May the history of human origins have a missing chapter? A 140,000-year-old skull of a child from Israel, hitherto relegated to a taxonomic conundrum, has been reconstructed virtually with an accuracy so high that it is challenging scientists to reconsider how and when Homo sapiens and Neanderthals first encountered and bred.
The fossil, unearthed in 1931 from Skhul Cave on Mount Carmel, was originally entombed in plaster, its delicate features obscured by the limitations of early 20th-century archaeology. For decades, its classification wavered between an unknown local species and early Homo sapiens. But thanks to new developments in micro–computed tomography (micro-CT) and high-resolution 3D mapping, Tel Aviv University and French National Centre for Scientific Research scientists have been able to look inside the bone to see a shocking mix of characteristics: a curvature of the cranial vault typical of Homo sapiens, combined with a Neanderthal-type inner ear morphology, mandibular shape, and patterns of intracranial blood vessels.
The scanning process comprised thousands of separate scans of the jaw and skull, stitched digitally into a virtual model. This enabled researchers to scan for features not visible to the human eye, including the vascular imprints on the endocranial surface. The blood vessels appeared like tributaries of a river, lead author Prof. Israel Hershkovitz said. These blood supply routes varied between species because their brain forms and hence their blood supply needs were different. The child’s mixture of motifs indicated mixed descent.
Up to now, the earliest known interbreeding of Homo sapiens and Neanderthals was dated at about 40,000 years ago in Europe. This new study indicates such contact in the Levant about 100,000 years earlier. The implications reach beyond biology. Skhul Cave is among the globe’s most ancient known burial grounds, its burials dating back to the Middle Paleolithic. The fact that there is a hybrid child here indicates that the two groups’ cultural practices formal burials, ochre pigment use, advanced stone tools were perhaps shared or, at least, mutually affected.
The geography of the Levant made it a natural meeting ground. Middle Paleolithic climatic changes increased its carrying capacity, spurring population increase and increasing contact between populations moving from Africa and Europe. As evidence from adjacent sites like the Tinshemet Cave, both the Homo sapiens and Neanderthals utilized the centripetal Levallois method of stone tool production, hunted similar large fauna, and used red ochre as part of symbolic or ritual practice. In a few of the burials, chunks of ochre from up to 100 kilometers away were deposited with the deceased, suggesting long-distance procurement of materials and common symbolic encoding.
The 3D reconstruction of the Skhul child skull also resolved previous distortions in the plaster model and showed a more elongated cranial form another Neanderthal characteristic. This mosaic of anatomy reflects genetic evidence that 2–6 percent of the non-African portion of the modern human genome comes from Neanderthals, although such DNA transfers were hitherto presumed to be much more recent. In the absence of recoverable ancient DNA from the Skhul remains, the hybrid hypothesis is based on morphology, but the anatomical signal is surprisingly robust. “The fossil that we analyzed is the earliest physical record of mating between Neanderthals and Homo sapiens,” Hershkovitz said.
Technological advance making this possible equals other advances in paleoanthropology. Virtual anthropology methods, previously only available to perfect fossils, are now used on fragmentary or deformed specimens, enabling scientists to digitally reconstruct, reflect, and retrodeform them with statistical precision. This not only improves morphological analysis but also makes decades-old collections available for new scrutiny. As Prof. Thomas Levy of the University of California San Diego explained, “The advances in scientific visualization allow more accurate measurements and comparisons of specimens.”
This work also highlights the sophistication of human–Neanderthal interactions. In contrast to the previously long-held story of violent takeover, the Skhul record attests to an era of peaceful coexistence, with biological and cultural interactions influencing each lineages. Hershkovitz dispels the imagery of our species as being aggressive: “What Skhul is telling us is that Homo sapiens are not a vicious, aggressive creature, but one that managed to live in peace with other groups.”
The discovery compels archaeologists to re-think the assignment of early symbolic behaviors. Were a hybrid child to have been interred in one of the earliest established cemeteries, the urge for ritualized dead treatment might have come not from a single line, but from their interactions. In this context, the Levant is less a species boundary and increasingly a crucible where human diversity biological and cultural was created.
