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Walking with mammals

Discussion in 'General Discussion Forum' started by ManlyBacker, Apr 2, 2007.

  1. ManlyBacker

    ManlyBacker Winging it Staff Member

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    Interesting stuff from the scientists. I am forever amazed at how slow some evolution is, the types of freaky developments we have had on this planet, and how far back it all seems to go.

    New Study Supports Idea That Primates, Dinosaurs Coexisted
    By Ben Harder
    for National Geographic News
    April 18, 2002

    Scientists have acquired new data supporting the idea that the last ancestor shared by all living primates walked with the dinosaurs more than 80 million years ago. The results came from a new technique used to reconstruct the course of animal evolution.

    Previously, opposing scientific camps estimated that the animal that gave rise to the primates lived as recently as 55 million years ago and as long ago as 90 million years. The newly proposed date is closer to the older end of the range.

    That's significant because the older estimate, which was derived from studies based on molecular genetics, identifies the earliest primates as contemporaries of the dinosaurs. The younger date, which was based on fossil records, represents a period after the dinosaurs had already become extinct.

    "Our results agree broadly with a molecular estimate [and] contradict widely accepted palaeontological estimates," Simon Tavaré of the University of Southern California and his colleagues reported in the journal Nature.

    Their finding sprang from a scientific collaboration that straddled the fields of biology and mathematics and spanned research centers from California to the Swiss Alps.

    Working with colleagues from Harvard University, the University of Washington, Chicago's Field Museum, and institutions in England and Switzerland, Tavaré used a novel mathematical approach to help answer a major piece of the evolutionary puzzle.
     
  2. ManlyBacker

    ManlyBacker Winging it Staff Member

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    I would prefer if there was no mention of the development of certain individuals on this site, but where would the fun be in that?... :blaugh: :lol: :lol:
     
  3. ManlyBacker

    ManlyBacker Winging it Staff Member

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    More good stuff (to me anyway). I do know that DNA samples in 2003 cast doubts that we have neanderthal genetic material in the human population despite strong evidence of cross-breeding in Portugal, but this is a first that we did not originate from Africa.

    Skeleton challenge to Africa theory
    April 4, 2007

    A 40,000-YEAR-OLD skeleton found in China has raised questions about the "out of Africa" hypothesis on how early modern humans populated the planet.

    The fossil bones are the oldest from an adult "modern" human to be found in eastern Asia.

    They contain features that call into question the widely held view that all humans alive today are descended from a small group of sub-Saharan Africans who made their way out of the continent about 60,000 years ago. Gradually they colonised other parts of the planet, replacing older human species such as the Neanderthals, which became extinct. The older humans had themselves originated in Africa but moved out more than 1 million years earlier.

    A rival theory suggests modern humans evolved into their present form in a number of locations around the world, not just Africa.

    The new discovery came after local workers stumbled across the bones in Tianyuan Cave, in Zhoukoudian, near Beijing. Experts reported on Monday in the journal Proceedings of the National Academy of Sciences that they had dated the skeleton to between 38,500 and 42,000 years ago. It was the first properly dated adult modern human from eastern Asia known to be more than 30,000 years old.

    However, certain features of the individual were puzzling, said the scientists, led by Dr Hong Shang from Washington University in St Louis, Missouri.

    As well as having "modern" human traits, the skeleton had physical characteristics normally seen in Neanderthals and other ancient humans such as Homo erectus. These included the difference in size between the front and back teeth, unusually thick and sturdy leg bones, and enlargement of a wrist bone called the hamulus.

    The scientists said it was likely there was "at least substantial gene flow" from modern humans who had settled in regions to the south and west of Tianyuan Cave at an earlier date.

    But they added: "At the same time,the presence of several archaic features … implies that a simple spread of modern human morphology eastward from Africa is unlikely."
     

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