It's an interesting article, on a topic I've read about before. I think the answer is that is no one answer - maybe milk became fashionable, and the guys who had a regular supply of milk attracted more females, and thus more offspring. Maybe it was fashionable and, if being consumed as yoghurt, somehow acted as medicine to a bacteria getting around at the time. Maybe it was fasionable, had medicinal qualities and gave you stronger bones, so you were more able to survive childbirth and things like battles or hardships.
I'm just glad I'm not lactose intolerant, so thanks to whoever in my billions of ancestors decided to keep at it.
I wonder how much of it is due to having cows and harsh winters.
(as someone with lots of northern European ancestry and lactose intolerance, it's a fun subject. I can still eat cheese and yoghurt and half-digested milk, so it isn't much bother)
Well, the start of dairy wasn't in a cold climate, so I don't know about that. There was clearly some advantage in being able to digest lactose. Maybe it was the occasional winter that had to be lasted through, and having a cow or goat to milk helped out. Anything that weeded out the competition would have done.
I was thinking about it in two stages; among the people that are using dairy, the ones that can easily consume fresh milk have better access to calories during a cold winter (which might be a difficult time to make yoghurt or such).
I'm just glad I'm not lactose intolerant, so thanks to whoever in my billions of ancestors decided to keep at it.