Sexual selection and the evolution of behavior, morphology, neuroanatomy and genes in humans and other primates

Explaining human evolution means developing hypotheses about the occurrence of sex differences inthe brain. Neuroanatomy is significantly influenced by sexual selection, involving the cognitive domainthrough competition for mates and mate choice. Male neuroanatomy emphasizes subcortical brain areasand visual-spatial skills whereas that of females emphasizes the neocortex and social cognitive areas. Inprimate species with high degrees of male competition, areas of the brain dealing with aggression areemphasized. Females have higher mirror neuron activity scores than males. Hundreds of genes differin expression profiles between males and females. Sexually selected differences in gene expression canproduce neuroanatomical sex differences. A feedback system links genes, gene expression, hormones,morphology, social structure and behavior. Sex differences, often through female choice, can be rapidlymodulated by socialization. Human evolution is a dramatic case of how a trend toward pair bonding andmonogamy lowered male competition and increased female choice as a necessary step in releasing thecognitive potential of our species.