Adolescent intelligence and socio-economic wealth independently predict adult marital and reproductive behavior

Counter-intuitively, sociobiological and evolutionary theories predict a negative relationship between g and reproduction when applied to modern humans. Although existing research has documented this dysgenic trend, the association between g and socio-economic factors presents a confound that has not systematically been addressed in prior research. Based on a sample of 325,252 individuals drawn from the nationally representative Project Talent database, we examined the unique effects of g and socio-economic wealth, assessed in adolescence, on marital and reproductive behavior over the next 11 years. Results show that both g and socio-economic wealth have unique, independent negative effects on marital and reproductive behavior such that individuals of higher intelligence and higher wealth delay marriage and reproductive longer than those of lower intelligence and wealth. The effect of g was slightly stronger than that of wealth, though for both variables much of their influence was mediated by educational attainment. Consistent with sociobiological theory, these dysgenic effects were stronger among females than males.