When paleoanthropologist Lee Berger unearthed a fossil near Johannesburg, South Africa, it seemed to be a jumble of parts: a braincase similar in size to that of an Australopithecus africanus, a Homo erectus pelvis, and the arms of a Miocene ape. But in April Berger announced that they all belonged to the same skeleton, that of a 12-year-old boy who lived 1.9 million years ago. The boy, called Karabo, may represent a bridge species between our Homo genus and its Australopithecus ancestor.
Berger thinks Karabo and an adult female found nearby represent a new hominid species, Australopithecus sediba, that may have been the first to walk upright the way modern humans do. A. sediba had long, apelike arms; a braincase one-third the size of a modern human’s; and a modern-looking pelvis that suggests it was a better upright walker than previous australopithecines.
Others contend the two are not human ancestors ...
