Ideas53:59Smell: The Invisible Superpower
When Jessie Cabot lost her sense of smell in 2021, the absence that hit her hardest was the scent of the sea.
Aromatic sea breezes used to bring her back to childhood summers on the beach. Now, when she visits her parents on the New Zealand coast, the air has no fragrance at all.
“It changes my whole relationship to the world,” Cabot, 32, told CBC’s Ideas.
Cabot, who lives in Montreal, doesn’t know what caused her loss of smell, which came on gradually over a period of months. But it occurred at the height of the COVID-19 pandemic — at a moment when millions of people around the world found themselves without smell or taste after contracting the virus.
As the loss of smell — known medically as anosmia — has become a less common symptom of SARS-CoV-2, many of those who continue to suffer feel misunderstood and forgotten.
“People tend to tell me, ‘Oh, you’re so lucky. At least you don’t smell the bins, compost and all these horrible, you know, smells,'” Cabot said.
“I feel like it’s taken for granted.”
For millennia, the sense of smell has been widely undervalued — ranked far below vision by the likes of Immanuel Kant and Sigmund Freud. In 2021, a survey in the journal Brain Sciences found that people consistently ranked smell below vision and hearing — and even below commercial products. One quarter of college students surveyed said they’d prefer to give up their sense of smell than their smartphones.
But modern research suggests that smell, also known as olfaction, is less dispensable than we might think. In recent decades, we’ve gained a greater understanding of just how much humans rely on the sense of smell — for everything from social communication to the detection of environmental hazards. Researchers even believe that changes in patients’ sense of smell could eventually be used to diagnose neurodegenerative diseases.
As the science of smell continues to progress, it’s becoming increasingly clear how much we stand to gain by focusing on it.
The surprising functions of smell
During the Enlightenment, Kant, a German philosopher, famously dismissed the sense of smell, calling it the “least rewarding” of all the senses. He argued that it is more likely to pick up bad smells than good ones.
But those who enjoy gastronomy may beg to differ.
When Derek McLeod, 43, lost his sense of smell in 2017, the experience was life-altering — particularly when it came to food.
“I would bake bread,” the Toronto-based furniture designer said. “Bagels, all sorts of baked goods. And [I] really, really enjoyed cooking.”
Since becoming anosmic, however, those pleasures have largely evaporated.
“I’m grocery shopping and I walk through the store just completely aimlessly,” McLeod said. “I don’t have any desire for anything.”
While smell and taste are typically treated as separate senses, most nuanced flavours are actually experienced through retronasal olfaction — a form of smell that’s taken in through our oral cavity, rather than our nostrils.
For McLeod and others who cannot smell, food is largely reduced to texture.
“I stopped drinking coffee,” McLeod recalls. “I was sipping it, and it [was] just like, ‘This is just, like, weird water. Weird hot water.’ It was such a strange sensation that this beverage I’ve loved for 20 years is now, like, wrong … it’s broken.”
Olfaction also plays an important role in our health and safety — thanks to the unpleasant odours that Kant dismissed.
Earth gave us so much to smell. There’s such a big repertoire … It’s like a superpower.– Jessie Cabot
“We smell gas, we smell smoke, we smell rotten food,” said Dr. Johannes Frasnelli, a researcher and professor studying olfaction at the Université du Québec in Trois Rivières.
In certain cases, our ability to detect “off” foods using our sense of smell may actually be superior to that of other animals — including dogs.
According to Frasnelli, that’s the case for certain alcohols produced through fermentation. It’s a sensitivity that would have made evolutionary sense for our foraging ancestors as they sought food, helping them to discern the smell of overripe fruit.
And it’s just one of many ways in which humans’ sense of smell is better than we typically assume.
Smell as a subconscious language
Every now and then, if she leans in very close while cooking, Cabot will smell the slightest hint of garlic. It’s one of the only smells she’s perceived in years.
“I automatically close my eyes and smile,” she says. “It feels like travelling time.”
Frasnelli, who specializes in the neuroanatomy of olfaction, says our memories and emotions are processed in the same part of the brain that is responsible for processing smell — creating an “intimate link” between our experience of all three.
But our sense of smell doesn’t just help us connect with our own memories and emotions. It also helps us to communicate with others, primarily through body odours like sweat.
“We communicate if we are related, if we are partners, if we’re strangers, if we’re happy, if we’re sad. All this is communicated via our body odours,” Frasnelli said. “We process it, even if we usually don’t perceive it consciously.”
One famous 2008 study found that humans are capable of detecting the scent of fear in others’ sweat. In 2015 a study from Israel’s Weizmann Institute of Science found that after a handshake, people consistently brought their own hand to their nose — subconsciously smelling each other. The researchers surmised that we could be taking in chemical information about each others’ health or social status.
When Cabot describes her experience of anosmia, she comes back again and again to one word: neutral.
“I feel like I’m in a neutral environment,” Cabot said. “I lost all [the] nuances.”
Lessons from COVID-19
While the loss of smell emerged as a possible symptom of COVID-19 as early as March 2020, it took months for governments to add it to their screening guidelines for the virus — even after researchers flagged it as one of the most accurate indicators of infection.
“We all of a sudden saw [that] we have basically no infrastructure to do smell testing. And smell testing can actually give us information,” said Frasnelli.
Frasnelli says he believes smell tests could one day be used as a medical diagnostic tool for other illnesses as well — including neurodegenerative diseases like Alzheimer’s and Parkinson’s, which tend to be preceded by a loss of smell.
“There’s many reasons why you can lose the sense of smell that have nothing to do with Alzheimer’s and Parkinson’s,” Frasnelli noted. “And so we are working on finding really specific olfactory markers for those diseases.”
Meanwhile, millions of people worldwide continue to suffer from anosmia.
A recent study published in the academic journal Life suggests that at least seven per cent of those who lost their sense of smell to COVID-19 have never fully recovered it.
And the sense of smell is fragile — susceptible to everything from a sinus infection to head trauma or even cancer.
For Cabot and McLeod, both of whom have been living with anosmia for years, the absence is still deeply felt every day.
Their message for folks with an intact sense of smell? Don’t take it for granted.
“Earth gave us so much to smell. There’s such a big repertoire,” Cabot said. “It’s like a superpower. It’s a superpower to embrace.”
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