linguistic:paraphrasing, structural:scholar_edition
Wild species surviving into modern times

A truly wild horse is a species or subspecies with no ancestors that were ever successfully domesticated. Therefore, most "wild" horses today are actually feral horses, animals that escaped or were turned loose from domestic herds and the descendants of those animals. Only two wild subspecies, the tarpan and the Przewalski's horse, survived into recorded history and only the latter survives today.

The Przewalski's horse (Equus ferus przewalskii), named after the Russian explorer Nikolai Przhevalsky, is a rare Asian animal. It is also known as the Mongolian wild horse; Mongolian people know it as the taki, and the Kyrgyz people call it a kirtag. The subspecies was presumed extinct in the wild between 1969 and 1992, while a small breeding population survived in zoos around the world. In 1992, it was reestablished in the wild by the conservation efforts of numerous zoos. Today, a small wild breeding population exists in Mongolia. There are additional animals still maintained at zoos throughout the world.

Their status as a truly wild horse was called into question when domestic horses of the 5,000-year-old Botai culture of Central Asia were found more closely related to Przewalski's horses than to E. f. caballus. The study raised the possibility that modern Przewalski's horses could be the feral descendants of the domestic Botai horses. However, it remains possible that both the Botai horses and the modern Przewalski's horses descend separately from the same ancient wild Przewalski's horse population.

The tarpan or European wild horse (Equus ferus ferus) was found in Europe and much of Asia. It survived into the historical era, but became extinct in 1909, when the last captive died in a Russian zoo. Thus, the genetic line was lost. Attempts have been made to recreate the tarpan, which resulted in horses with outward physical similarities, but nonetheless descended from domesticated ancestors and not true wild horses.

Periodically, populations of horses in isolated areas are speculated to be relict populations of wild horses, but generally have been proven to be feral or domestic. For example, the Riwoche horse of Tibet was proposed as such, but testing did not reveal genetic differences from domesticated horses. Similarly, the Sorraia of Portugal was proposed as a direct descendant of the Tarpan on the basis of shared characteristics, but genetic studies have shown that the Sorraia is more closely related to other horse breeds, and that the outward similarity is an unreliable measure of relatedness.