Predisposed to differences in parental investment, men and women are expected to enact different reproduction-oriented, accelerated life-history strategies when facing high extrinsic risks or resource insecurity. Sexual selection processes would strengthen the sex differences in support of such accelerated life-history strategy, causing women to divert more time and energy to reproductive activities and depend more on men's economic provisioning and therefore enforcing sexist attitudes and gender inequality. This paper provides empirical support for this life-history explanation of sexism based on data from the World Values Survey and four United Nations sources. The results generally support our explanation in the following manners: (1) Societal-level extrinsic risks (worries over intergroup violence) were associated with higher sexism. (2) Men were more sexist, and the association between individual-level resource insecurity and sexism was more moderate in countries and regions with greater society-level extrinsic risks. (3) Societal-level extrinsic risks (adult mortality) and resource availability were associated with higher and lower gender inequality, respectively, through the mediating effects of accelerated life-history strategies, indicated by adolescent birth rates and total fertility.