Smell is our mute sense, we hardly realize it is there except at certain times. It is also the most evocative sense: there is nothing more memorable than a smell. But it is also the one that gives us the most problems when describing it because, how do we define the smell of roses? We can only do it by comparison: it smells like…
Like the rest of the animals, we all have our scent mark; some more than others, if we pay attention to the fumes in crowded urban transport… But we are not going to talk about it but about something related to a certain practice that occurs in some places in Greece and the Balkans: during parties, men they carry handkerchiefs in their armpits to give to the women they invite to dance . A not at all irrational practice; The expert in the psychology of smell Rachel Herz dedicated herself to asking women what it was that made a man attractive enough to go to bed with him. Regardless of appearance or tone of voice, it was her scent that was decisive.
C. Neil Macrae, professor of psychology at Dartmouth College, published a study in Psychological Science in which he analyzed the sexual response of a group of women during two phases of their menstrual cycle: when the risk of conception was high (the day of ovulation and the next two) and when it was low (first 3 days of the cycle). It found that women preferred masculine faces during ovulation and more feminine at another point in the cycle. In fact, ovulation has been found to increase the response to androstenol , a pheromone that contributes to male body odor.
On the other hand, our taste for kissing may have evolved from the usual sniffing among animals and, why not say it, not so rare among us. This is what Kazushige Touhara and his colleagues at the University of Tokyo defend. Kisses are an echo of a more primitive, more chemical form of communication, as revealed by their studies with mice. While pheromones, the famous molecules that are capable of provoking a response (not only sexual) in another individual of the same species, can be smelled at great distances and attract potential mates, this Japanese team has found certain non-volatile pheromones secreted from the eyes and transmitted by contact. Although mice and humans are genetically very similar, the gene that codes for this pheromone does not exist in humans. “We lost this gene at some point in evolution,” adds Touhara.
Both species share a common ancestor between 75 and 125 million years ago, a rat creature called Eomaia scansoria ( Eomaia , from the Greek “mother of the dawn” and scansoria , from the Latin “climber”), which is the first known placental mammal . Touhara speculates that we humans must retain a vestige of gnawing behavior because we still like to kiss or rub noses, an automatic behavior intended to osmogenically sample another’s scent. To detect odors, the inspired air must reach the deepest part of the nose and for this we must breathe in very hard. Thus, natural breathing brings air into the nose at a speed of 6 km/h. In the case of a correct odoriferous inspiration, the air must enter at 32 km/h; hence the characteristic sniffing sound.
What can be its function? Some philematologists, scientists who study kissing, believe it has to do with identifying genetically compatible couples . The smell of a potential mate that is perceived during the ensuing make out provides us with reproductively relevant information, even if we are not aware of it. Although there is still some debate about whether humans can perceive pheromones since we do not have specific receptors for them -the so-called vomeronasal organ-, like rats or pigs, some biologists think that we can detect them with our nose. In fact, some, like biologist Sarah Woodley, believe that women can smell certain proteins while kissing , and what they smell can affect their judgment of finding their partner attractive. Quite a demonstration of chemical influence.
Of course this is nothing more than an extrapolation of what is known about animal behavior. In them, the person responsible for all this smelly mess is the vomeronasal organ, located in the nose. Rodents use it to find a mate: they detect the pheromones present in the urine of other rats and avoid choosing sexual partners with an immune system too similar to theirs to ensure healthy offspring. Males and females tend to choose partners that differ in major histocompatibility complex or MHC markers. In humans, this corresponds to a family of genes located on the short arm of chromosome 6 and that encode vital information for our immune system. Most biologists believe that mice can literally smell how different the MHC is from their potential mate since, as a general rule, the more different the MHC, the stronger the immune system of the offspring. “These genes also make people smell different,” says Sarah Woodley.
In 1995 Swiss biologist Claus Wedekind was able to determine this mate selection based on MHC dissimilarity in humans. A group of female students was made to smell T-shirts that had been worn for two nights by male students , without putting on deodorant, cologne or bathing with scented soaps. A high number of women chose odors from men with a different MHC. Interestingly, this trend was reversed when women took birth control pills. However, Wedekind’s findings have not been reproduced in other studies, so swords remain high on this issue.
Among the substances that are postulated as human pheromones are, in addition to the already mentioned androsterol, vaginal hormones called copulins, which according to some researchers trigger testosterone levels and increase sexual appetite in men. Things are not very clear, but the desire to make money at the expense of the need we have to attract another human being has already made them commercialize, at more than 25 euros a little bottle.
Now, both North Americans and Japanese consider the smell offensive; For the latter, it may be due to that long tradition of marriages of convenience, but there is no explanation for the former: is it perhaps because of their excessive use of deodorants?
