Men shed light on the mystery of human longevity, s...(s all women andmost men in the six group...)

Date:9/13/2007

s, all women and most men in the six groups stopped having children by their 50s, the researchers found. But some men, particularly high-status males, continued to reproduce into their 70s. The paper noted that the age gap is most pronounced in societies that favor polygyny, where a man takes several wives, and in gerontocracies, where older men monopolize access to reproductive women. The authors also cite genetic and anthropological evidence that early humans were probably polygynous as well.

Older male fertility also exists in societies supporting serial monogamy, because men are more likely to remarry than women. "For these reasons, we argue that realized male fertility was substantial at ages well past female menopause for much of human history and the result is reflected in the mortality patterns of modern populations," the authors say. "We conclude that deleterious mutations acting after the age of female menopause are selected against ... solely as a result of the matings between older males and younger females."

According to Puleston, the "grandmother hypothesis" may be true, but the real pattern of male fertility extends beyond this explanation. "The key question is: Does the population have a greater growth rate if men are reproducing at a later age" The answer is 'yes.' The age of last reproduction gets pushed into the 60s and 70s if you add men to the analysis. Hamilton's approach was right, but in a species where males and females have different reproductive patterns, you need a two-sex model. You can't correctly estimate the force of selection if you leave men out of the picture. As a man myself, it's gratifying to know that men do matter."

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Contact: Lisa Trei lisatrei@stanford.edu 650-725-0224 Stanford University Source:Eurekalert

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