And yet, where are the hunter gatherers? Seems the agriculture people won, for the most part.

Also, how long exactly does it take human digestion to adapt? Are there any studies about that? Bear in mind that not only the human genome is involved, but also bacteria and so on in the gut.

Who knows, perhaps part of the human success story is that they can adapt to lots of different diets quickly (humans living in the weirdest places with constrained food sources).

I've read that for example lactose tolerance (the ability to digest dairy products as an adult) spread relatively quickly through the population (can't find exact quotation right now, unfortunately :-( ).