral during the last few millennia."
The semi-wild Przewalski's have an upright mane, sometimes associated with wild equids, and have a dun coat like the ones in the Ice Age cave paintings in France and Spain, so biologists assumed they were genuinely wild, the study said.
Researchers said that many of the earliest Przewalski's horses had white, spotty Dalmatian-style coats, and thousands of years ago, a surprisingly large number were bred to have the Dalmation-style coloring, possibly because it looked attractive.
"There are a lot of equine biologists who have been studying Przewalski's, and this will be a big shock to them," said co-author Sandra Olsen from the University of Kansas.
Przewalski's once roamed freely along the Mongolian-China border and have recently been reintroduced to the region after having been saved from extinction in captivity.
The study also found that the Botai horses was not the progenitors of all modern domesticated breeds as previously thought.
"Based on DNA results, Botai horses didn't give rise to today's modern domesticated horses," said Olsen. "They gave rise to the Przewalski's horse."
Researchers sequenced the genomes of 20 horses from the Botai and 22 horses from across Eurasia that spanned the last 5,500 years. They compared these ancient horse genomes with already published genomes of 18 ancient and 28 modern horses.
It has been supported by archeological evidence. The Botai's ancestors were nomadic hunters until they became the first-known culture to domesticate horses around 5,500 years ago, using horses for meat, milk, work and likely transportation.
They said if they were still wild horses hunters, it wouldn't have been feasible or supported a large human population with large villages of up to 150 or more houses.