Charles Choi, LiveScience Contributor
Date: 11 April 2013 Time: 02:03 PM ET
reconstruction of au. sediba skeletons
Here a composite reconstruction of Au. sediba, which may be humanity’s closest relative. The reconstruction is based on material from a younger male skeleton (MH1), a female skeleton (MH2) and an adult (MH4), and based upon the research presented in the accompanying manuscripts in the journal Science.
CREDIT: Photo by Lee R. Berger. Image courtesy of Lee R. Berger and the University of the Witwatersrand.

The most complete investigation of the anatomy of what may be the immediate ancestor of the human lineage is now shedding light on secrets about how it might have behaved, researchers say.

For instance, the human ancestors may have moved in an entirely new way, with a somewhat pigeon-toed gait with a twisty trunk, the researchers added.

The first specimens of the extinct species Australopithecus sediba were accidentally discovered by the 9-year-old son of a scientist in 2008, in an area in South Africa named the Cradle of Humankind, one of the richest fossil sites in Africa. Australopithecus means “southern ape,” while sediba means “fountain” in Sotho, one of the 11 official languages of South Africa, due to how scientists hint the human lineage might spring from this species.

Au. sediba lived nearly 2 million years ago, about the time when scientists think the human lineage Homo originated. It possessed a bizarre jumble of human and more apelike traits, perhaps revealing this might be the species from which humans’ branch of the family tree originated. [See Images of Au. Sediba, Our Closest Human Ancestor]

“These skeletons are just interesting, wonderful blends of characteristics,” researcher Steven Churchill, an evolutionary anthropologist at Duke University, told LiveScience.

The findings, detailed in six papers in the April 12 issue of the journal Science, firm up the idea that Au. sediba was one of humanity’s closest ancestors.

Who was Au. sediba?

Now scientists have probed more deeply into the anatomy of the remarkably well-preserved skeletons of Au. sediba. These include a younger male skeleton, commonly referred to as MH1, and a female skeleton, known as MH2, as well as the shinbone of an adult known as MH4. This is the most comprehensive exam yet of the anatomy of an early member of the hominins — the group that includes modern and extinct human species and their direct ancestors.

the skull of australopithecus sediba
A team of scientists have completed the most detailed investigation of the anatomy of what may be the immediate ancestor of the human lineage, calledAustralopithecus sediba, shedding light on secrets about how it might have behaved.

The reconstructed skull and mandible of Au. sediba.
CREDIT: Reconstruction by Peter Schmid, Photo by Lee R. Berger. Image courtesy of Lee R. Berger and the University of the Witwatersrand.