The shared genome constraint: why between-sex genetic correlation matters for evolutionary social science

Abstract

Evolutionary social scientists propose adaptationist hypotheses that contribute significantly to our understanding of human traits. However, relatively little attention has been given to the constraints imposed by the largely shared genome of males and females, which results in substantial positive between-sex genetic correlations (rMF) for many complex traits. This oversight can lead researchers to propose sex-specific adaptive functions for traits that may instead persist in one sex primarily as a correlated genetic response to selection acting on the other (i.e., indirect selection via rMF). I briefly review the quantitative genetics literature underlying the logic of correlated responses, before turning to the implications of large and positive rMF for evolutionary hypothesizing in the social sciences. The implications are explored using human behavioral traits where rMF is likely high but remains unmeasured (paternal care, male choosiness, female aggression), as well as traits for which rMF has been estimated and found to range from high to low (risk taking, same-sex sexual behavior, extra-pair mating). I present genetic signatures for distinguishing between sex-specific selection and correlated responses to selection on the opposite sex and conclude by advocating for explicit consideration of high positive rMF and correlated responses in evolutionary social science, recommending that researchers state their assumptions about rMF.