Male survival advantage on the Baja California Penninsula

A consistent finding from contemporary Western societies is that women
outlive men. However, what is unclear is whether sex differences in
survival are constant across varying socio-ecological conditions. We test
the universality of the female survival advantage with mortality data from
a 19th century population in the Baja California peninsula of Mexico. When
examined simply, we find evidence for a male-biased survival advantage.
However, results from Cox regression clearly show the importance of age
intervals for variable survival patterns by sex. Our key findings are that
males: 1) experience significantly lower mortality risk than females
during the ages 15-30 (RR = 0.69), 2) are at a significantly increased
risk of dying in the 61+ category (RR = 1.30), and 3) do not experience
significantly different mortality risk at any other age interval (0-14,
31-45, 46-60). We interpret our results to stem from differing intrinsic
and extrinsic risk-factors for sex-biased mortality across age intervals,
highlighting the relevance of a lifecourse approach to the study of
survival advantage. Ultimately, our results make clear the need to more
broadly consider variability in mortality risk factors across time and
place to allow for a clearer understanding of human survival differences.