By JOHN NOBLE WILFORD
c.2010 New York Times News Service
As early as 3.4 million years ago, some individuals with a taste for meat and marrow - presumably members of the species best known for the skeleton called Lucy - apparently butchered with sharp and heavy stones two large animals on the shore of a shallow lake in what is now Ethiopia.
Scientists who made the discovery could not have been more surprised. They said the cut marks on a fossilized rib and thighbone were unambiguous evidence that human ancestors were using stone tools and sometimes consuming meat at least 800,000 years earlier than previously established. The oldest confirmed stone tools are less than 2.6 million years old, perhaps from only a little before the emergence of the genus Homo.
Some prominent researchers of early human evolution were skeptical, saying the reported evidence did not support such claims.
If true, though, the new find reveals unsuspected behavior and dietary habits of the Lucy species, Australopithecus afarensis. Though no hominid fossils were found near the butchered bones, A. afarensis is thought to be the only species living in this region at the time. The species' large teeth with thick enamel indicated it subsisted mainly on tubers and other vegetation.
So the international team of paleoanthropologists, archaeologists and geologists concluded that it had found the first evidence that kin of the 3.2-million-year-old Lucy had used some form of stone tools and would not pass up a chance to feast on a cut of meat and nutritious bone marrow.
Pending new discoveries, the team wrote in a report being published Thursday in the journal Nature, A. afarensis is the only hominid group "to which we can associate the tool use." Whether these individuals made the tools or only selected naturally sharpened pieces of stone, the scientists added, was not yet determined. Nor is it known whether they were hunters or, more likely, scavengers of a lion's leftovers.
The leader of the research project, at Dikika, Ethiopia, was Zeresenay Alemseged, an Ethiopian paleoanthropologist at the California Academy of Sciences in San Francisco. The lead author of the Nature paper was Shannon P. McPherron, an archaeologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
"Now, when we imagine Lucy walking around the East African landscape looking for food, we can for the first time imagine her with a stone tool in hand and looking for meat," McPherron said in a statement issued by the Leipzig institute.