For more than a century, scientists have wondered when and where modern humans arose--and what they looked like. Now three partial skulls from Ethiopia are putting a face on the earliest modern humans. These ancestors were African, with big brains, robust features, and a taste for hippopotamus and buffalo meat.
Genetic evidence has suggested that modern humans originated in Africa in the past 200,000 years, but there have been few fossils to back up that assertion. The new skulls fill this gap. They were discovered on a quick stop in November 1997, when paleoanthropologist Tim White of the University of California, Berkeley, spotted a butchered fossil hippopotamus skull on the ground near the village of Herto, about 230 kilometers south of Addis Ababa. When his team returned to explore, they found two skulls in one day; another turned up a week later.
It took the team 3 years to clean, prepare, and reassemble the fossils. By comparing the skulls with 6000 others from around the world, the scientists concluded that the most complete adult skull was clearly a Homo sapiens, with the vault of its braincase shaped like a pentagon, a wide upper face, and a moderately domed forehead. It also had divided brow ridges and a flat midface like modern humans. A few primitive features, such as a flexed bone at the rear of the braincase and protruding brows, link it with more ancient African fossils. The team named it H. sapiens idaltu, using the word for elder in the local Afar language. "It is so similar to ours that there is no doubt it is the face of a direct ancestor," says White. This skull was found embedded in ancient sandstone, and team geologists dated it to between 154,000 and 160,000 years ago.
The site also yielded a surprising mix of stone tool technologies. The team found crude stone hand axes as well as stone flakes produced by a more efficient and sophisticated toolmaking technique. Another puzzle is that all the skulls have cut marks, suggesting that they were defleshed and handled after death, perhaps in rituals for the dead. A child's skull also had polish on its side and back. The team reports on its find in the 12 June issue of Nature.
Although a few colleagues are grumbling about whether the subspecies designation is needed, no one disputes that the new fossils are early H. sapiens. "This is a great discovery because there is no doubt these fossils are the forerunners of the early modern people [in Israel]," who until now were the oldest known members of our species, says Harvard University archaeologist Ofer Bar-Yosef.