The evolutionary genetics of personality revisited

• Evolutionary forces that maintain genetic variance in traits can be inferred from their genetic architecture and fitness correlates.
• A substantial amount of new data on the genomics and reproductive success associated with personality traits and intelligence has recently become available.
• Intelligence differences seem to have been selected for robustness against mutations.
• Human tendencies to select, create and adapt to environments might support the maintenance of personality traits through balancing selection.

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.