We think of horses as domesticated animals, and no wonder since we've been breeding them for millennia for everything from hunting and jumping to herding and ranch work to pulling plows and heavy carts. Over the centuries, some horses have gone feral, like the famous American mustang, the Camargue horses of France, and the brumbies of Australia. We call them wild, but technically they're not. However, unlike the equids we're used to seeing on farms or roaming over hillsides, the Przewalksi's horse was believed to be a truly wild horse breed, having never been domesticated by humans.

But the surprising conclusions of a 2018 genetic study found that the breed long believed to be the last completely wild horse species in the world is actually a descendant of the first horses thought to have been domesticated by humans. Modern horses can't be traced back to these horses, so somewhere along the way, humans tamed horses again.

"We scientists are a bit sad because we feel that a bit of biodiversity has been lost, in that there are no more wild horses," Sandra Olsen, an archaeologist at the University of Kansas, tells NPR. "But the reality is, they disappeared some time ago."

If not truly wild, the Przewalski's horse, native to the steppes of central Asia, is endangered. Here are 10 cool facts about these special horses and what's being done to protect them.

1. The Przewalski's horse is a subspecies of Equus ferus and is considered the closest relative of the domestic horse. It is cousin to zebras and the wild ass, which all fall under the Equidae family. The split between Przewalski's horse species and the ancestors of domestic horses happened somewhere between 120,000 and 240,000 years ago.

2. Przewalski’s horses are named after Col. Nikolai Przewalski, who was the first Western scientist to describe the species in writing in 1878. However, the first sighting by a European occurred centuries earlier, when Johann Schiltberger recorded his sighting in the early 1400s during a trip to Mongolia while a prisoner of the Turks.

3. The Przewalski's horse nearly disappeared into extinction. Very few in captivity made it through WWII and the last wild individual was spotted in 1969. The species was listed as extinct from the wild in the 1960s until the 1990s, when one surviving individual was found in the wild and other bands of captive-bred horses were reintroduced with continuing success. Currently, there are about 400 horses living in the wild and around 2,000 individuals in captive breeding programs and zoos, and the species' status is now listed as endangered.

przewalski mare and foalA 12-year-old mare named Ieda with her new foal are in the pasture at the Highland Wildlife Park in 2013 in Kingussie, Scotland. The foal was the first newborn Przewalski's horse at the park in five years. (Photo: Jeff J Mitchell/Getty Images)

4. All the Przewalski's horses alive today are descended from 12 horses — 11 captured and brought out of Mongolia around 1900, and a female captured in 1947. Captive breeding has increased the species' numbers from a low of about 30 individuals to today's count approaching 2,000 individuals. The first Pedigree Book was created by zoologist Dr. Erna Mohr, and a detailed studbook has been kept and updated ever since to minimize inbreeding and thus maximize genetic diversity.

5. Despite the careful captive breeding programs, a major threat to the species today is a loss of genetic diversity and thus disease. Their original decline was brought about by hunting, loss of water resources to domestic animals, and loss of habitat. Hybridization with domestic horses was (and is) a threat.

6. Like feral domestic horses, Przewalski's horses live in small family groups comprised of a stallion and his harem of mares and foals, and bachelor groups of males who have yet to form (or have lost) their own harems. But they differ in appearance: they have a shorter, stocky build, thick necks, upright manes with no forelock, low-set tails, and coloring that more closely resembles wild equid ancestors including light-colored muzzles and bellies, a dark dorsal stripe along their backs and bar-stripe patterns on their legs.

Przewalski's horses grow thick, warm coats for the winter, complete with long beards and neck hair. Winter coats are important in the harsh winter desert, where temperatures can be freezing. In high winds, Przewalski's horses turn their back to the storm and tuck their tail tightly between their back legs! This may be an adaptation to help protect the eyes and nostrils, while also protecting the sensitive reproductive parts, from the severe winds and sand storms of the Gobi Desert.

A herd of Przewalksi's horses graze in summer. A herd of Przewalksi's horses graze in summer. (Photo: Vlasto Opatovsky/Shutterstock)

7. The four largest reserves where captive Przewalski's horses roam are in Le Villaret, France; Buchara, Uzbekistan; the Hortobágy-National Park, Hungary; and the Chernobyl exclusion zone, Ukraine. The horses released in the exclusion zone thrived and their numbers grew to a high of around 200, but poaching has reduced their population to about 60 individuals in recent years.

8. Though most people know the species as the Przewalksi's horse, it goes by several other names: Asian wild horse, Mongolian wild horse, and Takh (or takhi as the plural).

9. In 2013, the first Przewalksi's horse born through artifical insemination was welcomed into the world. This success represents an exciting breakthrough in the preservation of the species, and the possibility of increasing genetic diversity without having to transport horses among captive breeding facilities.

10. If you'd like to see a Przewalksi's horse in person, several zoos in North America have them as residents, including San Diego Zoo, Denver Zoo and Toronto Zoo. But for the real history and heart of the conservation of the species, Prague Zoo is the place to go. That's where Len lives, the grandson of the last Przewalski's horse caught in the wild.

Editor's note: This story has been updated since it was originally published in January 2014.

Jaymi Heimbuch ( @jaymiheimbuch ) focuses on wildlife conservation and animal news from her home base in San Francisco.

Przewalski's horse: 10 things you didn't know about the last 'wild' horses on Earth
These small horses were thought to be the only truly wild horse species left on the planet and have a fascinating history.