Recent research has shown that Neanderthals, once denigrated as our primitive and loutish cousins, actually had much in common with humans of the present day. They hunted in groups, mastered the technology of making fire and even made art. But when it comes to their skeletal structure, Neanderthals may have been quite different from anatomically modern humans in certain respects—just not in the way scientists previously thought.
Neanderthals are often depicted as hunched, with hulking barrel chests. Two years ago, an international team of researchers created a 3-D virtual reconstruction of the spine of Kebara 2, an adult male specimen found in Israel in 1983, which is among the most complete Neanderthal skeletons known to scientists. The study showed not only that Neanderthals had an upright posture, but also that their spines were straighter than those of modern humans.
Now, as Frankie Schembri reports for Science, the researchers are back with a 3-D reconstruction of Kebara 2’s chest, or thorax, which comprises the ribs, upper spine and vital organs like the lungs and the heart. The results of the team’s study, published in Nature Communications, suggest that Neanderthals’ chests actually were about the same size as ours, but had important differences that allowed for greater lung capacity.
For anthropologists, understanding the structure of the thorax is key, because it offers insight into how ancient specimens moved and breathed. But the delicate bones of the ribs and spine often do not survive to the present day, or are otherwise too fragile to handle. Rather than attempt a risky physical reconstruction of Kebara 2, researchers painstakingly conducted computed tomography (CT scans) of each of his vertebra and rib fragments, and then reassembled the data into a 3-D model. They also compared the reconstruction to medical scans of 16 modern men in Israel, according to PBS.
The team’s model showed that Kebara 2’s ribs connected to the spine in an inward direction, which pushed the chest cavity outward and caused a slight backward tilt of the spine. The reconstruction also reaffirmed that Neanderthal spines were straight; in fact, Kebara 2 appears to have had very little in the way of a lumbar curve, unlike modern humans.
Kebara 2’s rib cage was wider at the bottom than ours, but not significantly bigger in volume—“one of the big surprises of the study,” Asier Gómez-Olivencia, study author and fellow at the University of the Basque Country in Spain, tells Colin Barras of New Scientist. Neanderthals were stockier than modern humans, and “[h]eavier bodies require a higher caloric intake and a higher oxygen consumption,” Gómez-Olivencia says. Scientists had assumed that Neanderthals therefore had relatively large chests to accommodate relatively large lungs. But this appears not to have been the case.
Instead, the wide lower thorax of Kebara 2 suggests that Neanderthals’ breathing relied heavily on the contraction of the diaphragm, which sits in the lower rib cage. “Modern humans, on the other hand, rely both on the diaphragm and on the expansion of the rib cage for breathing,” explains study author Ella Been of Ono Academic College in Israel. The shape of Kebara 2’s rib cage suggests that its diaphragm was large in comparison to those of modern humans, which would have allowed for greater lung capacity.
The study raises interesting questions about how Neanderthals’ unique breathing mechanism helped them survive in their environment. Further research is needed, but for now, the paper shows how modern technologies can be used to paint a more accurate picture of an extinct and often misunderstood species.