Fossil Skull of Human Ancestor Has Similarities to Several Species

Scientists say the newly found skull of a human ancestor suggests that researchers ought to be more cautious about declaring the discovery of new species. The skull comes from Australopithecus boisei, known for massive jaw muscles and huge back teeth. It is the first A. boisei skull to include a lower jaw.

But the skull has some unexpected features. The cheekbones look more like those of a different species called A. robustus, and the back of the head suggests still another species, A. aethiopicus. The palate is shaped like one from Homo, the evolutionary grouping that includes people. This weird combination is much different from previous A. boisei skulls and shows that various members of a single species of human ancestor can look different in their fossil details, researchers report in today’s Nature.