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Science: Fossils stir new debate

Posted on: Wednesday, 18 June 2003, 06:00 CDT

This adult male skull of the Homosapiens idaltu was one of three thatscientists believe to be around160,000 years old. Previously, theearliest fossils of Homo sapiens foundin Africa had been dated to about130,000 to 100,000 years.

DAVID L. BRILL / Associated Press

Some say the human skulls help establish Africa as the birthplace of man.

Scientists working in northeast Ethiopia have unearthed the 160,000-year-old remains of two adults and a child, providing the oldest fossil evidence ever found of how modern humans evolved and a new indication that they arose from a common African ancestor.

The remains -- fragments of three skulls found near the site of an ancient freshwater lake -- are 60,000 years older than the oldest previously known specimen of Homo sapiens, and serve as an anatomical bridge between Africa's earlier human ancestors and the fully modern humans who began appearing throughout the world about 100,000 years ago.

The discovery fills a temporal and geographical gap in the evolutionary record and provides new evidence for the so-called "out- of-Africa" theory, which holds that modern humans evolved in Africa as a single species and not as the result of interbreeding with human precursors -- especially the European Neanderthals.

"This is a big robust individual," said paleoanthropologist Tim White in describing the most complete of the three skulls. "I can't tell you (how tall he is), but we're not talking about a little man. This is a very large, muscular adult male. If you had a rugby team, you'd want this guy."

White, from the University of California at Berkeley, led a multinational team who discovered the new remains in the rich fossil beds near Herto village in Ethiopia's Middle Awash region, about 140 miles northeast of the capital at Addis Ababa. The team's findings are being reported in Thursday's edition of the journal Nature.

The Herto fossils help fill in the time sequence and may reflect the actual movement of early humans heading north out of Africa to the Middle East and the rest of the world. Scientists have found modern human fossils 100,000 years old in Israel.

White described the Herto skulls as "near-modern," but sharing some characteristics with pre-human species: "The brow ridges are very strong, and the area of the neck muscle attachment is very robust," giving the individuals a very powerful aspect even though the facial features are generally recognizable as modern.

"When you add these new fossils to past discoveries and genetics, the weight of evidence that modern humans basically came from Africa is very large," White said. "There will always be skeptics, but their arguments are becoming increasingly lawyer-like."

Some of those who believe in interbreeding, known as "multi- regionalists," however, argued that White's team had not proven anything: "He gave us a nice piece of evidence that places the fossils in a nice sequence in Africa," said University of Michigan anthropologist Milford Wolpoff. "But then he makes a jump -- saying that since this fits into a sequence, then this is the origin of all humans."

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