Don’t sniff at humans’ ability to smell, says US researcher

Rutgers University scientist says people can detect close to one trillion different odours.

A dog handler with a Chinese Crested. Humans and canines have equal ofactory abilities, a researcher at Rutgers University said in a report in the journal Science published on May 11, 2017. Timothy A Clary / AFP / February 13, 2017Show less

Miami // People’s sense of smell is just as sharp as those of rats and dogs, a US researcher said on Thursday, calling for an end to a century-old “myth” to the contrary.

Rutgers University neuroscientist John McGann reviewed research and historical writings he says led to the misconception that human sense of smell is inferior, according to the report in the journal Science.

“For so long people failed to stop and question this claim, even people who study the sense of smell for a living,” he said.

“The fact is the sense of smell is just as good in humans as in other mammals, like rodents and dogs.”

Humans have long been believed capable of detecting about 10,000 different odours. In fact, the number is closer to one trillion, Mr McGann said.

A 19th-century brain surgeon and anthropologist named Paul Broca provided the origin of the myth about humans' poor sense of smell, according to the Science report.

In his 1879 writings, Broca cited the smaller volume of humans’ olfactory area in the brain compared to other, larger parts.

It meant that humans had free will and did not have to rely on smell to survive like dogs and other mammals, he argued.

Broca’s theory even influenced the Austrian neurologist and father of psychoanalysis Sigmund Freud, who believed people’s lack of smell makes them more susceptible to mental illness.

“It has been a long cultural belief that in order to be a reasonable or rational person, you could not be dominated by a sense of smell,” Mr McGann said.

“Smell was linked to earthly animalistic tendencies.”

The human olfactory bulb makes up just 0.01 per cent of the brain’s volume compared to 2 per cent in mice, he said.

But its absolute size in people is actually quite large – in adults it can reach around 6 centimetres and has a similar number of neurons compared to those of other mammals.

The difference between humans, dogs and rodents when it comes to sense of smell may come down to different sensitivities to certain odours.

“We are capable of tracking odour trails, and our behavioral and affective states are influenced by our sense of smell,” Mr McGann wrote.

But although humans may be better at sniffing fine wines, dogs are likely to keep excelling at analysing the various types of urine on offer at the nearest fire hydrant.

* Agence France-Presse