Wealth and the opportunity for sexual selection in men and women

Sexual selection theory suggests that males benefit more than females from multiple mates and that sexual selection is weak in monogamous mating systems. However, little research on sexual selection has been conducted simultaneously in men and women, and we lack a detailed understanding of the socioecological factors that can influence it. Here, we examined the effects of wealth and sex on 2 distinct episodes of human sexual selection (marry once and remarry) in historical Norwegian populations with imposed monogamy, where remarriage was only possible after widowhood. We quantified sexual selection using the Bateman gradient. We also examined the underlying proximate factors that might influence the odds of remarriage and reproduction after widowhood. We found that the intensity of sexual selection corresponds well with Bateman gradients measured in other monogamous populations and was stronger for those who married once than for those who remarried. The selection gradients on "marry once" were affected by neither sex nor wealth. However, when we measured the gradients on "remarry," sexual selection was stronger on wealthy men and women compared with those who were poor. Remarriage age was the most important underlying factor explaining how widows increased reproductive success. For widowers, it was to remarry a younger woman than themselves. In conclusion, we show that sexual selection can operate on both sexes in a monogamous population and suggest that under certain circumstances (when very wealthy), women can benefit as much as men can by remarriage.