Laura López-Mascaraque is a scientific researcher at the CSIC and directs a research group at the Cajal Institute in Madrid. This Madrid native is president of the Spanish Olfactory Network and was the president of the Women’s Committee of the Spanish Society of Neuroscience. She is co-author of the book The sense of smellwith José Ramón Alonso. He receives a sunny Tuesday, June 4, in his office. Outside, on the street, it smells of lavender and summer.
Ask. How many genes do we have dedicated to smell?
Answer. Humans have almost a thousand genes for smell, of which today, functionally, we have exactly 396 genes that regulate the processing of odors in the brain. When this was known it was a huge surprise: there are many.
Q. For eyesight, for example, how many genes do we use?
R. Three. The basic colors. And yet 3% of the human genome is dedicated to smell; It is much more important than we imagine.
Q. Shall we give it to them?
R. All Animals, all humans, depended greatly on the sense of smell for everything. The brain was almost olfactory. As we evolve, the entire cerebral cortex is formed, the other regions are formed, we humans evolve in a way and give more prominence to other senses; We become bipedal, we separate our nose from the ground, and we sharpen senses such as sight or hearing, which are the ones that are the main focus of our lives.
Q. Our eyesight got worse as we needed it less, as we had things closer. And the smell?
R. The evolution of smells throughout history has been very special. If you go to the ancient culture of the Egyptians, smells were a cult to the gods: they offered them aromas. The legend of the Three Wise Men, what do they offer to the baby Jesus?: gold, incense and myrrh. Frankincense and myrrh were smells. They compared them to gold then.
Q. What happens in the pandemic?
R. Suddenly people, by losing their sense of smell, see how important it is. For example, you don’t taste things, all you have is taste: sweet, salty, bitter, sour and umami. If you take peppermint without knowing what it is, you taste it and it has no flavor. It may taste a little bitter. A bit. But you don’t detect that it’s peppermint until you unclog your nose. The same thing happens with cinnamon. To enjoy life it is important to enjoy flavors in general.
I have done workshops with people with neurodegenerative problems, Alzheimer’s, Parkinson’s and others, who have memory problems, and they have shown incredible symptoms of joy or have started crying simply at that smell.
Q. At Mugaritz, Andoni Luis Aduriz’s restaurant, they test sucking on a bitter-tasting white strip.
R. By having so many genes for smell, we have a unique olfactory register: that is, no one is going to smell what you are going to smell. For the part of smell, but also for the part of taste. There are genes that are regulating how you like things. And there is a group of people called supertasters who have a special sensitivity to bitter taste.
Q. What does that do?
R. It means that suddenly in a stew, for example, you can detect in detail all the flavors it has. It is genetically encoded. And you have a gene for that. You can do the genetic test: suck on that strip of paper that is impregnated with a substance and it may taste so horrible that you have to drink water, or it may not taste like anything at all. It’s like if you’re blonde or brunette: it’s your turn. Sensitivity to bitter taste in children is very high, that is why they do not want to eat vegetables, spinach, broccoli: it tastes bitter to them, they have to get used to it.
Q. The memory.
R. The olfactory memory process is very evocative. A certain smell comes to you and first you have a hedonic sensation that can be good or bad. Why is this happening? Because the sense of smell is the only one of all the senses that is not filtered in the brain. You have some neurons here in your nose, which are the only neurons that are in contact with the outside and that are renewed every 40 days, and they process information to the brain to reach a structure called the olfactory bulb. With any other sense, the processing of a stimulus goes through the thalamus, which filters the information and tells you: you are going to go to the visual cortex, you are going to the auditory cortex, or the frontal cortex, wherever. However, smell passes from the thalamus: it goes directly to its cortex, and immediately connects with two very important structures in memory, which are the amygdala and the hippocampus.
Q. …
R. The amygdala is what processes emotions and the hippocampus processes memory. What does that mean? That you are not going to remember a smell: you are going to evoke a memory. You can think about the sea, but you can’t go beyond it. But if you smell it, smell takes you to memories without you looking for them.
Q. And in people who lose their memory?
R. I have done workshops with people with neurodegenerative problems, Alzheimer’s, Parkinson’s and others, who have memory problems, and they have shown incredible symptoms of joy or have started crying simply at that smell. Many older people have lost their sense of smell and food does not excite them, it does not taste like anything, it only nourishes them. If you use a flavor enhancer (for example, chocolate) it helps.
Q. You participate in the documentary The meaning of cocoaby Jordi Roca [producido por BBVA, puede verse en internet].
R. It’s about trying to restore the taste of chocolate to people who have lost their sense of smell or taste. Due to radiation from chemotherapy, due to a traumatic accident. Recreate that flavor and feel again what you felt at that moment when you last tasted chocolate. People end up crying. By tasting it, by smelling it.
Q. Are there more smells than ever?
R. I do not think so. Different, perhaps. It has been said that humans can detect millions of odors. Depending on the concentration, the mixture of molecules and so on. But I don’t think we have more or less, but rather different ones.
Q. What are pheromones?
R. Some substances that are detected through an organ that we do not have. The vomeronasal, Jacobson’s organ. Pheromones are a type of substances that are processed not in the olfactory epithelium, but in the vomeronasal epithelium, and that does not exist in humans. Those pheromones that are said to be put in perfumes are stories: everything is a lie, we cannot have a different processing. Can we have aromas that can have the function of pheromones? Probably. But they have not been discovered.
Q. We don’t have pheromones.
R. There have been many attempts to see pheromones. The only one that seems to occur is when a woman is breastfeeding. Around the nipple there is an areola with small vesicles that could be some type of pheromones, not exactly a pheromone. The human genome has been searched to see if these pheromones exist and it has been found that they do not.
Q. And does evil smell?
R. [Sonríe] Smell the disease. And this is interesting because many experiments are being done. The volatilome, for example. The molecules that you release through your breath. Each of us has a unique smell, and that is called the olfactory fingerprint, our volatilome. Already in the Middle Ages there was what they called the smell wheel, where people brought their jars of urine to doctors. The doctors looked at the color, smelled it and even tasted it, from there they knew if, for example, you had diabetes mellitus, it tasted like honey. When I was little, I remember my mother telling me: “Give me a breath, you have sore throat or your stomach is bad.” What dogs can already detect, we are trying to do it with a sensor that knows if you have cancer, or diabetes, whatever. There are research groups in Israel and the United States that are already designing smart watches: you can put a chip in them and with that watch you can even bring it close to a food if you are allergic and see if it has lactose or gluten.
Q. And in criminology? If you don’t leave footprints, you leave odors.
R. It is studied If they can detect the scent footprint of a person who has been in a certain place, yes. And it could be the olfactory fingerprint like the fingerprint, another biomarker, like the iris of our eye. Because despite all the perfumes we carry on us, the food (because food changes the smell that you have, your own metabolism) you have a base smell that will never change, like your fingerprint. That, of course, has many ethical problems; If you have a watch and you bring it close to someone, suddenly you know what’s happening to them. There is much to do.
Q. What are odotypes, logos but in smells?
R. When you have a smell that identifies a certain brand, that makes you stay on the brand’s site or not. This already started with the Disney parks: they smelled like popcorn and attracted people. It continued in New York, at Abercrombie: at a certain point it occurred to them to add a scent to the store. It is very basic because it is a dark store with tables where the t-shirts and clothes are on top. But they saw that people did not leave the store, they stayed and they did not know why, it was simply that they had put an aroma. Brands are looking for their own odotype. Since I am the president of the Olfactory Network, they call me a lot from places, and I put them in contact with perfumers. Right now half of the houses smell like Zara: Zara started with a scent that was like clean clothes, and then they started selling it.
Q. And the food places.
R. In fast food restaurants, for example. Those are now prohibited, but before what they did was blow the smell of the hamburgers directly out from the kitchen and that way people would come in. Of course, it evokes you, awakens memories or outright hunger.
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