[solarmist]

We know very little about pre-historical diets, there are almost as many theories on it as there are current human diets. Just look at any two descriptions of the "paleo diet".

I'm sure though that the tribes/groups that had best access to food were the most successful, so I'd assume that fasting was something to avoid for them, not embrace. I'd be willing to bet that in reality, before the rise of civilization (and expansion to less hospitable climates), that fasting was more uncommon than the general population believes (most modern hunter/gatherer tribes eat pretty well), if food started to get scarce you went and found more. Food isn't really scarce if you live in a good area, and while our species was growing up we lived on very fertile lands.