East African paleo-anthropological sites have yielded 2.5-million-year-old fossils of a possible direct human ancestor. "These fossils are providing exciting new evidence about the long-sought evolutionary connection between species of early hominids, like Australopithecus, and the genus Homo," said National Science Foundation (NSF) Physical Anthropology Program Director Mark L. Weiss.
The cranial, leg, and arm bone fossils of this newly discovered species were unearthed in Ethiopia by a team of scientists led by NSF-supported anthropologist Tim White of the University of California-Berkeley and Berhane Asfaw of Ethiopia, and are publicized in the April 23 issue of Science magazine. Significantly, the femur is elongated-a million years before hominid fossil evidence shows forearm shortening-which, together with shortened forearm, creates the familiar modern human limb proportions.
Similar-age animal fossils discovered in the same area, the Middle Awash study area in the Afar desert, indicate that the meat and bone marrow of large mammals (antelopes and horses, specifically) were obtained with the world's earliest stone tool technology, according to a companion article in Science. White cautioned that "we cannot yet conclusively link the new species with the butchery or the more modern limb proportions."
Both sets of fossils were dated using the argon-argon radioisotope method as well as biochronology and paleomagnetism. The same research team had discovered the earliest-known hominid, the 4.4-million-year-old Ardipithecus, at the nearby Aramis site in 1992.
These fossil finds are significant for several reasons, according to the
discoverers. "The hominid fossils may allow us to add a new member to the human
evolutionary family tree," said Weiss, "and the evidence regarding the use of
stone tools in food processing indicates an early reliance on meat in hominid
diet. This adaptation would have allowed
Contact: K. Lee Herring
National Science Foundation