Ideas - Why smell — our invisible superpower — deserves more acclaim

Episode Date: September 16, 2025

Smell this yogurt, is it still good? Our sense of smell has the ability to keep us healthy and safe. In fact in some cases, our ability to detect "off" foods using our sense of smell can be superior to dogs and other animals. Smell is often undervalued and yet capable of inspiring profound admiration if we stop turning our noses at it. Producer Annie Bender examines what we lose when we take our powerful — but often misunderstood — sense of smell for granted. *This episode originally aired on June 3, 2024.

Did you know that it was once illegal to shop on Sundays? That's true for when I was born. I remember this, and I'm not that old. I'm not, okay? Leave me alone. Anyway, I'm Phelan Johnson, and I host See You in Court, a new podcast about the cases that changed Canada and the ordinary people who drove that change. From the drugstore owner who defied the Lord's Day, to the migma man who defended his treaty right to fish, to the gay teacher who got fired and fought back. Find and follow, see you in court, wherever you get your. your podcasts. This is a CBC podcast. How would you describe the sense of smell to someone who had never experienced it?

To someone that never experienced it? Yeah. Wow. Welcome to Ideas. I'm Nala Ayyad. It's a really good question. Oh, it's a good question. Smell gives you, I don't know, an extra layer of depth.

It gives so much texture to life. A sense of smell is such an immediate connection to place and experience. For me, it's the ultimate tour to connect to things. And without it, everything is neutral. In the textbook of our senses, smell has long been relegated to the margins. We don't really pay attention to a sense of smell. You know, if you ask people, if you had to give up one sense, which one would you pick? And they often would say, well, I would give up the sense of smell.

And I feel like it's taken for granted. It's been called the Cinderella sense, chronically underestimated and ignored. You've got this cultural dimension, which was codified by the ancient Greeks, and then was very strongly revived in the Enlightenment and in the early 19th century. But whatever bias we might hold against smell, aromas themselves, themselves are inescapable. You know, right before you get the bread in the oven, you have to slash the dough

to get that nice, like, oven spring. And the whole house fills with baking bread. And the COVID-19 pandemic, which caused a devastating and widespread loss of smell, has renewed interest in its power. We've kind of fooled ourselves into thinking we've got a rubbish sense of smell, which is just not true.

We can train our sense of smell, we can exercise it, And we can smell billions of odors. It's a superpower to embrace. We're calling this episode Smell the Invisible Superpower. This thing's really loud. Okay.

Producer Annie Bender will take it from here. What would you use this for? So this is the bandsaw. So you cut up pieces of wood with this. Derek McLeod is a furniture designer based in Toronto. He works out of a big industrial space that backs out onto a tangle of train tracks. Oh, wow.

That is literally like 20 feet away. Yeah. Awesome. That's a lumber. Yeah. Just like the trains rolling by, the walls of Derek's workshop are stacked high with pieces of lumber. and the scent of wood is everywhere.

So if you were to look around this space, what would be some of the scents you would associate with a space like this? It's hard to describe a smell. Like I know that walnut had a particular smell, and like pine certainly does as well. Cedar for sure. Like that's aromatic cedar is a big one, you know, for closets and things like that.

I don't know. Like cedar is sort of a warm of, warm smell, let's put it that way. Whereas walnut is maybe more, I don't know if you'd say earthy, or I'm not sure how you'd put it into words at this point. Yeah, I couldn't really accurately describe them anymore. Derek lost his sense of smell in 2017. He still doesn't know what caused the loss,

and he's never gotten used to it. For me, now, my smell world is not even gray. It's just blank. There's just nothing there. Yeah, it really definitely threw me into a depression. I had to see a therapist pretty quickly after that to try to cope with the sense of loss and the strangeness of the whole thing. To get over that strangeness, he's had to let go of his memories of smell, including the scent of wood. I guess I don't associate the shop with smell anymore.

It's like that memory is vanished. It's just sort of gone. I can't conjure it. I can't really conjure any smell memories anymore, which is strange loss, I guess. The sense of smell has a very intimate connection to our emotional world. It has also a very intimate connection to our memory. My name is Johannes Fresneli. I'm a professor for anatomy at the University of Quebec in Tuare Rivier,

and my lab focuses on smell and taste and the link to the brain. One smell that I really love is the smell of pine trees, because it makes me go back to my childhood where I would spend summers up in the mountains, in the Alps, in a cottage where we wear for a month at a time. and this smell is just something that is very, very calming to me and brings me back to nostalgic moments of which I really love thinking. Close your eyes and you can probably conjure up a smell memory of your own.

For me, it's the scent of maple syrup. Even just thinking about that smell can take me back to my childhood, bundled up with my cousins in the sugar shack waiting to be granted a spoonful of that deliciously sweet, sticky hot, This power of aromas to transport us back in time is known as the Proust effect, named for Marcel Proust, who wrote about it in his novel In Search of Lost Time. Is there a scientific explanation for that connection between smell and memory and nostalgia? Yes, there is. And so if we want to understand this link, we have to look at the brain.

When we smell something, there's a receptors in the nose, and they send a signal to the brain. and this signal is then processed in the olfactory processing areas of the brain. And the olfactory part of the brain, it's the so-called limbic system. This part of the brain is a very old part of the brain, if we are looking at it from an evolutionary perspective. And this part of the brain is responsible for smelling, but also for emotions and for memories. So the reason for this intimate link is that it's the same parts of the brain that process. And so if we get an input from one side or the other, we can trigger these memories, we can trigger these emotions with smells.

This scent and memory trigger is well established. But when you ask people which sense they'd give up first, time and again, the sacrificial lamb is smell. A 2021 survey in the journal Brain Sciences found that people consistently ranked smell below vision and hearing and even below commercial products. A quarter of college students surveyed said they'd rather give up their sense of smell than their smartphones. But a world without scent can feel incredibly empty.

Hi. Hi. Hi, are you, Jessie? Yes. Why don't we start by having you introduce yourself? Yes, definitely. So yeah, my name is Jesse Cabot. I was born in raised in Paris and I've been living in Montreal for nine years now. I was fully conscious that I had lost my sense of smell in December 2021 when I was in London with my family for Christmas

and we were all outside and my family was complaining about outdoor smells like really not pleasant ones and I quickly discovered that I couldn't smell at all and since then I think I went through the five stages of morning there was a long period of denial Then came rage last summer. I am still today trying to figure out who I am now without that with me

because it changes my whole relationship to the world because I feel like I'm involving in a neutral environment and that's, I lost all nuances. Do you think the sense of smell is undervalued? Definitely. It is definitely undervalued. And I think it goes back to the 19th century. The church played a role in this.

Darwin showed that we are related to other animals. And the sense of smell is very important for many animals. it's very closely related to our emotional world, to the hormonal world, to our memories, to a very deep section of our brain, where we do not have a very easy access rationally. And so there was a backlash that wanted to show that we are different from animals. The human is this noble being that is visual, that is hearing, that makes literature, that talks to each other. And this stayed on for centuries. A long line of philosophers and scientists played a role in the historic demotion of smell.

Aristotle, who was the first to introduce the idea of the five senses, put vision at the top of his hierarchy. In the 16th century, René Descartes declared that sight was the sense of science. During the Enlightenment, philosophers Georg Hegel and Friedrich Nietzsche followed suit. Emmanuel Kant famously declared smell. to be the most dispensable of all the senses. To which organic sense do we owe the least? The sense of smell.

It does not pay us to cultivate it or to refine it in order to gain enjoyment. This sense can pick up more objects of aversion than of pleasure, especially in crowded places. And besides, the pleasure coming from the sense of smell cannot be other than fleeting and transitory. Sigmund Freud was yet another famous olfactory detractor. He claimed that human sense of smell became irrelevant once we stopped moving around on all fours.

Smell was seen as a base, animalistic trait that humanity had supposedly risen above. In effect, our noses became passe. There is a common misconception that we think we humans have a bad nose. we can smell billions of odors. There was a paper several years back in science that actually claimed we would be able to smell a trillion of different odors. So now maybe it's not a trillion, maybe it's just a hundred billion or ten billion or one billion, but it's an extremely big number of odors that we can smell. There are studies that have shown that if you look at the detection threshold,

so which is the lowest concentration that you need to perceive an odor? On average, dogs are better than humans, but for certain smells, humans are better than dogs. Like what? What are some of the things that we're better at smelling than dogs? Yeah, alcohols, ethanol. We are very sensitive compared to carnivores such as dogs, and we are very sensitive to them. And of course, in evolution, it's always difficult in hindsight to say, you know, this was like that. It's an interpretation. But it was, of course, important for our ancestors when they went through the savannah and they were hungry. and there was some tree with some fruits on it and the fruits were really ripe.

And so they emit those alcohols that our ancestors would be able to smell them and detect, oh, this is a food source for us. And for a dog, this is not so important. And for these odors, we are better than dogs. We are better than rats. This connection to our ancestral diet points to another of smell's essential functions.

because beyond its ties to memory, smell is also deeply connected to taste. You've likely heard this before. Outside of the basics, sweet, salty, sour, bitter, most of the nuanced flavors we experience are actually processed not through taste, but through olfaction, the scientific word for smell. Without it, our experience of food and drink

is more texture than taste. I stopped drinking coffee. You know, that's part of your morning ritual, and it hit me. I was sipping it, and it's just like, this is just weird water, weird hot water. Like, it was such a strange sensation that this beverage I've loved for 20 years is now, like, wrong. Like, it's just broken. Let me tell you another example that may convince you that our sense of, The smell is actually much better than we think.

You know, if you take the dog that is this wonder of smelling as this awesome nose, but you can give him the same kibbles every day, every morning, every evening, and you will have the happiest dog in the world. And now imagine, I mean, what is your favorite food? Oh, I don't know. Butter chicken. Okay, butter chicken. Okay, let's assume I give you butter chicken tomorrow morning, tomorrow lunch, tomorrow evening.

And we repeat that the day after and the day after again. after one week your favorite food you cannot see it anymore and after three weeks we have a revolution although I gave you your favorite food and this is because we constantly need excitement we need stimulation but we need diversity

and this retronasal affection the perception of smells from the mouth via the nose by the back door this is extremely important for us humans we have developed incredible amounts of cultural techniques to process our food to make it more tasty

And when we say tasty, it's actually smelly to just make it better. We can roast, we can sear, we can grill. And this shows, again, that it depends on what function of the sense of smell you're looking at. I just had a trip, an international trip. So there's duty-free shops. If you go to the duty-free shops, you have perfumes, tobacco, you have alcoholic beverages. They all come with the sense of smell. There's a whole luxury industry all around the sense of smell.

If the sense of smell would not be important, well, all these industries wouldn't work. They wouldn't make any money. But they work. We are spending a lot of money on our sense of smell. And this again shows that our sense of smell is more important than we usually think. If you could get one smell back, what would it be? Boy.

Hmm. Oh, my God. I've asked those questions. to myself so much. I was thinking of my great-grandmother's house and she would make lunch for my brother and I. She'd make this Hungarian dish, Tudosh Testa, which is cottage cheese and noodles,

and it's cooked with an unhealthy amount of butter. And that gets browned on the stove and, like, that browned butter, sweet, sort of caramelized smell. The sea. My parents live in New Zealand, it's a paradise place, and we are surrounded by the sea and going to my family house and not being able to embrace all these smells that make you realize, ah, I'm definitely in holiday. The smell of smoke, like around a campfire or when you're barbecuing something. I miss the Christmas tree.

It's been two or three years that I'm here, I can see the tree, I can touch it. I mean, there's all these elements that are evident that we are in Christmas, but I don't smell, which makes me feel that I'm a bit, again, detached to it. You know, right before you get the bread in the oven, you have to slash the dough to get that nice, like, oven spring, and it pops open, and it looks beautiful. and the whole house fills with baking bread. Full disclosure here. I've never really known how good or bad my sense of smell is. So I found myself wondering, what might I be missing when it comes to smell?

You can get better at it. So we can train our sense of smell. We can exercise it. And we can get better in naming orders. And this is actually what sommeliers do. And this is the fascinating thing about the sommeliers. And that's also the fascinating thing about our sense as well. We can exercise it.

We can get better. But we have to do it on a very regular basis. I think what is important is, you know, it's like everything else. Nothing comes for free. You have to actively smell smells and think about the smell. So it's not enough to watch TV and, you know, have a battery of smells going by on a conveyor belt in front of your nose. that wouldn't help anything. You have to actively smell.

You have to probably talk about the smells to other people, smelling, recognizing, naming, remembering. Hi, Kate. Are you able to hear me? I can hear you. I can you hear me? Oh, great. I was worried that my microphone wasn't working for some reason.

If I wanted to become a more active smeller, I'd need a guide. So I tracked down a professional smell enthusiast. My name's Kate McLean, And I am a designer, a researcher who's really interested in how we might communicate smell perceptions in different places around the world. Kate spends a lot of time helping people tap into their sense of smell. For the last 12 years, she's been running what she calls smell walks in cities all over the world. What exactly is a smell walk?

A smell walk is, it's a walk where the first. piece of information that you get from around you, rather than coming through your eyes, is you try to get that information through your nose. And yes, you do an awful lot of sniffing. So it's kind of like a walk in which you try and engage your inner dog. Exactly. Yes. Couldn't have put it better. That's exactly it. How many smell walks have you done at this point, do you think? Plea. I keep a log of all of them. And I think the last time my love, looked. I'm somewhere around sort of like 200 mark.

Having done 200 plus of these smell walks, have you gleaned anything about smelling techniques that I might want to know? Smelling techniques, there's some really useful ones that you can deploy to actually sort of like gently ease yourself into the process of smell walking. Smell catching is fun. first. This is the real refocus on yourself to receive smell as your primary source of information. So smell catching, you walk steadily, you breathe regularly and you note when a smell crosses your nose. So you're basically smelling in the air around you. And when you

detect a smell, then the idea is that you actually actively sniff to inhale more air and as a result, inhale more olfactory molecules of whatever it is that you've detected. And as you're doing that, you're recording some details about the smell or you're thinking about them. What comes next is where you start to deal with smells as close up so you can pick things up and crush them in your hands to release odour from them. Green leaves are really good for that. You break them and you release green leafy bolotiles and you get the unique scent from leaves. So you're saying, Okay, if I was going to give that smell a name, what would it be? You're thinking about the intensity of the smell.

Is it a particularly strong smell or is it a weak smell? And you're also thinking about how long does that smell last? Is it something that's just temporary or does it appear to be more permanent? Another very cool thing to do actually is to think about the associations that you have with it. Where have you come across it before? What's it like? do you like it? Do you dislike it? And possibly even if the smell had a color, what color would it be? Oh, that's an interesting one. Is that something that you come across a lot? Do you have one that you think of as being a particular color that you could share with us?

There's the really obvious ones like the smell of the sort of like the ocean is for me it's never that bright sort of like crystal clear aqua. It's much more of a sort of like a greeny, greeny almost chalky greeny brown color because you've got the smell of kelp mixed in with a smell of sea mixed in with a smell of salt and so you're going for that sort of like that whole mix it sounds quite poetic it's very poetic it's ever so poetic well i'm i'm gearing up to go out on a small lock now is there anything you would recommend that people who are engaging on a Smell Walk, avoid smelling? No, actually. I mean, it's not illegal, but smelling other people's armpits, you may want to ask you first. Fair enough. Well, I'm very excited to give this a try. Have fun.

You're listening to Ideas and to a documentary titled Smell, The Invisible Superpower, by producer Annie Bender. Ideas is a podcast and a broadcast heard on CBC Radio 1 in Canada, across North America, on U.S. public radio and SiriusXM, in Australia, on ABC Radio National, and around the world at CBC.com. Find us on the CBC Listen app and wherever you get your podcasts. I'm Nala Ayad. What kind of person takes on the law? Can they ever really know what they're getting into? A really tough-looking guy came up to us and said,

Are you part of this gay case? My family started getting death threats. I wasn't able to go outside alone anymore. I'm Phelan Johnson, host of See You in Court, a new podcast about the cases that changed Canada and the ordinary people who made history. This is David and Goliath we have here. Find and follow, see you in court

wherever you get your podcasts. During the COVID-19 pandemic, the airwaves were a buzz with dispatches from a world without smell. It's about three weeks. I made a cup of coffee and I didn't smell it and I didn't taste it. And I would sniff and sniff and there would be absolutely nothing.

It was so severe I could have literally drunk a cup of vinegar. But as the world moved on from the virus and the loss of smell became a less common symptom, those testimonies have largely faded away. I'm definitely like interested in trying anything at this point. Our sense of smell has often been ignored and even denigrated. But in today's episode, we're bringing you inside the miraculous world. of Smell, courtesy of producer Annie Bender.

Smell of number one. We're at Falls Falls Hiking Area in Ontario. I smell... Nothing. One of the things that quickly becomes apparent when you start trying to engage with the world knows first is just how difficult it can be to talk about sense. I've opened a small shed, and inside I've found very fragrant firewood.

But I'm realizing I don't know my types of wood, so I can't describe what type of wood I'm smelling. We don't have so many words to describe smells. Sometimes it's almost easier to use the descriptive terms from other senses. You can have smells that are warm and smells that are cold. So if you think of a minty smell, you'll think of it as a cooler smell. If you smell something that is a little bit more spicy or curry, then you may think of that as being a warmer smell. Kate McLean has devised a way of matching words

to a given scent. But in general, our vocabulary for smell, at least in English, is surprisingly threadbare. If you think about it, the words we use to describe smells are virtually always other smells. Matthew Cobb said he's smell at the University of Manchester. If you think of people doing wine tasting, you know, they'll say, oh, it's got, you know, rose and tarmac and, you know, boiled sweets and they come up with all these analogies which are in fact the other smells and we don't have words that are just related to smell that's not quite true there's a handful of them dank fetid and they're not terribly nice words are those words we have but that's about it and in everything else we don't have a vocabulary for it walking on busy Bloor Street at night

in the summer And it's the smell of garbage. Bags and bags of garbage and composts sitting out waiting to be taken away in the morning. Smells like, I don't know, you're just like decaying stuff you definitely don't want to spend too much time around. If you look beyond the English Dictionary and other European languages, the vocabulary for scent becomes much richer. The Quechua language, for example, which is still spoken in the Andes, has eight different terms for the act of taking in odors.

In Cameroon, the Kapsiki people have 14 distinct categories for different types of smells. But there are also exceptions among European languages, particularly in industries where having a good smell vocabulary is a key part of the job. So we set up here, I suggest that we set up here. So I'm saying to cut what we call a perfume organ. And this is our tool, so the perfume organ, that contains, what, 70, 80 raw materials, like said? More or less, more or less.

To start, can you just introduce yourself to who you are and where we are right now? Yes, so my name is Ruby Brown. I'm the founder of eponymous brand Ruby Brown. We are here in our studio in Montreal in front of what we call the perfume organ, so we can just sit, chat, and snow. Amazing. It's hard to think of anyone more fluent in scent

than a perfume maker, and the language of perfume is surprisingly musical. You called this descent organ? What a cool name. organ like a musical instrument? Because basically, just like in music, we work with a core in order to get a composition. So very similar the way we work. And there's different tiers. Is that significant?

And different colors. So where all our notes identify as head, heart, or base, depending on their impact and their tenacity. Whatever Immanuel Kant said about smells supposed a did. dispensibility, the perfume industry reflects a reverence for fragrance that stretches back thousands of years. The ancient Egyptians believe they could reach the afterlife by climbing a staircase of perfumed incense smoke. In the first century AD, Pliny wrote that perfume was one of the most elegant and honorable enjoyments in life. I've heard scientists pine for a look at the perfume industry's incredible olfactory data sets. After all, perfumers have been studying and celebrating smell

for much longer than scientists have been researching it. And their terminology mirrors that fact. So we all agree on five or seven olfactory families. So the first, the most popular one, especially here in North America, is the floral. Powdery notes. Delicate. Fragile. Phryia. So you have those powdery notes, but you also have the exotic flowers. Erlang Elang, Niroli, which is orange blossom. Classic, elegant, opulent, sophisticated. Second olfactory family would be the witty.

Herbal, aromatic, vegetal. Everything that's kind of woody and green and spicy would fit in that category. Mossy notes, black pepper. Third family would be the Oriental family. There are notes that were brought back from the Middle East, L'Oriand. Rich, creamy and vicarious. Adelping, addictive, so vanilla, tongue bean, very enveloping and sensual. Then we have the citrus.

Lime, grapefruit, bergamot. That's really interesting because in perfumery, we have a word, a very specific word we call espiridic. Sporty, fresh, citric, abidic. The last family would be the leather family. Animalic, leathery. So very bold and powerful notes such as leather, obviously. but also tobacco, which is probably one of the most surprising note on the organ. All these different descriptors for fragrance seemed pretty straightforward.

But when Ruby and her colleague Excel started uncapping little bottles of fragrance for me to smell, I lost confidence quickly. That's one. I can try to see if I can identify it. Oh, this smells like food. Yeah. Oh, it smells really yummy. Like, it smells like a savory dish that I really want to eat.

But it's like, no, cumin. You wouldn't have something like cumin in a perfume, so it must not be that. Oh, I don't know. I think I need you to tell me. So it's very local. It's actually maple syrup. Oh, my God. My parents make maple syrup.

Like, how could I not know that? I grew up going to sugar shacks. That's funny. I thought it was something like much. Why would it be that I would smell maple syrup and think spice? It's very difficult. I love to have people smell stuff that are part of our everyday life. Rice is a really good example.

I'd have you smell rice. You'd be like, what is this? I know this. I know this. And I'd say 97% of us won't identify the rice. Right. Why is that you think that it's so hard to identify things? Because we don't really pay attention to a sense of smell.

So it's there somewhere in our memory, but we never take the time to just sit down and analyze and put words into smell. I took my discouraging smell performance back to scientist Johannes Frazznelli. Despite everything you've said about how good humans are at smelling, I found it surprisingly difficult to identify certain sense, even things that seem like they should be really obvious. Why is that?

How common is that? Well, it is actually very, very common. We are very, very context dependent with our sense of smell. If you see a banana in front of you, it's going to smell like banana. But if you smell the same banana and you have no other information, it's going to be extremely difficult to smell that banana. If I give you an orange juice that I color blue, this orange juice will taste. And again, taste is not really taste, but it's actually smell.

much less like orange than an orange or yellow juice, just because we have this extremely important component of the context with the sense of smell. And if we do not have the context, such as smelling just some bottles where you don't know what is in it, it's going to be extremely difficult. One of the reasons that identifying odors

may be so difficult is that they're so complex. The example I normally give is a tomato. Smell scientist, Matthew Cobb. People have looked at the odors that are the molecules that are given off by a tomato, and you will get around about 200 different odors coming off that tomato. Plus, we live in an environment which is full of what the delightful technical term is insults. So there are chemicals in our environment, which may be damaging our nose. It's through the weather as well.

When it's cold, things don't smell as good, because the molecules can't. drift in the air, they're not volatile, as they say. Smell log number six. Squire Rivier in the cold evening rain. It's hurt to actually smell the rain. But if I breathe in really deeply, then I can. I think that's a cold rain smell. different from a summer rain smell, maybe a little bit more subtle.

Despite our widely shared struggle to describe and identify odors, scientists like Matthew Cobb and Johannes Fresnelli remain convinced by decades of lab research that humans are better at smelling than we think. So I decided to go and smell it for myself. No. No, and then there is a lot, those are. Johannes Fresnelli studies the neuroanatomy of olfaction out of a lab at the University of Quebec in Trau-Rivier.

His lab manager, Frank Clucet, showed me around. So here, that's the two-final etanol. This is Rose. This is the scientific name for Rose. Do you ever open it up just to get a sniff for aromatherapy and a stressful workday? No. It's funny, but no.

It's a tiny space, just two rooms on a narrow corridor. The first is a chemical lab where a row of cabinets house a miniature smell library. Like here we have like coffee. Oh, that's, yes, I know that one anywhere. We have a strawberry. We have a lemon. So we have those.

We have a lot out here, like a different, like lemon, fish. Uh, almond, yeah, yeah. Peach. Smoke? With help from Frank and a team of students, Dr. Fresnelli uses this lab to better understand

how the brain processes smells. We rely on our sense of smell more than we actually think. Dogs have incredible abilities, you know, tracking and finding animals and whatnot. But there are studies that showed that we are also able to do that.

We can learn that. We can follow a scent track. We can get better in it. Wait. I'm sorry. We can follow a cent track? Well, there is a study that was done 20 years ago in Berkeley where they put the scent track on the grass and the campus and they had people follow the track. And they showed that people, A, could do it, and B, got better at it. And, of course, the sand track they put there wasn't a deer smell or something, which would be probably good for dogs, but they put the chocolate trays there. And with the chocolate trays, people could do that.

Probably dogs would be better. I need to know more about this. They had a piece of chocolate in the grass. No, no, they put some scents there. I don't know how they, you know, some drops, I guess. And they just moved it along the grass in a zigzag. And then they had their participants blindfolded. And, you know, they could not touch anything and see anything or hear anything.

They could just rely on their nose. And then they followed this sand track. That's fascinating. And people were able to do this with no prior training. They could do it. But when they got trained, they got better and better at it. Not everybody got better, but roughly half of the participants got better. I looked this study up.

The trail that participants followed was, in fact, a 10-meter-long piece of scented string. The participants were blindfolded with earmuffs and big gloves on their hands to stop them from feeling their way around. And do you have any other questions to that study? Yes, of course. People were doing this without any prior training. Like anyone, anyone that you blindfold and put down in a field would be able to do this. That is what the study says. I haven't tried it myself, but I believe that we are able to do that. You know, maybe at some point when spring hits, we can try it out ourselves. I don't know. I mean, I just have staggered. I don't even know what to say it.

Not everyone would be as surprised as I was by this study. In a book from the 1990s called Aroma, the cultural history of smell, a trio of researchers at Concordia University observed that many forest-dwelling indigenous peoples relied on smell rather than vision for their distance perception, because it's easier to detect far off smells than to see through the dense foliage. In the Amazon rainforests of Columbia, the day-scenters, Sauna, who refer to themselves as weirah, or people who smell, have been known to track the scent of animals, humans, and plants.

They call these trails of scent wind threads. And while the average westerner is far less conscious of these wind threads, we're constantly taking them in. Smell log number 15, early May. I'm standing out on my little balcony, and I can just smell the fragrance of lilacs wafting up from the driveway where there's a tree it took me a minute to realize where the smell was coming from but it's just perfect you know the sense of smell first of all protects us from dangerous in our environment

we smell gas we smell smoke we smell rotten food or something like that another aspect of the sense of smell is everything that has to do with feeding and with food perception from a very young age, from the attachment mother to child smelling the breast while breastfeeding and then finding food sources. And then the sense of smell has a third very important function which has something to do with social communication. So we communicate with each other non-verbally via the sense of smell that's typically unconscious. But we communicate if we are related, if we are partners, if we are strangers, if we're happy, if we're sad, all this is communicated via our body odors and we process it even if we usually don't perceive it consciously

and all these functions would get lost if we lose our sense of smell. So our life becomes a little bit colorless, poorer, less social interactions or flatter social interactions and that of course can be quite problematic for some people. The first that comes into my mind is my boyfriend's smell. For Jesse Cabot, losing her sense of smell back in 2021, left her feeling profoundly disconnected. Like being close to my boyfriend and not smelling him. And that's really, really confusing.

And it's hard because it's something that I used to adore because it was my way to connect with people to fully embrace the presence of a person and I don't have it. So I feel very much detached to people. It's very neutral. Everyone is neutral to me. Odour and identity are deeply associated with each other in many cultures around the world.

Among the Ongi of the Andman Islands off the coast of Myanmar, people's very selfhood, their life force, is believed to reside in their smell. And while we may not love to talk about body odor in the West, we consider it entirely normal to breathe in the scent of partner, say, or the top of the baby's head? Generally speaking, we all have an individual body odor. And this body odor is further modulated by the emotional status we're in.

So there are studies that have shown that, you know, they took the parachuters, and the researchers gave them some t-shirts in which they put a breastfeeding pad into the axillary region. And these pads would then soak up the sweat that was produced by these parachuters. And when they safely landed, they had, of course, had quite extreme fear during that time. The researchers took those t-shirts and gave them to another group of participants that they were watching a horror movie. And when they were exposed to this kind of sweat, they found a horror movie much more frightening than when they were smelling the odor or sniffing the body odor, the sweat odor of somebody who had just been cycling or something like that. So, which means we are also communicating this kind of information, but we have no idea yet what is the substance that causes this.

And this is something that's quite difficult to study, actually, but there is research done on that question as well. So we're all subconsciously smelling things and each other all the time as we move around in our environment without realizing it? Yes, yes. And in most cases, we are not aware of it. Small log number seven walking along with St. Catherine in Montreal a night, a windy night. I just caught a whiff of someone's cologne as they walk by me. It smelled musky and warm with just a hint of spice. And I just caught another whiff as someone else's cologne. It was similar, musky, warm, just a little rush scent, and then it passed me by.

Dr. Fresnelli isn't just interested in the ways that we're subconsciously using smell to communicate. He's also interested in what our sense of smell, or more specifically changes to our sense of smell over time, may be able to tell us about ourselves. And he does much of his research with a retro-looking, futuristic-sounding machine called the olfactometer. Right away you can smell, rose, eh? Yes, yeah.

This is the olfactometer. This is a big machine. So people will sit down here and just, you will take, some tube like that and then they will put the tube in the nose and they smell and so this huge machine

it's taller than me and so the odors are in these cylinders in the entire apparatus like tubes everywhere in this tall system with all these different compartments these are all here essentially to keep each of these

odorants separate from each other so that they don't get contaminated with other smells with my smell or your smell or anything else that's around one time i brought some lunch here for me and the guys just say hey frank don't do that we can see on the on the screen that the electrical activities because the people are smelling i remember one woman say oh wow i smell really good this lunch what is it and they could see on the on the electrical activities on the brain so this is not good Your lab manager, Frank, told me that the olfactometer doesn't actually measure anything. It sounds like it would, but it's essentially a smell dispenser. Yeah. You're spot on. It's not a machine to measure odors.

There is other affectometers, and there's probably people out there that, you know, have alphectometers, and they actually measure the smells. There's not what we do. And what is, I was saying it wrong, the old. factometer, allowing you to study. Our main research question is with regards to Alzheimer's and Parkinson's disease. Nearly everybody who has Parkinson's disease or Alzheimer's disease loses their sense of smell 10 to 15 years before the actual diagnosis. Currently, we do not have methods to heal the disease.

We can stop the symptoms. We can maybe slow it down in the case of Parkinson's, but there's nothing we can actually do. And the reason for that is that we detect those diseases when they're relatively far progressed, which means that the degeneration in the brain has already happened. So what we are looking for is to find methods that allow us to say, with certainty, several years ahead this person has a high probability to suffer from Parkinson's in 10, 15 years, and this person has a high probability to suffer from Alzheimer's in 10, 15 years. If we would be able to do that, then we could develop interventions that could

slow down the progression of the disease or maybe stop them altogether. So there's different methods that we can use, and one of those methods is with smell testing. One of the problems with developing this sort of smell test is that, as we saw with COVID-19, people lose their sense of smell for all kinds of reasons. Dr. Fresnelli estimates around 20% of people at any given time will have a problem with their sense of smell. But of course, most of those people won't go on to get Parkinson's or Alzheimer's. So what we are working on is finding a specific pattern of olfactory dysfunction specific for those medical conditions.

And this is why we need an olfectometer to do that with high precision. It does sound like smell tests could be quite a powerful medical diagnostic tool. Yes, but olfactory markers do not have the importance in the diagnostic procedure. yet that I think they could have. Do you think people would benefit from having routine smell exams alongside eye exams? Well, of course, my heart as a researcher says, yes, yes, everybody should get smell tests. However, we live in our real world, everything comes with the price tag. Oh, don't worry about that.

So we have to, we have to, of course, think about that as well. But during COVID, when so many people lost their sense of smell, we all of a sudden saw, we have basically no infrastructure to smell testing. And smell testing can actually give us information. After centuries of derision from thinkers who rejected olfaction as inaccurate and unscientific and even subhuman, Modern research is finally revealing the intricacies of smell. Dr. Fresnelli's research on the use of smell tests to diagnose illnesses is just one hint of where the science of smell may be headed.

And as we open up our noses, we're also opening up entirely new dimensions. We don't know how many dimensions smell has. And it still, for the moment, defeats us. although we've nearly cracked it, and my guess is within the next maybe 10 years, we'll have a much better idea of what's going on. If there was one thing you could convey to people who still have the sense of smell,

but maybe don't think about it that much, what would you want people to think about differently or to know, I guess, as someone who's kind of gone with and then without it? Good question. Yeah, I would say, be more mindful about it. Like, there was a reason why we were able to smell things and just, yeah, embrace it more, like, because it gives so much texture to life. I think it is underappreciated how vital and how much it enriches your life.

I want people to just take it in, take every little thing in throughout their day, good and bad. I mean, Earth gave us so much to smell. There's such a big repertoire. And, yeah, it's like a superpower. It's a superpower to embrace. There's a whole invisible world out there. And I don't know about you, but I don't know about you, but I don't. intend to take it all in, one breath at a time.

I'm in Kensington Market on May 1st, and I'm walking past a freshly cut lawn and the smell of freshly cut grass. It smells like childhood and springtime and all things green. You've been listening to Ideas and to a documentary called Smell, the Invisible Superpower. This episode was produced by Annie Bender. Our web producer is Lisa Ayuso. Technical production, Danielle Duval and Gabby Haggorilis. Acting senior producer Lisa Godfrey. The executive producer of Ideas is Greg Kelly, and I,

I'm Nala Ayyed.