Don’t underestimate the human sense of smell!

MARION AND I SHARED three mandarins yesterday, and were struck by the differences in taste. We declared the first the winner, the second relatively lacking, and the third must have been older.

But are we interested in taste? The evidence is that we moderns are alienated.

English speakers only added umami (savoury) to the standard four tastes of sweet, salty, sour and bitter towards the end of last century, and there’re more, seemingly, including fattiness.

We separately detect texture, temperature and “cool” menthol, “hot” chilli, “stinging” carbonation, etc, as well as the crunchy sound of those mandarins. On top, flavour relies on aroma, detected in the nose, and far too neglected.

Scientifically, Linda Buck and Richard Axel only discovered something as crucial as the human olfactory receptors as recently as 1991, sharing a Nobel Prize in 2004 (see explanatory diagram below).

As well, taste depends on the surrounding aesthetics and social comforts, and mindfulness.

Nonetheless, it’s an ill wind … The the science of smell has looked up these past months, after its loss (called anosmia from Greek an– not + osm­é smell) turned out to be a tell-tale characteristic of covid-19 (less so with the delta variant).

The sense can remain absent with long covid, and, if it returns, become mixed up. Under parosmia, normally pleasant smells can turn nasty, a problem for relationships.

Dogs and bees have now been trained to sniff out the virus in humans, and people presumably could, too, once they removed their masks – you might recall that good, old-fashioned, pre-“telehealth” doctors used smell as a diagnostic tool.

“What can covid-19 teach us about the mysteries of smell?” asked Brooke Jarvis in the New York Times magazine. As she explains, “The virus’s strangest symptom has opened new doors to understanding our most neglected sense…

“Where vision depends on four kinds of receptors — rods and three types of cones — smell uses about 400 receptors, which are together estimated to be able to detect as many as a trillion smells.”

Being anosmic herself, Jarvis already knew how modern people regard smell as the least important sense, the one they would be most willing to lose. Yet its loss devastates them. It’s dangerous not to smell the smoke of a fire, let alone “off” food, but it’s the pleasure that people miss.

Olfaction has tremendous hedonic importance. Smell sensations are now known to run through the olfactory bulb in the brain not to any one site, as with sight, but more widely to the brain, and not just for identification, but also to connect to memory and emotion. Smell is important for life’s enjoyment.

While doggy webpages continue to boast incredible canine abilities, in a breakthrough paper entitled “Poor human olfaction is a 19th-century myth” in 2017, Rutgers University neuroscientist, John McGann, decided:

The human olfactory bulb is actually quite large in absolute terms and contains a similar number of neurons to that of other mammals. Moreover, humans have excellent olfactory abilities. We can detect and discriminate an extraordinary range of odors, we are more sensitive than rodents and dogs for some odors, we are capable of tracking odor trails, and our behavioral and affective states are influenced by our sense of smell.

Pigs and dogs only seem superior for detecting truffles from their wonderful aroma (as in the beautiful movie, Truffle Hunters), because they have their noses closer to the ground, and are rigorously trained.

We are taught to read good books and admire great art, with few introductions to scent. Wine and perfume lovers undertake their educations as adults.

Ironically, lockdown gave a boost to sight’s dominance, as we concentrate on one continuous screen in hand and on wall, showing visual gags, slick dances, cool lifestyles, emojis, binges, cats, recipes presented by stylists, and cooking game shows (satirised in the kitchenette opera, Chop Chef).

But a wide world of smells or “osmocosm” has its supporters. That derivation from osme, the ancient Greek for ‘smell’ or ‘odor’” comes from food science writer Harold McGee in one of at least three books on the sense of smell that showed up as the virus struck:

• McGee, Harold (2020), Nose Dive: A field guide to the world’s smells, London: John Murray
• Barwich, Ann-Sophie (2020), Smellosophy: What the nose tells the mind,Harvard University Press
• Dunn, Rob, and Monica Sanchez (2021), Delicious: The evolution of flavour and how it made us human, Princeton University Press

Even the human ability to detect a “trillion” separate odours is undoubtedly an underestimate, cognitive researcher Asifa Majid has now just reported in the journal, Trends in Cognitive Sciences. She has located conjectures as high as 10⁹⁰ potentially detectable smells. “Contrary to the view that we are microsomatic [poor smellers], humans have higher odor sensitivity – that is, lower odor detection thresholds – than animals traditionally considered to be super smellers, including dogs and pigs.”

Majid is waking scholars to enormous cultural differences in the sense of smell. She reports that English has strikingly “few words for smell qualities” and “smell talk is infrequent, and people find it difficult to name odors in the laboratory”. From surveys, English speakers encounter vision words 1768 times more often than smell words.

Not having specific words, requires speakers to improvise, so that wines exhibit “pepper”, “vanilla” or “raspberry” notes. As a Ph.D. candidate at Monash University, Thomas Poulton, puts it, lacking many smell words, Australian English speakers resort to source-based descriptions, saying “like mint”, for example. He has just published a paper in Language and Cognition finding that, by preference, we rate a smell as pleasant or unpleasant, finding it “sweet”, for example.*

Cross-cultural data tell a different story. Many languages “have large smell lexicons (smell can even appear in grammar) in which smell talk is also more frequent and naming odors is easy”.

Majid is a leader in research that is finding hunter-gatherer cultures to be highly attuned. Unlike we moderns, hunter-gatherers give names to, and talk about, numerous smells. The olfactory “codability” is high. Linguists refer to the ease with which speakers find the right word as “codability”.

While the olfactory aspects of Indigenous Australian languages have been little studied, Clair Hill from the University of NSW has contributed pungent evidence from Umpila to an international study.** Umpila is still spoken among elders forcibly removed to Lockhart River, far north Queensland.

Remember that English shows high codability for colour, shape, and sound, and low codability for touch, taste, and smell. Hill’s data show that the Umpila language is precisely the reverse – whereas colour is ineffable (only three specific colour words – for red, white and black), the conversation bursts with smells.

Again, in Malay, shape is the most codable of the senses, on average, and smell the least; whereas, “in Umpila the exact opposite pattern holds—smell is the most codable and shape is the least”.

For pleasure, if no other reason, we’ve got to re-engage with smells.

Yet again, Brillat-Savarin proved ahead of his time with Physiology of Taste (1826). His first two “Meditations” cover scientific aspects of the senses, and taste, in particular. Taste is “the one of our senses which, all things considered, gives us the most pleasures”, he explains (§13). The rest of the book then examines the “moral history” of this most fundamental of senses, making for an Economics of Taste (as I argue in Meals Matter).

Even while carefully analysing the process, Brillat-Savarin tends to use “taste” for the combination of taste, other detection in the mouth, smell in the nose, plus the contributing factors, including physical and social circumstances, and attentiveness.

Next time Marion and I share mandarins, I should perhaps make tasting notes, articulating the finer aspects of the experience. Or maybe just enjoy them.

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*Poulton, Thomas (2020), “The smells we know and love: Variation in codability and description strategy”, Language and Cognition, 12(3): 501-525

**Majid, A. et al., “Differential coding of perception in the world’s languages,” Proceedings of the National Academy of the Sciences USA, 6 November 2018; 115(45): 11369–11376

***Clair Hill has a chapter, “’Language of perception in Umpila”, in the Oxford Handbook of Language of Perception, published next year.

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