The burden of bearing sons

In this week's _Science_ ...

"Bearing sons was associated with a reduction in human maternal life-span after menopause, whereas bearing daughters was associated with an increase, according to an analysis of preindustrial demographic records by Helle et
al. (p. 1085)."

SCIENCE VOL 296 10 MAY 2002 P. 1085

http://www.sciencemag.org/content/vol296/issue5570/twis.shtml (requires subscription)

Abstract
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In humans, sons are physiologically more demanding to produce than daughters, as indicated by their faster intrauterine growth rate and heavier birth weight and the longer time it takes mothers producing sons to reproduce again. Large, and particularly strongly male-biased, family size is thus predicted to reduce maternal longevity.

However, the long-term effects of gender-biased reproductive investment remain unknown. Here we show that in preindustrial humans, the number of sons delivered reduced expected maternal longevity, whereas the number of daughters raised improved it.

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