Study Suggests Early Humans Were Bipedal

TUCSON, March 24 (UPI) — A U.S. anthropologist says his studies suggest early tree-dwelling ancestors of modern humans were bipedal — capable of walking on two feet.

University of Arizona Assistant Professor David Raichlen said he and his colleagues at the University at Albany and City University of New York conducted experiments that show fossil footprints made 3.6 million years ago are the earliest direct evidence of hominids using the kind of upright posture and gait seen in modern humans.

The research focused on footprints preserved in volcanic ash that were found in Laetoli, Tanzania, more than 30 years ago. The footprints have been controversial since they show evidence of bipedalism, or walking on two legs, but other fossilized remains of the species indicate they spent significant time climbing in trees.

To resolve the controversy, Raichlen and his team said they devised the first biomechanical experiment designed to address the question. The team built a sand trackway and filmed people walking across the sand both with normal, erect human gaits and with crouched, chimpanzee-like gaits.

“Based on previous analyses of the skeletons of Australopithecus afarensis, we expected the Laetoli footprints would resemble those of someone walking with a … gait typical of chimpanzees, and not the striding gait normally used by modern humans,” Raichlen said. “But to our surprise, the Laetoli footprints fall completely within the range of normal human footprints.”

The research appears in the online journal PLoS One.

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