Natural selection is differential reproduction. Demographic and ethnographic, historical and genetic evidence suggest that, over the course of our evolutionary past, members of H. sapiens varied in reproductive success. Selection for emotions and other adaptations underlying intrasexual and intersexual competition should have been strong. In foragers across continents, from Africa to Australia, reproductive variance among women often was limited to single digits, though reproductive variance occasionally reached double digits among men. Those numbers were higher in more sedentary societies. In the first empires, from Asia to the Americas, emperors consistently left behind hundreds of sons; and genetic evidence suggests that the effective breeding population of women was greater than the effective breeding population of men, by a factor of 17 to 1. Adaptations have developed, and have been put to use, in order to promote reproductive success.