The skeleton of a child discovered some 90 years ago in the Skhul Cave on Mount Carmel (Israel) has provided the oldest evidence of interbreeding between Homo sapiens and Neanderthals.
The fossil, estimated to be about 140,000 years old, is the oldest human fossil in the world that exhibits morphological characteristics of both human groups.
The study was led by Professor Israel Hershkovitz of Tel Aviv University's Gray Faculty of Medical and Health Sciences and Anne Dambricourt-Malassé of the French National Center for Scientific Research. The findings are published in the journal L'Anthropologie.
"Genetic studies over the last decade have shown that these two groups exchanged genes," Professor Hershkovitz explains in a statement. "Even today, 40,000 years after the disappearance of the last Neanderthals, part of our genome (between 2% and 6%) is of Neanderthal origin. However, these genetic exchanges occurred much later, between 60,000 and 40,000 years ago."
"This is a 140,000-year-old human fossil. In our study, we demonstrate that the child's skull, whose general shape resembles that of Homo sapiens, especially the curvature of the cranial vault, features an intracranial blood supply system, a lower jaw, and an inner ear structure typical of Neanderthals.
For years, Neanderthals were thought to be a group that evolved in Europe and migrated to present-day Israel only about 70,000 years ago, following the advance of European glaciers. In a 2021 study published in Science, Professor Hershkovitz and colleagues showed that the earliest Neanderthals lived in Israel as early as 400,000 years ago.
This human type, which Professor Hershkovitz named "Homo Nesher Ramla" (after the archaeological site near the Nesher Ramla factory where it was found), encountered groups of Homo sapiens who began moving out of Africa around 200,000 years ago and, according to the findings of the current study , interbred with them.
OLDEST FOSSIL EVIDENCE OF SOCIAL AND BIOLOGICAL LINK
The Skhul Cave Boy constitutes the world's oldest fossil evidence of the social and biological ties forged between these two populations over thousands of years. The local Neanderthals eventually disappeared after being absorbed into the Homo sapiens population, as did later European Neanderthals.
The researchers reached these conclusions after performing a series of advanced tests on the fossil. First, they scanned the skull and jaw using micro-computed tomography technology at Tel Aviv University , creating an accurate 3D model from the scans.
This allowed them to perform a complex morphological analysis of the anatomical structures (including hidden structures such as the inner ear) and compare them with various hominid populations. To study the structure of the blood vessels surrounding the brain, they also created an accurate three-dimensional reconstruction of the interior of the skull.
"The fossil we studied constitutes the oldest known physical evidence of mating between Neanderthals and Homo sapiens," says Professor Hershkovitz. "In 1998, the skeleton of a child was discovered in Portugal that displayed traits of both human groups. However, this skeleton, nicknamed the 'Lapedo Valley Child,' dates back 28,000 years, more than 100,000 years after the Skhul Child.
Traditionally, anthropologists have attributed the fossils discovered at Skhul Cave, along with those from Qafzeh Cave near Nazareth, to an early group of Homo sapiens. The current study reveals that at least some of the Skhul Cave fossils are the result of the ongoing genetic infiltration of the local—and older—Neanderthal population into the Homo sapiens population.
