Contrary to a long-held misconception, the human sense of smell is not inferior but may be just as good as that of mammals like dogs and rodents — some of the best sniffers in the animal kingdom, say researchers.
The human sense of smell was thought to be inferior because of the size of the olfactory bulb — nerve tissue which sends signals to other areas of a very powerful human brain to help identify scents.
However, the study published in the journal Science, showed that the human olfactory bulb is quite large and similar in the number of neurons to other mammals.
"For so long people failed to stop and question this claim… The fact is the sense of smell is just as good in humans as in other mammals, like rodents and dogs," said John McGann, associate professor at Rutgers University-New Brunswick in the US.
The idea that humans do not have the same sense of smell abilities as animals flourished over the years based on some genetic studies which discovered that rats and mice have genes for about 1,000 different kinds of receptors that are activated by odours, compared to humans, who only have about 400.
But the study showed that humans can discriminate maybe one trillion different odours which is far more than the claim by "folk wisdom and poorly sourced introductory psychology textbooks", that insist humans could only detect about 10,000 different odours.
"We can detect and discriminate an extraordinary range of odours; we are more sensitive than rodents and dogs for some odours; we are capable of tracking odour trails; and our behavioural and affective states are influenced by our sense of smell," McGann added,