6 days ago
A 140,000-Year-Old Skull May Point to a Lost Branch of the Human Tree
Here's what you'll learn when you read this story:
Researchers determined that a skull of a female child from Skhūl Cave in Israel shows both Homo sapiens and Neanderthal features, leading researchers to think she is possibly a hybrid.
If she is a hybrid, that means that neither modern humans nor Neanderthals exclusively invented burial rituals.
It is also possible that the skull belongs to a yet undiscovered hominin lineage.
Among the sun-baked mountains of Israel, in the Mount Carmel range just south of Haifa, lies a cave with an extraordinary and sometimes confusing past. Skhūl Cave is known for fossils and other artifacts marking human evolution over hundreds of thousands of years.
In 1929, archaeologists discovered the 140,000-year-old skeleton of a young girl in Skhūl Cave. The researchers believed her parents belonged to Paleoanthropus palestinensis, a transitional species between Neanderthals and modern humans (Homo sapiens).
The child's bones, estimated to be between 3 and 5 years old when she died and now referred to as the Skhūl Child or Skhūl I, were anatomically identified as a modern human—but that categorization is now in question.
Some of the girl's features resemble Homo sapiens, but others are an echo of Homo neanderthalensis, leaving scientists wondering whether she belonged to either of these species or was a previously unknown type of hominin.
Now, an international team of researchers has taken the most detailed look yet at the features of the child's skull in an effort to distinguish from whom she is descended. The skull's pastiche of Neanderthal and modern human features suggests she was possibly a hybrid—and that the earliest burial rituals were not exclusively invented by either species.
'In the Middle Pleistocene, the Levant was the crossroad of gene flows between Indigenous lineages and other taxa from Africa and Eurasia, which is likely the explanation for Skhūl I anthropological,' they said in a study recently published in l'Anthropologie.
Some parts of the skull that were missing or misplaced only deepened the controversy.
During the original excavation, the mandible separated from the skull in the process. Researchers later reconstructed the mandible in plaster and found that it leaned heavily toward a Neanderthal lineage. It seemed to be plesiomorphic, meaning that it was similar to other mandibles with that clade, or group of organisms that evolved from a common ancestor. Because the mid-face and most of the skull base had been lost to time, the plaster mandible could not be properly articulated. Its identity had been obscured.
To identify the fossils, the researchers used CT scans of the mandible and neurocranium, virtually reconstructing the enamel-dentin junction of her teeth and right bony labyrinth of her skull to give a clearer idea of which hominin they might have belonged to.
Bony cavities make up the bony labyrinth, which is found in the temporal bone of the skull, in the middle and inner ear. The enamel-dentin junction is where enamel and dentin meet in a tooth. The frontal squama, or forehead, needed to be repositioned virtually. What they found was still not easily distinguishable as either Homo sapiens or Neanderthal.
While the bony labyrinth appeared more like our own, scans of the neurocranium revealed that the cranial vault was low for a modern human, and that the occipital bone, which forms the back and base of the skull, was too elongated. The shape of the mandible and lack of a chin made it more Neanderthal. The position of the teeth and the enamel-dental junction were also closer to those of Neanderthals. Any modern features integrated so well with the more ancient features that it only strengthened the case for a hybrid.
But one thing has continued to haunt the researchers: Even though this could be evidence for the interbreeding of modern humans and Neanderthals in the region, other Neanderthal fossils from the Levent are far younger. That's why they considered the possibility of Skhūl I belonging to an older, yet undiscovered species.
The researchers also aren't sure why this was carried out. Burying the dead might have not only been for practical reasons, such as keeping out decay and disease, but also as a claim to territory.
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