An analysis of 2 million-year-old bones found in South Africa offers the most powerful case so far in identifying the transitional figure that came before modern humans, findings some are calling a potential game-changer in understanding evolution.
The bones are from Australopithecus sediba. The research places that pre-human branch of the evolutionary tree as the best candidate to be the ancestor of the human line, said Lee R Berger of the University of Witwatersrand in South Africa.
The bones, found in 2008 in the fossil-rich cave region of Malapa near Johannesburg, show a head-to-foot combination of features of Australopithecus and the human genus, Homo.
“It's as if evolution is caught in one vital moment, a stop-action snapshot of evolution in action,” said Richard Potts, of the Smithsonian Institution. Scientists have long considered the Australopithecus family, which includes the famous fossil Lucy, to be a primitive candidate for a human ancestor. The new research establishes a creature that combines features of both groups. Mr. Berger said the brain, hand and foot have characteristics of both modern and early pre-human forms that show a transition under way. It represents a bona fide model that could lead to the genus Homo, he said. the brain of A sediba is small, like that of a chimpanzee, but with a configuration more human, particularly with an expansion behind and above the eyes.