Neuroendocrinology of Human Cooperation and Parental Care

Human parental care appears to rely on the same neuroendocrine mechanisms that support parental care in other species, and other types of human prosocial behaviors may also depend on the same neuroendocrine systems. Research has examined associations between peripheral hormone levels and parental behavior or parental brain function using fMRI. Other studies have experimentally manipulated hormone levels by exogenous administration and examined the impact on brain function and parental behavior. These studies suggest that oxytocin acts on midbrain dopamine circuits to promote parental motivation in both human mothers and fathers. Oxytocin also suppresses the amygdala response to infant crying, potentially rendering infant cries less aversive. On the other hand, high levels of testosterone appear to interfere with direct caregiving activities, although indirect caregiving activities may be supported by low to moderate levels of testosterone. A smaller body of research has investigated the role of vasopressin and prolactin in human parental care. Similar approaches have been used to study human cooperation. Oxytocin facilitates cooperation, but only in specific contexts and in individuals with particular personality types. In response to cooperative interactions, oxytocin modulates activity within components of the midbrain DA system, but these effects differ starkly by gender, perhaps due to nonlinear dose–response relationships. There is also emerging evidence that vasopressin and testosterone support cooperation in some contexts. More research is needed to replicate many of the reported findings, but current evidence is consistent with considerable overlap in the neuroendocrine mechanisms that support parental care and cooperation in humans.