Carl Vondra, Geological and Atmospheric Sciences, (515) 294- 4477
Skip Derra, News Service, (515) 294-4917
ISU RESEARCHERS PLAY ROLE IN DISCOVERY OF OLDEST FOSSIL WITH STONE TOOLS
AMES, Iowa -- Two Iowa State University researchers are part of an international team that has discovered a 2.33 million- year-old fossil with primitive stone tools. The find, in Hadar, Ethiopia, is the oldest firmly dated association of stone tools with a fossil human ancestor, said team member Carl Vondra, chair of Iowa State's geological and atmospheric sciences department.
"There have been older stone tools found, some dating as far back as perhaps 2.5 million years, but these are the oldest tools found in association with an ancient fossil hominid," Vondra said. "The fossil, an ancestor to humans, may have made these tools."
The fossil and stone tools were discovered on the surface of a barren hill near a dry stream bed at the Hadar site, in northern Ethiopia's Afar badlands. Hadar is the home of "Lucy," the most complete example of a small-brained, big- jawed, upright-walking Australopithecus afarensis, which is not known to have made stone tools. Lucy is one of the most ancient examples of human-like species that walked on two legs.
The research team was led by William Kimbel, Robert Walter and Donald Johanson of the Institute of Human Origins (IHO), Berkeley, Calif. ISU graduate student Tesfaye Yemane is also part of the team. A report on the find will be published in the December issue of Journal of Human Evolution.
"The chief importance of the discovery is that the new jaw falls in a time period, 2 to 2.5 million years ago, that is very poorly known with respect to the ancestry of the earliest Homo species, says IHO's Johanson. "So, the Hadar fossil helps plug a gap in the evidence for the early evolution of our own lineage and perhaps will help us forge links back in time to Australopithecus afarensis."
The age of the Hadar jaw and tools is 2.33 million years with an accuracy of plus or minus 70,000 years. Before this find, the oldest association between a hominid fossil and stone tools was roughly 1.85 million years old.
The team has been working at the site in Hadar since 1990. In 1992, the researchers began to search the uppermost, geologically youngest levels of a sequence of rocks known as the Hadar formation. One of their objectives was to trace the evolution of Australopithecus afarensis to its fate in the period of 2 to 3 million years ago, a period that scientists know little about but considered to be of intense evolutionary activity.
The new fossil and stone tools were discovered on Nov. 2, 1994. Scattered on the surface alongside the Homo jaw were 20 fresh appearing stone flakes and several chopping tools, river cobbles chipped to two adjoining faces. The researchers, in additional field work, will try to ascertain whether the fossils made these tools, Vondra said.
Vondra and Yemane's work established the geological setting during the fossil's lifetime. Through their study of the rocks and sediments in the areas around where the discoveries are made, the paleoanthropologists can get a better read on where to focus their search and to understand what the ancestors to humans had to deal with in their physical environment.
Vondra said that the tools discovered at the site are similar to other east African excavations in younger rocks bearing hominid fossils with Oldowan stone tools. Vondra and Yemane plan to go back to Ethiopia in January for additional field work.
In addition to Iowa State and the Institute of Human Origins, the team includes researchers from Case Western Reserve University, Cleveland; State University of New York, Stony Brook; University of Washington, Seattle; Hebrew University, Jerusalem; Tel Aviv University, Israel; and the University of Toronto.
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