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Discovery in Ethiopia sheds new light on history of man
Posted: Wednesday, October 22, 2003
by Abram Katz, www.zwire.com
Michael Rogers was scaling a slope in Ethiopia when he spotted the earliest evidence that tools were used to butcher animals 2.3 million years before the first modern humans appeared on earth.
The small angular rock that Rogers found was chipped from a stone blade.
This significant find shows that our hominid ancestors were far more capable than previously thought.
The trove of stone flakes and associated bones also suggests that Homo sapiens evolved a large brain in response to growing manual dexterity, rather than the other way around.
Rogers, assistant professor of anthropology at Southern Connecticut State University and his international colleagues were exploring the Gona region of the Ethiopian badlands in 2000 when the tools and bones were discovered.
The research was published in the September Journal of Human Evolution.
"One of the main goals is to find the maker of those tools," Rogers said.
The earliest human-like primates found so far are 2 to 3 million years old.
Modern humans did not inhabit the plains of Africa until about 200,000 years ago.
"We traditionally thought that the hominid Australopithecus didn’t use tools. This may have to change," Rogers said.
Two species of Australopithecus lived about 2.3 to 2.8 million years ago in the Gona area.
"There’s no reason Australopithecus couldn’t have used tools. Modern chimpanzees use sticks and stone … to crack nuts," Rogers said.
Whoever chopped up animals at Gona 2.6 million years ago did not pick up the first handy rock.
Stone flakes show that the Gona hominids intelligently selected stones and fashioned them into sharp edges.
"They obviously had the capability to know good stones from bad," Rogers said.
They selected chert, aphanamitic lava and trachyte, which split naturally into pieces with sharp edges.
Finding the bones mingled with the stones is especially significant, Rogers said.
Geologists had previously found bones with tool marks — but no tools, and stone tools without bones.
"This is the first site of bones and stones of this age," he said.
The site, which is only about 4 meters by 1 meter, was located on the banks of a prehistoric channel.
Strata of rock that gradually formed above the site include a 20-foot band of volcanic ash, which can be precisely dated.
Analysis put the excavation site at 2.58 million years ago.
"Bone preservation is very poor," Rogers said, so no cut marks were evident.
However, a stone flake was found embedded in one of the bones. The largest bone belonged to a 200-pound mammal of some kind.
Rogers said the initial flake was lying on the surface.
"Purposeful flaking is not hard to recognize. I saw a dozen of them," he said.
Rogers said the site contained a wide range of rocks and fragments, ruling out the possibility that the materials were washed together in a prehistoric stream.
"Finding a hominid that goes with the tools is the next step," Rogers said.
That will depend largely on luck. "We know what to look for and where to look," he said.
If the tool chippers turns out to be Australopithecus, then that will be evidence that fabrication of tools came before increased brain capacity, Rogers said.
That would answer a longstanding "chicken and egg" question about whether bigger brains led to tool making, or tool making resulted in Homo sapiens’ big brain.
"Any future find will reshape what we know," Rogers said.
Meanwhile, all of the bones, tools and stone flakes are in storage in Addis Ababa, Ethiopia.
Rogers was part of the international Gona Paleoanthropological Research Project, led by Sileshi Semaw, an Ethiopian anthropologist at Indiana University.
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