At least in Europe, milk drinking may have given people a source of calcium to aid in vitamin D production, as they moved north and sunlight, the usual source of vitamin D, decreased.

在欧洲，人们需要饮奶吸收钙元素，来帮助人体制造维生素 D。因为当他们往北迁徙时，提供维生素 D 的阳光会逐渐减少。