Neanderthal Brain Size Matches Modern Humans, New Study Reveals

If you compare a Neanderthal skull to a Homo sapiens skull, the differences are striking: Neanderthal skulls are lower and longer, while modern human skulls tend to be rounder. However, these external differences may not reflect the brains inside, according to a recent study that analyzed MRI scans of living humans alongside casts of Neanderthal skull interiors.

The findings indicate that brain size variation is greater among modern humans than between Neanderthals and Pleistocene-era Homo sapiens. Since brain size is a poor predictor of cognitive ability, Neanderthals may have been far more similar to us than earlier research suggested—a conclusion supported by archaeological evidence of their complex lifestyles. This also implies that Homo sapiens did not outcompete Neanderthals due to superior intelligence or adaptability.

Neanderthal Brains Fall Within the Modern Human Range

After death, the inner vault of the skull preserves the shape of the brain. Future archaeologists could create a resin model of a person’s brain contours by casting the empty skull cavity, a process known as an endocast. Natural endocasts have even formed over millions of years, such as the 2.8-million-year-old sediment-filled skull of an Australopithecus africanus child, which produced a half-rock, half-crystal brain replica.

For decades, researchers have studied Neanderthal endocasts to determine how their brains compared to ours. The debate has persisted: Were Neanderthals cognitively inferior, or did they possess abilities comparable to modern humans?

Key Findings from the Study

• Greater variation in modern human brain sizes than between Neanderthals and early Homo sapiens.
• Brain size is not a reliable indicator of intelligence, challenging long-held assumptions about Neanderthal cognitive limitations.
• Archaeological evidence supports Neanderthal complexity, including tool use, symbolic behavior, and social structures.
• Homo sapiens did not dominate Neanderthals through superior cognition, suggesting other factors—such as environmental changes or demographic shifts—played a role in their decline.

The study underscores that Neanderthal brains were not fundamentally different from ours, reinforcing the idea that they were a highly advanced human species with capabilities akin to our own.