Another nail in the Coffin for Darwin's Missing Link Theory

Discussion in 'Science and Technology' started by Sunni Man, Oct 7, 2009.

  1. Sunni Man
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    Sunni Man Diamond Member

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    Oldest Skeleton of Human Ancestor Found

    Move over, Lucy. And kiss the missing link goodbye.


    The fossil puts to rest the notion, popular since Darwin's time, that a chimpanzee-like missing link—resembling something between humans and today's apes—would eventually be found at the root of the human family tree. Indeed, the new evidence suggests that the study of chimpanzee anatomy and behavior—long used to infer the nature of the earliest human ancestors—is largely irrelevant to understanding our beginnings.

    Ardi instead shows an unexpected mix of advanced characteristics and of primitive traits seen in much older apes that were unlike chimps or gorillas . As such, the skeleton offers a window on what the last common ancestor of humans and living apes might have been like.

    The Ardipithecus ramidus fossils were discovered in Ethiopia's harsh Afar desert at a site called Aramis in the Middle Awash region, just 46 miles (74 kilometers) from where Lucy's species, Australopithecus afarensis, was found in 1974. Radiometric dating of two layers of volcanic ash that tightly sandwiched the fossil deposits revealed that Ardi lived 4.4 million years ago.

    Older hominid fossils have been uncovered, including a skull from Chad at least six million years old and some more fragmentary, slightly younger remains from Kenya and nearby in the Middle Awash.

    While important, however, none of those earlier fossils are nearly as revealing as the newly announced remains, which in addition to Ardi's partial skeleton include bones representing at least 36 other individuals.

    "All of a sudden you've got fingers and toes and arms and legs and heads and teeth," said Tim White of the University of California, Berkeley, who co-directed the work with Berhane Asfaw, a paleoanthropologist and former director of the National Museum of Ethiopia, and Giday WoldeGabriel, a geologist at Los Alamos National Laboratory in New Mexico.

    "That allows you to do something you can't do with isolated specimens," White said. "It allows you to do biology."

    Ardi's Weird Way of Moving

    The biggest surprise about Ardipithecus's biology is its bizarre means of moving about.

    All previously known hominids—members of our ancestral lineage—walked upright on two legs, like us. But Ardi's feet, pelvis, legs, and hands suggest she was a biped on the ground but a quadruped when moving about in the trees.

    Her big toe, for instance, splays out from her foot like an ape's, the better to grasp tree limbs. Unlike a chimpanzee foot, however, Ardipithecus's contains a special small bone inside a tendon, passed down from more primitive ancestors, that keeps the divergent toe more rigid. Combined with modifications to the other toes, the bone would have helped Ardi walk bipedally on the ground, though less efficiently than later hominids like Lucy. The bone was lost in the lineages of chimps and gorillas.

    According to the researchers, the pelvis shows a similar mosaic of traits. The large flaring bones of the upper pelvis were positioned so that Ardi could walk on two legs without lurching from side to side like a chimp. But the lower pelvis was built like an ape's, to accommodate huge hind limb muscles used in climbing.

    Even in the trees, Ardi was nothing like a modern ape, the researchers say.

    Modern chimps and gorillas have evolved limb anatomy specialized to climbing vertically up tree trunks, hanging and swinging from branches, and knuckle-walking on the ground.

    While these behaviors require very rigid wrist bones, for instance, the wrists and finger joints of Ardipithecus were highly flexible. As a result Ardi would have walked on her palms as she moved about in the trees—more like some primitive fossil apes than like chimps and gorillas.

    "What Ardi tells us is there was this vast intermediate stage in our evolution that nobody knew about," said Owen Lovejoy, an anatomist at Kent State University in Ohio, who analyzed Ardi's bones below the neck. "It changes everything."

    Against All Odds, Ardi Emerges

    The first, fragmentary specimens of Ardipithecus were found at Aramis in 1992 and published in 1994. The skeleton announced today was discovered that same year and excavated with the bones of the other individuals over the next three field seasons. But it took 15 years before the research team could fully analyze and publish the skeleton, because the fossils were in such bad shape.

    After Ardi died, her remains apparently were trampled down into mud by hippos and other passing herbivores. Millions of years later, erosion brought the badly crushed and distorted bones back to the surface.

    They were so fragile they would turn to dust at a touch. To save the precious fragments, White and colleagues removed the fossils along with their surrounding rock. Then, in a lab in Addis, the researchers carefully tweaked out the bones from the rocky matrix using a needle under a microscope, proceeding "millimeter by submillimeter," as the team puts it in Science. This process alone took several years.

    Pieces of the crushed skull were then CT-scanned and digitally fit back together by Gen Suwa, a paleoanthropologist at the University of Tokyo.

    In the end, the research team recovered more than 125 pieces of the skeleton, including much of the feet and virtually all of the hands—an extreme rarity among hominid fossils of any age, let alone one so very ancient.

    "Finding this skeleton was more than luck," said White. "It was against all odds."

    www.ngm.com
     
    Last edited: Oct 7, 2009
  2. Setarcos
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    Setarcos BANNED

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    Never heard of Darwin's Missing Link Theory...
     
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  3. Old Rocks
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    There never was a 'missing link'. Many, many missing links. But we are seeing more of the picture every day. The genetic map of Homo Sapien and Chimpanzee is about 90% identical, so we are closely related. Where the division took place in time in our individual lines is the question.

    This is a wonderful find, and in no way challenges the Theory of Evolution as it is understood today. It just changes our understanding of the details for one particular animal line that is on the Earth today. Just because that line is our own changes the fact of its evolution not one whit.
     
  4. rdean
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    The only "missing link" is the empty space between your right cochlea and your left cochlea.
     
  5. Sunni Man
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    Sunni Man Diamond Member

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    You do realize that the article is a just published National Geographic Magazine release?
     
  6. eagleseven
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    eagleseven Quod Erat Demonstrandum

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    They found a human-ape hybrid, as opposed to a human-chimpanzee hybrid.

    You still came from an ape, Sunni ;)
     
  7. Old Rocks
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    Not a hybrid. An ancestor, or a close cousin of our ancestors.
     
  8. Sunni Man
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    Sunni Man Diamond Member

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    Nope
     
  9. rdean
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    rdean rddean

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    And what it's saying is that the ancestor of man and other primates probably walked upright and later, chimps and apes "evolved" longer fore arms to move around better in their environment.

    We didn't come from them. We all came from an earlier, more primative form.

    No where does it mention the earth is only 6 thousand years old.
     
  10. Sunni Man
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    Sunni Man Diamond Member

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    What are you talking about??? :confused:
     

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