Fossils from South Africa of the Australopithecus sediba display a unique mix of primitive and modern, human-like features

Is the Australopithecus sediba our ancestor? New research in the journal Science suggests so, as high-resolution scans and uranium-dating tests reveal that this hominin exhibited primitive as well as human-like traits and existed around the same time early Homo species first walked the Earth.

"The many advanced features found in the brain and body, along with the earlier date, make it possibly the best candidate ancestor for our genus," says Lee Berger, the project leader from the University of the Witwatersrand in Johannesburg, South Africa, in a news release.

Berger and his colleagues discovered the remains of a juvenile male (MH-1) and an adult female (MH-2) Au. sediba in one of the caves of Malapa in South Africa last year. Several uranium-dating tests and high-resolution synschrotron X-ray scans of the nearly complete fossils of pelvises, hands, and feet suggest that the Au. sediba is about 1.977 million years old. Until this discovery, fossils of the Homo habilis and Homo rudolfensis dated to 1.90 million years ago have been considered ancestral to Homo erectus, the earliest undisputed human ancestor.

In the gallery below, see images of the Au. sediba's fossils, behind-the-scenes photos of experiments, and visualizations of this remarkable species's human-like features.