The legacy of privilege: Social inheritance reverses sex differences in reproductive inequality in the spotted hyena

Inequalities in reproductive success among females and males shape natural and sexual selection. For sexually reproducing species, the Darwin-Bateman paradigm predicts greater reproductive inequality in males than females. A mechanism driving reproductive inequality in humans and other animals is social inheritance of privilege. Here, we show that this mechanism can reverse the male bias in reproductive inequality. Using a 29-year dataset spanning eight generations of spotted hyenas ( Crocuta crocuta ), a species in which social rank and privileges are inherited from the mother, we show that reproductive inequality was lower among females than males when estimated annually but increased more strongly in females over generations, quickly reversing the sex bias to females. Our findings suggest that social inheritance of privilege (i) is a powerful driver of sex differences in reproductive inequality and (ii) may explain why females are the more competitive sex in some species. We outline how reproductive inequality influences female and male reproductive strategies, intrasexual competition, and genetic evolution.