[Paleopsych] BH: Genes Show Men Slept Around
checker at panix.com
Tue Sep 21 15:15:06 UTC 2004
Genes Show Men Slept Around
By Liz Brown
9/20/2004 3:58 PM
New research confirms the stereotype: Men have indeed been sleeping
around more than women. The proof is in the genes.
Researchers at the University of Arizona in Tucson have dispelled
some widely held beliefs about mating and migration patterns in humans
with the compilation of a genetic record of humanity's reproductive
The scientists report that men appear to have traveled widely to mate.
They also say that men and women differed in their participation in
reproduction, while it was previously thought that men and women both
played an equal role in mating. And the researchers have found that
more men than women get squeezed out of the mating game, while twice
as many women as men pass their genes to the next generation.
"It is a pattern that's built up over time," says Jason Wilder,
lead author of the study. "The norm through human evolution is for
more women to have children than men. There are men around who aren't
able to have children, because they are being outcompeted by more
For their study, Wilder and colleagues looked at the Y chromosome
and mitochondrial DNA. The Y chromosome differentiates males from
females. Mitochondrial DNA is used to trace the lineage of females.
Scientists have long believed that the reason DNA from the Y
chromosome has much less variability than mitochondrial DNA is because
a beneficial mutation on the Y chromosome swept through the whole
Wilder and colleagues examined this theory by testing Y chromosome DNA
and mitochondrial DNA from three far-flung populations of humans: The
Khoisan of southern Africa, Mongolian Khalks and highland Papua
New Guineans. For each group, DNA from 25 people was tested.
If in fact a beneficial mutation had swept through males, men's common
paternal ancestor would be the same age no matter where the
researchers looked. Instead, the age of men's common ancestor differed
between the groups.
"Because we don't think the pattern we see was caused by an event that
swept across the globe, we had to reexamine our assumptions about
whether equal numbers of men and women are mating," says Wilder.
The second common belief that the researchers proved false is that
women's genes traveled farther than men's. In fact, the genes of both
sexes traveled equal distances.
Previously, scientists thought that women's genes were more widely
dispersed due to the common marriage practice of patrilocality, where
women moved from their native village to their husband's village.
This would mean that there should be bigger differences between
populations in Y chromosome DNA than in mitochondrial DNA. However,
through testing 389 people from 10 distinct human populations, the
researchers found otherwise.
Using new technology, the researchers also found many more variations
of the Y chromosome than previously thought. The new technique
revealed that both types of DNA differ to the same degree among
This implies that even though only half as many males are getting
their genes into the next generation, they are traveling around more
than women to do it.
And it doesn't mean that mass populations are migrating across
continents--more likely it was explorers and sailors who slept around
during their travels.
The research will be reported in the journals Nature Genetics
(read abstract) and Molecular Biology and Evolution.
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