As far as I understand, an important change occurred when we began to drink the milk of cattle. Until then, man had used goat and sheep milk. We drank goat milk for a long time,...and then like most things...slid back into cow milk. I don't actually 'drink' milk, but my DH still does. However, he had no weight problems at all and I do. Besides I never was a 'milk' drinker even as a child.