Fossils provide evidence that humans evolved in Africa
  Fossils of modern human skulls estimated to be some 160,000 years old have been discovered by an international team working in Ethiopia, offering some of the best evidence yet that Homo sapiens developed in Africa before spreading across the globe.
The new fossils, found in river deposits near the village of Herto, approximate the anatomy of modern humans but aren’t quite what would be considered normal shape today. The fossils feature a deep face and a long, rugged braincase just at the edge of the modern human range of features.
The more complete of two adult braincases has a capacity of 1,450 cubic centimeters, slightly above the modern human average of between 1,350 and 1,400.
“Despite the presence of some primitive features, there seems to be enough … evidence to regard the Herto material as the oldest definite record of what we currently think of as modern Homo sapiens,” said Christopher Stringer, a researcher into human origins at The Natural History Museum, London, who commented on the find described Thursday in the journal Nature.
The researchers from Japan, Ethiopia and several American universities decided there were enough differences between the Herto humans and modern people that they named them a new subspecies, Homo sapiens idaltu (which means elder in the local Afar dialect).
Anthropologists have argued for decades about whether modern humans evolved separately in Africa or arose at roughly the same time in several spots across the globe, perhaps through cross-breeding of several precursor species, like the Neanderthals of Europe and the Middle East.
Recent genetic backtracking of modern human roots seemed to suggest that the out-of-Africa theory was correct, but there were no fossil remains of humans from the right time and place to confirm it.
“We’ve lacked intermediate fossils between pre-humans and modern humans, between 100,000 and 300,000 years ago,” said Tim D. White, a University of California-Berkeley paleoanthropologist who was one of the project leaders. “Now, we have a great sequence of fossils showing that we evolved in Africa and not all over the globe.”
White discovered the prehistoric camp in November of 1997, when he spotted a butchered fossil hippopotamus skull and associated stone artifacts eroding from sandy sediments east of Herto village, which even today serves as transient quarters for nomadic herdsmen.
Although the region is now arid, scientists say that 160,000 years ago the village lay on the shore of a shallow freshwater lake filled with catfish, crocodiles and hippos. Meanwhile, most of Europe was buried under the ice of a major glacier period, but with well-adapted Neanderthals keeping a foothold in a region they’d inhabited for some 400,000 years.
Although some scientists still argue that the Neanderthals somehow managed to evolve into modern Europeans — or at least bred with modern humans coming from other regions before their kind disappeared about 30,000 years ago — the genetic evidence for this hasn’t been found. The new fossils seem to even more conclusively shut the door on Neanderthal ancestors.
“These well-dated and anatomically diagnostic Herto fossils are unmistakably non-Neanderthal,” said F. Clark Howell, professor emeritus of integrative biology at UC Berkeley and a co-author of the study. “They demonstrate conclusively that there was never a Neanderthal stage in human evolution.”
The scientists also collected extensive samples of Stone Age tools from the site, which were studied extensively by Berkeley prehistorian J. Desmond Clark before his death last year. The tools illustrate a transition between heavy stone hand-axes and more delicate flaked stone blades.
There are also cut marks and signs of polishing on two of the skulls that suggest they may have been defleshed and specially preserved as part of some ritual by surviving members of their clan.
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