Good bye Eve!?

From: Glenn Morton (
Date: Thu Feb 28 2002 - 23:48:23 EST

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    There is a fascinating report which seriously questions the neutral theory
    of gene mutation. It can be found in this week's Nature or information about
    it at

    "A comparison of the A/S ratio of polymorphism in Drosophila melanogaster
    with that of divergence from Drosophila simulans shows that the A/S ratio of
    divergence is twice as high—a difference that is often attributed to
    positive selection. But an increase in selective constraint owing to an
    increase in effective population size could also explain this observation,
    and, if so, all genes should be affected similarly. Here we show that the
    difference between polymorphism and divergence is limited to only a fraction
    of the genes, which are also evolving more rapidly, and this implies that
    positive selection is responsible. A higher A/S ratio of divergence than of
    polymorphism is also observed in other species, which suggests a rate of
    adaptive evolution that is far higher than permitted by the neutral theory
    of molecular evolution." Justin C. Fay, Gerald J. Wyckoff & Chung-I
    Wu,"Testing the neutral theory of molecular evolution with genomic data from
    Drosophila" Nature 415(2002), 1024 - 1026

    The fascinating thing is that if mtDNA genes are not neutral, then
    mitochondrial Eve is history. And some authorities believe that mtDNA is
    subject to selection:
         "The low levels of human mtDNA diversity have been
    used as support for the out-of-Africa replacement
    hypothesis (CANN et al. 1987; VIGILANT et al. 1991);
    however, directional selection could also explain the
    reduced mtDNA diversity in humans compared with chimpanzees
    ( [pi]= 0.24% for humans and 0.73% for the chimpanzee
    subspecies P. t. verus. Table 2). Because there is no
    apparent genetic recombination in mtDNA, this depletion of
    variation could be the result of an advantageous mutation
    anywhere within the mitochondrial genome sweeping through
    the human population." Cheryl A. Wise, Michaela Sraml and Simon Easteal,
    "Departure from Neutrality at the Mitochondrial NADH
    Dehydrogenase Subunit 2 Gene in Humans, but not in
    Chimpanzees." Genetics, 148(1998):409-421, p. 419-420

            "The interpretation that the departure from neutral
    mutation-drift equilibrium reflects population size
    expansions assumes selective neutrality for these gene
    systems. However, several geneticists have suggested that
    selection may influence the distribution of mtDNA and Y
    chromosome variation in humans." John Hawks, Keith Hunley
    Sang-Hee Lee, and Milford Wolpoff, "Population Bottlenecks
    and Pleistocene Human Evolution," Mol. Biol. Evol.,
    17(2000):1:2-22, p. 10

    What will the ID and RTB folk, who have been claiming that mankind can't be
    older than 100-150kyr old, do if Eve dies?


    for lots of creation/evolution information
    personal stories of struggle

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