An apelike creature that lived 9 million years ago might be the earliest known direct ancestor of humans, scientists from France and Greece suggest in a study in today's issue of the British journal Nature.
Their analysis of a fossil found in September in northern Greece implies that ancestors of humans might have started evolving away from ancestors of chimps and gorillas millions of years earlier than many scientists believe.
But experts familiar with the study said they strongly doubted that the creature is really a direct ancestor of humans.
The fossil represents a previously known animal called Ouranopithecus macedoniensis. It includes the right part and a portion of the left part of an adult's face plus the upper jaw and almost all of its teeth, the researchers said.
They said its anatomy suggests that Ouranopithecus macedoniensis appeared on the human branch of the evolutionary tree after that lineage split from the ancestors of gibbons, orangutans, gorillas and chimpanzees. That would make it a direct ancestor of humans.
The researchers suggested that human lineage might have started evolving from the ancestors of chimps and gorillas as long as 12 million years ago. Other scientists have put that split at only 5 million to 7 million years ago, said Lawrence Martin, an assistant professor of anthropology at the State University of New York at Stony Brook.
Martin, who has studied other fossils from Ouranopithecus macedoniensis, said he is "absolutely sure" that the new study is wrong in assigning the beast to the human lineage. He said he puts the beast further back in evolution, before the human lineage started evolving from ancestors of chimpanzees and gorillas.
Peter Andrews of the Natural History Museum in London, who wrote an editorial accompanying the Nature report, said that "I don't believe for a minute" that the creature was a direct human ancestor. Instead, he said, it might have preceded the split between human and ape lineages.