Internal view of the micro-scanner of the AST-RX platform (« Scientific Access to X-Ray Tomography ») of the National Museum of Natural History in Paris, with the Neandertal cranium from La Chapelle-aux-Saints ready to be numerized. Photo by P. Goetgheluck.

California State University, Northridge anthropology professor Hélène Rougier and her research colleague, Antoine Balzeau of the National Museum of Natural History in Paris and France’s Nation Center for Scientific Research, have used a “super scanner” to identify a unique way extremely thin bony structures are organized in Neanderthal skulls, which can help researchers in their efforts to identify the Neanderthal remains.

It is crucial that scientists studying human evolution and identifying prehistoric humans can single out anatomical traits of a particular species skeleton that are unique to the individuals within that given species. This unique trait, or feature, is called a derived trait, and they are difficult to find.

“This research illustrates the importance of applying cutting-edge technology toward fossil studies, as it could allow scientists to identify even the most fragmentary specimens which, in turn, will allow us to better understand our past,” Rougier said.

(A) Posterior view of the occipital bone of the Neandertal child La Ferrassie 8; Study of its inner structures as revealed by high resolution x-ray imaging (50 microns): (B) detail of the structures over the whole occipital and (C, corresponding to the white rectangle in A) thickness distribution of the external layer of the bone in the suprainiac fossa area.

Balzeau and Rougier, using micro-scanner imaging methodologies, have identified a potential derived trait characteristic of Neanderthals as the suprainiac fossa, an oval depression on the occipital bone (the bone that forms the back of the skull). Whether the suprainiac fossa of Neanderthals is homologous to depressions observed in the same area on other human groups is a question that has been widely discussed by anthropologists around the world.

For their study, the results of which are being published in the American Journal of Physical Anthropology, Balzeau and Rougier used the AST-RX platform, which includes one of the top high-performance micro-scanners available in a museum. They characterized the thinnest inner structure of the occipital bones of fossils and especially those of the Neanderthal child La Ferrassie 8, believed to have died at about age 2 and whose remains are kept at the Museum of Man in Paris.

Their study shows that the suprainiac fossa of Neanderthals can be identified even in childhood as a depression with specific external bone features along with a unique thinning of the diploe, the central layer of bone. The researchers said it also appears that the developmental pattern and causes of expression from the depressions observed in modern humans are uniquely different.

This is the first time that such features of the inner bony structure have been analyzed and characterized in Neanderthals. The research confirms that the suprainiac fossa is a derived trait of the species.

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