The evolutionary genetics of personality revisited

Like all human individual differences, personality traits and intelligence are substantially heritable. From an evolutionary perspective, this poses the question what evolutionary forces maintain their genetic variation. Information about the genetic architecture and associations with evolutionary fitness permit inferences about these evolutionary forces. As our understanding of the genomics of personality and its associations with reproductive success have grown considerably in recent years, it is time to revisit this question. While mutations clearly affect the very low end of the intelligence continuum, individual differences in the normal intelligence range seem to be surprisingly robust against mutations, suggesting that they might have been canalized to withstand such perturbations. Most personality traits, by contrast, seem to be neither neutral to selection nor under consistent directional or stabilizing selection. Instead evidence is in line with balancing selection acting on personality traits, probably supported by human tendencies to seek out, construct and adapt to fitting environments.