Last year, a British woman named Joy Milne made headlines for a seemingly superhuman ability: She could smell Parkinson’s disease.
Several years before her husband died of the disease, as the BBC reported, Milne had noticed that his scent had become slightly muskier. One day, while at a lecture on Parkinson’s, she mentioned the scent to a few of the scientists in attendance, who brought her into a lab to test her claim: The researchers gave her 12 T-shirts, six that had been worn by people with Parkinson’s and six by people without, and asked her to tell them which ones belonged to people who had the disease. At the time, Milne correctly identified 11 out of 12 — and she was later proven right on the 12th, when the owner was diagnosed with the disease months after the experiment.
When you consider the animal kingdom as a whole, Milne isn’t that unique: Scientists have long been training dogs, rats, and other animals to sniff out diseases like cancer and diabetes. Within her own species, though, she’s a clear anomaly — and indeed, as news of her ability spread, plenty of articles hailed her as a “super smeller.” Whether or not that label holds any weight, though — most smell researchers argue that there’s no such thing — Milne was remarkable for another, simpler reason: She paid attention to smell, a sense that, by most of us, is woefully underused. Even those of us who lack unusual smelling abilities are missing out on a trove of accessible sensory information, one that makes the world a little richer and a little more vibrant, for no reason other than our own ignorance to it.
To be fair, when it comes to smelling disease specifically, rats and dogs are more biologically suited to the task than we are. Many animals rely on smell as an important tool for helping them make sense of the surrounding environment; humans, though, have better options. “We can see the world beautifully through our eyes and don’t need our nose to define what’s in front of us,” says Alexandra Horowitz, a psychology professor at Barnard and the author of Being a Dog: Following a Dog Into the World of Smell.
But just because we don’t need smell to the same extent doesn’t mean we don’t need it at all — it’s just that unlike sight or hearing, we don’t really notice how much we use it. “People who are anosmic [have no sense of smell], they really feel like they’re missing out on a huge amount,” Horowitz notes, both in terms of the sense’s practical uses — “there are smells that tell you when something is safe or dangerous, [like] if milk is spoiled or good, or if there’s a gas leak,” she says — but also the things we take in unconsciously, like the smell of a loved one or a home or a pet.
Enhancing your sense of smell, then, is mostly about become more cognizant of what you’re already smelling. As part of her research for Being a Dog, Horowitz took an introductory perfumers’ class, where she learned to identify different odors without any cues, visual or otherwise, to help her place them. The experience made her keenly aware of how much she’d been missing out on: “I think noticing those things, as opposed to them just unconsciously happening to us, is somewhat enriching,” Horowitz says. “The richness of the smells of the urban world and the natural world — it’s a little discouraging to think that I went for 40-something years without noticing most of those, or only noticing them when they happened to blast into my nose.”
But it’s hard to pay attention to something we have no words for — and smell, one of the least-understood senses, also lacks its own vocabulary. “In most languages, we don’t have words for smell — we say we like it or we don’t like it, or we say it smells like X object,” says Gary Beauchamp, a researcher at the Monell Chemical Senses Center in Philadelphia. “We don’t have words like green and red and pink for smell, for the most part.”
Some people do, though: perfumers, but also sommeliers and chefs and others who work in jobs where an acute sense of smell is a required skill. Beauchamp argues that having the necessary vocabulary, more than any innately superior perceptual ability, is what allows members of those industries to smell what others miss: “These people are remarkable, but what they’re remarkable about is, they can take something complicated and name it.”
There’s no one universal scent language, however, meaning that each of these each industry works within its own specific set of terms — and that it’s possible to the rest of us to develop our own, too. “If you start to describe the odors using lots of words — maybe it evokes an object or a time in your life or a season or a place — then it does become easier to recall that smell later,” Horowitz says. Having the name already in your mind makes it that much easier to pick out the scent that matches, but the word itself isn’t what’s important; it’s that the word forces you to pay attention.
And research has shown that focusing in on a smell really can change how you experience it. The way you perceive a given scent will likely be a mix of genes and circumstance; as an example, Beauchamp cites a widely studied chemical called androstenone, a boar pheromone (incidentally, the compound is also found in truffles, which is why pigs are so successful at sniffing them out). Depending on genetic makeup, some people find the scent strongly unpleasant, while others can’t detect it at all or even perceive it as sweet or vanilla-y — but research has shown that even people who initially couldn’t smell it were able to do so after training.
But it’s unclear just how much potential we’re allowing to go untapped — even scientists can’t agree on the limits of what the human nose is capable of. One buzzy 2014 paper, published in the journal Science, claimed that humans could detect more than a trillion different odors. Last year, a pair of researchers published a rebuttal in the journal eLife, arguing that the original paper had used faulty calculations and that one trillion was actually the upper limit (and that the true number may be as low as several thousand).
And as writer Maddie Stone noted in Gizmodo last year, the debate isn’t likely to be definitively settled anytime soon, because our definition of smell is still so fuzzy: “We have clearly defined boundaries for human vision (390–750 nanometer wavelengths on the electromagnetic spectrum) and hearing (20–20,000 hertz), and we also have a pretty good understanding of the resolution of these senses — that is, how far apart two colors or frequencies have to be in order for our senses distinguish them,” she wrote. “Smell isn’t so straightforward,” because “[m]ost of the scents we encounter in nature are actually mixtures of tens to hundreds of different, odorous molecules.” A given color occupies its own distinct place on the visible color spectrum; a smell, on the other hand, is rarely its own, pure thing.
This much is clear, though: The more effort you make to interact with the olfactory world, the wider the olfactory world becomes. “If you’re sitting at a desk, you’re surrounded by dozens of objects that have smells. It could be your wallet or a plant or paper or books or the metal of a pen or a pencil — anything that you see around you, if you just bring it to your nose and start sniffing, you realize it carries an odor,” Horowitz says. We’ve gotten lazy with our noses — because we’re typically aware of scents only when they smack us in the face, it’s easy to forget that everything smells, if you get close enough.
