2007-10-18 11:55:51
Charles Q. Choi
Special to LiveScience
LiveScience.comWed Oct 17, 8:10 AM ET
In humans and many other animals, males age faster and die earlier than
females.
New research suggests this might happen because of intense competition over
sex.
Scientists compared monogamous species with polygynous species, in which each
male mates with many females. Males in monogamous species, such as the barnacle
goose or the dwarf mongoose, naturally compete less over females than ones in
polygynous species, such as the red-winged blackbird or the savannah baboon.
After investigating about 20 different vertebrate species, researchers Tim
Clutton-Brock and Kavita Isvaran at the University of Cambridge in England
found the more polygynous a species was, the more likely their males were to
age faster and die earlier than females.
The researchers explained that as competition among males for sex grows more
intense, each male on average has less time to breed. As such, there is no
strong incentive to evolve longevity among males in such species.
Since men age faster and die earlier than women, these findings suggest that
"at the time when current human physiology evolved, perhaps around the late
Stone Age, polygynous breeding was the norm," Clutton-Brock told LiveScience.
"Of course, this doesn't provide any justification for polygyny or promiscuity
now for males."
Clutton-Brock and Isvaran detailed their findings online Oct. 17 in the journal
Proceedings of the Royal Society B.
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Original Story: Why Males Die Before Females