Evolution of Fatherhood (Family Relationships: An Evolutionary Perspective)
David C Geary; 2007
>Cultural debates regarding men’s contributions to families and their children and the occasional rancor over the unequal contributions of men and women to parenting belie a deeper and rarely considered scientific riddle; specifically, on the basis of little or no male parenting in nearly all other mammalian species and among our two closest living relatives, it is a scientific curiosity that men invest in families and children at all. To understand how men’s parenting evolved and how it is maintained in the here and now, we must consider the factors related to the evolution and expression of male parenting across other species. These factors involve tradeoffs that balance the benefits of male protection and provisioning to the health and later competitiveness of his offspring, weighed against the risk of cuckoldry and the cost of lost mating opportunities. Of course, it is likely that male parenting would benefit offspring even in species where this parenting does not occur. However, in these species, males that compete for access to mates out-reproduce any parental fathers, and thus any tendency toward the latter does not evolve.
Men’s parenting is consistent with the same cost–benefit tradeoffs in other species in which paternal investment is found. In traditional and developing societies today and in the historical record, men’s investment in families substantively reduced children’s morality risks and improved their physical health and development. In these societies and in Western societies today, men’s investment often facilitates their children’s ability to acquire the skills needed to compete in adulthood. Children who become successful adults are able to better care for and thus lower the mortality risks and enhance the later competitiveness of men’s grandchildren. Men also benefit because of comparatively high levels of paternity certainty, although cuckoldry does occur and men and women show evidence of corresponding adaptations. Women’s reluctance to engage in casual sex greatly reduces men’s mating opportunities, and in so doing, lowers the opportunity cost of paternal investment.
Even with an evolved bias to invest in children, there is considerable variation among men as to when and with whom they will invest in a family. The influences on the expression of men’s parental behaviors are multifaceted and range from the genes that influence the expression of parentingrelated hormones to the quality of the marital relationships to cultural mores regarding marriage practices (e.g., whether or not polygyny is allowed). A comparative and evolutionary perspective on men’s parenting provides a broader perspective for understanding these patterns and allows us to more fully understand when, where, and with whom men will invest in families.<