A research group including a University of South Florida professor may rewrite human history with an Ethiopian find of fossilized bones bearing distinct cut marks.
USF geology professor Jonathan Wynn and others with the Dikika Research Project have dug up evidence that human ancestors used tools nearly a million years earlier than previously thought.
Their findings were reported this week in the journal Nature.
Led by Zeresenay Alemseged of the California Academy of Sciences, the researchers found the bones in a region of Ethiopia where the same team discovered the skeleton of a creature dubbed "Selam" in 2000.
Selam also was called "Lucy's baby" because she's the same species as the famous "Lucy," the name given the creature scientists imagined after finding a 3-1/2-foot-tall skeleton in Ethiopia in 1974. Lucy represented the first nearly complete skeletal remains of the apelike human ancestor known as Australopithecus afarensis, which lived in Africa 3.2 million to 4 million years ago.
The latest discovery presents a new picture of Lucy, Selam and others of their species, Wynn said.
"We had a previous picture that Lucy and her kind were living in between the woodlands and on the savanna," eating mostly vegetation, Wynn said. "Now we can form a picture of Lucy and Selam going out and acquiring animal foods."
Rather than hunting, they probably were scavenging the raw meat from carcasses and smashing the bones for the marrow inside, Alemseged said.
But they were using tools. And they may have been cooperating to guard the carcass while they were eating.
"This takes a lot more than the early primates were able to do," Wynn said. "It means a completely different behavior from what we imagined."
The researchers didn't find stone tools at the site, but they think the bones show evidence of tool use because of sharp cut marks on the bones. One bone is a rib from an animal the size of a cow. The other is a leg bone from something the size of a goat.
The bones were found a few hundred yards from where Selam's skeleton was found. They were about the same age, based on Wynn's soil studies in the area.
Until now, evidence of tool use went back only 2.6 million years.
Some experts questioned the Dikika researchers' conclusions, saying the marks could have come from animal bites. Others also see evidence of stone tools in the discovery.
Wynn, who joined Alemseged's team in 2002 and came to USF in 2006, said the Dikika researchers didn't realize what they had found when they first excavated the bones.
They examined the marks with microscopes that magnify to a high degree and help show the chemistry of an object.
Everything they saw confirmed the marks had been made by tools, he said.
Wynn said the bone find has given the researchers new questions to ask.
His next step is to start studying the chemical composition of the human ancestors' teeth, which will show the kind of food they ate.
Based on the idea that "you are what you eat," researchers hope to understand Selam's daily diet and round out the picture of how these human ancestors lived.