Monday, February 27, 2006

Neadertals and Homo Sapiens: A Brief Moment In Time

The Grave Digger

What is happening with this picture?

Last week in the journal Nature, a new radiocarbon study has demonstrated that the H. sapiens and Neandertals spent less time together than was previously believed.

The old radiocarbon calculation is now known to be off by as much as several thousand years, the new research shows. That means that modern Homo sapiens barged into Europe 46,000 years ago, 3,000 years earlier than once estimated. But the radiocarbon dating under the new calculation also shows that their takeover of the continent was more rapid, their coexistence with the native Neanderthals much briefer.
That doesn't mean they didn't interbreed with the Neanderthals.

Link. Katerina Harvati of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, points out that a shorter coexistence would have decreased the time available for cultural or genetic exchange.

"Since these two species may have been able to interbreed, as many closely related mammal species can," Dr. Harvati said, "a restricted coexistence interval may be easier to reconcile with the observed lack of Neanderthal genetic contribution to the modern human gene pool and with the paucity of convincing fossil evidence for hybridization."

Just last year, the New York Times reported on a symposium held at NYU, 'Neanderthals Revisited: New Approaches and Perspectives.', in February 2005.

A strong consensus was emerging, they agreed, that the now-extinct Neanderthals were a distinct evolutionary entity from modern humans, presumably a different species. They were archaic members of the human family, robust with heavy brow ridges and forward-projecting faces, who lived in Europe and western Asia from at least 250,000 years ago until they vanished from the fossil record about 28,000 years ago.

The debate about Neandertals and H. sapiens interbreeding is ongoing. Much of the genetic testing that has been executed thus far has been limited to mitochondrial DNA, which is "is typically passed on only from the mother during sexual reproduction." Here we have a discussion of 2004 findings on mtDNA.

The approach taken recently by Serre et al [2004] avoided this problem by searching only for the presence of Neandertal mtDNA sequences in both early modern human and Neandertal fossils, while ignoring modern human sequences because they are potentially contaminants. Four additional Neandertal specimens tested positive, but Neandertal sequences could not be detected in five early modern human fossils with biochemical preservation consistent with DNA survival from the Czech Republic and France. This appears to confirm that sequences characteristic to Neandertal remains were not widespread in early modern humans.
In summary: Mitochondrial DNA sequences recovered from eight Neandertal specimens cannot be detected in either early fossil Europeans or in modern populations. This indicates that if Neandertals made any genetic contribution at all to modern humans, it must have been limited, though the extent of the contribution cannot be resolved at present.

What I think is really fascinating about the picture above is a subtle statement - if H. sapien ladies were interested in Neandertal men, this would explain the discrepancy in the findings.

Then again, the artist may just have been insecure about portraying a Neandertal lady's bottom. Then again, the Neandertal man is clothed. Tell me - do you think the art is accidental or intentional? Was David Danz trying to say something about interbreeding, or is it a more cultural anthropological statement about nudity and women?

Indexed by tags Neanderthal, Neandertal, hybrid, sex, radiocarbon dating, DNA, intelligence, interbreed.
Image credits: Untitled, David Danz, courtesy New York Times, borrowed for news-reporting and comment purposes.