Talk like a man

Da sciencemag.org
(pag esatta qui)

By Elizabeth Culotta
ScienceNOW Daily News
18 October 2007

The gift of gab sets humans apart from all other species. But what about Neandertals? A new genetic study offers tantalizing evidence that our closest extinct cousins may have been talkative, too.

Nailing down whether Neandertals spoke to each other has been tricky. Studies show that they had big brains and engaged in some sophisticated behaviors, including burying their dead. But the evidence has been indirect because the soft structures of the throat don't fossilize, and researchers have debated whether they could speak as well as we do. Recent work on a gene known as FOXP2 seems to undermine the speaking hypothesis. Many animals, including mice and bats, have the gene (ScienceNOW, 19 September), but specific variations in the human version appear to have contributed to our language ability. Research indicates that these variations appeared in the past 120,000 years--long after our species split from Neandertals (ScienceNOW, 14 August 2002). "So the speculation was that [the FOXP2 variations] were unique to humans and not there in Neandertals," says evolutionary geneticist Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who traced FOXP2's ancestry. "If there was one single gene I really wanted to see in Neandertals, it was this one."

Pääbo appears to have gotten his wish: His team extracted ancient DNA from two 43,000-year-old Neandertal bones found in a cave in northern Spain. Genetic analysis revealed that the FOXP2 sequence in both Neandertals matched that in living people. It harbored the two mutations that help set the human gene apart from those of all other animals. This doesn't necessarily prove that Neandertals could speak, because many other, unknown genes probably influence language ability. But "with respect to FOXP2, there's nothing to say that Neandertals could not speak just like we do," says Pääbo. He now suggests that the gene was favored by selection much earlier, before Neandertals and modern humans had completely diverged, perhaps 300,000 or 400,000 years ago. The team reports its findings online 18 October in Current Biology.

Several experts say that vocal Neandertals fit what we know of these hominids, especially the fact that they had large brains and lived in groups. "I think many of us are prepared to grant Neandertals language capacity, even if ... it may not have reached our modern levels," says Chris Stringer of the Natural History Museum in London. Still, evolutionary geneticist Jeff Wall of the University of California, San Francisco, cautions that it's possible that the Neandertal samples were contaminated with modern human DNA (ScienceNOW, 29 August). Pääbo says that for this paper, the team added extra controls to try to make sure that they were analyzing Neandertal rather than modern human DNA.

Even if there were no contamination, Wall says, it's not clear exactly when Neandertals acquired the humanlike FOXP2 gene and its potential effect on speech. Instead of belonging to a common ancestor of both species, Wall says it's possible that the study's Neandertals, who lived in Europe just as modern humans were beginning to enter the continent, picked up the FOXP2 variant by mixing with the newcomers. Pääbo calls that scenario "a formal possibility but one we think unlikely."