that voluntarily, regularly seek out and consume the milk of another mammal. Milk is nature's food for infant mammals, it's not made for adults and it's not made for cross-species consumption (at least not in ideal circumstances, you hear stories all the time of some baby animal being adopted by the mother of another species and drinking her milk, but that is something done for survival, not the natural course of things). Mammals are not intended to drink milk past infancy, which is why lactose intolerance is so widespread except in cultures where we feed dairy to our children constantly (your body will naturally stop producing lactase, the enzyme required to break down the sugar in milk, after a couple years of age).
Milk is fatty, pussy, and disgusting if you ask me. And unless you buy organic milk, it's chok-full of synthetic growth hormones, antibiotics, and pesticides. You will not, however, find a "scientific consensus" regarding milk because the dairy industry has spent decades spreading the meme that milk is healthy and they've invested a lot of money into this, including funding "research."
Here is some good info on milk from the Physicians Committee for Responsible Medicine:
http://www.pcrm.org/health/veginfo/milk.html