Dembo’s team found no signs that bones assigned to H. naledi represent a variant of Homo erectus, as some scientists have argued. H. erectus originated about 1.8 million years ago in Africa and rapidly spread to West Asia. But Dembo’s statistical model assumes that H. erectus skulls and teeth vary in shape throughout Africa and Asia much less than they actually do, says paleoanthropologist Christoph Zollikofer of the University of Zurich. Bones assigned to H. naledi most likely represent a form of H. erectus, he argues.