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  • Comments Solicited: E3b Postulates

    The following three postulates have been gleaned and distilled from a variety of scientific sources. I am soliciting responsible comment in opposition to any one or all three postulates. Simply state your case. There will be no discussion but I will respond to requests for greater clarity or specificity. Thank you in advance for your kind consideration of this matter.

    1. The E3b haplogroup is a lineage with a
    variety of subclades and with the origin
    undoubtedly of an indigenous population
    group of Africa, therefore they had autosomes
    for dark skin and other characteristics
    commonly associated with Black Africans.

    2. All light skin European E3b individuals are
    ultimately the result of inheritance due to indigenous
    African E3b males breeding with females
    who had autosomes for light skin and other
    characteristics associated with Europeans.

    3. Light skin autosomes arose somewhere in
    ancient Europe and nowhere in ancient Africa.

  • #2
    Haplogroups arose before many of the autosomes that lead to modern racial characteristics.

    It is possible that E3b arose from a "swirl" population bearing the characteristics of many modern groups. From this population, with isolation, selection and genetic drift, arose the modern separate groups we can identify based on autosomes or phenotypes.

    To help us imagine one of these "swirl" populations, my anthro professors used to refer to the Bushmen. They bear the eyelid traits and shovel shape incisors of modern East Asian populations, yet the kinky hair of Africans. If groups of Bushmen were to populate widely disparate areas, natural selection, genetic drift and founder effect may cause a group to emerge that had one trait and not the other.

    I thought E3b arose from a pre-Arab population of North Africa, and spread with Neolithic farmers. Therefore it is quite possible the first E3b never had black skin as we know it today.

    Comment


    • #3
      Originally posted by Rossi
      1. The E3b haplogroup is a lineage with a variety of subclades
      Correct

      and with the origin undoubtedly of an indigenous population
      group of Africa,
      The studies point to this conclusion.

      therefore they had autosomes for dark skin and other characteristics commonly associated with Black Africans.
      E3b or more correctly M35 which defines the haplogroup E3b is supposed to have appeared about 29K years ago, according to Semino et al., but we don't have a way of knowing what were the phenotypical traits of the particular population in which the mutation occurred. We can not automatically extrapolate our current demographical notions to such prehistorical time.

      2. All light skin European E3b individuals are ultimately the result of inheritance due to indigenous African E3b males breeding with females who had autosomes for light skin and other characteristics associated with Europeans.
      All and ultimately may not be the best words to phrase your postulate. If we accept that all humankind shares a common ancestor and that certain populations have acquired distinctive traits over the course of millenia why should one specific haplogroup be excluded from the external influences that acted on the others under the same circumstances?

      3. Light skin autosomes arose somewhere in ancient Europe and nowhere in ancient Africa.
      No one has conclusively determined that to be so. For example, we know that some Asiatic populations don't have dark skin. Also, since this has to do with E3b haplogroup, the origin of the ancient, blond, blue-eyed Guanche people that inhabited the Canary archipelago is still inconclusive, but theories exist that link them genetically to North African Berber populations, which as we know belong predominantely to E3b. There's no evidence that shows the Guanches arrived to the Canary Islands from Europe.
      Last edited by Victor; 26 January 2006, 12:50 AM.

      Comment


      • #4
        This seems relevant here. There are many possible scenarios based on the new evidence which might explain the current diversity of human populations.

        http://dienekes.blogspot.com/2005/06...ects-pure.html

        Dienekes' Anthropology Blog


        Research on the X chromosome rejects the pure Out of Africa model
        I had previously posted about how Hammer et al. discovered a 2-million year old East Asian polymorphism, thus rejecting the pure Out of Africa model. Now, in a paper published in the journal Genetics they report a haplotype over a 17.5 kilobase sequence of the X chromosome where 2 out of 3 Mbuti (pygmoid) Africans have a haplotype that is over a million years old. Moreover, in the context of their statistical framework, the authors are able to reject the null hypothesis of "a single, historically panmictic population" originating in Africa.

        These findings do not negate the fact that most human variation has a "shallow" time depth, but it is strong evidence that some humans have ancestry that is much more ancient than that of the bulk of mankind. In this case, the Mbuti pygmoids have apparently assimilated elements from archaic Africans.

        This result may lend some support to my pet theory that the main differentiation in human genetic variation is between Paleoafricans who were reproductively isolated for a long time from the Afrasians, with subsequent hybridizaton between Afrasians and Paleoafricans in Africa. In this scheme, the Paleoafricans, perhaps descended from the earliest Homo sapiens population of East Africa picked up some pre-sapiens ancestry as they spread to the interior of Africa.

        Genetics (online early)

        Deep haplotype divergence and long-range linkage disequilibrium at Xp21.1 provide evidence that humans descend from a structured ancestral population.

        Garrigan D, Mobasher Z, Kingan SB, Wilder JA, Hammer MF.

        Fossil evidence links human ancestry with populations that evolved modern gracile morphology in Africa 130,000 - 160,000 years ago. Yet fossils alone do not provide clear answers to the question of whether the ancestors of all modern Homo sapiens comprised a single African population or an amalgamation of distinct archaic populations. DNA sequence data have consistently supported a single origin model in which anatomically modern Africans expanded and completely replaced all other archaic hominin populations. Aided by a novel experimental design, we present the first genetic evidence that statistically rejects the null hypothesis that our species descends from a single, historically panmictic population. In a global sample of 42 X chromosomes, two African individuals carry a lineage of non-coding 17.5 kilobase sequence that has survived for over one million years without any clear traces of ongoing recombination with other lineages at this locus. These patterns of deep haplotype divergence and long-range linkage disequilibrium are best explained by a prolonged period of ancestral population subdivision followed by relatively recent interbreeding. This inference supports human evolution models that incorporate admixture between divergent African branches of the genus Homo.
        One thing to bear in mind about skin color is that the tropical sun can be brutal to a light skinned person from a termperate climate. If you took a population of northern Saami and stuck them on a deserted island in the tropics without any modern technology, a good number might not survive. The ones who did survive to have children would likely have relatively darker skin. Over several generations that would probably lead to a fairly dark-skinned population. If you added on or two black Africans to that population, the members of the population who inherited those genes would have a distinctive advantage.

        Comment


        • #5
          Originally posted by Rossi
          The following three postulates have been gleaned and distilled from a variety of scientific sources. I am soliciting responsible comment in opposition to any one or all three postulates. Simply state your case. There will be no discussion but I will respond to requests for greater clarity or specificity. Thank you in advance for your kind consideration of this matter.

          1. The E3b haplogroup is a lineage with a
          variety of subclades and with the origin
          undoubtedly of an indigenous population
          group of Africa, therefore they had autosomes
          for dark skin and other characteristics
          commonly associated with Black Africans.

          2. All light skin European E3b individuals are
          ultimately the result of inheritance due to indigenous
          African E3b males breeding with females
          who had autosomes for light skin and other
          characteristics associated with Europeans.

          3. Light skin autosomes arose somewhere in
          ancient Europe and nowhere in ancient Africa.
          heres the shocker sit down everyone is from africa supposedly

          Comment

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