Fossils could represent unknown human ancestor

A discovery at a fossil site in South Africa made public on Thursday signals a new ancestral addition to the hominid species – one that may prove to be the origin of modern humans from apes.

The nearly two million-year-old fossil, dubbed Australopithecus sediba, is being described as a new species of hominid, which is defined as a primate of a family that includes humans and their fossil ancestors.

It also might prove to be the link between "ape-man" and the first known human species, says Prof. Lee Berger from the University of the Witwatersrand in Johannesburg.

A team of paleoanthropologists, led by Berger, made the discovery at a UNESCO site, the Maropeng and the Cradle of Humankind World Heritage Site, 40 kilometres outside the city. They have worked for two years to extract the bones from rock, and their findings will be published in two papers from Berger and Prof. Paul Dirks, in the journal Science on Friday.

"Sediba, which means natural spring, fountain or wellspring in Sotho, one of the 11 official languages of South Africa, was deemed an appropriate name for a species that might be the point from which the genus Homo arises," Berger said in a news release.

More specifically, the find is suspected to be the "transitional species" between the Australopithecus africanus and either Homo habilis, the first species considered to be human, or even a direct ancestor of Homo erectus.

The fossils – an adult female and juvenile male – were found almost intact in a deeply eroded cave. They are described as having long arms, like an ape, short powerful hands, a very advanced pelvis and long legs capable of striding and possibly running like a human. It is likely that they could have climbed, said researchers.

"It is estimated that they were both about 1.27 metres, although the child would certainly have grown taller. The female probably weighed about 33 kilograms and the child about 27 kilograms at the time of his death," said Berger.

"The brain size of the juvenile was between 420 and 450 cubic centimetres, which is small (when compared to the human brain of about 1,200 to 1,600 cubic centimetres) but the shape of the brain seems to be more advanced than that of australopithecines."

It has been reported that the discovery is considered so significant that Jacob Zuma, South Africa’s president, has visited the university to view the fossils and a media campaign including television documentaries is being planned.

According to the Maropeng website, the oldest hominid ever discovered is Sahelanthropus tchadensis, from Chad, which is about seven million years old.

In the Cradle of Humankind, about 1,000 hominid fossils have been discovered, spanning several million years.

The oldest hominid fossils from the Cradle are more than three million years old and belong to the genus Australopithecus.