Beauty Of Animals | The Beauty Of The Yak | The yak, Bos grunniens or Bos mutus, is a long-haired bovine found throughout the Himalayan region of south Central Asia, the Tibetan Plateau and as far north as Mongolia and Russia. In addition to a large domestic population, there is a small, vulnerable wild yak population. In the 1990s, a concerted effort was undertaken to help save the wild yak population.
The English word "yak" derives from the Tibetan (Tibetan: Wylie: g.yag), or gyag – in Tibetan this refers only to the male of the species, the female being called a dri or nak. In English, as in most other languages which have borrowed the word, "yak" is usually used for both sexes.
Yaks belong to the genus Bos, and are therefore closely related to cattle (Bos primigenius). Mitochondrial DNA analyses to determine the evolutionary history of yaks have been somewhat ambiguous. 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. 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.
The species was originally designated as Bos grunniens ("grunting ox") by Linnaeus in 1766, but this name is now generally only considered to refer 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 permitting the use of the name Bos mutus for wild yaks, and this is now the more common usage.
Wild yaks are among the largest bovids, with males standing about 2 to 2.2 metres (6.6 to 7.2 ft) tall at the shoulder and weighing up to 1,000 kg (2,200 lb) and having a head and body length of 3 to 3.4 m (9.8 to 11 ft). The females weigh about one third of this and are about 30% smaller in their linear dimensions. Domesticated yaks are much smaller, males weighing 350 to 580 kg (770 to 1,300 lb) and females 225 to 255 kg (500 to 560 lb).
Yaks are heavily built animals with a sturdy frame, short legs, and rounded hooves. They have small ears and a wide forehead, with smooth hollow horns that are generally dark in colour. In males, the horns sweep out from the sides of the head, and then curve forward; they typically range from 48 to 99 centimetres (19 to 39 in) in length. The horns of females are smaller, only 27 to 64 centimetres (11 to 25 in) in length, and have a more upright shape. Both sexes have a short neck with a pronounced hump over the shoulders, although this larger and more visible in males.
Both sexes have long shaggy hair with a dense woolly undercoat over the chest, flanks, and thighs to insulate them from the cold. Especially in males, this may form a long "skirt" that almost reaches the ground. The tail is long, with a large plume of hair over much of its length. Wild yaks typically have black or dark brown hair over most of the body, with a greyish muzzle, although some wild golden-brown individuals have been reported. Domesticated yaks have a wider range of coat colours, with some individuals being white or piebald. The udder in females and the scrotum in males are small and hairy, as protection against the cold. Females have four teats.
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