8 jul 2012
What a nose
Neanderthals had bigger noses than we do, but tracking a scent was never one of their specialties (maybe for the best).
New three-dimensional medical imaging scans of fossil human skulls reveal that the so-called olfactory bulbs, the part of the brain that processes odors, are 12% larger in Homo sapiens than they were in Neanderthals.
Markus Bastir and Antonio Rosas of the Spanish Natural Science Museum and their colleagues carefully assessed the shape of the base of cranium to quantify the volume of gray matter that would have filled in above.
Their research, reported in Nature Communications, divulged another size difference: the temporal lobes, the part of the brain involved in language, memory and social functions, are also larger in Homo sapiens.
That latter finding may not come as a surprise, considering how modern humans have evolved linguistically and socially. But the researchers say that the fact that both the temporal lobes and olfactory bulbs are larger in modern humans suggests that our species evolved a combined use of brain functions related to cognition and olfaction that may not have been true for Neanderthals.
Evidence has been accumulating that Neanderthals and modern humans developed their large brains independently, and so the expectation, then, is that their brains might have worked differently.
For us modern humans, the tight relationship between sniffing ability and higher brain functions makes even more sense when you consider that olfaction is the only sense that establishes a direct connection between the brain and its environment. While information from our eyes and ears must pass through different filters in the brain, smell signals go straight into the highest centers of the brain—those directly responsible for processing emotion, motivation, fear, memory, pleasure, and attraction.
So, it seems our superior sense of smell may have evolved in tandem with many of our higher cognitive abilities. As Rosas pointed out in a press release, the neuronal circuitry of olfaction coincides with that of memory and emotion, “which explains the enormous memory retention and vital intensity of olfaction-mediated life events.”
