The lactase gene, which allows for lactose digestion, was strongly selected for in human evolution, suggesting the nutritional value of milk.

“in the 1900s so milk has been a part of the human diet for probably 8 000 years and we know humans have been using this and the lactase Gene is probably one of the most strongly selected for genes in human evolution early in Europe maybe 9000 years ago humans didn't have lactase in their genome we lost it so only babies have it and then Toddlers and we lose it and when humans started drinking milk we held on to that Gene longer and longer which is just a suggestion that how nutritious this food is”