Tibetan nomadic yak herder Karsal's wife, Phurba, milks one of the family's dris in the early morning at their home in the Tibetan Plateau. (From the the book What I Eat: Around the World in 80 Diets.) The male yaks remain free at night, grazing at higher elevations, and the dris and their calves are tethered close to the tent to make milking in the morning convenient, and to prevent the calves from suckling all the milk.