Alerted by the glint of a single fossil tooth in the desert sand, scientists found remains of a chimp-size creature that is the earliest known link in the chain connecting humans with the ancestors of apes.
The ape-man roamed woodlands about 4.4 million years ago in Ethiopia, and "this is the first time we've seen a human ancestor in such a wooded environment," said Tim White of the University of California at Berkeley.
Many scientists believe humans evolved after their ancestors left the forest for grasslands, said Bernard Wood of the University of Liverpool in England, who was familiar with the discovery. The finding provides evidence that the first stages of human evolution probably happened in a more wooded environment instead, he said.
"It's not the savannah that forced us along the evolutionary road," White said. "The first steps seem to have been taken in a forest habitat" after the human lineage split from the ancestors of chimps.
White said the creature was closely related to the last ancestor shared by humans and chimps.
The fossils are about 800,000 years older than the earliest firmly established remains of Australopithecus afarensis, which had been the oldest known link to ancestors of the apes.
White and colleagues announced the discovery in today's issue of the journal Nature.
They found fossils from 17 individuals of the species they dubbed Australopithecus ramidus, including teeth, parts of a skull and lower jaw, and complete bones of a left arm. …