When first excavated the bone was thought to be about 35,000 years old, but new research shows it to be significantly older -- between 44,000 and 41,000 years -- a study published in the journal Nature reported Wednesday.
The new dating is helping scientists identify how quickly modern humans spread across Europe during the last Ice Age, and is seen as possible confirmation of the controversial theory that early modern humans coexisted with Neanderthals.
"If the jawbone is, in fact, 44,000 to 41,000 years old, that means it was from a time when Neanderthals were still present in Europe, so we first had to confirm that the bone was from an anatomically modern human, and not a Neanderthal," Beth Shapiro, a biology professor at Penn State, said.
"While the dominant characteristics are modern, there are some that are ambiguous or that fall into the Neanderthal range," she said.
That may reflect inadequate sampling of modern human variation, shared primitive features between early modern humans and Neanderthals, or even interbreeding between the two species, she said.
"We'll have to delve a little deeper and do more work to resolve these questions," Shapiro said.