Though humans often consider ourselves far more evolved and refined than Neanderthals, new research has shown we have a lot common with our stocky, hairy cousins in terms of behavior and development. Now, scientists say Neanderthals’ thoraxes—the cozy cavities enclosed by the ribs, breastbone, and spine—might actually have been the same size as ours, not larger, as was previously assumed.
The size and shape of the thorax—which contains the lungs, heart, and other precious organs—holds important clues about human evolution, including posture, gait, and lung capacity. But it has been tough for researchers to analyze Neanderthal torsos because ribs and spines are fragile, and therefore scarce in the fossil record.
So, a team of researchers took the skeleton with the most complete thorax, called Kebara 2, and sent it through a computerized tomography (CT) scan. Next, the researchers used visualization software to create a 3D virtual model of the torso, which they then compared with CT scans of 16 modern men around the same height as the fossil.
Compared with the modern thoraxes, Kebara 2’s rib cage was wider toward the bottom but not significantly larger in volume, the team reports today in Nature Communications. The Neanderthal’s ribs also protruded from the spine more horizontally than the downward slope of modern ribs. But because his spinal column was situated deeper in the chest cavity, it would have canceled out any extra breathing volume from the wider arc of the lower ribs.
The researchers suspect the difference in thorax shape means Neanderthals may have had a slightly different breathing mechanism than modern humans. They might have had longer diaphragms and a better ability to flare out their lower ribs, allowing them to make more space for air as they inhaled. But short of finding new soft tissue evidence, or taking a trip 40,000 years back in time, it’s difficult to say whether a wider thorax helped Neanderthals breathe any easier.