Selection in utero contributes to the male longevity deficit

The literature offering evolutionary explanations of the male longevity deficit does not address temporal variation in the deficit. This circumstance appears attributable to the fact that natural selection intuitively explains the deficit’s pervasive and persistent nature, while social processes more parsimoniously explain its temporal variability. I offer consilience of these perspectives by speculating that selection in utero, a mechanism both conserved by natural selection and affected by social processes, could induce deviations around trend in the male longevity deficit. I describe the mechanism and offer an empirical test of its possible effect among Swedes – a population with the longest continuous record of sex-specific longevity in annual birth cohorts. I replicate the test with data from England and Wales. Results support the hypothesis that selection in utero against less fit males may explain part of the difference in longevity between males and females in modern populations.

► Women have persistently and pervasively lived longer than men, but the difference has varied considerably over time.
► Social scientists attribute temporal variation in the male longevity deficit to cultural and social circumstances, such as war and childbirth practices, that differentially affect mortality among young men and women.
► Here I show that a fundamental biological mechanism, selection in utero, can also induce temporal variation in the male longevity deficit.
► Selection in utero may fall more in the realm of the biological than social sciences, but I argue for consilience when exploring its implications for longevity. I do so because research shows that social processes can trigger the mechanism.