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  •  we are them (20+ / 0-)

    there was cross-breeding, and we carry some of their genes.

    The cold passion for truth hunts in no pack. -Robinson Jeffers

    by Laurence Lewis on Fri Feb 22, 2013 at 08:57:06 AM PST

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    •  according to my nephew, not mtDNA (3+ / 0-)
      Recommended by:
      wu ming, Laurence Lewis, Cliss

      the young man is brilliant, and we discussed that recent PBS piece on Neanderthal, and though they suspect there was cross breeding, the absence in mtDNA is puzzling.

      Neanderthals and mtDNA--------------------------------------------------------------------------------
       Finding out about our most recent common ancestor relies solely on inferences from the mtDNA of people living today. What if we could actually compare our mtDNA with mtDNA of a distant ancestor? This, in fact, has been done, with mtDNA from the bones of Neanderthals. Comparing mtDNA of these Neanderthals to mtDNA of living people from various continents, researchers have found that the Neanderthals' mtDNA is not more closely related to that of people from any one continent over another. This was an unwelcome finding for anthropologists who believe that there was some interbreeding between Neanderthals and early modern humans living in Europe (which might have helped to explain why modern Europeans possess some Neanderthal-like features); these particular anthropologists instead would have expected the Neanderthals' mtDNA to be more similar to that of modern Europeans than to that of other peoples. Moreover, the researchers determined that the common ancestor to Neanderthals and modern Homo sapiens lived as long as 500,000 years ago, well before the most recent common mtDNA ancestor of modern humans. This suggests (though it does not prove) that Neanderthals went extinct without contributing to the gene pool of any modern humans.
      •  It's not at all puzzling. It's very easy if there (0+ / 0-)

        is prolonged breeding at low levels for mtDNA (or Y chromosomal - very similar story) lines to fail to carry on, despite the production  of viable offspring.

        Since women only pass it on to daughters, you would need an unbroken line of daughters in order to see it in modern populations.  You have to think about how low birth rates were back then, and how small populations were.

        If every generation even a dozen children were born in the Levant and Anatolia from Modern Human and Archaic Human populations (Denisovan and Neanderthal at least, possibly others) each child would have only represented a 50/50 chance of a mitochondrial line being passed on.

        Now, in the next generation, we'd be looking at practically the same odds from their descendants.

        This is a time when "doing well" for human species was having 1.1 children live to adult hood and reproduce.  It's very easy for the direct same-gender line to be broken, without leaving a person with no descendants.

        Tens of thousands of years later, of course, our populations exploded and that initial "Hybrid" (probably an overly strong term) ancestor might have 20 million descendants.  But for 120 generations, they may have had only a handful of descendants alive at one time.

        income gains to the top 1% from 2009 to 2011 were 121% of all income increases. How did that happen? Incomes to the bottom 99% fell by 0.4%

        by JesseCW on Fri Feb 22, 2013 at 07:15:59 PM PST

        [ Parent ]

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