Instant Genius - Why Smell is Our Most Overlooked Sense

Episode Date: September 20, 2026

Though often thought of as the poor cousin to our other senses, our sense of smell has played a key role in human life since its very beginnings. It helps us to determine whether certain foods are safe to eat, protects us from environmental dangers such as fire, mould and toxic chemicals, and has even been weaponised for use as a form of racial or economic discrimination. Without it, the world would be a vastly different place. In this episode we’re joined by Dr William Tullett, an historian and author based at the University of York, to talk about his new book, Sniff – A History of Smells. He tells us how advances in technology over the last several centuries have resulted in significant impacts on the odours that pervade our everyday lives, how many of us would rather give up our sense of smell than our phones, and explains how we can all reconnect with our sense of smell to widen our experience of the world we live in. Take your curiosity further with a subscription to BBC Science Focus magazine. Every issue is packed with fascinating insights into the science behind everyday life, the latest breakthroughs and expert analysis, delivered straight to your door. Receive an extra £5 when you subscribe using the code SF5OFF, (minimum spend £20, see full terms and conditions on our website). https://www.ourmediashop.com/bbc-science-focus-magazine-pod30 Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Hurt! Moblad, new season is now streaming on Paramount Plus. Hello, and welcome to Instant Genius. masterclass in podcast form. Every Monday and Friday, you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor, a BBC science focus. Though often thought of as the poor cousin to our other senses,

our sense of smell has played a key role in human life since its very beginnings. It helps us to determine whether certain foods are safe to eat, protects us from environmental dangers such as fire, mold, and toxic. at chemicals and has even been weaponised for use as a form of racial or economic discrimination. Without it, the world would be a vastly different place. In this episode, we're joined by Dr. William Tullet, a historian and author based at the University of York to talk about his new book, Sniff, a history of smells. He tells us how advances in technology over the last several centuries have resulted in significant impacts on the odours that pervade our everyday lives. Tells us how

many of us would rather give up our sense of smell than our phones and explains how we can all reconnect with our sense of smell to widen our experience of the world we live in. So welcome to the podcast. Thanks so much for joining us. Thanks for having me. So today we're talking about your new book, Sniff, A History of Smells. So, you know, it does what it says on the tin, really. It's a book about various scents and fragrances over the years. But that's a really, it's not a topic that you see every day. So what path led you to write this? So I think very many different things led me to end up working on the history of smell. I think one thing is that my dad, as many dads are, was a big history fan and loved in particular his military history. So I went to lots and

lots of transport museums and military museums and also industrial museums as a kid. And they are smelly places. They are full of smells, right? I mean like rust and oil. And, and grease and steam train smoke and things like that. So that was quite kind of formative experience for me. And I think the more I've worked on smell, the more I've felt that clearly other people feel that those kinds of smells in those kinds of museums matter. And I kind of therefore want to understand why they matter to people

and kind of help preserve them, really. But the other thing is that it's kind of not as unusual as you might think it is to work on smell and the past, in the sense that we've all. got noses. We can all smell, or to, you know, to one degree or another. Some of us might be more sensitive sniffers than others. And it was the same for people in the past. They, you know, they had noses, they could smell. And so it's a kind of important part of our everyday experience. And it's also one that we happen to share with lots of other animals, not just humans as well.

So it's this kind of like very wide-ranging thing. Yeah. So sort of quite earlier in the book, you write about how the sense that pervade our lives of undergone. on significant changes over the years. And you bring up a term called the, if I'm pronouncing this correctly, chemocene. Yeah. So what do we mean by that? So I use the chemocene to kind of talk about the idea that we live in a world, particularly over the last sort of two centuries or so, that we have constantly changed by introducing new chemicals in particular into it. So we're maybe a bit more familiar with the term Anthropocene to describe the period since the Industrial Revolution where we have altered the climate and the environment of the earth, often in very damaging

ways. And the chemo scene is really attempt to say, well, an important part of that is the way in which we've introduced loads and loads and loads and loads of new chemicals into our earth, into our water, into our air, that have often had unintentional effects, right? So one of the examples that I give in the book is when we began to add macaptan and other smelly molecules to gas, natural gas to make it smell, so that we didn't have gas leaks. They started to do this in the United States in the 1940s, partly as a result of like an explosion at a school actually that killed loads of people because of a gas leak. And when they started to add macaptan to natural gas,

they discovered that they could find leaks in the pipelines because vultures, and coyotes would congregate those leaks, because McCaptan is a very smelly molecule, and it's one of the molecules that rotting or dead bodies give off. So these creatures were going there because they thought they would find a tasty snack, and of course they were severely disappointed. But it was really good for the people who were running the pipelines, because it made it easier for them to spot leaks. And that's just one of the kind of many unintentional, I think,

kind of results of the ways in which we've manipulated the smells around us, And that's kind of what I'm getting at with the chemo scene. Yeah. So we'll look at some sort of examples that I've picked out of the book. But I sort of first wanted to ask you about this sort of research process. So we'll often watch, you know, dramas set in the past like ancient Greece or Victorian London or something. And, you know, maybe one of the characters will say something like, call blarmy, what a stench.

But as a historian, you know, how do you go about finding out what the past in different areas? actually did smell like? Yeah, this is a really good question. And I think the thing is with smell is that it is everywhere in historical documents. We can find it in loads and loads and loads of different sources. I was giving a talk at my local bookshop in Letchworth Garden City yesterday. And I went around and did some research and found that actually, you know, in some ways, smell was quite important to the early people who developed the Garden City movement

at the end of the 19th and the early 20th century. because one of the things they were trying to do was create a nice smelling natural space in which people could live rather than the horrible smelling kind of late Victorian early Edwardian cities that were really smoky and unsanitary. So it's everywhere once you start looking. And I think the problem has been that a lot of the earlier people who worked on the history of smell, they often looked to those kind of, you know, Dickensian characters living in stench and said, oh, you know, oh, so things must have smelled really bad. so I will look at sanitary documents, right?

Like people who were in charge of sewage and stuff like that. Or they'll take completely the opposite approach and look at perfume. And so you've got this view of the smell of the past that was like very extreme. It was kind of either it smelled really bad or you were looking at really nice smells. And one of the things I tried to do in the book is just look at as many different smells as possible, right, whether they're kind of good or bad and everything in between. Yeah, so let's have a look at some of these. You talk about the kind of link between scent and memory.

So one personal one for me is that it's deeply ingrained. My grandmother's house almost always smelled faintly of bleach. So obviously these days now, we've got loads of these fragranced cleaning products that we use. You know, they smell like you write a lot about the smell of pine, which is a very popular one and things like that. But how far back does this idea of having a nice, fragranced home, or even, as you talk about, a place of worship, go back? Yeah, so the idea that we might want to make our homes smell nice has a very long history. And that's partly because one of the reasons, particularly in the medieval and the early modern period, people scented their homes, was to try and prevent the generation of disease, right?

So, you know, it was not uncommon in, say, the 15th or 16th centuries, particularly in richer households, to burn aromatic herbs and perfumes and things, to try and both get rid of foul smells, but also potentially stop the diseases that those foul smells might either communicate or generate. So it has a kind of longer history, but I think the difference is that, you know, since, I guess, the 19th century and really rammed. ramping up in the second half of the 20th century, we increasingly sent our homes simply for the sake of scenting them rather than necessarily, you know, with any other purpose, right? So, you know, when I talk about pine in the book, one of the reasons that people used pine was because it was believed to have particular properties that were good for the lungs and that were healthy and there were antiseptic and disinfectant, right? So it wasn't just that smell that was important, but the things that the smell did.

Whereas today, you know, what smell tends to do is it either signifies that you've cleaned something. So it's a kind of a lesson to people visiting your house that you have taken care of your property. Or it's essentially just sent for the sake of scent's sake. It's just to, you know, show off a side of your personality, essentially. This is how I like to make my home smell. So I think like it's lost some of that kind of earlier, perhaps. medical and other use that it had in the past. Yeah, so something I'd like to bring on that you kind of touched on there is the connection of scent and the perception of luxury or even class.

Yeah, absolutely. And I think, you know, understandings of class are really central to the history of smell. The history of smell is, you know, in part a history of commercialisation and of the attempt to buy scented products that mark you out as different. So, you know, a good example, I guess, would be something like lavender, which has this kind of long history as a use for scenting clothing and for scenting houses. It has a long association with calming, comforting, kind of soporific qualities, particularly in Britain. But in the 18th century, if you wore a lavender scent,

you were seen as quite dour and boring and, like, bourgeois, whereas all of the really fashionable people were wearing things like Atar or Otter of Roses imported from India that had a kind of much more fashionable cachet. So I think kind of fashion and luxury is really important, but also when we think about class, we're thinking about questions of inequality, right? Because I think one of the big strands in the book is kind of detailing the way in which the choice of which smells we get exposed to, particularly nasty smells. are often determined by our space within the social hierarchy and our kind of access to economic and political resources. So, you know, a good example of that is the development of intensive livestock agriculture in the 20th century where, you know, if you have, particularly early on,

if you had to live next to one of these really big chicken or pig farms, it was absolutely horrific. And the only way to get around that was either moving, which was difficult because the presence of that farm would mean that the value of your home would significantly decrease, so it would be difficult to sell it. So you could only move if you had lots of money, or to stop it happening in the first place, which of course required political power and influence.

So I think, you know, George Orwell once talked about how the working classes smell, right? He was taught that as a child. He talks about this in the road to Wigham Pier. And, you know, the idea that the working classes smell is partly something that's ingrained in middle class minds to stop them from engaging with working people and to almost sort of fear them and keep them at arm's length. But there's also a sense in which the working classes smell often

because they have been exposed historically to horrible conditions that have made their world smell. And that's been one way of signifying class difference. Yeah, so sort of even if you're middle class and you go down a mind for 10 hours, you're probably not going to smell great, are you? No, no, precisely, right? And I guess, you know, I guess maybe part of the difference would be there, you know, if you're a middle class, you know, I mean, obviously minors, you know, particularly in the 19th and 20th century,

were more likely to come out the pit and be able to wash and stuff afterwards, right? But, you know, clearly if you're a middle class person, you can go and have a nice wash and then put on some nice clothing and go back to your relatively nice smelling home. So you don't have to endure the smell in the same way, perhaps that somebody of a lower status might. So it's sort of related to this. It's one really interesting study that I'd like to pick out. That was carried out in Germany, if I'm correct, in a cinema. They used a mass spectrometer to analyze the odors and the fragrance of the people who were watching the film playing.

And they could figure out what age rating it was. Yeah, so the idea, essentially, of this experiment in Germany was that they use a mass spectrometer to measure the smells that were in the air of the cinema. And in doing so, they were able to measure certain molecules. molecules that were given off by bodies, particularly when they're in states of stress or excitement, right? And the idea being that the more stressed and potentially the more excited you are, the more likely that the film might receive a kind of a higher age rating. This isn't something obviously that's been taken up by the people who are in charge of deciding

whether our films are, you know, PG or 15 or 18, whatever. But it's a really interesting idea. And I think it speaks to this kind of really interesting term since, the mid-19th century to thinking about smell in ways that are potentially quantifiable. Because one of the really difficult things with smell is it's famously difficult to measure. But starting in the kind of the middle of the 19th century, you begin to see people experimenting with various scientific instruments. So one of them is called an olfactometer, which is invented by a Dutch psychologist called Hendrik Zwadamek.

And he's a kind of pioneer of smell psychology. and what the olfactometer does is it allows you to measure either the strength of a smell or how strong somebody's sense of smell is. So they can begin to kind of build up a kind of quantifiable understanding of like how good is the average nose at smelling and how powerful is a smell, right? And that has then kind of informed lots of later, particularly in the 1970s and 1980s, regulations about things like odour pollution, where one of the things you need to do is understand, you know,

what's the threshold at which a smell can be detected and therefore, you know, how far away do we need to build one of those chicken farms or pig farms that have blighted the noses of many people? Guessing is for game shows, not your business. Workday is the enterprise AI platform for HR, finance and IT, with AI grounded in your context to get work done and done right. It's a new workday.

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We mentioned earlier that, the connection between kind of personal expression and fragrances. And so, you know, perfumes and clones, etc. have been around for, you know, an awful long time. And, you know, of course, a lot of the traditional ingredients do come from plants. But a lot of people probably don't know that traditionally, a lot of traditional ingredients in these fragrances come from the glands of animals. Yeah, absolutely. And this was the case up to a very late stage, right?

So it was only really in the second half of the 20th century that all of those animals secretions that we use in put, had been using in perfume. began to be replaced by synthetics, partly for animal cruelty reasons, partly because they were cheaper, partly because of simply lack of supply in the case of of some of those ingredients. And I think it's something we often forget. I think there's a tendency in popular culture to imagine that, you know, particularly the kind of the medieval and the early modern world of perfume and of scent as one that's kind of all about plants and herbs and kind of, and indeed, there are advertising campaigns by actual companies in the UK who promote their

perfumes by saying, you know, oh, up until the 19th century, everything was made with plants, and now we have these nasty synthetics and we're going to, but we're bringing back natural perfumes, right? Which is all nonsense. But it plays into a sort of understanding of the pre-modern world as like more natural. But actually, you know, we were using civet. So civet is from the civic cat, scraped from the perineal gland of the civic cat. It's brown, it's unctuous, it's what we would politely fecal smelling. There's musk, which is from pods in the musk deer, imported largely from places like China and Mongolia and Russia. And then you've got ambergris, which is sort of like, as well, a loose explanation would say it's whale sick that's washed up and coagulated in the ocean.

The smell changes as it floats around and then it washes up on beaches. And all of these substances have been used in perfume, partly because they're really good, what we call fixatives. So they help, basically, they help perfumes last longer by reducing the kind of overall, what we call the volatility of the smells that are in that perfume. So they help that kind of give it that staying power, basically. And even in the 16th and 17th century, people like Robert Boyle and Francis Bacon knew this and kind of wrote with wonder about the fact that these smells could last forever and ever and ever. Yeah, so sort of central, if we're talking about, smells, and we should really talk about a sense of smell, which presumably we have to help us determine

what's good to eat and, you know, help us keep away from danger and things like that. But you talk, you cite, study in the book where young people were surveyed, I think it was 16 to 30 years old. And they said, you know, what would you prefer to give up? Your sense of smell or your phone. and the majority says, well, I'd give up my sense of smell. Yeah, right, which is, I think, I mean, it's surprising but also not surprising. It's surprising in the sense that, well, you know, this is part of our, you know, amazing bodily sensory organs. Why would you want to give that up? And indeed, you know, I suspect if you ask those who suffered from temporary anosmia during COVID,

as a result of contracting the COVID virus, they would probably say, actually, no, smell. is quite important. But I think it's also unsurprising in the sense that we do live in this world of screens and of AI and stuff where the visual and sometimes the auditory, what we hear, are given much more importance. And they're given much more importance partly because children are taught to use their eyes and their ears and they're not taught necessarily to use their noses. So we grow up in a context where, you know, to smell is understood pejoratively, right? We tend, you know, if you go to school, you're not taught how to use your nose, but what you are taught is that smelling is bad and that those who smell bad will get bullied, right? Which is awful,

right, because there are lots of people in this country, in the UK, who experience hygiene, poverty and can't afford necessarily to get deodorant or shower gel or whatever, and therefore or at the mercy of people who are going to bully them potentially for not smelling as clean or not smelling at all. So yeah, so I think it's basically that we're not taught from an early age to engage our sense of smell. So then why would we choose to value it? Nobody's told us to value it. Yeah, so having said that, you know, is it possible that we can we can do something about this? Like can we sort of train our sense of smell, I guess? So personally, I really like cooking. I've got like hundreds of recipe books.

And my favourite ones are always the ones that talk about smell, you know, like cook the rue until it's nutty or reduce the wine until it doesn't, you know, the alcohol doesn't offend your nostrils, etc. Like people like Jeremy Lee or Fergus Henderson, if you're interested in this sort of thing. How can we get people, how can we get smell back, like, up the hierarchy? Well, I mean, I think you've kind of hit the nail on the head there

in the sense that one way that we get people to re-engage with a sense of smell is just to do more things where they're explicitly involving their nose, right? I think that one way to look at this is that smell is in some sense like a muscle, and the more you train it, the more you use it, the better you will be at being able to identify and describe and compare smells, right? And one of the reasons for that is that the way we describe smells is either what perfumers call hedonics, so whether it basically, whether it's nice or nasty, does it please you or does it offend you. Or we reach for a kind of series of material comparisons, right? So we say, oh, this coffee

smells like bread or this tea smells like prunes, right? Like we use these kind of comparisons as a way to help us describe smell. And so if that's the case, then all you need to do is build up your list of comparisons, right? Smell more things so that you know more things and what they smell like, and then you can use them to compare them to other things. So, you know, go for walks, you know, go and sit in your garden and smell different stuff, even if you don't expect it to have a smell. And that doesn't just include nice smells. One of my fellow researchers on smell called Kate McLean does this amazing work where she takes people on smell walks and then she develops smell maps of like what places smell like. And she gets people to smell bins, you know,

all kinds of things because, like, everything has a smell. And once you kind of get past the stage where it's just about whether it offends you or whether it pleases you, I think you begin to see that like all smells are made up of all of these different molecules and they're often quite complex and they resonate with people in different ways. So yeah, the world is your olfactory gym. So you should just go out and train it. Thank you for listening to this episode of Instant Genius brought you from the team behind BBC Science Focus. That was Dr William Tollett. To discover more about the topics we've just discussed, check out his book.

Sniff, a history of smells. If you liked what you just heard, then please do consider subscribing to Instant Genius on your preferred podcast platform. If you'd like to see our guests and hosts and person, then why not check out our YouTube channel, at Science Focus. If you've enjoyed this podcast,

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