Human sense of smell is not to be sniffed at
Study suggests that human olfactory abilities are not to be sniffed at compared with those found in dogs
If someone told you that humans can smell as well as dogs, you would probably tell them they were barking. But new research suggests that the reputation dogs enjoy as superior sniffers is a “big myth”. Scientists in the US have concluded that mankind is just as good at smelling things as our canine counterparts, and in some instances better. Analysis found humans can discriminate between some one trillion different smells, not 10,000 as previously believed.
WHETHER it’s sniffing out bones, bombs or even cancer, dogs have long been believed to possess a far more powerful sense of smell than humans.
But new research reveals this is simply a “big myth”. Scientists in the US have concluded that mankind is just as good at smelling things as our canine counterparts, and that for some odours, notably banana flavours, we are even better.
An analysis of years of experimental data found humans can discriminate between some one trillion different smells, far more than the 10,000 previously believed. Researchers say the human olfactory system, which regulates the sense of smell, is considerably larger than previously thought and contains a similar number of neurons to dogs and other mammals.
The culprit for the 150-year-old misconception that humans have an impoverished olfactory system has been named as the 19th-century brain surgeon and anthropologist Paul Broca.
The Frenchman insisted that a powerful sense of smell was an inherently animalistic trait and that, as rational beings, the capacity must be far less potent in humans.
“For so long people failed to stop and question this claim, even people who study sense of smell for a living,” said Prof John Mcgann, who led the new research at Rutgers University in New Jersey.
“The fact is the sense of smell is just as good in humans as in other mammals, like rodents and dogs.”
Odours are detected when olfactory receptor neurones in the nose come into physical contact with the molecules comprising a particular smell. Information is then sent back to the olfactory bulb in the brain.
For years scientists believed the small size of the olfactory bulb relative to the overall size of the brain compared with other species meant humans had inferior powers of smell.
But the new paper, published in the journal Science, found that human sense of smell is “excellent”, only in different ways to animals.
While dogs may excel at discriminating between the many types of urine on a given fire hydrant, the researchers write, humans can determine the geographical provenance of wine varieties on the basis of smell alone.
In the case of bananas, humans are more sensitive than both dogs and rabbits because of a superior sensitivity to
‘Some research suggests that losing the sense of smell may be the start of memory problems and Alzheimer’s’
amyl acetate, one of the principal ingredients of the fruit’s smell. In an additional blow to Broca’s theory, the latest data also shows human behaviour is strongly influenced by smell.
“Environmental odours can prime specific memories and emotions, influence autonomic nervous system activation, shape perceptions of stress and affect, and prompt approach and avoidance behaviour,” the researchers wrote.
Sense of smell deteriorates as part of the ageing process, but Prof Mcgann said doctors should be less sanguine than they currently are when patients begin to lose the facility as it can presage serious illnesses.
“Some research suggests that losing the sense of smell may be the start of memory problems and disease like Alzheimer’s and Parkinson’s,” he said.