for National Geographic News
Editor's note: The original headline for this story—"New Fossil Ape May Shatter Human Evolution Theory"—has been changed to more clearly reflect the implications of the discovery.
Fossil teeth found in Ethiopia might represent a previously unknown species of great ape that lived in Africa ten million years ago, paleontologists report.
The find not only fills an important gap in the fossil record, the Japanese and Ethiopian team says, but could also demolish a working theory of human evolution.
The teeth—eight molars and a canine—come from Ethiopia's fossil-rich Afar region, a valley made famous by the 1974 discovery of the early human ancestor known as Lucy. (What was Lucy?)
For years scientists have been unable to find fossils of direct ancestors of modern great apes in Africa dating back to between 8 million and 14 million years ago.
But the fossil record of great apes—including gorillas, chimpanzees, and bonobos—is abundant in Asia and Europe during this time (see related pictures of an ancient great ape found in Spain).
Experts had speculated that the common ancestor of all apes and humans had left Africa and split off into separate species.
Among the new species was the ancestor of African apes and humans, which returned to Africa sometime around seven million years ago. Molecular analyses of fossils from Europe and later African species seemed to back up this hypothesis.
The recent fossil discovery, however, means that ancient gorilla-like apes lived in Africa as far back as ten million years ago.
"Based on this fossil, that means the split is much earlier than has been anticipated by the molecular evidence," said Berhane Asfaw, a study co-author at the Rift Valley Research Service in the Ethiopian capital of Adis Abeba (Addis Ababa).
"That means everything has to be put back."
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