We like to think that we're smarter than than the neanderthals that went extinct some 30,000 years ago. As homo sapiens, we have good evidence--the wheel, skyscrapers, rollercoasters--but the fact remains that neanderthal skulls were significantly larger than our modern human skulls, and that meant they had the capacity for brains just as big or bigger than our own. So why didn't they put that roomy brain cavity to better work?
According to Smithsonian Mag, a recent scientific study from Oxford proposes a new explanation for why neanderthals never wrapped their big brains around farming or a written language. The study proposes that neanderthals dedicated far more of their brains to controlling their bodies than we do. Though they were shorter than humans, they were also stockier and stronger, particularly in the upper body. The study also suggests neanderthals had to commit more brain power to vision than we do.
Oxford's researchers took a new approach to studying the skulls of neanderthals and the ancient humans that lived thousands of years ago. Instead of simply comparing volume, they tried to figure out how the size of the neanderthal brain related to its differently proportioned body. Their larger, stronger bodies required more brain control, and the researchers deduced that their larger eye sockets also indicated a larger visual cortex than humans. From the study:
"Neanderthal brains contained significantly larger visual cortices. This is corroborated by recent endocast work, which found that Neanderthal occipital lobes are relatively larger than those of AMHs [anatomically modern humans]. In addition, previous suggestions that large Neanderthal brains were associated with their high lean body mass imply that Neanderthal also invested more neural tissue in somatic areas involved in body maintenance and control compared with those of contemporary AMHs.
Neanderthals simply didn't grow socially the way humans did, which indicates that different parts of their brains developed--those more focused on individual survival.
...our findings tie in with the suggestion that the Neanderthal and AMH lineages underwent separate evolutionary trajectories. Starting from the brain size of their common ancestor Homo heidelbergensis, we suggest that Neanderthals enlarged their visual and somatic regions, whereas AMHs achieved similarly large brains by increasing other brain areas (including, for example, their parietal lobes)."
The most significant difference the study found between humans and neanderthals was how they developed social groups. Neanderthals simply didn't grow socially the way humans did, which indicates that different parts of their brains developed--those more focused on individual survival. And then the big finish--tying this theory for smaller brains into why our human ancestors survived while neanderthals went extinct:
"Whereas AMHs appear to have concentrated neural investment in social adaptations to solve ecological problems, Neanderthals seem to have adopted an alternative strategy that involved enhanced vision coupled with retention of the physical robusticity of H. heidelbergensis, but not superior social cognition. For instance, only in Neanderthals, not AMHs, does body mass, and hence brain volume, increase over time. While the physical response to high latitude conditions adopted by Neanderthals may have been very effective at first, the social response developed by AMHs seems to have eventually won out in the face of the climatic instability that characterized high-latitude Eurasia at this time."
It's interesting to picture neanderthals actually becoming physically stronger and mentally more capable of controlling their bodies and vision as they evolved, but eventually going extinct without humans' evolved social abilities. That may not have actually caused their extinction--there are multiple theories concerning that, including the possibility that neanderthals and ancient humans interbred--but it's perhaps slightly comforting to know that we we're putting our smaller brains to more efficient use.