It is highly possible that humans and chimpanzees diverged from a common ancestor about 8 million to 7 million years ago, earlier than previously thought, a team of researchers thinks.
The team, which includes scientists from Kyoto University, will publish the estimate in the online edition of the Proceedings of the National Academy of Sciences of the United States of America.
Many believe the two species diverged 6 million to 4 million years ago. But the discovery in 2002 of the oldest human fossil, estimated at 7 million to 6 million years old, caused controversy because of the gap with the previously believed time of divergence.
After re-examining the average number of years required for the heterogeny of wild chimpanzees and gorillas, the team calculated the time of divergence based on the pace of DNA mutation in the two species and that of Homo sapiens.