The C19th brain surgeon and anthropologist Paul Broca, exemplifies the inherent limitations of elevating ‘theory’ over empirical experiment. He argued, that because a powerful sense of smell was an inherently animalistic trait, it must be far weaker in humans because we are rational beings The idea remained unquestioned for many years, though well before that, indeed, until the C18th, doctors relied on smell as much as anything else. They ‘squeezed, observed, smelled and tasted.’ Diphtheria smelled sweet, scurvy smelled pungent, typhus smelled like freshly baked rye bread and scrofula smelled like stale beer. I confess I rather like the idea of a doctor sniffing me, some doctors at least, others less so. But such fancies are for the moment academic.
The Enlightenment and later Paul Broca disparaged and demolished these age old skills, until now it is widely assumed ‘smell’ is our weak link, the Cinderella of our senses. However it may be, to misquote Mark Twain, the death of this sense ‘has been greatly exaggerated,’ and that we are much better ‘smellers’ than we think.
Yes, the dog has certain advantages, slits in their noses that direct air to the side and not purely forward. The whole nostril is designed for sniffing and, moreover, a wet nose lets it know which way the wind is blowing, should you ever need to know.
Even without wet noses and side slits the human sense of smell is good enough to detect butyl mercaptan diluted to a concentration of 0.3 parts per million – i.e. the rotten eggs smell added to natural gas to warn us of it.
Traditionally, the number of smells we could ‘officially’ detect stood at 10,000. Quite a respectable figure, but one researcher argues that ‘We can probably distinguish as many smells as we can colours – millions of them.’
Others go farther, one scientist arguing that, ‘An analysis of data found humans can discriminate between around one trillion different smells.’ How he or she arrived at that number I have no idea. It would take more than a lifetime to count, never mind catalogue that number of smells, but there you go; who am I to even argue? But this I can understand and appreciate: ‘the human olfactory system which regulates a sense of smell is considerably larger than previously thought and contains a similar number of neurons to dogs and other animals.’
The key difference lies in priorities. Dogs for example are superb at discriminating between the many types of urine on a lamppost or tree, but they’re rubbish with bananas. Moreover, they’re not that impressive with wine. A trained sommelier can determine the geographic provenance of wine varieties purely by smell. Urine or wine, even bananas? I know where my priorities lie.
It is only when it disappears, that people fully realise the power of smell. Thousands of covid sufferers who lost a sense of smell found food meaningless, because taste and smell are so intimately linked. To argue the point, one writer advised holding your nose and closing your eyes to see whether you could tell the difference between ketchup and mustard. They may have a point with ketchup and French mustard. I’m less sure it holds true with English mustard and am not willing to put it to the test.
Smells ‘directly connect to the brain where memory is stored rather than other senses, which get bypassed through a central part of the brain.’ It is why a particular smell can instantly evoke a memory of times past, a particular incident good or bad. It also perhaps explains the negative effects on those who lose their sense of smell—especially of roses, which apparently aids with memory.
A study followed 2,300 people between the ages of 71 and 82, testing their ability to smell by asking them to sniff such scents as chocolate, petrol, lemon, onion and smoke. After a decade around half of the participants understandably died but those with the weakest sense of smell died significantly earlier. A weak sense of smell is also linked to mental decline in later life. Pass me the smelling salts!
A mouse’s sense of smell may also be linked to memory though I’ve never found one to ask. However, scientists have found that by giving a mouse an electric shock whilst it was smelling cherry blossom, saw its grandchildren suffering severe anxiety within smelling distance of the same blossom.
So, smell has met its Prince, several in fact. It is no longer the Cinderella of the senses.
The UCL Institute for the Sustainable Heritage of York University have established the UK Heritage Smell Inventory, where the public can submit suggestions for smells that should be conserved for the future. Ideas so far include bluebells, steam trains and red phone boxes—now perhaps more attractive to dogs. Other suggestions include church hymn books. Personally I’d go for the smell of a packed Liverpool bus on a rainy day, the smell of the Mersey, baked potatoes and the smell of Hartley’s jam factory.
Other countries have the same idea. In 2001, Japan’s Ministry of Environment compiled a list of 100 notable smell-scapes, including the sea fogs of the Kushiro region and the second-hand bookshops of Tokyo’s Kanda-Jinbocho region. Each to their own. In 2001 France passed the Sensory Heritage Law with similar emphases on its own fairly unique
And finally, to conclude with a real visionary, a man before his time. In the mid C19th an 'off the wall' chemist, G.W. Septimus Piesse, combined music and scent with his own especially designed 'perfume organ,'an instrument that emitted one of 46 different smells when a note sounded. It never got farther than the prototype stage, but it may at last have come into its own. Herald the day when churches and cathedrals bless congregations with light shows and a trillion evocative smells. Dream on dogs!
