Yaks are bovids adapted to life at high altitudes in the Himalayas. Most yaks are domesticated but there is some small wild population.
Yaks are very well adapted to living in a high altitude. The adaptations are similar to the ones show by humans in the same area, but different from what the llamas exhibit. Yak blood can transport oxygen more efficiently than the blood of normal cattle. Yaks also can tolerate cold much better than other bovines but they cannot tolerate higher temperatures too well.
Yaks are the most important domestic animals in Tibet used for riding, and as beasts of burden. Yak meat, yak milk and butter are important food sources. Yak wool is used as fiber for clothing. Yak butter and yak butter tea are particularly important food sources for humans who wish to survive the harsh conditions living at high altitudes in the Himalayas.
Domestic yak on the Toronto Zoo website.
Yakking about Yaks.
Yaks in the Himalayas.
10 Fascinating Facts about Yak.
Yak butter on Wikipedia.
Butter tea on Wikipedia.
The yak genome and adaptation to life at high altitude.