Neanderthals flourished across Eurasia for more than 300,000 years before the arrival of anatomically modern humans, only to vanish after just a few thousand years of coexistence. Scientists have long proposed that modern Homo sapiens outcompeted their robust cousins through sheer intelligence. Using Neanderthal cranium shapes to estimate specific brain regions’ volume, some investigators claimed to see signs of a mind with feeble linguistic abilities, poor executive function and an unremarkable memory.
But a new study argues that Neanderthal cognition may have rivaled our own. “I don’t think we would detect a difference if they were around today,” says Tom Schoenemann, an anthropologist at Indiana University Bloomington and lead author of the study, which was published in the Proceedings of the National Academy of Sciences USA. “I think they would fit comfortably within the range of cognitive functioning that we see among modern humans.”
The study relied on a technique called deformation mapping: to create digital reconstructions of the inner surface of the skull to infer the volume of different brain regions. This approach is “possibly the best we’ll get,” Schoenemann says, barring the discovery of a preserved Neanderthal brain. Deformation mapping is far from a perfect way to deduce internal brain anatomy, he says, but as provisional results, the new findings indicate, at most, a modest intelligence gap between modern humans and Neanderthals.
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To make the comparison, the researchers estimated the average volumes of more than a dozen brain regions in modern people of Han Chinese and European descent, as well as in Neanderthals. For several of those regions, they found greater variation between the two modern populations than between Neanderthals and today’s humans—our much-maligned ancient cousins would have largely fit right in based on neuroanatomy.
On top of that, larger brain region volume doesn’t necessarily mean higher cognitive ability. There’s only a faint link between the two, reinforcing the idea that Neanderthals likely spanned an intelligence spectrum that was comparable to that of their human neighbors.
This study builds upon deformation mapping research from 2018 that suggested that, on average, Neanderthals had a smaller cerebellum than early humans did. Given the cerebellum’s importance to language processing, memory and other cognitive functions, the 2018 study’s authors reasoned that this neuroanatomical difference might have given modern humans the upper hand. Yet if we consider that difference evolutionarily significant, Schoenemann says, we must view similar differences between today’s human groups in the same light—a conclusion that, he notes, is not supported by the vast majority of recent research. He suspects that, rather than being outsmarted, Neanderthals simply merged with modern H. sapiens through interbreeding and that their genes were subsumed into the vastly larger population.
University of Tokyo biomechanics researcher Naomichi Ogihara, a co-author of the 2018 study, agrees that this process of “genetic swamping” played a role in Neanderthals’ disappearance. But he argues that a complete explanation must also include an intelligence gap, minuscule though it may be. “Even a small average difference in cognitive or behavioral tendencies could have evolutionary significance over many generations,” Ogihara says.