What We Know About Neanderthal Brain Size
The Neanderthals were smart. But, what, specifically, differentiated their brains from those of our own ancestors?
Sam Walters
Specialists say that the brains of Homo neanderthalensis and Homo sapiens were similar. But slight differences in the structure and development of the two species' brains could've changed the ways they thought about the world. (Credit: life_in_a_pixel/Shutterstock)
Tradition says that Homo neanderthalensis and Homo sapiens were intellectually distinct. But archaeologists and anthropologists increasingly insist that the intellectual divide between the two species is shrinking.
In fact, the traces of their ancient activities show more and more that the two species followed similar survival strategies. Residing in similar societies, they made similar sounds and manipulated similar tools. Apart from that, the most recent research shows that the two created similar art, too, signifying their shared taste for abstraction.
But what about their brains? Was there anything in their anatomy that differentiated their thinking?
Some specialists say yes. Working in the fields of paleontology, paleoneurology and paleogenetics, experts suspect that the slightest distinctions in the structure and development of the two species’ brains could’ve set their cognition apart in complex and consequential ways.
The Brutish Beginning of the Neanderthal
When academics found the first Neanderthal fossils around two centuries ago, they weren’t sure what they were working with. While some supposed that they stumbled across their own ancient ancestors, others thought that the specimens signified something else entirely.
At the time, there was only one conclusion for which they felt confident: Whatever the fossils’ formal classification, the creature that they found was far from intelligent, they thought, when it wandered the world thousands of years ago.
Neanderthal Thinking
“Darkness characterized the being to which the fossil belonged,” asserts an analysis of one set of specimens from the 1860s. “The thoughts and desires which once dwelt within it never soared beyond those of a brute.”
Articulated around the same time that the Neanderthals secured their status as a separate species, this now out-of-favor sentiment stemmed from the fact that the Neanderthals displayed a “singularly different” skull structure from that of our own species.
Because of this difference, the Neanderthals were swiftly branded as a species of brutes, who were trapped in ignorant “benightedness” until our own intellectually superior species beat them around 40,000 years ago.
Neanderthal Intelligence
In the years since then, archaeologists and anthropologists have found an abundance of hints that the Neanderthals acted with a similar sophistication to our own species. In addition to their similar survival strategies and tools, recent research also suggests that the Neanderthals communicated and created cultures of art and adornment comparable to those of our ancestors.
The complexity of these activities suggest that the Neanderthals’ minds mirrored our own. But what, specifically, do we know about the structure and development of their brains?
Did Neanderthals Have Bigger Brains?
Specialists are still searching for their first bits of brain from the Neanderthals, since these tissues tend to be the first part of the body to decompose after death. That said, they’ve found an abundance of preserved skulls from the species, which feature the casts or inner surfaces of the brains they once contained.
Neanderthal Brain Size
Overall, these skulls indicate that the brains of H. neanderthalensis and H. sapiens were similarly sized, with H. neanderthalensis brains beating H. sapiens brains only slightly in terms of their total volume.
Neanderthal Cranial Capacity
Though the measurements aren’t always consistent and change over time, specialists say that the typical Neanderthal skull contained around 1500 cubic centimeters (or 51 ounces) of cerebral tissue, though the skulls of their more modern counterparts showed a smaller cranial capacity of only 1350 cubic centimeters (or 46 ounces).
A Stretched Brain
In addition to their size, Neanderthal brains and braincases were also slightly stretched, producing a strange, semi-spherical skull that terminated in a big bump toward the back. Termed the “occipital bun,” this bump was one of the first features of Neanderthal anatomy that experts discovered and described.
The Structure of the Neanderthal Brain
Paleontologists and paleoneurologists suspect that the strange traits of Neanderthals impacted the size, shape and arrangement of the separate structures inside their brain, too, transforming their particular patterns of thinking.
Some studies suppose, for instance, that the structure of the Neanderthal skull meant that the H. neanderthalensis cerebellum was smaller than the H. sapiens cerebellum. A small cerebellum, these studies say, can cut a species’ capacity to learn and think logically, to process language, and to interact socially, which would all substantially impact its survival.
Adding to this is an assortment of similar proposals about the peculiarities inside the Neanderthal mind. For instance, some paleontologists and paleoneurologists say that much more of the species’ brain was concentrated on controlling basic body movements, all thanks to the species’ bigger, bulkier bodies, which were more difficult to move than our own.
The Development of the Neanderthal Brain
Beyond its simple structure, specialists are also learning a lot about the development of the Neanderthal brain from birth to adulthood.
For instance, the shape and size of juvenile, adolescent and adult skulls suggest that H. neanderthalensis minds matured much more slowly than our own minds mature. They were below 90 percent of their average adult volume at 8 years old. And though that may not seem sluggish, specialists say that that’s basically the same age that H. sapiens brains become full-fledged today, in terms of their overall volume.
Building Neanderthal Brains
Genetic analyses add additional support to the idea that the development of the Neanderthal brain differed from our own. In fact, though specialists traditionally stick to skulls in their attempts to study Neanderthal smarts, the recent reconstruction of the Neanderthal genome is inspiring some to turn to the ancient genes that guide brain growth, instead, as a way to differentiate between H. neanderthalensis and H. sapiens thinking.
NOVA1
In 2021, for instance, a team of geneticists investigated a gene called NOVA1, which directs the development of brain tissues in H. neanderthalensis and H. sapiens. Inserting two distinct forms of the gene into clusters of uncultured cells, the team discovered that the form of NOVA1 found in H. neanderthalensis created bumpier blobs of brain tissue when cultured, while the form of NOVA1 found in H. sapiens created smooth, spherical clumps.
TKTL1
The following year, in 2022, a second team of geneticists followed a similar approach with a gene called TKTL1, which prompts neuron production. While the H. neanderthalensis form of TKTL1 fostered some neurons, the H. sapiens form fostered many more.
Though these findings do demonstrate that the brains of H. neanderthalensis and H. sapiens developed differently, they don’t disclose all the details of this difference. Individual genes are only tiny threads in a greater genetic tapestry, specialists say, suggesting that a true appreciation of the influence of NOVA1 and TKTL1 on something as complex as cognition can only come in the context of a more complete genome.
Though it will take time, specialists say that future work within this field will untangle the influence of an assortment of other genes on the growth of the Neanderthal brain. Combined with the insights taken from the structure of skulls, this work will ultimately create a clearer picture of the differences between our own cognition and that of our closest cousins.