not sure we'll ever 'adapt' to carbs in that they won't affect an insulin reaction, I think that's just how we're made

in the distant past, people often didn't live long enough to become fat in middle age--which was old age back then

also the activity level was far different than today, once agriculture was developed, people got fat if they were of the leisured class. I remember reading somewhere that if the women in a sheik's harem were fat, that was a status symbol as it showed the world he had an abundance of food. So people did put on weight even back then.

as far as some races being more lactose tolerant than others, I think that is also 'how they're made,' not an adaptation

the reason for and function of the different races is not really known very clearly, if at all. It's my very unscientific opinion, based on observation, that some of us have lower cholesterol and some are lactose intolerant, and it's just a part of our genetic make-up.

have no way of proving my hypothesis though!