Self-esteem, but not narcissism, positively predicts fertility across the cultures

Abstract

Estimating the links between behavioral traits and fertility (e.g., number of children) is a fundamental step in the analysis of contemporary natural selection on behavioral traits. Self-esteem and narcissism are two frequently examined personality traits with partially shared content, but their associations with fertility are rarely analyzed. We examined these associations using a publicly available, large intercultural database (N = 43,029; 65 countries). We fitted multilevel Poisson regressions with random slopes; furthermore, we analyzed the interactions between personality traits, participants' sex, and the size of their settlement (urban vs. rural) in the prediction of the number of children. The results showed that self-esteem positively predicted fertility, while narcissism had no contribution to the prediction; significant variations in these effects across countries were captured as well. Interactions showed that the positive link between self-esteem and fertility was particularly expressed in males and in urban environments; conversely, narcissism showed a negative association with fertility in rural settlements. The data suggest that self-esteem may be under positive directional selection, which has implications for the evolutionary personality ecology in contemporary human populations.