According to an article in the February 2011 edition of Scientific American entitled ‘You Smell Flowers, I smell Stale Urine’, Andreas Keller, a geneticist at Rockefeller University is quoted thus ‘everybody’s olfactory world is a unique private world’. The evidence emerged from several large-scale studies to suggest that large variations exist between how each individual perceives many if not all odours. Keller and colleagues conducted a study involving 500 hundred people who were asked to evaluate a panel of 66 odours for intensity and pleasantness. The results showed the full range of responses from weak to intense and from pleasant to unpleasant.
Meanwhile back in Europe, Thomas Hummel and his associates at Dresden University have tested 1,500 young adults using a panel of 20 odours and found specific insensitivities to all but one – citralva, which has a citrus aroma. Based on the findings of these two studies Keller suggests that each of us has an olfactory blind spot meaning that there is at least ‘one scent’ that each individual cannot detect at all.
There is nothing really unexpected here except that the converse of the last point is not proposed, namely that there are other scents to which each of us might be very sensitive to. In my experience cumin is something to which many people have an adverse re-action to and can detect tiny amounts in a fragrance.
I am left unsatisfied by the conclusions of these studies for three reasons. Firstly, because it doesn’t look at the effects of cultivation of olfaction, secondly I find it hard to believe that as members of the same species we do not have some consensus of experience on the smell spectrum. The third point is that smelling is a psycho-physiological event and as such it is not just about genetics as concluded by both Keller and Hummel.
Common sense and schoolboy logic can be applied to points one and three to show that smell cannot be reduced entirely to the holy single cause of DNA. Let us take the scent of frankincense to make the point. As we know Catholic churches often have the lingering aroma of frankincense because it is still used as incense during the mass. A person’s relationship with Catholicism will likely determine their fondness or revulsion for the scent because it becomes associated with memory through experience. A person at the wrong end of some Catholic loving is unlikely to find it at all appealing. On the other hand a person who associates the smell with the peace offered by the mass to believers who engage meaningfully with the ritual will find the scent appealing.
As babies we arrive fully equipped with an amazingly capable nose but because culturally it is a neglected sense: we do not ordinarily play with it so the faculty in most people becomes unconscious. The process of cultivation of olfaction involves turning it back on and we do this by bringing our awareness to it and using it. The next step is to learn a vocabulary and match this with the experience of smelling a vast array of scents as we do on our courses.
In my book I describe some experiments that were done using sommeliers and people who had not undergone any olfactory training. It was found that the novices could smell every bit as well as the sommeliers but were incapable of describing the notes in the wines that they were given. On a monitor it was possible to see which parts of the brain were active and which passive. When a novice was describing a wine the rational part of their brain was active and when they smelt a wine the limbic system connected to the olfactory bulb was active. However, with the sommeliers both these parts of the brain were active simultaneously. It appears that their training had enabled pathways between these two parts of their brains. This proves that cultivation is possible and logically we can infer that our ability to smell cannot therefore be just genetic.
Now let’s turn our attention to the second point namely that ‘everybody’s olfactory world is a unique private world’. It is well known that people do experience some aromas quite differently. A few months ago I was working on a bespoke fragrance for a client and they kept describing an unpleasant note in a sample I had sent them. The phrase they used repeatedly was ‘it smells like urine’. I couldn’t get this note at all however hard I sniffed. Eventually, we figured it out and the culprit was beeswax absolute. Since then I have encountered several other people who also are reminded of urine by smelling beeswax absolute – so not so unique after all.
Botrytis cinerea is fungal infection responsible for shrivelling grapes whilst still on the vine. The effect is to concentrate the sugar in the grape so that after fermentation there is residual sugar in the wine making it sweet. On the nose such wines have strong aromas of Seville oranges. However, not everybody smells it as such and many commonly will describe notes of lanolin, wet wool, jumpers etc. Many of us get both sets of notes. Again what we see here is not each person in their own unique private world but two or three groups, which is quite a different proposition entirely.
There is certainly a shared language of smell and my experience in teaching perfumery and in numerous wine tastings is that there is a large consensus of aromatic reality. With practice one can use an olfactive vocabulary to make smaller and smaller distinctions. In perfumery this is a necessary skill because when linked to familiarity with ones aromatic arsenal it becomes possible to blend more refined and sophisticated fragrances. The assessment of wine or fragrance will always be entirely subjective but large groups of cultivated individuals will always agree when something is sublime.