One scientific analysis is arguing that the human sense of smell has not only been underestimated over the years, but that it may rival that of dogs and rodents. John McGann, a neuroscientist at Rutgers University in New Jersey and the paper’s author, said: “For so long people failed to stop and question this claim, even people who study the sense of smell for a living. The fact is the sense of smell is just as good in humans as in other mammals, like rodents and dogs.” McGann has reached this unexpected conclusion after spending 14 years studying the olfactory system. The Guardian reports: McGann identifies a 19th century brain surgeon, Paul Broca, as the primary culprit for introducing the notion of inferior human olfaction into the scientific literature. Broca noted that the olfactory bulb — the brain region that processes odor detection — is smaller, relative to total brain volume, in people compared with dogs or rats. The discovery inspired Freud’s belief that human sexual repression may be linked to our “usually atrophied” sense of smell. In the latest paper, published in Science, McGann points out that in absolute terms the human olfactory bulb is bigger than in many mammals and a literature search revealed that the absolute number olfactory neurons is remarkably consistent across mammals. McGann goes on to deconstruct other metrics that have been used to support the idea that human smelling abilities are limited. Humans have approximately 1,000 odor receptor genes, for instance, compared to 1,100 in mice, which some had taken as confirmation of mouse superiority. However, other work suggests there is not a tight relationship between the number of olfactory genes and smelling ability. One study found that cows have 2,000 such genes – far more than dogs.
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