ramidus shows that it was still climbing trees, on the ground it walked upright." Ardi's feet do point to a comfort with life in the trees. In a summary to one of the Science papers led by Lovejoy, the authors note that, "although the foot anatomy of Ar. White asserts, however, that after working with the fossils himself, there is no way that they could belong to "an animal that wasn't often walking on its hind legs," unless the data "were deliberately ignored, or if we had made them up," he argues.Įven if Ardi's reconstructed hips don't convince everyone, her feet could provide some important insights into the species's locomotion. Jungers also notes the perils of reconstruction, which in a case like Ardi's "requires a lot of guesswork."Īs the upper pelvis appears like it could belong to an early human, the bottom part looks more like a quadrupedal, nonhuman primate, says Jungers, who recently met with White and examined photos of the bones. "It's very difficult not to make them look like something you have in your mind if there's any chance of play," he says. Begun says: "Maybe the pieces do fit together nicely, but the reality is they start out with a very damaged specimen, and they end up with something very similar to an australopithecine" (the group that includes " Lucy," the 3.2-million-year-old Australopithecus as well as a 2.7-million-year-old Paranthropus). ramidus could walk upright without shifting its center of mass from side to side" (unlike today's lumbering great apes), but a different interpretation of the ilium could change all of that.ĭespite the numerous images and descriptions put forth by the researchers, others are reluctant to take the reconstructions without a grain of salt. The summary in one of the Science papers, led by Owen Lovejoy of Kent State University in Ohio, argues that by Ardi's time, "the gluteal muscles had been repositioned so that Ar. Depending on how this bone is oriented, muscles around the hip joints work differently, explains David Begun, a professor in the Department of Anthropology at the University of Toronto. as hominids-although the latter title now often includes the great apes, as well)īut piecing together how Ardipithecus fits into the evolutionary story of humanity may prove even more difficult than reconstructing Ardi's fragmented and fragile bones, and the process has already turned out to be a contentious one.īecause the traditional hallmark of an early human has been the adaptation for upright walking, much of the debate over Ardipithecus's status hinges on how her lower body bones fit together-in particular, the position of her damaged ilium, the winglike upper pelvis bone. ramidus as being ancestral to Australopithecus," thus proposing she might indeed be an early hominin (the ever-changing nomenclatural group that usually includes living humans and our close extinct relatives, also referred to by White et al. So, does Ardi represent a true step toward humanity, or should she remain up in the side branches of the evolutionary tree? White and his fellow authors do not propose to have a definitive answer, but through painstaking analysis of the fossil data and surroundings, they conclude in the overview paper that, "There are no apparent features sufficiently unique to warrant the exclusion of Ar. In fact, Jungers says, "I think some of the things they said might have been for effect." The authors of the papers, including Tim White of the University of California, Berkeley, propose that Ardipithecus was "an effective upright walker" and that it "resolves many uncertainties about early human evolution, including the nature of the last common ancestor." But many others in the field propose that some of these statements may be overblown. The 11-paper Science analysis has, indeed, sharpened more differences than it has smoothed over. "This is a fascinating fossil no matter what side you come down on," says William Jungers, a professor and chairman of the Department of Anatomical Sciences at the Stony Brook University Medical Center in Long, Island, N.Y. The momentous find-announced 15 years ago and formally described in Science this October-has deepened academic debates about when bipedalism evolved, what our last common ancestor with chimpanzees looked like, and how some ancient primates gave way to modern humans. For such a petite creature, the 1.2-meter-tall " Ardi" ( Ardipithecus ramidus) has made big waves in the paleoanthropology world.
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