A New (Extinct) Human Ancestor

Scientists have discovered two partial skeletons of a new species of the genus Australopithecus near Johannesburg, South Africa, which they named Australopithecus sediba. The new australopithecines, nearly 1.95 million years old, appear to be closely related to both A. Afarensis and A. africanus.

Of course, paleoanthropologists are already debating where to place A. sediba in the human family tree; direct human ancestor, or evolutionary dead end? Regardless of the outcome, the new find is significant in that it fills some gaps in our understanding of evolutionary processes leading to humans. For instance, it appears that changes in the shape of the pelvis occurred before brain enlargement, and that the legs underwent adaptive changes for upright walking before the arms took on smaller, more human-like proportions.