Why men have shorter lives than women: effects of resource availability, infectious disease, and senescence.
Senescence arises from age-specific deterioration of the soma as a consequence of optimization of life history, and such effects of senescence should appear when comparing species that differ in intensity of sexual selection, as well as when comparing, within a species, the two sexes that often differ in intensity of sexual selection. However, any extrinsic cause of mortality that reduces life expectancy will reduce the possibility of detecting sex-specific differences in senescence. We investigated geographical variation in human sex differences in longevity across 121 countries to test whether differences in sexual competition for limiting resources, reflecting intensity of sexual selection, affected sex differences in longevity. Men on average lived 5 years shorter than women. High rates of childhood morbidity and mortality reduced the sex difference in longevity, while increased overall longevity increased the sex difference in longevity. Increased resource availability estimated from gross domestic product per capita reduced the sex difference in longevity, accounting for 10% of the variance, while there was no additional effect of income inequality as reflected by the Gini coefficient. In a separate analysis of sex differences in longevity among the states of the US, there was a strong effect of the Gini coefficient on sex difference in longevity, with the negative effect on male longevity being stronger than that on female longevity. In contrast, there was only a marginal effect of average household income. Thus, there was evidence of increased competition for resources contributing to increased sex differences in longevity within a single nation.
Møller
A P
AP
CNRS, UMR 7103, Laboratoire de Parasitologie Evolutive, Université Pierre et Marie Curie, Paris Cedex 05, France. amoller@snv.jussieu.fr
Fincher
C L
CL
Thornhill
R
R
D000375:Aging / Q000235:genetics*; D003141:Communicable Diseases / Q000453:epidemiology; D019049:Developed Countries; D003906:Developing Countries; D004467:Economics; D005260:Female; D014943:Global Health; D054624:Health Status Disparities; D006801:Humans; D008017:Life Expectancy; D008136:Longevity / Q000235:genetics*; D008297:Male; D008954:Models, Biological; D012737:Sex Factors; D014481:United States / Q000453:epidemiology