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Australia Earth Science

Australian Aboriginal DNA Suggests 70,000-Year History 228

Posted by timothy
from the what-a-timeline dept.
brindafella writes with a link to an abstract at the journal Science that says "Scientists have obtained a DNA genomic sequence from a 100-year-old, voluntarily donated hair sample from a full-blood Australian Aboriginal man. [Analysis of the hair] shows 'Aboriginal Australians are descendants of an early human dispersal into eastern Asia, possibly 62,000 to 75,000 years ago. This dispersal is separate from the one that gave rise to modern Asians 25,000 to 38,000 years ago. ... [Their] findings support the hypothesis that present-day Aboriginal Australians descend from the earliest humans to occupy Australia, likely representing one of the oldest continuous populations outside Africa.' A news story gives more detail."
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Australian Aboriginal DNA Suggests 70,000-Year History

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  • by MaskedSlacker (911878) on Saturday September 24, 2011 @02:46AM (#37499938)

    No. The evolution of the hominid family is WAY more complex than that. Basically you have a set of inter-breeding semi-distinct populations from 4 million years ago all the way to circa 30,000 years ago (maybe even as late as 20,000 years ago based on some finds of neanderthal tools). All the way through most of the populations would have been genetically similar enough to interbreed successfully (especially after H. ergaster and H. erectus 2 million years ago). H. heidelbergensis, neanderthalensis, and sapiens likely all interbred. Neanderthals were Europeans descendants of an earlier H. ergaster or H. heidelbergensis exodus from Africa. Australian aboriginals, like all modern humans, would be predominantly H. sapiens, with differing traces from the interbreeding with earlier populations.

    Moreover, you've misunderstood the data on the Cro Magnon man. Modern humans arrived in EUROPE (Cro-Magnon is the place in France where skeletons were found) 35,000 years ago (as best as we can tell). They appear in Africa almost 200,000 years ago, and in the Middle East before 60,000 years ago.

  • Re:Head Start? (Score:2, Interesting)

    by MaskedSlacker (911878) on Saturday September 24, 2011 @02:56AM (#37499966)

    It may not be politically correct, but you also have to be a rather simple-minded fool to not be able to figure it out.

    It's all about location, location, location.

    Settled, agrarian, and technological civilizations arise in regions where farming is advantageous over hunter-gatherer lifestyles. Civilizations only progress as far as their environments encourage them to--if developing new technology costs more than the increase in production, it isn't done.

    It's not a racial, or even a "head start" thing. Over history major civilizations crop up in the exact same places over, and over, and over. The Nile River Valley, the Tigris/Euphrates, the Indus, the Yangtze/Yellow River Valleys, etc. Virtually all major civilizations started along major rivers with extremely fertile land along their shores, and spread out from there. Europe only gained civilization because of the spread of technology and culture from the Middle-East (Nile/Tigris/Euphrates) regions into Europe. Africa didn't gain it (it did actually, but in a more limited way), because the Sahara made a hell one hell of a barrier to cultural exchange. Where there was exchange, however (along the East African coast in the Middle Ages in particu

  • Re:Wow (Score:4, Interesting)

    by flyingsquid (813711) on Saturday September 24, 2011 @03:15AM (#37500024)
    60,000-75,000 years is well before when many anthropologists believe we started using language and symbolic thought. Either they're wrong, or these developments were made independently across different isolated populations.

    They're probably wrong. The evolutionary tree of Homo sapiens has four major branches: Aborigines, Eurasians, Africans, and Khoisan. The Aborigines and Eurasians are each other's closest relatives, Africans are more distantly related, and the Khoisan (bushmen) are the most ancient branch of our evolutionary tree. All four groups have the mental hardware to do things like use language, create artwork, and make sophisticated stone tools. While it's concievable that they each evolved that capability independently, Occam's razor says it's simpler to assume that it evolved once, than to assume it happened four separate times. And since Aborigines were around 70,000 years ago, this hardware package- what we'd called the "behaviorally modern" human- would have appeared by that time.

    Consistent with this idea, you get cave paintings in Australia around 50,000 years ago, as soon as the Aborigines show up there. And you get cave paintings and sophisticated stone tools in Europe around 30,000 years ago, when the Eurasians move out of Africa. In this scenario, the reason sophisticated stone tools and cave art don't show up earlier is that advanced humans were restricted to Africa. If so, then we would expect evidence for similar behavioral complexity- cave paintings, Neolithic-quality stone tools- in Africa prior to 70,000 years. My guess is that it almost certainly exists, but we just haven't looked in the right places (because it's a lot easier to do fieldwork in Europe than in Africa) or we've found it but haven't recognized it for what it is because the artifacts haven't been dated yet.

  • Re:evolution (Score:4, Interesting)

    by rgbatduke (1231380) <rgb@@@phy...duke...edu> on Saturday September 24, 2011 @07:36AM (#37500790) Homepage
    You mean like dogs can mate with wolves and foxes and create perfectly normal offspring? Or the way lions can mate with tigers? I thought at this point the notion that speciesization involved an inability to crossbreed with nearby branches and produced "normal", often fertile, offspring was passe'. Evolution is a lot more interesting than "just Darwin" these days, with the discovery that breeding across species is possible and even commonplace as well as the even more interesting discovery that a significant fraction (maybe 8%) of the human genome is viral DNA probably intercalated via retroviruses in a way that "stuck". It isn't all about simple single-site mutation and in-species crossover anymore (although natural selection itself survives, of course).

    However, your point is well taken -- as far as I know the aboriginal genome isn't sufficiently divergent to count as a separate species, any more than the pigmy genome. Or if they are, it's so uber-politically incorrect to point it out that nobody is doing so. OTOH, there was the recent discovery that one single bay in Australia is home to a unique species of porpoise that is genetically divergent enough to be considered separate (although I'd bet it is smoothly crossfertile with other Tursiops).

    rgb

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