At a family reunion of the direct evolutionary predecessors of our species, there would be a lot of arguing over whether Australopithecus sediba gets in the door.
Australopithecus sediba is the name of an ancient species discovered in South Africa in 2008. Researchers now have substantial evidence, published in this week's edition of the journal Science
, that Australopithecus sediba could be a direct ancestor of the Homo genus, of which humans are a part (we are Homo sapiens). If that's true, it means our family tree may have to be redrawn, with Australopithecus sediba at the stem of the Homo line.
But that's just one possibility, and a controversial one at that.
Researchers studied two partial skeletons, a young male named Karabo and an adult female who has not yet been named, which were found in the remains of a collapsed cave. "Australopithecus" means "southern ape," and "sediba" is "natural spring" or "fountain" in the Sotho language. The team announced the discovery of the previously unknown species in 2010
Scientists have several theories about what these skeletons might mean for human evolution.
The earliest undisputed Homo genus member is Homo erectus, which researchers estimate to be about 200,000 years younger than Australopithecus sediba, so Homo erectus could theoretically be the direct evolutionary descendant. Alternatively, Australopithecus sediba could be the direct ancestor of Homo habilis, considered to be a toolmaker because its hand bones were found next to stone tools, or of Homo rudolfensis, a contemporary of Homo habilis of disputed evolutionary origin. Australopithecus sediba could be related to both of them, and perhaps their current labels are inaccurate. Or, of course, it could be a dead end, although researchers say the skeletons' human-like features suggest otherwise.