Early human ancestors walked on the wild side

Early human ancestors walked on the wild side

Still, even if it only evolved once, the new research suggests there was a lot of tinkering within subsequent lineages.

"Think of the robust australopithecines as having developed a variation on the theme of bipedalism," Schwartz said. "Undoubtedly, it was not as efficient as the way we walk today, but it might have conferred some other evolutionary advantages."

Just what those advantages might have been remains a big unknown, Schwartz said, but finding out is the next big step for his research.

"Scientists have long been fascinated with robust australopithecines because they were so distinctive from the neck up," Schwartz said. "Now we have evidence that they were interesting from the knee down as well."