Flexibility of the father’s brain

Females are responsible for the direct rearing of offspring in more than 95% of mammalian species (1). Humans are an intriguing exception to this pattern of paternal investment, and shifts in society and culture have led to increases in men’s involvement in the care of infants. The modern-day family comes in a variety of structures, and more and more people are playing unconventional roles in childrearing. In PNAS, Abraham et al. (2) show that fathers’ brains are malleable and can adapt to different parental roles. This is the first investigation of the relationship between parenting behaviors, oxytocin, and neural activity in both mothers and fathers raising their firstborn infant in different parenting structures. The researchers investigated this relationship in heterosexual primary-caregiving mothers (PC-mothers), heterosexual secondary-caregiving fathers (SC-fathers), and primary-caregiving homosexual fathers who are raising the infant without the mother’s involvement (PC-fathers). The set of results is fascinating and has widespread implications for the understanding the plasticity of the brain–body orchestration of parenting. Abraham et al. first assess parenting behaviors, such as warmth, gaze, touch, and vocalizations and how these are coordinated with the infants’ signals and changing states. This parent–infant synchrony was significantly higher in PC-mothers and PC-fathers than in SC-fathers, although oxytocin levels were similar across groups. Notably, there were no differences between biological and adoptive PC-fathers in the parenting behavior and oxytocin levels. Thus, genetically related and unrelated PC-fathers yield the similar caregiving and hormonal ties to fatherhood. Pregnancy and childbirth are thought to help program the mother’s brain for caregiving duties. It is well known that the neurohormone oxytocin plays a pivotal role in enabling the uterine contractions for childbirth and breast milk ejection during nursing. It also facilitates maternal behaviors required for caring for a child, including …