I refer you to this link on genetic variance and nutritional adaptations:http://anthro.palomar.edu/adapt/adapt_5.htmThe whole "humans weren't adapted to X in paleo times" is bullshit. There is an argument to be made against eating processed foods and eating less carbs/grains, that is where the focus should be if people want others to take this thing seriously. Nothing that cavemen actually ate is probably all that appetizing. They certainly weren't eating lean meats on a daily basis, or oils and fats, or whatever. Sure they had berries and nuts when they could find them. And nasty raw ass veggies, probably a lot of generally bad tasting food.
Relevant passage:
The common ability of people in Europe and some other areas of the world to continue producing lactase as adults is very likely a relatively recent evolutionary development. Prior to the domestication of cattle, sheep, goats, and horses, which occurred after about 9000 years ago, milk was most likely only consumed by babies and very young children. That milk was human milk. Dairy products such as cow's milk, yoghurt, and cheese did not exist. When nutrient rich nonhuman milk became widely available in pastoralist societies, the rare genetic variations that allowed some adults to easily digest lactose were selected for and this trait became more common.