Neanderthals Brain Scans Challenge Old Assumptions About Why They Vanished
Neanderthals are back in the spotlight after new research found that brain differences between them and modern humans were very small. The findings, drawn from MRI comparisons and published studies, raise fresh questions about the long-held idea that brain power alone explains why Neanderthals disappeared. Researchers say the picture is more complicated, with other work pointing to climate, geography, population dynamics, and intergroup connections in Europe between 60, 000 and 35, 000 years ago.
Neanderthals and modern brains may have been closer than assumed
Researchers comparing two large MRI datasets of living people found that variation within modern human groups could exceed the differences previously identified between Neanderthals and early modern humans. The study examined 100 ethnic Han Chinese brains and 100 brains from Americans of European ancestry, and in nearly 70% of the regions assessed, the volume differences between those living populations were larger than the differences seen in Neanderthals and early modern humans.
That result challenges a familiar explanation for the disappearance of Neanderthals around 40, 000 years ago. The idea that early modern humans had a decisive brain advantage has long shaped public thinking, but the new findings suggest that anatomical differences alone do not neatly map onto cognitive superiority. The researchers said those differences were not placed in the context of the substantial variation already present within modern human brain anatomy.
Neanderthals brain scans and the problem with old assumptions
Tom Schoenemann, an anthropologist at Indiana University Bloomington, and colleagues wrote that skull shape differences have long been used to argue that Neanderthals differed cognitively from modern humans. Those assumptions included claims about speech, planning, and short-term memory, but the new comparison of brain variation weakens that argument.
The researchers also reviewed existing literature and said cognitive ability is only very weakly associated with brain anatomy in modern humans, if at all. In their view, if differences between modern human populations are not treated as evolutionarily meaningful cognitive gaps, then Neanderthal differences should not automatically be treated that way either.
A wider explanation for extinction is taking shape
A separate study led by Ariane Burke, a professor of anthropology at Université de Montréal and head of the Hominin Dispersals Research Group in Quebec, points to a broader mix of forces. Her team used methods inspired by digital ecology to model ancient human populations in Europe during the last glacial cycle, between 60, 000 and 35, 000 years ago, when Homo sapiens first appeared in the archaeological record there and Neanderthals disappeared.
Burke said the team used archaeological sites as presence points and combined them with environmental data to build habitat models. The results suggest that climate stress or direct competition alone cannot fully explain Neanderthal extinction. Instead, the outcome appears to have depended on climate, geography, population dynamics, and interactions between species, with conditions differing by region.
Burke said that areas suitable for Homo sapiens tended to be more interconnected than those used by Neanderthals, and that such connectivity mattered because networks can help groups move, share information, and access support during crises. She added that Neanderthals were not completely isolated.
What the new research means now
The emerging picture is not that Neanderthals lacked brains, but that their extinction cannot be pinned on a simple story about intelligence. The brain scan work suggests Neanderthals may have been much closer to modern humans than old assumptions allowed, while the modeling study points to a more complex environment in which networks and regional conditions shaped survival. For now, Neanderthals remain central to one of science’s most closely watched debates, and the new findings make that debate harder to reduce to a single cause.
As researchers continue testing these ideas, the next step will be to see how far the brain evidence and the ecological models can be brought together. What is clear is that Neanderthals are no longer being framed as a people simply outmatched by brain size alone.
