UCLA

Perinatal mood and anxiety disorders (PMADs) are estimated to affect as many as 17.7% of mothers in agricultural and postindustrial societies. Various lines of research converge to suggest that PMADs may be diseases of modernity, arising from a mismatch between the environments in which humans evolved over hundreds of thousands of years and contemporary postindustrial lifestyles. Here we highlight the social context of childrearing by focusing on three sources of mismatch associated with PMADs: closer interbirth spacing, lack of allomaternal support and lack of prior childcare experience. The transitions to agriculture and industrialization disrupted traditional maternal support networks, allowing closer birth spacing without compromising infant survival but increasing maternal isolation. Caring for closely spaced offspring is associated with high levels of parenting stress, and poses a particular challenge in the context of social isolation. The mothers kin and community play a critical role in allomothering (childcare participation) in all contemporary hunter-gatherer societies, facilitating a system of simultaneous care for children of a range of ages with unique age-specific needs. The absence of social support and assistance from allomothers in postindustrial societies leaves mothers at increased risk for PMADs due to elevated caregiving burdens. Furthermore, the traditional system of allomothering that typified human evolutionary history afforded girls and women experience and training before motherhood, which likely increased their self-efficacy. We argue that the typical postindustrial motherhood social experience is an evolutionary anomaly, leading to higher rates of PMADs.