Well, high protien diets supressing fertility might actually be an advantage in a hunter-gather societies - in these primitive societies, most women spaced out children every 4-5 years; they could only carry one at a time, Now, the extended breast feeding in these societies supresses fertility, and sometimes these societys resorted to infanticide if they couldn't support the extra children. Fertility being supressed(as in reduced, but not eliminated by a high protein diet wouldn't be a problem.
Now, when you get to stationary agricultural societies, the women there could have a kid every year or two. Hunter-gathers were actually on average healthier than primitive agriculturist - the reason agriculture won out is that farmers could support more people on a given area of land/have a higher birth rate, not because the high carb diet they ate was all that healthy.