Evolutionary psychology is a field that has made headlines ever since its inception as a distinct discipline in the 1980’s. In this episode of Unsupervised Learning, Razib talks to Dr. Tania Reynolds of the University of New Mexico, who researches intrasexual competition and cooperation, as well as sexual and social selection. Reynolds outlines what evolutionary psychology means for her and explains why she thinks it is helpful in our quest to understand human behavior. In particular, her field of research aims to understand how human females compete and cooperate, the psychological mechanisms driving their behavior, and how our overall evolutionary history informs this behavior (why is this behavior adaptive?). Razib and Reynolds then discuss how men and women have quite different psychologies on average and how that plays out in things as universal and important as friendships. Razib also asks whether it is essential to contextualize evolutionary tendencies within their broader social background. Suppose human males tend to compete through physical aggression. How does it play out in a society like ancient China, which denigrated martial values, as opposed to a post-Roman Europe ruled by illiterate warriors?