A neuroscientist says that the idea that men have a poor sense of smell was born in the 19th century and has been perpetuated against current science.

Some are not afraid of allergies.

When someone excels at some kind of special intuition, be it for business, headhunting, solving crimes, or scoring goals, we say it has a nose. It is a metaphorical way of expressing that we do not understand how he does it, resorting to the most mysterious and unknown of our bodily senses, the one in which humans are completely clumsy among mammals.

Or so we believed; so much we do not know our sense of smell that perhaps until now we have been completely wrong: “The idea that human smell is poor compared to other mammals is a 19th century myth“Says neuroscientist John McGann, from Rutgers University in New Jersey (USA).

McGann has reviewed and cleaned up the compendium of what we have learned about smell during the era of modern science. And at the beginning of all this is the origin of the myth. “The idea that humans have a particularly poor sense of smell dates back to the 19th century, when the famous neuroanatomist Paul Broca classified humans as non-olfactory, based on our comparatively small olfactory bulb ”, McGann tells EL ESPAÑOL.

The olfactory bulb is a structure in the front of the brain that serves as a logistical control center for smell: it receives the sensations of smell from the nose, processes them and sends them to other regions of the brain, which will decide if that expired food that we have discovered buried at the bottom of the refrigerator can still be eaten or if we should discard it.

According to McGann, Broca observed that throughout our evolution we humans have enlarged the prefrontal cortex of our brain, where the intellect resides, but we have forgotten to do the same with the olfactory bulb. As a consequence, other mammals have this comparatively much larger structure in relation to the size of their brain. Thus, Broca concluded that “to have free will, humans had to do without from odor impulses, ”says McGann.

A second row sense?

Broca’s hypothesis, McGann continues, was so influential that even induced Sigmund Freud to attribute our propensity to mental illness to this olfactory deficiency. Later another anatomist classified humans as microsmatic, or with poor smell, and this idea has lasted until today. And as a consequence, for much of the 20th century many scientists put the study of smell aside as a second-rate sense in humans, focusing instead on sight or hearing. McGann mentions a 1924 treatise on neurology who spoke of the human olfactory organ as “very reduced, almost residual”, while that of other mammals conferred “powers far beyond our comprehension”.

The result of all this is that “the scientific community and the general public still seem to believe in this myth, which remains in textbooks and popular culture.” Yet, McGann argues, collect the anatomical studies, the sensory experiments, and the genetic analyzes, study them all together, and the bottom line. it’s very different. In his review, published in the journal Science, McGann recalls that even since the nineteenth century there were scientists like Hendrik Zwaardemaker, inventor of the olfactometer in 1888, who have defended the importance of human smell as a sense capable of awakening intense emotions.

The sense of smell can also be used to do evil.

The sense of smell can also be used to do evil.
Barney MossFlickr

The truth is our olfactory bulb is large in absolute terms. And while rodents like mice and rats possess about 1,000 odor receptor genes, compared to 400 in humans, the idea that we can only differentiate a few thousand odors is completely wrong, McGann says. The neuroscientist cites a 2014 study that estimated a trillion different smells that we can perceive. And although this figure has been disputed by other experts, it matters little whether it is a hundred or a thousand times lower; the important thing is that “we can detect and distinguish an extraordinary range of odors”, he sums up.

olfactory superpowers

In fact, and although we think of dogs or rodents as possessing olfactory superpowers beyond our reach, the reality is that “each species is different, with its distinctive nose, its brain and its complement of olfactory receptor genes”, points out McGann. “Dogs can be better than humans at distinguishing urine in a hose, and we are better than they with the smells of a wine, but there are few of these comparisons that are experimentally proven“. Some are, the researcher adds: for example, it has been shown that humans are more sensitive than dogs to the smell of bananas; after all, we are primates. And we also outperform mice by detecting the smell of our own blood.

“The human smell is excellent,” writes McGann in his review. Like other mammals, we can follow scent trails. Smells bring back memories and provoke emotions. In many cases our behavior is influenced by smell, although we are not aware of it: “communication between individuals through smell, which was previously believed to be limited to lower animals, is understood today as a vehicle of information on family relationships, stress and anxiety levels, as well as reproductive status in humans, although this information not always consciously accessibleSays the study.

The best of all this is that we can train our sense of smell to turn it into a much more powerful tool for interacting with our environment. According to McGann, in general the great ability of sommeliers or perfumers to perceive and separate subtle odors is not due to any intrinsic ability that differentiates them from the rest, but to training, since they have a richer vocabulary to describe the different aromas. “However, their sheer abilities aren’t vastly different from anyone else’s, even after years of training,” he suggests. The neuroscientist points out that there is not much scientific literature on how to train smell, but it invites us to focus on smells, compare them and name them. And above all, to stick their noses in new places: “a carpet! A basement! The grass! A crowd in a bar! “