A last refuge for neanderthals?
The completion of a 7-year excavation of a site in southern Spain provides some evidence that neanderthals may have lived for thousands of years longer than was previously thought.
Clive Finlayson led the international team of palaeoanthropologists, which discovered 103 neanderthal artifacts, including spear points and knives, while excavating Gorham’s Cave near the Rock of Gibraltar. Most of these artifacts have been dated to about 28,000 years before present (BP), and some are dated as late as 24,000 years BP.
The study, reported in an advance online publication at Nature, led Finlayson and his team to conclude that an isolated population of neanderthals lived in the region surrounding Gorham’s cave until about 28,000 years BP. This is the latest recorded date yet for neanderthals, and is at least 2,000 years later than previous estimates. It again raises the possibilty that early modern humans and neanderthals interbred.
The findings hint at a scenario in which neanderthals sought refuge in the southern-most point of the Iberian peninsula at a time when they had been wiped out from the rest of Europe, and when modern humans were expanding across the continent. Finlayson, an evolutionary biologist at the Gibraltar Museum, speculates that neanderthals were driven south because of climatic changes to which they could not adapt quickly enough.
“While the rest of [Europe] was getting colder, down here at the southernmost tip of Europe there were still little pockets of Mediterranean climate, so the world of the neanderthals there didn’t change that much,” says Finlayson, an evolutionary biologist at the Gibraltar Museum.
Finlayson is, however, cautious about the results for several reasons. Firstly, the artifacts were found in hearth areas around Gorham’s Cave, and tiny samples of hearth charcoal, rather than the tools themselves, were used for the radiocarbon dating. Secondly, some of the samples give radiocarbon dates that are earlier than those of other samples found buried higher up. This is inconsistent with the notion that earlier artifacts overly older ones.
The tools are examples of Mousterian technology, or middle palaeolithic flint tools. Because they are often found buried alongside neanderthal fossils, these tools are associated primarily with that species, although they are known to have been made by others. Because no hominid fossils were found buried with the tools that were found, it is possible that they were made by another hominid species.
Erik Trinkaus, a physical anthropologist at Washington University, is skeptical about the findings. He says that the charcoal samples used to date the tools can easily migrate between sedimentary layers, and therefore cannot provide an accurate estimate of when the tools were made. Therefore, the only firm conclusion that can be reached from the findings is that Mousterian toolmakers inhabited the Gorham’s Cave area until around 28,000 years BP, although the accuracy of this date is questionable. Whether or not the tools were made by neanderthals is another question altogether; the discovery of hominid fossils in or around the cave may clarify this matter.
Trinkaus has also had research published recently. He conducted a comparative study of human and neanderthal fossils to determine ”the extent [to which] Neanderthals are derived, that is distinct, from the ancestral form [and] the extent to which modern humans are derived relative to the ancestral form.”
In August’s issue of Current Anthropology, Trinkaus reports that humans differ more from other members of our hominid family than did neanderthals. Homo sapiens is the only hominid species which lacks brow ridges, shortened faces and internal nasal cavities which are greatly reduced in size. The human limb skeleton also has features that are unique.
“What I came up with is that modern humans have about twice as many uniquely derived traits than do the Neanderthals,” said Trinkaus. “In the broader sweep of human evolution, the more unusual group is not Neanderthals, whom we tend to look at as strange, weird and unusual, but it’s us – modern humans.”
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I’ve just written an essay about Neanderthals for my blog, in which I link to an article of yours about the Neanderthals genome project, and I thought it might be of interest (as might the rest of the blog hopefully).