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Re: Archaic humans in East Asia

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  • richardwsproat
    Though note the introductory sentence of their paper, which would seem to lend uncritical support to Atkinson s thesis: Widespread evidence from genetics,
    Message 1 of 3 , Nov 1, 2011
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      Though note the introductory sentence of their paper, which would seem to lend uncritical support to Atkinson's thesis:

      "Widespread evidence from genetics, linguistics, fossils, and
      archeology suggests that a wave of migration of anatomically
      modern humans out from Africa occurred within the last ∼100,000
      years (1â€"8)."

      One of the problems in all of this is that a "result" in one field is talked up by people in another, who obviously can't be expected to think through the details.

      --Richard

      --- In Indo-Eurasian_research@yahoogroups.com, Steve Farmer <saf@...> wrote:
      >
      > Evidence has been piling up for nearly a decade now that the once-standard out-of-Africa model is dead -- with all that implies for studies of the evolution of language & mythology, etc. (Attn. e.g. Quentin Atkinson, who is on our List.)
      >
      > We've looked now at the List at perhaps a dozen major papers on that topic.
      >
      > A new one published now in PNAS, open access, today.
      >
      > Link to full paper here:
      >
      > http://www.pnas.org/content/early/2011/10/24/1108181108.full.pdf
      >
      > Abstract only below.
      >
      > Steve
      >
      > **********
      >
      > Archaic human ancestry in East Asia
      >
      > Pontus Skoglunda,1 and Mattias Jakobssona,b,1
      >
      > aDepartment of Evolutionary Biology and bScience for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden
      >
      > Recent studies of ancient genomes have suggested that gene flow from archaic hominin groups to the ancestors of modern humans occurred on two separate occasions during the modern human expansion out of Africa. At the same time, decreasing levels of human genetic diversity have been found at increasing distance from Africa as a consequence of human expansion out of Africa. We analyzed the signal of archaic ancestry in modern human popula- tions, and we investigated how serial founder models of human expansion affect the signal of archaic ancestry using simulations. For descendants of an archaic admixture event, we show that genetic drift coupled with ascertainment bias for common alleles can cause artificial but largely predictable differences in similarity to archaic genomes. In genotype data from non-Africans, this effect results in a biased genetic similarity to Neandertals with increasing distance from Africa. However, in addition to the previously reported gene flow between Neandertals and non-Africans as well as gene flow between an archaic human population from Siberia (�Denisovans�) and Oceanians, we found a significant affinity between East Asians, particularly Southeast Asians, and the Denisova genome�a pattern that is not expected under a model of solely Neandertal admixture in the ancestry of East Asians. These results suggest admixture between Denisovans or a Denisova-related population and the ancestors of East Asians, and that the history of anatomically modern and archaic humans might be more complex than previ- ously proposed.
      >
    • Steve Farmer
      Interesting point, Richard. I guess the sad lesson: if you need to bolster an argument you don t need to look past the most recent abstract or pop-science news
      Message 2 of 3 , Nov 1, 2011
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        Interesting point, Richard. I guess the sad lesson: if you need to bolster an argument you don't need to look past the most recent abstract or pop-science news report? :^(

        Steve

        On Nov 1, 2011, at 8:58 AM, richardwsproat wrote:

        > Though note the introductory sentence of their paper, which would seem to lend uncritical support to Atkinson's thesis:
        >
        > "Widespread evidence from genetics, linguistics, fossils, and
        > archeology suggests that a wave of migration of anatomically
        > modern humans out from Africa occurred within the last 100,000
        > years)."
        >
        > One of the problems in all of this is that a "result" in one field is talked up by people in another, who obviously can't be expected to think through the details.
        >
        > --Richard
        >
        > --- In Indo-Eurasian_research@yahoogroups.com, Steve Farmer <saf@...> wrote:
        >>
        >> Evidence has been piling up for nearly a decade now that the once-standard out-of-Africa model is dead -- with all that implies for studies of the evolution of language & mythology, etc. (Attn. e.g. Quentin Atkinson, who is on our List.)
        >>
        >> We've looked now at the List at perhaps a dozen major papers on that topic.
        >>
        >> A new one published now in PNAS, open access, today.
        >>
        >> Link to full paper here:
        >>
        >> http://www.pnas.org/content/early/2011/10/24/1108181108.full.pdf
        >>
        >> Abstract only below.
        >>
        >> Steve
        >>
        >> **********
        >>
        >> Archaic human ancestry in East Asia
        >>
        >> Pontus Skoglunda,1 and Mattias Jakobssona,b,1
        >>
        >> aDepartment of Evolutionary Biology and bScience for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden
        >>
        >> Recent studies of ancient genomes have suggested that gene flow from archaic hominin groups to the ancestors of modern humans occurred on two separate occasions during the modern human expansion out of Africa. At the same time, decreasing levels of human genetic diversity have been found at increasing distance from Africa as a consequence of human expansion out of Africa. We analyzed the signal of archaic ancestry in modern human popula- tions, and we investigated how serial founder models of human expansion affect the signal of archaic ancestry using simulations. For descendants of an archaic admixture event, we show that genetic drift coupled with ascertainment bias for common alleles can cause artificial but largely predictable differences in similarity to archaic genomes. In genotype data from non-Africans, this effect results in a biased genetic similarity to Neandertals with increasing distance from Africa. However, in addition to the previously reported gene flow between Neandertals and non-Africans as well as gene flow between an archaic human population from Siberia (�Denisovans�) and Oceanians, we found a significant affinity between East Asians, particularly Southeast Asians, and the Denisova genome�a pattern that is not expected under a model of solely Neandertal admixture in the ancestry of East Asians. These results suggest admixture between Denisovans or a Denisova-related population and the ancestors of East Asians, and that the history of anatomically modern and archaic humans might be more complex than previ- ously proposed.
        >>
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