If you look at a Neanderthal skull and a Homo sapiens skull, they’re visibly different: Neanderthal skulls are lower and longer, whereas ours tend to be rounder. However, according to a new study by Indiana University cognitive scientist P. Thomas Schoenemann and colleagues, those skull differences probably don’t say much about the brains within them.

Research Methodology: 400-Person Brain MRI Comparison

The research team compared MRI scans of 400 modern people’s brains with casts of the inside of Neanderthal skulls (endocasts). The sample included 200 US residents of European descent and 200 ethnic Han Chinese people, all volunteers from the Human Connectome Project.

The results showed that for 9 of the 13 brain regions measured, the differences in volume between some modern people were larger than the differences found between Neanderthals and Pleistocene Homo sapiens. “Our analysis shows that Neanderthal differences in brain and cognition would fit comfortably within the range of differences seen among modern humans,” Schoenemann and colleagues wrote in their paper.

Brain Volume ≠ Intelligence

Decades of research have found that brain volume — whether looking at the whole brain or the size of a particular region — has little to no connection to how well a person performs on cognitive tests. As the research team put it, “cognitive implications of neuroanatomical size differences are very weak in modern humans, when found at all.”

In other words, when it comes to intelligence, brain size doesn’t determine everything. Neanderthal brain volume differences fall entirely within the normal variation range of modern humans, meaning their cognitive abilities were likely on par with ours.

Challenging Conventional Wisdom

Conventional wisdom credits human evolutionary success to our intelligence and “big brains,” but this study challenges that assumption. The archaeological record already tells us that Neanderthals were capable of making complex tools, using fire, caring for the sick, and possibly even some form of artistic expression — behaviors that indicate high cognitive capacity.

If Neanderthals were no less intelligent than Homo sapiens, then why did our species ultimately replace them? This question becomes even more complex. The answer may lie in social structure, language capabilities, or other factors not yet fully understood, rather than simple intellectual differences.

Rethinking Species Boundaries

This study also lends support to paleoanthropologists who argue that perhaps we shouldn’t think of Neanderthals and Denisovans as entirely separate species at all. Modern human internal diversity is already substantial, and Neanderthal characteristics can comfortably fit within this spectrum of variation.

Sources: Ars Technica | ScienceAlert