> I can understand their argument though, that cows milk has not existed long enough in northern europe to have affected the population. But that doesn't mean t

> I can understand their argument though, that cows milk has not existed long enough in northern europe to have affected the population. But that doesn't mean the population wasn't already tolerant before cows came along. FYI, human evolution has been ongoing in recent history and the gene that bestows lactose tolerance on most Northern Europeans is one of the fastest spreading adaptations that scientists who study ancient genomes have found. IIRC, that gene first showed up about 4,000 years ago. As to why lactose tolerance is more prevalent the farther north you go, I think the generally accepted reason is that harsher winters required more dependence on pastoral animals, since they are a good way to store calories. If you can get a regular supply of calories out of them without killing them, even better.