[Paleopsych] BH: Genes Show Men Slept Around

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Genes Show Men Slept Around
http://www.betterhumans.com/Print/index.aspx?ArticleID=2004-09-20-1

    By Liz Brown
    Betterhumans Staff
    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 [3]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
    history.

    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 [4]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
    successful males."

    Male mutation

    For their study, Wilder and colleagues looked at the [5]Y chromosome
    and [6]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
    world.

    Wilder and colleagues examined this theory by testing Y chromosome DNA
    and mitochondrial DNA from three far-flung populations of humans: The
    [7]Khoisan of southern Africa, Mongolian Khalks and highland [8]Papua
    New Guineans. For each group, DNA from 25 people was tested.

    Uncommon ancestors

    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.

    More variations

    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
    populations.

    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 [9]Nature Genetics
    ([10]read abstract) and [11]Molecular Biology and Evolution.

References

    2. http://servedbyadbutler.com/go2/;ID=144366;size=300x250;setID=70192
    3. http://www.arizona.edu/
    4. http://amadeus.biosci.arizona.edu/~jawilder/
    5. http://www.wikipedia.org/wiki/Y_chromosome
    6. http://www.wikipedia.org/wiki/Mitochondrial_DNA
    7. http://www.wikipedia.org/wiki/Khoisan
    8. http://www.wikipedia.org/wiki/Papua_New_Guinea
    9. http://www.nature.com/ng/
   10. http://www.nature.com/cgi-taf/DynaPage.taf?file=/ng/journal/vaop/ncurrent/abs/ng1428.html
   11. http://mbe.oupjournals.org/