Archaeologists digging in a cave in northern Israel have uncovered teeth dating to at most 38,000 years ago that display a mix of Neanderthal and Homo sapiens features.
Neanderthals are thought to have been long extinct in Israel by then, though some may have survived later in isolated pockets elsewhere. The teeth therefore likely belonged to humans who had interbred with our evolutionary cousins – but not in Israel: this meet-’n-greet likely happened in Europe. Then their hybrid offspring roamed back to the Levant, a team of researchers from Israel, Austria and the United States has concluded.
The teeth found in Manot Cave, a prehistoric site in the Western Galilee, are associated with the Aurignacian culture, which is known for producing spectacular cave paintings and exquisite statuettes in Europe starting around 43,000 years ago.
The Aurignacian, named after Aurignac Cave in southwest France, is considered to be the first human culture to make widespread use of art and symbolism (though art dated to 52,000 years ago has been found in Asia). The rise in symbolism in Europe coincided with the arrival of Homo sapiens from the Levant and Africa and the demise of the Neanderthals, an extinction whose causes are still hotly debated.
The discovery of the Manot teeth, which date to at least 5,000 years after the beginning of the Aurignacian in Europe, further attests that the Neanderthals did not disappear completely, in the sense that their genome survived in sapiens populations with which they interbred. This is something scientists have already been aware of for nearly a decade, as genetic research shows that all humans outside sub-Saharan Africa carry between one to three percent Neanderthal DNA.
The newly-found remains also suggest an answer to the longstanding archaeological mystery of how the Aurignacian culture spread from Europe to sites in the Levant, say the researchers involved in the analysis of the teeth, which was published in the Journal of Human Evolution.
Manot Cave was discovered by chance during construction work in 2008. Archaeological digs there over the last decade have uncovered a treasure trove or prehistoric finds, including a 55,000-year-old skull thought to belong to some of our earliest human ancestors out of Africa.
However, the recent study is based on much later finds at Manot: six teeth that were unearthed in Aurignacian layers dated to between 38,000 and 34,000 years ago.
Aurignacians in the Galilee
The researchers, led by Tel Aviv University dental anthropologist Rachel Sarig, conducted micro-CT scans and 3D analysis on four of the teeth, comparing multiple features in their morphology to a sample of dozens of prehistoric chompers from other sites across the world.
“Unlike bones, teeth are preserved well as they are made of enamel, which is the substance in the human body most resistant to the effects of time,” Sarig explains. “We were able to use the external and internal shape of the teeth found in the cave to associate them with typical hominin groups: Neanderthal and Homo sapiens.”
All four teeth – which belonged to different individuals – displayed a mix of Neanderthal and Homo sapiens features, Sarig says.
“This usually happens in cases of interbreeding,” says Israel Hershkovitz, a physical anthropologist from Tel Aviv University. “In my opinion this was a Homo sapiens population with a strong Neanderthal genetic component.”
We cannot be completely sure of that conclusion because it was not possible to extract DNA from the teeth, a problem often encountered when dealing with finds that were preserved in the hot climes of the Middle East.
Still, the Manot teeth most closely resemble Aurignacian-period specimens like those found in Oase Cave in Romania. There researchers do have strong genetic evidence of Neanderthal-sapiens miscegenation, Hershkovitz tells Haaretz.
“There is a huge discussion about how the Aurignacian culture came to the Levant, whether it spread by migration from Europe or through cultural contact,” he says. “I think the answer is in these teeth: it was an actual influx of people.”
Given that by 38,000 years ago there were no more Neanderthals in the Levant with whom to have sex, and that we have human remains from Europe with the same hallmarks of interbreeding, we can assume that the ancestors of the Aurignacians in Manot came from that northern continent, Sarig concludes.
Two very different cultures
But wait, we know that early sapiens and Neanderthals did coexist in the Levant during the millennia that preceded the Aurignacian – possibly mingling thousands of years before humans even reached Europe. Couldn’t the people of Manot, and their culture, descend from a local hybrid lineage of the two hominid groups?
It’s possible, but very unlikely, explains Omry Barzilai, an archaeologist with the Israel Antiquities Authority who participated in the study.
The tool culture that preceded the Aurignacian in the Levant is known as the Ahmarian, and remains from it have also been found in Manot, dating to between 46,000 and 42,000 years ago.
But the Ahmarian and Aurignacian are very dissimilar cultures, in terms of the tools they produced and the technologies they used. For example, the Ahmarians used spearpoints made of stone, whereas the Aurignacians preferred to use points made of deer antlers, Barzilai says. This too may be part of the European cultural heritage of the Levantine Aurignacians, since in Europe they would have found and hunted large herds of antlered animals, he says.
Additionally, if the Manot population had been the result of local interbreeding that occurred much earlier, say 50,000 or 60,000 years ago, we would have expected the Neanderthal features to be diluted and disappear in the much larger sapiens genetic pool – just like we see in today’s humans. Instead, the fact that the Neanderthal features are very prominent in the Manot teeth suggests that the injection of Neanderthal DNA into that particular genome had happened fairly recently, which could only occur in Europe, Barzilai concludes.
While the Aurignacian culture in Europe lived on for more than 10,000 years, its Levantine incarnation disappeared much earlier, around 34,000 years ago, for unknown reasons.
Still, the discovery of the Manot teeth reminds us that we should not look at prehistoric human dispersal as a one-way trip that humans undertook from Africa to the Levant and then on to the rest of Eurasia, Hershkovitz notes.
“At Manot we see how humans passed through the Levant to Europe, and then came back here thousands of years later,” he says. “It shows us that, when there are no borders, humans are always on the move, always looking for that next frontier. It is part of human nature.”