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(CNN) –– Early modern humans and Neanderthals lived in Europe and parts of Asia at the same time. In fact, they overlapped for several thousand years before our archaic relatives disappeared about 40,000 years ago.
During this time, Homo sapiens and Neanderthals met. Sometimes they even had sex and gave birth to children. The evidence is buried within our genes, DNA analysis has shown. Most Europeans have around 2% Neanderthal DNA in their genomes due to this ancient interbreeding.
However, relatively little direct physical evidence of these encounters and fossilized bones has been found. The skeletons that have been discovered do not offer definitive evidence.
Now, a new analysis of 11 teeth found in a cave on Jersey Island, in the English Channel, suggests that some of them could have belonged to individuals with mixed ancestry of Homo neanderthalensis and Homo sapiens.
The teeth, identified as Neanderthals, were found when the site, known as La Cotte de St. Brelade, was first excavated in 1910 and 1911. A new analysis of the teeth was published in the Journal of Human Evolution on Monday. And it shows that the teeth actually came from two different individuals who lived there 48,000 years ago. Seven of the teeth had features of both modern humans and Neanderthals.
“We found the same unusual combinations of Neanderthal and modern human features in the teeth of both identified Neanderthal individuals,” said study author Chris Stringer, research leader in human origins and professor at the Natural History Museum in London.
“We consider this to be the strongest direct evidence (of interbreeding) found in fossils. Although we do not yet have DNA evidence to support this.
The team was trying to recover DNA from the teeth to confirm whether they belonged to people with a dual Neanderthal-modern human heritage, Stringer said. Preserving DNA was “a matter of chance,” given the age of the teeth, he explained.
‘The roots of the teeth look very Neanderthal. While the neck and crowns of the teeth look much more like those of modern humans, “he said.
The only other explanation, he said, is that this population was extremely geographically isolated and developed these unusual features in their teeth.
“It could be that this (is) a very unusual population that developed this combination of traits in isolation. However, at this time, because of the lower sea levels of the last Ice Age, Jersey was definitely connected to neighboring France. So isolation is unlikely, ”Stringer explained by email.
It was surprising to find this evidence of “hybrid” individuals with Neanderthal and Homo sapiens ancestry in northwestern Europe, he said. This is because the earliest evidence of modern human influence in Europe has been discovered much further east. Evidence in present-day Bulgaria potentially dates back 47,000 years. And in Iberia and southern France 42,000 years ago.
Similarly, existing fossil evidence of interbreeding has also been found further east.
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The most definitive case is that of the Oase Cave in Romania, where a 40,000-year-old jaw was unearthed. It has unusual characteristics. Genetic analysis found that there was 9% Neanderthal DNA, coming from crossbreeding that likely occurred in the previous five generations, Stringer noted.
A 50,000-year-old bone fragment, discovered in 2018 inside a Russian cave, represented the first known remains of a child with a Neanderthal mother and a father who was Denisovan. The latter is another extinct relative of modern humans believed to have lived predominantly in Asia.
Teeth are especially important to archaeologists and paleoanthropologists because they are stronger than bones. The enamel is already largely mineralized and not organic, so it survives very well in the fossil record.
The La Cotte site in Jersey shows that Neanderthals used the cave for 200,000 years, the Natural History Museum said. The earth layers show repeated reoccupation by different groups of Neanderthals and at least two piles of mammoth bones.