It’s a well accepted fact that certain animals, like dogs and rodents, have an excellent sense of smell. Humans, not so much. But according to one neuroscientist, our sense of smell is much much better than we think. We may all smell like dogs, or even rats…
Humans v. Mammals
In a paper accepted by Science, neuroscientist John McGann disputes the belief that humans can’t compete with other mammals. It’s a myth with very little science to back it up.
McGann is not exactly a lightweight when it comes to making sense of our sense of smell. He is an associate professor in the Department of Psychology, School of Arts and Sciences of Rutgers University-New Brunswick. He has spent fourteen years studying the human olfactory system. And he has spent much of the last year reviewing the research that supports the belief of human nasal inferiority. Research that he has found wanting.
“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.” – John McGann
Humans can detect around one trillion odours according to McGann. That is a bit more than the paltry 10,000 claimed in “poorly sourced introductory psychology textbooks.”
A 150 Year Old Myth
But why have we sold ourselves short?
Blame a 19th century brain surgeon and anthropologist called Paul Broca. He was the first scientist to claim that humans had a poorly developed olfactory system. There may have been a certain snobbery around the assertion. Because humans have a smaller volume of the brain devoted to smelling, it came to be accepted that the sense of smell was more animalistic than our other senses. Broca believed that by abandoning the need to rely on smell to survive, we were able to develop free-will and rise above our fellow mammals.
The olfactory bulb is a part of the brain that can detect and discriminate between different odours. It then passes signals to different parts of the brain where these odours are identified. Other mammals have a larger olfactory bulbs by volume. In addition, rats and mice have genes for about 1000 different kinds of receptors that are activated by odors. Humans by contrast have about 400.
But there is no evidence that a larger olfactory bulb correlates with a better sense of smell. And McGann believes that we have just as good a sense of smell as dogs and rodents. Although it may be different.
But, What About Bloodhounds?
While humans may have a nose as sensitive as other mammals, it doesn’t mean that we’re identifying odours in the same way. As McGann puts it, “dogs may be better than humans at discriminating the urines on a fire hydrant and humans may be better than dogs at discriminating the odors of fine wine, but few such comparisons have actual experimental support.”
So, stick to sniffing wine and don’t try to discern what is so interesting about dog’s butts.
There is a serious side to this myth, however. We’re discovering that smell has a much bigger role in our lives than previously thought. Smell can trigger Post Traumatic Stress Disorder episodes. It helps us select what we eat and who we find attractive. It guides our social interactions with others. And it greatly influences our thoughts, behaviour and even our memories.
It can also warn us about cognitive decline.
“Some research suggests that losing the sense of smell may be the start of memory problems and diseases like Alzheimer’s and Parkinson’s. One hope is that the medical world will begin to understand the importance of smell and that losing it is a big deal.” – John McGann
So go celebrate your nose’s elevated status and smell something sweet. It probably smells just as sweet to a rat…