THE ANIMAL FILES

Yak

Bos grunniens

The long coat is only the visible layer of a high-altitude animal.

The domestic yak combines a heavy body with a long outer coat and dense wool beneath. Its shape, digestion and oxygen transport all help explain its association with cold uplands. Domestic animals vary widely in coat colour; the uniformly dark wild-yak image does not describe every herd.[1]

Follow the evidence ↓
Yak
Image: 4028mdk09 · Commons · CC BY-SA 3.0
Coat
Long hair over dense insulating wool[1]
Tail
Long-haired rather than ending in a small tuft[1]
Diet
Grazing herbivore[1]

Insulation in layers

Long shaggy hair covers the flanks, chest and thighs, while wool underneath traps an insulating layer close to the body. Small ears and hairy exposed reproductive structures are further features associated with cold conditions.[1]

Moving oxygen at altitude

Compared with lowland cattle, yaks have relatively large hearts and lungs and blood traits suited to oxygen transport. A thick coat alone would not account for working in thin air: breathing and circulation must also supply the tissues.[1]

Time spent processing plants

The rumen is large relative to another stomach compartment, the omasum. This may allow longer fermentation of fibrous plant material and help extract more nutrients. Summer mating is followed by spring or early-summer births, and a calf soon follows its mother back to the herd.[1]

A COMMON MIX-UP

Are all yaks black and silent?

No. Domestic coats may be brown, cream, white or patchy, and yaks grunt and squeak. Bos grunniens refers to grunting.[1]

TRY A LITTLE REASONING

Why would a thicker coat alone be insufficient at altitude?

Reveal the explanation

Insulation limits heat loss, while low oxygen availability poses a different problem. Heart, lung and blood features address oxygen delivery.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Yak (fixed revision; adapted and translated)
  2. NCBI Taxonomy — Bos grunniens (identity and classification)

Last fact check:

One discovery leads to another

American bisonA dust bath can leave a small hollow with a lasting footprint.Bison bison ↗Water buffaloWater and mud help a buffalo manage heat.Bubalus bubalis ↗Domestic goatA browsing adult begins life on a very different diet.Capra hircus ↗