Blasts From The Past: Scent

Blogging, Neurology, And Perfume

In the interests of resurfacing things I have written that are not easy to find, I have gone back to a Blogspot site I started in 2009. At a certain age you hope your better stuff won’t vanish. Here is the first post from a blog (it was a real blog) that I started, called Digressions, based on a comment from Plato that someone made to Socrates – that his digressions were the most interesting thing about him. Me in 2009.

The idea of having a blog never particularly interested me before but I've been feeling more and more as if there are things I'd like to have on the 'net that don't necessarily fit well in some of the other venues I habitually use. Wristwatch discussion forums, for instance, are useful professionally and interesting personally, but they're hardly a good place for discussing (say) the neurophysiology of smell (or, in many cases, for being candid about watches in particular and the luxury goods world in general, for that matter.)

Which brings me to the subject of my first blog post, a wonderful book by Luca Turin called The Secret of Scent. It's been out a while -since 2006 -and it's interesting both as a sort of introduction to the fragrance industry (and it is an industry) and as a scientific detective story. The author's spent a good deal of his professional life researching the mechanisms by which we smell, and while he's profoundly fascinated by perfumes, their history, and their design, the book is equally an attempt to present a novel theory of how smell actually works. When I taught introductory neurology at the Swedish Institute we always had to gloss over a lot of the interesting details of how the special senses work -for one thing, stuff like conformational changes in photoreceptor pigments are not of immediate urgent importance to massage students, and for another the material came up at the end of the term, when I would have been hard pressed to get students to come to a lecture on how to use Swedish massage to cure cancer. So I'd parrot the conventional wisdom on olfaction: that odorant molecules bind to a repertoire of receptor molecules on the olfactory nerve endings, and that the almost infinite variety of scent sensations are achieved through the cognitive blending of a combination of receptor types.

Like most explanations of neurological events, there's an air of hopeful hand-waving about all this, and Turin uses the lush world of perfume chemistry to introduce an alternative theory, which is that what we're really detecting is the vibrational mode of odorant molecules. As a lapsed alternative medicine practitioner I'm predisposed to find anything that invokes molecular vibrations suspect, but as it turns out, the concept is based on well accepted chemical science -the vibrational mode of a molecule is more properly known as its Raman spectrum (after the Nobel Prize winning scientist, Chandrasekhara V. Raman, who discovered molecular spectra.) And there are databases of thousands of molecular spectra which have been developed since Raman became interested in the problem in the 1920s. While there are many open questions with the vibrational model, the notion that the nose functions as a spectroscope is a fascinating one. One olfaction researcher who pioneered the theory (Malcolm Dyson) wrote:

"Let us commence the inquiry with a simple case -selecting some group of substances with an indisputably characteristic odor which is unlike that of the vast majority. . . I have selected the mercaptans (-SH) as the most suitable; once their powerful and clinging odor has been observed it forms a most vivid impression and most chemists would recognize it again. . . Is there any corresponding characteristic feature in their Raman spectra? The answer is that there is indubitably a unique feature in the Raman spectrum of all alkyl mercaptans, a line with . . . frequency 2567-2580. No other compound has such a line."

Turin also writes very beautifully about the challenge of understanding science:

"In almost every science textbook, there is one point, usually of paragraph length, where the style of the author matches exactly one's style of understanding, and which we then grasp properly and permanently. The trick is then to read hundreds of books, so that the paragraphs gradually come to cover one's field of interest, like fliers strewn on a football pitch. This, over a period of about ten years, is what I tried to do with undergraduate solid state physics."

And for someone like me, who lies awake nights wondering if writing about luxury products for a living is really an intellectually respectable thing to do, there are his wonderful insider's observations on the frustrating mediocrity that he observes in his own industry:

"Ten years ago, a fine fragrance used to cost 200-300 euros per kilo. These days, 100 is considered expensive. Bear in mind that only 3 per cent or so of the price in the shop is the smell. The rest is packaging, advertising, and margins. The cheapness of the formula is the main reason why most 'fine' perfumes are total crap. Other reasons include slavish imitation, crass vulgarity, profound ignorance, fear of getting fired, and general lack of inventiveness and courage.