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.