September 30, 2008

Female life expectancy vs. Female Birth Rate

Evolution and Human Behavior doi:10.1016/j.evolhumbehav.2008.08.002

Sex difference in life span affected by female birth rate in modern humans

Alexei A. Maklakov


Sex differences in life span are common in different taxa, including primates, but not well understood. Theory and comparative evidence suggest that differential costs of reproduction between the sexes may explain the differences in sex-biased mortality across large taxonomic groups. The level of sex-specific reproductive effort may thus affect the difference in life span across populations. Modern humans (Homo sapiens), generally show the typical mammalian pattern of male-biased mortality. Here, I asked whether the differences in female birth rates between countries affect the sex difference in life span. I used the data on male and female life span and female birth rate in different countries from publicly available databases, while controlling for geographic and economic factors. The analysis suggests that female birth rate explains 17% of the variation in relative sex differences in life span across countries. Low female birth rate results in females living relatively longer than males. These data suggest that a simple biological factor—female birth rate—may explain a significant part of the variation in sex differences in life span across human populations.


1 comment:

Diogenes said...

Why shouldn't we reverse the proposal: when male embryo and birth ratio is threatened by an over fragility of the male structure; it is compensated by a greater male birth ratio, as females are more resistant per se as a biological structure ....?
Or I have not understand at all Your purpose?