Bingo. Everything we humans do, besides fucking and surviving, can be construed as unnatural, but it's also what makes life so amusing. The reason no other animal drinks breast milk all of their lives is because it's not practical to expect a 2,000 pound steer to get by solely on the milk of its 2,000 pound mother. The mom would be sucked dry in short order and "baby" would be left without a food source.
Because we are so superior to animals on an intellectual level, we've been successful in essentially removing ourselves from many so-called laws of nature. Thus we are able to drink many other species' breast milk, which contains a lot of viatmins, nutrients, and minerals, as well as a lot of sugar, hormones, and antibiotics, and enjoy our place at the top of the foo chain. Ya gotta love it.
BTW, I'm gonna need a link from you guys who say that if you stop drinking milk you become lactose intolerant. Never heard that one before.