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Przewalski’s– are they last wild horses on Earth?

a brown horse standing on top of a lush green field

The Przewalski’s horse is named after Russian explorer and geographer Nikolaj Przewalski. Nikolaj Przewalski found a skeleton of the horse during his expedition in 1881 and was the first person to recognize it belong to the species previously unknown to European science. The name Przewalski is of Polish origin and is pronounced as she-val-skee. The horse is also known as the Dzungarian horse or Asiatic wild horse and in Mongolia, amongst locals it is called takhi.

In comparison to domesticated horses, P. horses are heavily built, has shorter legs, thick neck and large head. They are 4.3 to 5 feet (1.3 to 1.5 meters) tall, and their length ranges from 7.25 to 8.5 feet (2.2 to 2.6 meters) . They weigh anywhere from 550 to 800 pounds (250 to 360 kilograms). They are dun-colored with a dark zebra-like erect mane and no forelock. A dark stripe continues from the mane along the backbone to a dark, plumed tail. They have a yellowish-white belly and dark lower legs and zebra-like stripes behind their knees. Their tail can be up to 3 feet in length, with a longer dock and shorter hair than seen in domesticated horses. Unlike domestic horses, they have short and spiky mane, with a dark brownish black shade. Male Przewalski’s horses are taller and have sturdier bodies. They are also heavier compared to females of the same age.The hooves of Przewalski’s horse are longer in the back and have significantly thicker sole horns than other feral horses. One unique feature of this species is that they have 66 chromosomes, compared to 64 in all other horse species. Przewalski’s horse and the domestic horse are the only equids that crossbreed and produce fertile offspring, with the offspring possessing 65 chromosomes. Normally, the offspring of a domestic horse and another equid, such as a zebra or a donkey, are sterile. Their life expectancy is 20-25 years.

P. horses live in steppes, shrublands and grasslands. They usually spend their days grazing on open plains, grasses and bushes being their favorites.

They are social animals, living in herds of 10-20 members. Herds with mares, their foals and a dominant stallion are called harem herds. Other males are driven off from harem as soon as they mature (usually at age of 2) and they move to bachelor herds. Only way for them to own a harem is to seize it from another dominant male. P. horses communicate with group members with the help of neighing sounds. Mares usually give birth to a single foal, which is capable of standing immediately after birth. The newborn feeds on mother’s milk only for 6-8 months. Both the mother and the whole herd are very protective of the newborns as they are quite small and an easy prey.

Until recently they were thought to be the world’s only remaining wild horses, but a new study shows Przewalski’s horses have domesticated ancestors.
Said genetic study has found that a population inhabiting Mongolian grasslands actually is a feral descendant of the earliest-known domesticated horses.

As we mentioned earlier, Mongolian wild horses, also known as Przewalski horses, were first described scientifically in the late 19th century by Russian explorer N. M. Przewalski, the horse once freely roamed Europe and Asia. Different factors contributed to the to the horse moving east to Asia, and eventually becoming extinct in the wild.

Their population was already very low at the time Przewalski first studied them. First successful attempts to obtain specimens for exhibit and captive breeding were largely unsuccessful until 1902, when around 30 captured foals were brought to Europe. These and other captives were distributed among zoos and breeding centers in Europe and the United States. Breeding was mainly unsuccessful at first due to many problems, one being reduced fertility caused by inbreeding. This led to genetic bottleneck in the P. horse population by the mid-1930s. Things went for the better when facilities started exchanging breeding animals among themselves. This increased genetic diversity and improved fertility. Then another catastrophe for the P. horse population happened – only third of the population survived the WWII which caused another genetic bottleneck. Population didn’t fully recover until a decade later. In the 1960s population consisted of little less than 150 animals spread among zoos and parks. Luckily in 1957, a wild-caught mare captured as a foal a decade earlier was introduced into the Przewalski captive population which lead to increased reproduction rate. As it turned out, this was the last wild-caught horse. At that point the captive population became the sole representatives of Przewalski’s horse. By the early 1990s population has risen to over 1,500 horses. Since then several populations have been released into the wild. Most significant is a successful reintroduction of these horses from zoos into their natural habitat in Mongolia. Nowadays hundreds of horses exist in free-ranging populations in the wild in Mongolia, China, Russia and with the rest of them living in captivity the population consists of about 2000 horses altogether.

The genetic studies we mentioned at the beginning analyzed the family tree of a Przewalski’s horse. Researchers took their DNA and compared it to the bones of ancient horses. Results showed Przewalski horses actually descended from domesticated horses that later returned to the wild. Przewalski’s ancestors turned out to be one of the first known domesticated horses, called Botai horses. They were native to northern Kazakhstan 5,500 years ago. Findings show that around that time people began domesticating horses and using them for food and transportation. It is assumed that Przewalski’s at some point escaped from early domestic herds and formed a new feral population in the wild.

These findings were contrary to most scientist’s speculations that Botai horses were the ancient ancestors of modern domestic horses. The question of who ancestors of today’s domestic horses remains unanswered. More details can be found in researcher’s paper here:

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