When University of Arizona scientist Jay Quade gazed into the vacant eye sockets of a fossilized skull that lay buried for 300,000 to 500,000 years – perhaps the remains of one of his own forebears – he realized it was a once-in-a-lifetime experience.
Quade, a professor of geosciences, was leading a small team of investigators in a remote area of Ethiopia in February when the find was made by the African guide for the four-member team, Asahmed Humet, an Afar tribal member.
Quade believes it to be a “missing link” in the evolution of human beings.
“I knew at the time I saw it that this was a rare moment. I said to myself, you’ll never do this again. To look into the face of a human ancestor that old – I never expected it. It was a tremendous moment. This creature has never been seen before.”
Hominid remains of that antiquity, he said, usually are found fragmented, and it takes many months of painstaking restoration to see what’s been found.
The Gawis Cranium, as it’s now called, was virtually complete, broken into just three pieces and minus only the lower jaw.
Though the possibility remains that it will turn out to be an evolutionary “dead-end,” it is likely that it represents a link between the earliest known humans, Homo erectus, which existed 600,000 years ago; and so-called modern man, Homo sapiens, first known to have evolved 200,000 years ago.
“We have this gap of about 400,000 years in between, and know very little about it,” Quade said.
Homo erectus crania are heavily constructed, massively built, with skull thickness about twice that of modern man. There is a very prominent brow ridge, with a receding, sloping forehead.
One early example, called Bodo Man, also shows cut marks on top, indicating he was butchered and that his people were cannibals.
Quade said he will determine the age of Gawis Cranium by isotopic dating of geological samples collected from layers directly above and below its resting place. What already is known about the area would indicate it is about 400,000 years old “plus or minus 100,000 years,” he said.
Its gender has not been determined, but it was an adult individual, based on tooth wear and the fact that wisdom teeth are present.
Stone tools found in the immediate vicinity, he said, are smaller and more sophisticated than the earliest known human tools, but less so than those from 200,000 years ago.
The features of Gawis Cranium likewise appear to be “somewhere in between.” The brow ridge is much more prominent than that of modern humans, but less so than that of the Homo erectus examples. The slope of the forehead also is less pronounced than that of Homo erectus.
He said the cranium itself will be thoroughly examined by Scott Simpson of Case Western Reserve University, the project paleontologist, over the next two or three years. Simpson will write a final analysis of just what it represents to human evolution.
Sileshi Semaw, based at the CRAFT Stone Age Institute at Indiana University, is overall director of the Gona Project, of which Quade was a part.
This year’s search was Quade’s seventh season in Ethiopia. The fossil-rich area is an exceptionally barren, 200-square-mile area that skirts the Gawis River from which the cranium’s name derives.
Seasonal monsoon rains repeatedly uncover fossils, he said, and the famed Homo erectus skeletal remains known as “Lucy” were found in 1974 not far from the latest discovery site.
Area residents are “Stone Age,” Quade said, and tribal members are in constant warfare with each other, making a living by raiding and stealing each others’ cattle and goats.
The men file their teeth to sharp points (though their staple diet consists largely of milk and tortillas), and every man from about age 12 and older possesses an AK-47 assault rifle, one of their few concessions to modern technology. Each strives for the honor of killing an enemy tribesman.
In fact, he said, when the team guide, Asahmed Humet, discovered the cranium, he fired a single pistol shot to signal his find. Quade and another researcher “hit the ground,” thinking a raid by the traditional enemies of the Afar – the Issa – was in progress. They rose when no further shots ensued.
On the Web: http://wwwpaztcn.wr.usgs.gov/home.html