Prehistoric teeth found over 100 years ago are some of the best evidence yet for hybridized communities of Neanderthals and modern humans.
We know that Neanderthals and early modern humans interbred—our DNA tells us so—but fossil evidence in this regard is surprisingly lacking. Hence the importance of the new research paper, published today in the Journal of Human Evolution.
The evidence consists of prehistoric teeth recovered from the La Cotte de St. Brelade cave site in Jersey, an island located in the English Channel, in 1910 and 1911. The teeth, belonging to two individuals, exhibit characteristics consistent with interbreeding, pointing to the presence of hybridized populations.
There is now “considerable DNA evidence that interbreeding happened, both from fossils and modern genomes,” Chris Stringer, a co-author of the new study and an archaeologist at the Natural History Museum in London, explained in an email. Indeed, most people with recent ancestry from outside of Africa have around 2% Neanderthal DNA in their genomes. That said, archaeologists “still don’t know the exact circumstances, nor how much this was a blending absorption of the Neanderthals into expanding modern human populations,” added Stringer.
That communities of mixed ancestry existed during the Middle Paleolithic, some 48,000 years ago, is potential evidence that “extinction” is probably not the best word to describe the fate of Neanderthals. Instead, these hominins, and their DNA, were absorbed by the increasingly dominant newcomers to Europe: modern humans (Homo sapiens).
The cave at La Cotte de St. Brelade was occupied for well over 200,000 years. Excavations made during the early 20th century resulted in the discovery of over 20,000 stone tools, as well as bones from mammoths and woolly rhinos. Exceptionally low sea levels during the last ice age made it possible for groups to migrate to the Channel Islands.
The teeth, 13 of them, were found in a single location on a ledge behind a hearth. The fossils were kept as a single set and assumed to belong to a lone Neanderthal individual. Stringer, along with colleagues from the UCL Institute of Archaeology, the University of Kent, and other institutions, borrowed the teeth from the Jersey Museum & Art Gallery to conduct an analysis with modern methods and tools, including CT scans.
Of the 13 teeth, one went missing over the years, and another was found to belong to some kind of animal. The remaining 11 teeth, it was determined, belonged not to one but two individuals. Importantly, the teeth exhibited signs of hybridization. [ … ]