Researchers have revealed an unprecedented insight into Australopithecus sediba, a two million-year-old human ancestor discovered in South Africa which show a mixture of primitive features and of more advanced features typical of later human species.
With long arms, high shoulder blades and powerful fingers, the ancient creatures were built for climbing trees. However, they also had long lower limbs, flat feet and a flexible lumbar spine that gave them a distinct evolutionary edge - they were able to cover long distances by walking upright on two legs. The research also shows they had dexterous hands and a human-like thumb for precision grip.
Several partial skeletons of the two million-year-old species Australopithecus sediba were discovered in South Africa in 2008 at Malapa, near Johannesburg, South Africa. The human branch of the evolutionary tree, called Homo, is thought to have arisen from a group of ancient species called australopithecines. The newly studied species is a member of this group, and so its similarities to humans are interesting and may solve the mystery as to how Homo sapiens emerged.
As a result, it is believed that this new species is currently the best candidate for a direct ancestor of our own species. The human ancestor had a narrow upper rib cage which is similar to that of large apes, such as gorillas, but which is different to the human thorax which is uniformly cylindrical.
The skeleton fossils have so many human-like features "across the whole of the body that it must be considered, at the very least, a possible ancestor," said Lee R. Berger, a paleoanthropologist at the University of Witwatersrand in Johannesburg, South Africa, who discovered the fossils in 2008.
Berger noted that if modern humans were to observe an A. sediba walking by, their attention would probably not be drawn to its legs. "What would be a great difference would be how it swung its long upper limbs during that walk and the shrugged-shoulder appearance of its upper body," he said.
