“Out of Africa” Theory is under review.

Discussion in 'Human Science' started by Saturnine Pariah, Mar 23, 2013.

  1. Saturnine Pariah Hell is other people Valued Senior Member

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    Mar. 22, 2013 — Recent measurements of the rate at which children show DNA changes not seen in their parents -- the "mutation rate" -- have challenged views about major dates in human evolution.


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    In particular these measurements have made geneticists think again about key dates in human evolution, like when modern non-Africans split from modern Africans. The recent measurements push back the best estimates of these dates by up to a factor of two. Now, however an international team led by researchers at the University of Tübingen and the Max Planck Institute for Evolutionary Anthropology in Leipzig, present results that point again to the more recent dates. The new study is published in Current Biology.

    The team, led by Johannes Krause from Tübingen University, was able to reconstruct more than ten mitochondrial genomes (mtDNAs) from modern humans from Eurasia that span 40,000 years of prehistory. The samples include some of the oldest modern human fossils from Europe such as the triple burial from Dolni Vestonice in the Czech Republic, as well as the oldest modern human skeletons found in Germany from the site of Oberkassel close to Bonn.

    The researchers show that pre-ice age hunter-gatherers from Europe carry mtDNA that is related to that seen in post-ice age modern humans such as the Oberkassel fossils. This suggests that there was population continuity throughout the last major glaciation event in Europe around 20,000 years ago. Two of the Dolni Vestonice hunter-gatherers also carry identical mtDNAs, suggesting a close maternal relationship among these individuals who were buried together.

    The researchers also used the radiocarbon age of the fossils to estimate human mutation rates over tens of thousands of year back in time. This was done by calculating the number of mutations in modern groups that are absent in the ancient groups, since they had not yet existed in the ancient population. The mutation rate was estimated by counting the number of mutations accumulated along descendent lineages since the radiocarbon dated fossils.

    Using those novel mutation rates -- capitalizing on information from ancient DNA -- the authors cal-culate the last common ancestor for human mitochondrial lineages to around 160,000 years ago. In other words, all present-day humans have as one of their ancestors a single woman who lived around that time.

    The authors also estimate the time since the most recent common ancestor of Africans and non-Africans to between 62,000-95,000 years ago, providing a maximum date for the mass migration of modern humans out of Africa. Those results are in agreement with previous mitochondrial dates based on archaeological and anthropological work but are at the extreme low end of the dates sug-gested from de-novo studies that suggest a split of non-Africans from Africans about thirty thousand years earlier.

    "The results from modern family studies and our ancient human DNA studies are in conflict" says Krause. "One possibility is that mutations were missed in the modern family studies, which could lead to underestimated mutation rates." The authors argue that nuclear genomes from ancient mod-ern humans may help to explain the discrepancies.
     
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  3. Fraggle Rocker Staff Member

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    She's called Mitochondrial Eve. There is also a Y-Chromosomal Adam.

    Homo sapiens had speciated quite recently: the earliest fossil is from 200KYA. The population was still very small, so it is not as remarkable as it might seem, that one individual's bloodline could define the entire species.
     
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  5. arauca Banned Banned

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    If I remember well study on Y chromosome modern man was in Europa prior Glaciation period .
     
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  7. Fraggle Rocker Staff Member

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    New fossils and archeological sites are occasionally discovered, which change the timeline. But at this point it is generally accepted that the first group of Homo sapiens entered Europe around 35KYA, coming across the Bosporus into the Balkans. By 32KYA they were also coming up around the Black Sea and had populated the eastern part of Europe as well as southern Italy. By 30KYA they had spread through the entire main part of the continent except Iberia and a tiny bit of France, and were making their way up through Finland toward Scandinavia.

    These were the Cro-Magnon, a Paleolithic people. The Indo-Europeans, a Neolithic people, migrated to Europe 4-5KYA. The first tribe to arrive was the Celts. The Hellenic, Italic and Germanic tribes soon followed. With their superior technology of agriculture (the development of farming and animal husbandry defines the Neolithic Revolution) they took charge of the place and marginalized the Cro-Magnon. It's possible that the Basques are their last surviving descendants.

    Other groups migrated into Europe at later dates. Notable are the Finno-Ugric peoples (Finns, Estonians, Sami and Magyars), the Huns (probably a Mongolic people), the Bulgars (a Turkic people whose descendants identify themselves as Slavic), the Ottomans (they once ruled most of the Balkans and there is still a tiny piece of Turkey in Europe), the Mongols (they invaded quite far into Europe but were beaten back), the Moors (they crossed the Mediterranean into Iberia but were also beaten back) and the Jews (the Diaspora scattered them everywhere).
     
  8. arauca Banned Banned

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    Yo can continue believe what you want , but there are more information then what you have . So update your information otherwise you will be absolute like the dinosaurs
     
  9. iceaura Valued Senior Member

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    I'm not following how this presents any conflict with the Out of Africa theory. Modifications of aspects of the timeline do not seem either implausible or fundamentally challenging to that basic scenario.
     

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