It's sustained us since the beginning of time. The Lapplanders, Biblical Hebrews, Egyptians, Romans, Greeks, Spanish, and early American colonists all drank it. It's probably been the least controversial thing on the planet for the past couple thousand years or so. When cows eat grass in a pastoral setting, they produce good milk.
Pasteurization was invented as a way to sterilize wine, but along the way it got applied to milk. Supposedly it makes milk safe. In fact, drinking a glass of pasteurized, homogenized milk is pretty dangerous. After researching for this episode, I refuse to drink another glass.