The rise of civilization coincided with a strange twist in our evolutionary history. We became, in the coinage of one paleoanthropologist, “mampires” who feed on the fluids of other animals. No one can say why.
It could be medicine. Beyond nutrition, milk contains active gene-regulators. It's also known that breast milk has antibiotic properties. My wife is breast-feeding our baby, and she was told to apply a small amount of milk where the baby scratches herself. I'm surprised this article didn't mention any of these possibilites. This is one reason why I swore off non-organic milk. I'm sure that hormones, antibiotics and the stress of factory milk production changes the miRNA profile of cow milk, and I would doubt that it is in a way that is good for me.Milk, by itself, somehow saved lives. This is odd, because milk is just food, just one source of nutrients and calories among many others. It's not medicine. But there was a time in human history when our diet and environment conspired to create conditions that mimicked those of a disease epidemic. Milk, in such circumstances, may well have performed the function of a life-saving drug.
I can say why. The same reason that a dog licks his ass. Be cause we can. What other creature can effectively collect milk? Uh, none. Cats drink milk, but not in the wild, because no one is feeding it to them. I'm pretty sure a cat would keep a dairy farm if not for the whole intelligence and opposable thumb things.