Skulls find backs 'out of Africa' theory
By Clive Cookson, Science Editor
Published: June 11 2003 19:50 | Last Updated: June 11 2003 19:50

The oldest known fossils of modern humans have been discovered in Ethopia. An international team led by researchers from the University of California, Berkeley, found the skulls of two adults and a child dating from 160,000 years ago - 40,000 years earlier than the previous oldest remains of Homo sapiens.

The discovery, described on Thursday in the journal Nature, fills a big gap in the human fossil record: the absence of accurately dated hominid remains in Africa between 120,000 and 300,000 years ago.

Scientists say there are two implications for palaeontology. Firstly they provide new evidence for the "out of Africa" theory - that modern humans evolved only in Africa and not in several places around the world.

Secondly, says Clark Howell of UC Berkeley, "the fossils are unmistakably non-Neanderthal and show that [modern] humans had evolved in Africa long before the European Neanderthals disappeared. They demonstrate conclusively that there was never a Neanderthal stage in human evolution."

The fossils come from Herto village in the middle Awash area of Ethiopia, about 140 miles north-east of Addis Ababa - one of the world's richest hunting grounds for palaeontologists. The Berkeley team and its Ethiopian colleagues have previously found pre-human remains there of the genus Ardipithecus from about 5.5m years ago. They are some of the earliest hominids ever discovered.

Chris Stringer of London's Natural History Museum says the new finds "are complete enough to be identified as early modern humans, since they show the characteristic globular shape of the braincase and the facial features of our species.

However, both the adult skulls are huge and robust, and also show resemblances to more primitive African fossils."

The bones have been allocated to the sub-species Homo sapiens idaltu. Contemporary humans are Homo sapiens sapiens.

All three skulls show evidence of human modification such as cut marks, apparently representing mortuary practices rather than cannibalism. Associated volcanic sediments were dated by a reliable isotope method to 160,000 years, while archaeological layers showed evidence of the butchery of big game such as hippopotamus, and a range of stone axes and other tools.

It remains unclear, however, whether the evolution of Homo sapiens occurred rapidly in only one region of Africa or was a more widespread and gradual process across the continent. Although east Africa now has the oldest clear evidence of modern human origins, archaeological finds suggest that southern Africa may have played an important part in the development of modern human behaviour.

"So we will need further evidence from the whole continent to build up a complete picture of how our species began," says Mr Stringer. "Nevertheless the Herto fossils are landmark finds in unravelling our origins."