Keep sniffing

Anosmia refers to the inability to smell, the lack of olfactory activity. Hyposmia on the other hand refers to an increased ability to smell. It is hard to imagine a world without smell, a curse of sorts, as it is hard to imagine living in a world of enhanced smell, in the sensory world of the dog for example, a curse of sorts too.

Anosmia can be temporary or permanent. A cold or sinusitis or any upper respiratory tract infection may temporarily deprive you of a sense of smell. It is more than likely if not inevitable that you would lose your sense of taste too. Taste and smell are bound together, as if partners in a dance of sensory joy.

Salty, sour, sweet, bitter, umami (richness) and astringent (sharp or severe) are our six distinctive tastes but we are able to smell about 10,000 scents that conspire with taste to give us the magic of flavour. When one can’t smell anything food loses most of its flavour.

A permanent loss of smell, hard to imagine as it is, will be caused by damage to any part of the olfactory pathway, which has three essential parts: first is the olfactory sensory neurons in the olfactory epithelium, second the olfactory bulb and third, the brain’s olfactory cortex. Damage to any part will cause a problem.

Damage to the system can occur at birth due to genetic factors, referred to as congenical anosmia. It could arise as a consequence of Parkinson’s disease and Alzheimers. Environmental poisons, cigarette smoke or nasal sprays may also damage the smell receptors in the nose. And then there is the nasal polyp.

Richard Axel and Linda Buck jointly received the Nobel Prize in Physiology or Medicine as recently as 2004 for figuring out how smell works. Associated with the Howard Hughes Medical Institute, they cast serious light on to what was considered to be a trivial medical problem. Today it is taken more seriously.

Without smell it is difficult to detect gas leaks, fire, body odour and spoiled or rotting food. Without smell, many, many memories, a central part of living in a world of meaning, cannot be accessed from the brain’s system of neural cell memory. It may lead to a loss of libido, sexual interest, possibly impotence.

Still, scientists have established that up to 5 per cent of the genes in the human genome spread over 21 chromosomes coded for what is known as odorant receptors. That is a very, very significant and large number. It suggests that smell served many more functions in our distant past and what may those be?

Smell is often, among humans, viewed as an aesthetic sense. Smell is however a primal sense. It is the sense that afford most organisms the ability to detect food, predators and mates. Smell is therefore the central sensory modality by which most organisms communicate with their environment.

We do not today go around sniffing out predators. We do not have to. The days of living in constant fear of attack and predation is no longer, thankfully, with us. But we still have the machinery to sniff predators out, albeit in idle state. In time, evolution’s natural selection might edit it out of our sensory repertoire.

While we may go around sniffing out good mates, it is not the best or even, in today’s world of ubiquitous fragrance, a particularly viable strategy of choosing someone. Fragrance may blunt the work of that quite separate and special class of receptors to sniff out pheromones, chemicals that stimulate sexual desire.

‘Because smell is not about sex, contrary to popular belief, it’s about food and protection from decaying, poisonous things that can hurt you, to tell you whether whatever is in your hands is good for you’ writes Chandler Burr in the Emporer of Scent (London, Arrow, 2002, p.87).

What is a world without smell? A diminished world certainly. A world where food no longer holds an allure or gives pleasure. A world where you can no longer smell geraniums or perfumes. I suppose the only thing that is worse is to smell stink for fragrance, a disorder that must have a name.

So every morning that we wake to the glorious gift of smell we should say thank you, for it is hard to imagine a meaningful life without it.