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Chinese New Year Special: Wild horses being dragged back from the edge

Happy Chinese New Year! 恭禧發財 or ‘wishing you [are] prosperous in the coming year’! Today marks the start of the Year of the Horse, which will run from now until the 18th February next year. More specifically, as each year is also assigned one of the Five Elements, 2014 is the Year of the Wooden Horse—so perhaps we should be wary of any gifts that this year might bring.

According to Chinese astrology, those born in a Year of the Horse are active and energetic people, who love to be in a crowd—whilst real horses, of the four-legged variety, also feature heavily in Chinese mythology. One particular tale tells of an exile who, over two millennia ago, caught a wild horse near an oasis at a crossroads on the Silk Road. He called it a ‘heavenly horse and gave it as a gift to the Chinese emperor, Wu of the Han dynasty, who honoured it in a poem.

The same wild horses still roam the harsh steppe grasslands of far northwestern China and Mongolia. With their short necks, spiky manes and yellowish hue, Przewalski’s horses (pronounced sheh-VAHL-skee) look strikingly like the ancient horses depicted in Stone Age cave paintings, dating back 17,000 – 12,000 years ago. In fact, wild horses were once common in prehistoric Europe, Asia and North America; when mammoths, sabre-toothed cats and direwolves also roamed the Earth. Fossils indicate that Przewalski’s horses, in particular, were widespread across most of China in the Pleistocene period. However, habitat loss as a result of climate change and people hunting them for meat caused the numbers of the horses to dwindle dramatically. By 1960, Przewalski’s horses were on the brink of extinction: being considered extinct in the wild, with only a few living specimens remaining in zoos across Europe.

cave_painting_horse

Cave painting of horse in the Lascaux caves, France. Estimated to be 17,300 years old.

However, since 2010 the Chinese government have been reintroducing captive-bred individuals into the 1.6-million-acre West Lake national nature reserve in Gansu Province. To date, this project has returned about thirty Przewalski’s horses to the wild: whilst a similar program in Mongolia has released several hundred individuals.

PrezHorseHustai

Herd of Przewalski’s horses roaming in a Mongolian National Park | Image credit: Kelsey Rideout (CC-BY-2.5)

These efforts have been somewhat successful: with the clippity-clop of tiny hooves marking the births of several new foals. However, and not wanting to ‘look a gift horse in the mouth’; much more work is still needed. Importantly, all living Przewalski’s horses are descended from just 13 or 14 individuals—and this “very narrow genetic base” means that if a wild population is to have any chance of a long-term future it needs to be at least 1,500 strong. Achieving these numbers will be a big challenge, especially considering that, worldwide, there are only 2,000 or so alive today.

Wintercoat

Przewalski’s horse showing distinctive colourings and thick winter coat | Image credit:
©Lawrence Schaefer/Bill Waldrop (CC-BY)

However, as Przewalski’s horses are the last remaining truly wild horses, the effort is worthwhile. Unlike other so-called ‘wild’ horses living today—such as the American Mustang or the Australian Brumby, which are actually feral horses descended from domesticated animals that escaped and adapted to life in the wild—Przewalski’s horse has never been domesticated. Analyses of DNA from living and extinct hoses—including a fossilised foot bone from a prehistoric horse that had been frozen in the Canadian permafrost for 700,000 years—revealed that Przewalski’s horses diverged from other horses around 50,000 years ago. And what’s more, pure genetic lineages of these truly wild horses still remain to today. Nevertheless, they are the closest living relatives of domesticated horses, and are technically the same species, Equus ferus, but different subspecies—and as such, crossbreeding with their domesticated cousins represents a major threat to these wild horses, by diluting their gene pool.

Thus whilst these prehistoric-looking wild horses are no longer teetering on the edge of oblivion, their future is not a given—but let us hope that the Przewalski’s horse is also prosperous in the coming Year of the Horse, and beyond.

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About StuartKing

Hi, I'm Stuart, an Assistant Features Editor at eLife and recent life sciences PhD graduate. I blog about evolution and its weird and wonderful creations.

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