Tibetan White Yak – The Snow-White Yak Is The Rarest Color Phase Of Yak In The World

Belonging to the genus Bos, Yaks are related to cattle (Bos primigenius). Mitochondrial DNA analyses to determine the evolutionary history of yaks have been inconclusive.

The yak may have diverged from cattle at any point between one and five million years ago, and there is some suggestion that it may be more closely related to bison than to the other members of its designated genus.[4] Apparent close fossil relatives of the yak, such as Bos baikalensis, have been found in eastern Russia, suggesting a possible route by which yak-like ancestors of the modern American bison could have entered the Americas.[5]

The species was originally designated as Bos grunniens ("grunting ox") by Linnaeus in 1766, but this name is now generally considered to refer only to the domesticated form of the animal, with Bos mutus ("mute ox") being the preferred name for the wild species. Although some authors still consider the wild yak to be a subspecies, Bos grunniens mutus, the ICZN made an official ruling in 2003[6] permitting the use of the name Bos mutus for wild yaks, and this is now the more common usage