Smell in humans: characteristics and functioning

The sense of smell in humans can be truly amazingWhile the idea is still widespread and entrenched, it is an unnecessary, vestigial, and atrophied sense more characteristic of animals than of Homo sapiens, a species too rational to be guided by.

Since ancient times, and especially since the 19th century, smell has been considered a sense that gives us little information, but thanks to the latest research in cognitive science, we know this is not the case. In addition, cross-cultural studies have shown that there are many languages ​​in which smell is very important.

Next we will talk about the sense of smell, the anatomical structures that make it possible, why it is rooted in the belief that it is underdeveloped in humans and we will also see cases of cultures where it acquires great importance.

    How is the sense of smell in humans?

    Many people still believe that humans have an underdeveloped sense of smell. and that in no case can we compete with other animals, such as dogs or mice, when it comes to identifying smells. It was long thought that this sense remained in our species and that during its evolution it ended up being relegated mainly by the improvement of our sight and our hearing.

    This was a widely held belief but, thanks to cognitive science having already adopted an intercultural perspective, it turned out to be false. The (Western, by the way) idea that humans can’t smell very well is an old myth, the origins date back to the 19th century and it has greatly influenced science and popular culture.

    While it is true that there are many species that are better at identifying smells than we are, our sense of smell is as good as that of many other mammals. Human being we can discriminate about a billion different smells (It was previously thought that there were only 10,000) and despite a relatively small scent bulb, our abilities to recognize smells are better than what the scientific community initially thought.

    How it works?

    Before we go into more depth about how smell has been discredited, let’s talk about how it works in humans. Basically it makes sense is used to identify chemicals that swarm the air and come into contact with chemoreceptors found in the noseA nerve signal is sent to the brain where they are identified as smells.

    Inside the human nose are three nasal horns, one for each of the three nostrils. These bugles are surrounded by the pituitary gland, a mucous structure that is responsible for heating the air before it reaches the lungs. The pituitary gland secretes mucus, the pituitary gland, which moistens and protects the nasal walls. In the pituitary gland are the cilia which contain thousands of olfactory receptors, Cells responsible for capturing chemicals that enter the nose.

    The contact of chemicals with the eyelashes produces a nerve signal emitted by the receptors there. This signal will be sent by the nerve fibers to the olfactory bulb from which the information will go to the different regions of the brain where these stimuli will be interpreted and recognized as smells.

    Smell and taste are closely related, which is why when we suffer from a disease affecting the nose, it also affects the way we taste food.. This is clear when we have a cold and we make a lot of mucus, a fluid that clogs our smell receptors that prevents us from being able to detect smells and tastes, which are chemically the same.

      When did this meaning start to be underestimated?

      According to John McGrann, who in 2017 conducted extensive research into when we began to place little emphasis on odor, the origins of the myth that smell is an underdeveloped and vestigial sense in humans, we owe it to Paul Broca himself, a nineteenth. century French brain surgeon and anthropologist. It is he who is credited with having extended the belief that humans have an underdeveloped olfactory system compared to other species.

      In his 1879 articles, Broca, based on the fact that the human olfactory zone had a smaller volume than the rest of the brain, interpret this to mean that humans did not depend as much on smell for survival as other animals, such as dogs and rodents. So he indicated that this is what gives us free will and that instead of being guided by the scents, we use our mental capacities, in particular our reason.

      This statement came to influence major figures in psychology, including Sigmund Freud, who went so far as to say that due to the lack of odor in humans, it made us more prone to mental disorders. This statement is partly correct, but it is not applicable to the whole of mankind. What has been seen is that people with impaired or reduced sense of smell are more likely to suffer from psychiatric disorders, Not because the human species has this “reduced” meaning.

      These “discoveries” and interpretations made by Broca and Freud and so many other nineteenth century thinkers further fueled the deeply rooted belief that smell was inadequate and of little use to mankind. In the Western world, there was (and still is) the idea that those who allow themselves to be dominated by smell let their animal instincts dominate them, an instinct which is always perceived as something irrational and illogical, thus discrediting even more. meaning.

      however, modern, cross-cultural scientific evidence belies that we poorly detect odors. It is true that, compared to other species, our olfactory bulb is a little smaller, but this smallness is rather relative. This brain structure sends signals to other areas of the brain to help identify smells, and it’s actually quite large and similar in size and number of neurons to other mammals that no one has doubted. she is able to recognize and guide. If by the smells.

      The importance of smell

      Odor is important because it plays an important role in choosing food, avoiding damage and deciding who our partner is. In addition to these more “animal” functions, we must add to this that humans are the only species that use scents for religious (eg, incense in churches), medicinal (eg, aromatherapy), and purposes. aesthetics (eg deodorants) and deodorants). Feeling does not seem to be just an individual act, but an interactional act.

      We differ from other animals not because we have atrophied it, but because we give it a different use. For example, dogs are able to differentiate the smells of different urine for territorial and domain purposes, a skill that in humans is of no use to us. Instead, we are able to differentiate between wine smells, cheese smells, or even between varieties of cocoa and coffee, which is a useful skill that we use to recognize which foods work best for us or which have the highest calorie and fat intake.

      intercultural look

      Many studies have sought to delve deeper into the importance of smell by analyzing the vast repertoire of vocabulary that languages ​​might have for encoding smells., Starting from the idea that if a concept, a feeling or a meaning is important for the human species, several languages ​​must refer to it. In other words, if smells are important to humans, more than one linguistic community must have a large repertoire of words and grammatical structures to reference.

      When this question began to be addressed, many studies focused on English, a language in which it was perceived to have a rather reduced vocabulary related to odors and their properties. This same scarcity of vocabulary on odors has been found in other European languages, which has led many to rush to believe that indeed this meaning had little weight in the species. human.

      The language related to smell is rarer in English compared to other modes of perception. For example, in this language, words related with vision, they are used 13 times more than the words related to the most common smells. A study in which he analyzed 40,000 words in the language found that there were about 136 times more words related to vision than those related to smell.

      However, the analysis of the vocabulary of other languages ​​shows that what is in Europe is not at all extrapolable in the world. There were many languages ​​in which smells were represented in a wide variety of words, and not only that, but there were also languages ​​in which smells and their properties were grammaticalized or used as metaphors.

      Each language has a frequency of use and a number of words associated with different smells, with the languages ​​of Africa, Amazonia and Asia having the most words on this subject. Some examples of this are cha’palaa ,! Xóõ, wanzi, yombe, maniq and jahai to name a few, although the languages ​​in which smell is of great importance number up to a thousand.

      Many of these languages ​​are spoken by hunter-gatherer communities, Which makes sense for them to have an extensive vocabulary on scents. For them, knowing how to recognize themselves, identify themselves, position themselves and orient themselves according to what they find in nature is fundamental for their survival. Knowing the scent of lions, the distance from a fruit tree, or the scent of areas near your house is part of your daily routine and, therefore, smells are as important as any other modality of perception.

      Loss of smell as a sign of illness

      Loss of smell can be synonymous with something wrong with our brain. Yes, it can be caused by a problem directly associated with the nose, such as having too much mucus or an infection in the nostrils, but it can also be because the brain structure responsible for recognizing odors is failing. to neurodegenerative disease.

      The smell can deteriorate as part of the aging process and can be a warning sign of a possible case of dementia.. If a patient indicates that he or she has a feeling that things don’t smell like before doctors started to worry. You should not treat the sense of smell as if it is inferior, because in the same way that if a person becomes blind or deaf it causes great concern, the fact that they also lose their sense of smell and taste should also be frightening. .

      Among the diseases in which the loss of smell can be found as a symptom of the onset of the pathology, we have memory problems and dementias such as Alzheimer’s disease and Parkinson’s disease. Loss of smell has also been shown to predict COVID-19. And even in the event that the patient does not have dementia or illness, the loss of smell can lead to more accidents, such as cooking, burning something and starting a fire which will be noticed when it is already too late. .

      Outraged, loss of odor has been linked to depression and obesity, Health conditions that apparently do not appear to be related to the sense of smell. All these pathologies seem to show that yes, smell is important for humans beyond what is “instinctively animal” or as a vestigial sense and that in fact it is important in terms of health and social.

      Bibliographical references:

      • Majifa, A. (2020). The human scent at the intersection of language, culture and biology. Trends in cognitive science. 0 (0) 1-13.
      • McGann, JP (2017). The bad human smell is a myth of the 19th century. Science 356 (6338), 1-6.

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