Like Gregorio Samsa, Stephen D. woke up one day having undergone a metamorphosis. That morning, possibly due to recent amphetamine use, the smell took control of his entire perceptual world And this was what defined this young man’s life during the following days: an incredible sensitivity to aromas. The exaltation of his sense of smell meant that everything he noticed around him were fragrant notes and, although he retained the rest of his senses, they all seemed to have lost importance under the rule of the nasal.
For the first time, Stephen D. had the need to smell everything, he identified people by their smell before seeing them and he recognized the moods of his companions without looking at them. Not only did he become much more sensitive to all smells: all layers of reality became very powerful olfactory stimuli. Furthermore, this metamorphosis also meant entering a reality in which a strong emotionality colored everything making the here and now come to the fore while abstract thought became smaller as it dissolved into that rich range of sensations.
Unfortunately, after three weeks everything returned to normal. The loss of this gift, as sudden as his arrival, and was a strong emotional blow. Once the door to a world of such pure perception was opened, it was difficult to give up those sensations.
These events, narrated by Oliver Sacks in a chapter called The dog under the skin, are presented as true by the author (Sacks, 2010/1985). However, to most of us this may seem like an almost alien story, something that has little or no relation to our everyday experience. In general, We believe that smell is something like the poor brother of the five senses This is true to a certain extent.
Smell, emotionality and unconsciousness
All our lives seem to have audiovisual format: Both our leisure time and the people we interact with and the situations in which we find ourselves involved are defined by what we can see and hear. However, Stephen D.’s story has a peculiarity that calls this norm into question: this young man sees his sensitivity to odors increase due to the effects of a drug, but the large structures of his body do not suffer. no transformation.
Neither his nose enlarges nor his brain transforms into that of a dog, and the changes appear and disappear very quickly, suggesting that they are due to a relatively superficial alteration. Simply put, your nervous system works differently for three weeks on the brain mechanisms that are already there.
Perhaps everything can be explained because, in Stephen’s case, some processes that normally remain unconscious made the leap towards consciousness. Maybe, although we don’t realize it, we all have a dog under our skin, an unconscious part of us that reacts to odors beyond our control.
Scientific evidence seems to support this perspective. Today we know that the sense of smell has a crucial importance in our lives even though we do not realize it. For example, it has been proven that smell is a very powerful trigger of memories associated with each of the fragrances, and that this happens independently of our will to remember something. Furthermore, the experiences that smells bring to mind are much more emotional in nature than the memories evoked by images or words (Herz, RS, 2002). This occurs with a wide variety of odors.
However, perhaps the most interesting repertoire of reactions we have to smell occurs when that smell comes from another human being. Ultimately, the information that other people provide us is as important, if not more, than that provided by a ripe pear, a mowed lawn, or a plate of macaroni. If we want to understand how communication between people based on smell works, we have to talk about pheromones and of signature odors
invisible communication
A pheromone is a chemical signal emitted by one individual that alters the behavior or psychological disposition of another individual (Luscher and Karlson, 1959). They are chemical signals defined by each specific species and that produce instinctive reactions. Signature odors, for their part, serve to identify each specific member of the species and are based on the recognition of previously experienced odors (Vaglio, 2009). Both occur everywhere in many forms of life, and the case of humans does not seem to be an exception.
Although the human species is not as sensitive to odors as other mammals (an example of this is that our nose has drastically flattened, giving rise to fewer olfactory receptors), our body is capable of know aspects of other people such as their identity, their emotional state or other aspects of their psychology from these “traces” that we leave in the air.
For example, a 2012 study found how people can become emotionally synchronized through the smell they emit. During the experiment, a series of men were exposed to two types of movies: one of them was scary, and the other showed repulsive images. While this was happening, sweat samples were collected from these participants (all in all, it must have been a pretty disturbing experience). Once this was done, these sweat samples were exposed to a group of female volunteers and their reactions were recorded: those who smelled sweat secreted while watching the scary movie showed facial gestures associated with fear, while the language of the face of those who smelled the rest of the samples expressed disgust (de Groot et al, 2012).
Despite this, it is possible that the most important property of these scent trails is their ability to influence our reproductive behavior. Olfactory acuity in both men and women increases upon reaching puberty (Velle, 1978), and in the case of women this ability to perceive odors fluctuates with their menstrual cycle (Schneider and Wolf, 1955), so the relationship between sexual behavior and smell It is obvious. It seems that men and women judge the attractiveness of people in part by their smell, since this provides relevant information about the internal state of our bodies, an area about which sight and hearing cannot tell us much (Schaal & Porter, 1991).
Women, for example, seem to tend to prefer partners with a repertoire of immune responses different from their own, perhaps to generate offspring with a good list of antibodies (Wedekind, 1995), and they are guided by smell to receive this type of data. Beyond the search for a partner, furthermore, Mothers can differentiate their babies’ signature odor two days postpartum (Russell, 1983). Babies, for their part, are able to recognize their mother by smell from the first months of life (Schaal et al, 1980).
The explanation
How is it possible that smell influences our behavior so much without us realizing it? The answer lies in the disposition of our brain. It must be taken into account that the parts of the brain responsible for processing information about the chemical signals that surround us are very old in our evolutionary history, and therefore appeared long before the structures associated with abstract thinking. Both smell and taste are directly connected to the lower part of the limbic system (the “emotional” area of the brain), unlike the rest of the senses, which pass first through the thalamus and are therefore more accessible by conscious thought (Goodspeed et al, 1987) (Lehrer, 2010/2007).
For this reason, the chemical signals we receive through the nose act drastically on the regulation of emotional tone, even if we do not realize it, and that is why smells are a unique way to influence people’s emotional state even if they do not realize it. Furthermore, since the hippocampus (a structure associated with memories) is included in the limbic system, the signals collected by the nose easily evoke already lived experiences, and they do so by accompanying this memory with a great emotional charge.
All this means, of course, that theoretically some kind of handling on the rest of the people without them being able to do much to control their own feelings and psychological dispositions. The clearest example of this principle of manipulation is found, of course, in bakeries. Let’s hope that the big television and computer manufacturers take a little longer to discover it.
Sacks, O. (2010). The man who mistook his wife for a hat. Barcelona: Anagram. (Originally published in 1985).
Schaal, B., Motagner, H., Hertling, E., Bolzoni, D., Moyse, R., & Quinchon, R. (1980). Les olfactory stimulations dans les relations entre l’enfant et la mere. Reproduction Nutrition Development, 20, pp. 843 – 858.
Schaal, B., & Porter, R. H. (1991). “Microsmatic Humans” revisited: the generation and perception of chemical signals. Advances in the Study of Behavior, 20, pp. 474 – 482.
Schneider, R. A., & Wolf, S. (1955). Olfactory perception thresholds for citral using a new type of olfactorium. Applied Physiology, 8, pp. 337 – 342.
Vaglio, S. (2009). Chemical communication and mother-infant recognition. Communicative & Integrative Biology, 2(3), pp. 279 – 281.
Velle, W. (1978). Sex differences in sensory functions. Psychological Bulletin, 85, pp. 810 – 830.
Wedekind, C., Seebeck, T., Bettens, F., & Paepke, A.J. (1995). MHC-dependent mate preferences in humans. Proceedings of the Royal Society of London B, 260, pp. 245–249.
