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The Earliest Modern Human Secret - The Romanian Clue

"Field research" projects often require scientists to endure discomfort and danger to get where they need to be, but not many can trump this summer's expedition to what may be the world's most inaccessible human fossil site, a cave in the foothills of Romania's Carpathian Mountains.

For the seven-member team, the hazards of reaching the site, accessible only by diving through frigid underwater passages, were worth it. Their finds may help answer some of the most hotly debated questions about early humans: Did they make love or war with Neanderthals? Were Neanderthals intellectually inferior to our human ancestors?

Trinkaus made a CT scan of the face to measure the unerupted teeth. "To find wisdom teeth that big," he said, "you have to go back 500,000 years."

The team considered whether early humans might have interbred with other hominids with Neanderthal-like features, but "in this time period," said Trinkaus, "the only archaic humans those modern humans could have interbred with were Neanderthals." The mosaic of Neanderthal and modern traits remind Trinkaus and Zilhao of similar traits they found in a 25,000-year-old fossil of a child in Portugal.

Researchers pondering why the Neanderthals died out have speculated that early humans might have killed them off, and Zilhao said the signs of interbreeding do not exclude that possibility. "We know that even when people fight, the winner might kill the males and keep the females from the other side," he said.

The signs of interbreeding challenge the standard wisdom that Neanderthals were a distinct, less intelligent species.

"If you look at the archaeological evidence," argued Trinkaus, "which includes things like burials, there is very little difference between what we find associated with Neanderthals and what we find associated with early modern humans -- from the same time period."

Richard Klein of Stanford University thinks this holds true only until about 50,000 years ago, when modern human behavior changed dramatically. "There could have been interbreeding," Klein conceded. "But all the genetic evidence we have suggests that, if it occurred, it was remarkably rare."

Six years ago, Zilhao and Francesco d'Errico of the University of Bordeaux published evidence that Neanderthals independently invented and used personal ornamentation. Zilhao said these finds have changed the view that Neanderthals were an inferior species.

Klein said the picture is changing, but not in that direction. The real question today, he said, is "whether modern humans fully replaced the Neanderthals or simply swamped them" genetically, with greater numbers. "And it may never be possible to say."

This may be asking a lot of the scanty fossil remains of three individuals who lived 35,000 years ago, but their age makes them the earliest modern humans ever found in Europe. The uniqueness of the site, which was discovered in 2002, was motivation enough for the specially trained team to devote a month of cold and dangerous underground journeys to reach and excavate the site known as Pestera cu Oase -- Cave with Bones.