The evolutionary context of personality development: Ontogenetic and Deferred Adaptations

The evolutionary context of personality development. Marco del Giudice. In Handbook of Personality Development, Chapter 2. New York: Guilford, 2019. January 2019. https://www.researchgate.net/publication/316120672_The_evolutionary_context_of_personality_development

Ontogenetic and Deferred Adaptations
Looking at developmental stages through the lens of biological function suggests a useful distinction between two kinds of adaptations that are often observed in early life. Ontogenetic adaptations are designed to serve their fitnessenhancing function at a specific time in development, and often disappear as soon as they are no longer needed. Examples include the placenta (a fetal organ that provides nourishment and other vital functions during the fetal stage and is discarded immediately after birth) and infantile reflexes, such as the suckling reflex. Deferred adaptations are traits that appear in childhood but function—at least in part—to prepare children for adult behavior (Bjorklund & Ellis, 2014). Play is a paramount example of a deferred adaptation; in humans and other mammals, playing trains youngsters to deal with unexpected events and, at the same time, paves the way to the acquisition of specialized adult skills (e.g., foraging, fighting, parenting) (Geary, 2010; Spinka, Newberry, & Bekoff, 2001). The concept of an ontogenetic adaptation is particularly useful to understand the limits of early experiences in shaping adult personality. Some behavioral traits expressed in childhood serve important functions in the context of family life but may cease to be useful as the child turns into an independent adult. These traits may either disappear or get repurposed in a different form in the service of new developmental goals. For example, attachment styles in infancy are largely determined by the parents’ caregiving styles and show negligible genetic effects. In middle childhood, attachment styles start to become differentiated by sex, possibly under the influence of adrenal androgens; adults’ attachment styles to romantic partners are only weakly correlated with those of infancy, and reflect a sizable contribution of genetic factors (Barbaro, Boutwell, Barnes, & Shackelford, 2017; Del Giudice, 2009, 2015a). At an even deeper level, the existence of parent–offspring conflict implies that the parents’ behavior is not completely in the best interest of their children.

For this reason, children should not passively accept the influence of parents; instead, they should show a certain amount of developmental “resistance” to parental shaping. While it is difficult to directly test this hypothesis, parent– offspring conflict may well contribute to explain why family experiences have only small and inconsistent effects on the development of adult personality.