The quiet motorway between your nose and your heart
In the small town where I grew up there was a little pharmacy. A woman of around sixty worked there. I can still see her face as though she were standing behind the counter this very moment: calm, focused, with something in her expression that a nine-year-old reads at once as safe and wise. She made her own salves and lotions, and the whole shop smelled of her work.
On weekend mornings my mother would sometimes give me money to fetch painkillers. For me that was a small moment of pride — out on my own, with a task, opening that door behind which a whole world of scent lived.
Today — thirty-odd years later — I sometimes spray a perfume that puts me straight back in that pharmacy. Not as a thought. Not as a memory I deliberately call up. Instantly. Before my mind can say a word, I am there again. Nine years old, a note clutched in my hand, and the woman I have never forgotten looking up from behind her counter.
What is it about scent that can do this? Which route do those molecules take through my brain to send me thirty years back in half a second? That is what this piece is about.
The oldest sense
Of all our senses — sight, hearing, touch, taste, smell — smell is the oldest in our evolution. Long before our ancestors had eyes that could see sharply, they already had a system for smelling their surroundings. Scent told them what was edible and what was poisonous, who was kin and who was a stranger, which ground was safe and which was not.
That is why scent has settled into a different part of our brain than the other senses. Smell is not a luxury sense we picked up along the way. It is a survival sense, sitting deeper than we realise.
The direct line
Picture your brain as a large office building. When you see, hear or taste something, that signal first goes to a kind of central reception, where it is checked and filtered before it travels on to the departments for emotion and memory. That reception is called the thalamus — a control tower in the middle of your brain that receives almost all sensory information first.
Almost all. Because smell largely takes another route. A large part of the scent signal does not stop at the thalamus first; it travels very nearly straight to the regions that deal with emotion and memory. In that, smell is unique among our senses — it is the quiet motorway between your nose and your heart.
The American brain scientist Venkatesh Murthy puts it like this: scent information reaches the limbic system — the area where emotions and memories live — more directly than any other sense does. The other senses have to wait in the waiting room. Smell walks straight through.
Three neighbours in your brain
So what happens at the place where scent arrives directly? Three regions receive the signal almost at the same moment. I like to picture them as three neighbours, each with her own speciality.
The first is the amygdala: a small almond-shaped region that produces emotions — fear, excitement, joy. When scent reaches her, you feel something before you understand what you are smelling. That is not coincidence, it is order: emotion comes before comprehension.
The second is the hippocampus, the keeper of your autobiographical memories — who you were, where you were, what you were doing. When scent reaches her, she opens the drawer with exactly the right memory: a particular morning, a particular kitchen, a particular person.
The third is the orbitofrontal cortex, further toward the front of the brain. Her speciality is judging pleasure and dislike: do I find this lovely or not? That is why the same scent — jasmine, oud, cumin — can be a love for one person and something to avoid for another.
Three neighbours. Three responses. At once, in milliseconds, before you have consciously noticed a thing. That is why a scent can move you to tears before you understand why. That is why a scent in an unfamiliar supermarket can suddenly make you fourteen again.
A French writer wrote it down long ago
Long before science could show this with brain scans, the French writer Marcel Proust had already written it down. In À la recherche du temps perdu he describes dipping a madeleine — a small cake — into his tea. The smell, the taste, and suddenly he is no longer a grown man but a child in his aunt’s house. A whole world he had forgotten unfolds.
Scientists now call this the Proust effect: the phenomenon where a scent sends you back into a moment from your past in a fraction of a second, with a vividness other memories rarely reach. Research backs this up: scent-memories feel more emotional, give a stronger sense of being “brought back in time”, and cluster strikingly often in our first ten years of life. A photograph shows you a face. A song lets you feel an era. But a scent puts you back in the very chair you sat in then. The difference between an ordinary memory and a scent-memory is the difference between a postcard and a time machine.
Not only memory — emotion without a past
Scent can also stir emotion with no past beneath it. Not long ago I smelled a perfume I did not know — no memory, no place, no person. And still it moved me. Something in that scent was innocent, clean, lovely in a way I struggle to put into words. As if, for a moment, someone handed me back what life tends to take away — not a memory, but a state of being.
For me, as a woman who works at a hospital and who some years ago learned for herself what it is to lose her sense of smell, that scent was more than a beautiful moment. Some scent molecules fit the receptors in our nose in a way that calls up emotion without needing a story. It is as though scent speaks a language older than words — and the part of us that still understands that language sits deeper than our consciousness.
The third way — a scent that builds an image
There is a third way scent works in some people — myself included. Not everyone experiences it. Some scents build an image in my head straight away. Not a memory, not a vague emotion, but a whole scene with people, movement, light and atmosphere.
There are perfumes in which I see a person physically at work. Focused, full of life, with the sweat of effort on their forehead — not the sweat of being unwashed, but of toil and dedication. No office, no screens: body, material, resistance, movement.
This touches on what researchers call olfactory imagery. People differ greatly here: for some, a scent summons a complete picture, while others see almost nothing. Some researchers compare it to the way musicians can hear music in their heads with no instrument playing.
The quiet sense
What has fascinated me for years: how powerful this sense is, and how poorly we can name it. We have hundreds of words for colours, for sounds, for textures. But for scent we almost always borrow words from something else — “floral”, “fruity”, “woody”, “warm”. We borrow from plants, tastes, temperatures. We have no language of our own for what we smell.
With a few exceptions. The Jahai, a hunter-gatherer people on the Malay Peninsula, turn out in research to name smells as easily as colours. Their language has its own words for them — not borrowed from plants or tastes, but specific scent categories. The cognitive scientists Asifa Majid and Niclas Burenhult documented this in research published in 2014. Follow-up work with another people in 2018 showed that it is the hunter-gatherer way of life — and not the language family itself — that explains this ability.
The rest of us — in our cultures built on seeing and hearing — have largely lost that ability. Not because our nose works less well, but because our language does not ask for it. What we cannot show or say slips into the background. But it does not disappear. It waits.
What this means for you
- If a scent catches you off guard — in a shop, a garden, an embrace — you are not being sentimental. Your brain is doing exactly what it was made to do. You do not need to apologise for tears that seem to come from nowhere; there is a whole science beneath them.
- Scent is an instrument you can use on purpose. A particular coffee in the morning, a particular soap in the shower, a perfume for when you want to grow calm — these are tiny interventions in your emotional system, through the oldest route your brain possesses.
- We live in a culture that has undervalued scent. The smell of fresh bread as you cycle past a bakery is perhaps one of the most honest moments of pleasure in a day that has otherwise gone digital.
Breathe in more deeply. Not as a spiritual exercise, but as an investment in a part of yourself you do not often feed.
In closing
A scent is not a molecule drifting through your nose. A scent is a key that opens several doors in your brain at once: the door to a memory, the door to a feeling with no past, sometimes even the door to an image you had not yet imagined.
That science can now measure this does not mean it became magical — it means the magic was always real. We have simply been given new words for something our grandmothers, and the French writers of a hundred years ago, already knew: that a scent is stronger than you. And that this is not your weakness, but your oldest form of knowing.
What is a scent that caught you off guard recently? And what happened inside you the moment you smelled it?
Related reading
Sources
- Soudry Y, Lemogne C, Malinvaud D, et al. Olfactory system and emotion: Common substrates. European Annals of Otorhinolaryngology, Head and Neck Diseases. 2011;128(1):18–23.
- Murthy VN — quoted in the Harvard Gazette, How scent, emotion, and memory are intertwined (2020); panel discussion “Olfaction in Science and Society”, Harvard Brain Science Initiative.
- Willander J, Larsson M. Autobiographical odor memory. Annals of the New York Academy of Sciences. 2009;1170(1):318–323.
- Stevenson RJ, Case TI. Olfactory imagery: A review. Psychonomic Bulletin & Review. 2005;12(2):244–264.
- Majid A, Burenhult N. Odors are expressible in language, as long as you speak the right language. Cognition. 2014;130(2):266–270.
- Majid A, Kruspe N. Hunter-gatherer olfaction is special. Current Biology. 2018;28(3):409–413.
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