I find it really interesting that all of the replies to this comment take the fact that animals will consume dairy if it's available as an argument in favor of human consumption of it. Humans are the only animals, that as adults, take the milk of another mammal for their own consumption.

For that matter, other than the isolated, exceptional cases of a lactating mammal adopting the orphans of another mammal and nursing them, humans are the only mammals that consume the milk of a different species.

Cats drinking from a saucer of milk put on the floor in front of them is nothing like milking a cow — except, I suppose, at the level of digesting lactose.