Part of the IREL: Interpersonal Relationships Colloquium Series.

In psychological research, there are often assumptions about the conditions that children expect to encounter during their development. These assumptions shape prevailing ideas about the experiences that children are capable of adjusting to, and whether their responses are viewed as impairments or adaptations. Here, we synthesize evidence from history, anthropology, and primatology relevant to estimating childhood adversity across human evolution. Specifically, we integrate the findings of systematic reviews, meta-analyses, and cross-cultural investigations on three forms of threat (infanticide, violent conflict, and predation) and three forms of deprivation (social, cognitive, and nutritional). Our results show that mean levels of threat and deprivation were higher than is typical in industrialized societies, and that children have experienced much variation in the levels of these adversities across space and time. These conditions likely favored a high degree of phenotypic plasticity, the ability to tailor development to different conditions.