Was Ardi, the oldest hominid skeleton, a human or an ape?

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London, May 28 (ANI): A debate has erupted over the classification of Ardipithecus ramidus - popularly called Ardi - as to whether it was more human or an ape.Researchers are questioning the classification of the oldest hominid skeleton - dated at 4.4 million years old, reports Nature.The argument isn't an esoteric dispute among palaeontologists, but speaks to a fundamental theory of human evolution: that hominids began walking upright in response to the spread of grasslands in eastern Africa less than 8 million years ago.While the papers from White and colleagues showed a bipedal species with ape-like feet and arms living in woodlands, and not knuckle-walking like a chimpanzee, Matt Sponheimer, an archaeometrist at the University of Colorado in Boulder who peer reviewed the isotopic comment for Science, argues otherwise."This is not a simple issue to answer,""We don't want to throw the savannah hypothesis out prematurely.We need broader samples over a longer period of time," he says.Thure Cerling of the University of Utah in Salt Lake City and colleagues argue Ardi didn't live in the "closed wooded habitat" proposed originally by White and colleagues, but that the specimens came from a strip of trees along a waterway through a savannah.Their interpretations are based on an analysis of stable carbon isotopes in preserved soil, or 'palaeosol', at the site; oxygen and carbon isotopes in the enamel of mammalian teeth; the small-mammal fossils present; and the types of silica-rich plant remnants called phytoliths.In the other technical comment in Science, primatologist Esteban Sarmiento says he questions whether Ardi is in the human lineage because the fossil probably predates the divergence between humans and apes, which he estimates as 3 to 5 million years ago2.But White and co-authors disagree. In their response4, the group says Sarmiento's "tortuous, nonparsimonius evolutionary pathways" are not supported by many of the fossil's characteristics.The studies and comments are published in the journal Science. (ANI)

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