Men's but not women's risk proneness in early adulthood is associated with lifetime reproductive success: evidence for sexual selection in modern environments

Two studies were conducted in Japan (Study 1) and the US (Study 2) to test whether sexual selection acts on risk proneness in modern environments. Participants aged 45 to 55 years (total N = 2887) reported their risk proneness in early adulthood (20s to 30s) and the number of children they had. In both studies, the number of children was significantly correlated with risk proneness in early adulthood only among men. Although men's correlation was weak (smaller than 0.15), women's correlation was virtually zero in both countries. More importantly, the correlation was significantly stronger for men than for women. These results suggest that sexual selection still acts on men's risk proneness in modern environments (in this case, contemporary Japan and the US), whereas women's risk proneness is not under selection in either country.