Women's wellbeing and fertility in rural Tanzania: Overall, women's wellbeing was highest in husband-older marriages, but among women married to older men, spousal age gap was unrelated to wellbeing

Shared interests or sexual conflict? Spousal age gap, women's wellbeing and fertility in rural Tanzania. David W. Lawson et al. Evolution and Human Behavior, August 29 2020. https://doi.org/10.1016/j.evolhumbehav.2020.08.009

Highlights
• We explore whether husband-older spousal age gaps are costly or beneficial to women.
• Women frequently married older men than their stated ideal spousal age gaps.
• Spousal age gap was unrelated to the risk of divorce or to women's fertility.
• Overall, women's wellbeing was highest in husband-older marriages.
• However, among women married to older men, spousal age gap was unrelated to wellbeing.

Abstract: The marriage of older men to younger women is common across cultures. On one hand, husband-older marriage may serve the interests of both sexes, a conclusion broadly consistent with reported gender differences in mate preferences. On the other hand, men alone may benefit from such marriages at a cost to women if seniority enables men to exert dominance in conflicts of interest. Indeed, in public health large spousal age gaps are generally deemed “pathological”, both a cause and consequence of gender inequalities harmful to women. We investigate these alternative models of spousal age gap using data from a cross-sectional survey of women in Mwanza, northwestern Tanzania (n = 993). Consistent with the notion that spousal age gaps are a product of sexual conflict, women typically married with a larger age gap than stated ideals. However, adjusting for potential confounds, spousal age gap was not associated with fertility or the risk of divorce. Furthermore, women's mental health and autonomy in household decision-making was higher in husband-older marriages compared to rare cases of same-age or wife-older marriage. Beyond this comparison, the magnitude of spousal age gaps was unrelated to either measure of women's wellbeing among the overwhelming majority of marriages where the husband was older. Together these findings suggest husband-older marriage does not influence marital stability, relatively large spousal age gaps are neither especially costly nor beneficial to women, and that alternative sociodemographic factors are more important in driving variation in women's wellbeing and reproductive success in this context. Our results support neither a model of mutual benefits, nor a “pathological” conceptualization of spousal age gaps. We conclude by both encouraging evolutionary human scientists to engage more fully with models of sexual conflict in future studies of marriage and mating, and suggesting that public health scholars consider more neutral interpretations of spousal age differences.

Keywords: Spousal age differenceEmpowermentMental healthMarriageTanzaniaSexual conflict