Your Mind-Boggling Guide to Whisky, DNA, and Olfactory Diversity

Our olfactory system, the collective name given to our nose and its aroma-related apparatus, is truly remarkable. Not only due to its complexity, sensitivity and profound impact on our everyday lives. But also, because in a world that has created Artificial Intelligence, Quantum Computers, and Boris Johnson, the olfactory system remains one of the largest mysteries.

While we understand bits of the system, the crucial process of how our odour receptors identify individual molecules is still surrounded by head-scratching and occasional prodding. But we do know some things. One of the most reassuring notions to emerge is the fact that we all smell things differently.

This may not come as any big surprise. After all some people have become well-known for their heightened sense of smell. Perhaps even taking the precaution of investing in specialised schnozzle insurance. But while some may have superhuman abilities, peering into the science paints an even more extraordinary picture.

You like tomato and I like tomayto!

It’s a wonderful feeling during a whisky tasting when the aromas popping into one's head align with the proclamations from others in the room. Perhaps you are smelling vanilla, marzipan and sponge cake. Then your newfound allies announce battenberg cake with custard. It provides a sense of reassurance, confidence and a small bump of feelgood neurotransmitters too.

On the flip side, one person’s battenberg cake could be another person’s sherry trifle. Who’s right? Depending on your level of confidence, experience, or egocentricity, you may find yourself questioning your own judgement. Or, at the other end of the scale, the judgement of those around you.

The point is that it’s natural to adopt a standpoint of absolutes. We like things to be black or white, but rarely both. It’s either battenberg or trifle, but never battentrifleberg (though there’s an idea!). To accept something as being both black and white presents cognitive challenges. For budding whisky adventurers, it presents challenges too.

It creates social pressure. The ‘don’t-want-to-get-it-wrong’ syndrome. A stone monolith that stands in the way of self-expression and flavour dissection. Understanding that there are no absolutes in flavour detection is therefore self-empowering knowledge. This knowledge is all the more powerful because it comes from solid science.

The Riddle of the Odour Receptor Repertoire

The human genome contains approximately 800 odour receptor genes that are highly susceptible to variability. What does this mean? We all smell the same things quite differently. We may have genetic similarities with some folk, but we are all unique when it comes to aroma detection.

The olfactory overhang of the face leads to odour receptors in the nasal cavity, and we have around 400 receptors each, give or take. It’s these odour receptors that lay waiting for aroma molecules to come along and latch onto them. These are unlike the taste receptors on the tongue though, which are quite fussy with which molecules that can grasp hold of.

The odour receptors are less fussy. Each of the 400 individual receptors can grasp a variety of molecules. Which is a wonderful mystery. Receptors throughout the body, such as neurotransmitter receptors, work much like a key fitting a lock. Only very specifically shaped molecules can attach. But this is not so with odour receptors.

It also seems that our identification of individual odours is shaped by a sequence of different receptors being stimulated. A type of pattern recognition much like how we discern one song from another by its pattern of sounds. So you see the sense of smell is really quite complex. And it’s about to get more complex.

30% of your Odour Receptors are Different to Mine

Research from 2014 by J. D. Mainland et al studied the degree of functional variability of odour receptors. The research looked at odour receptors in vitro, literally meaning ‘in glass’, and referring to the fact that the cells were removed from the human body. From the receptors studied they found that 63% had polymorphisms, i.e. they had the possibility of two or more variations.

The research looked at pseudogene frequency, where specific genes have been switched off due to genetic mutations. They found a 43% frequency that the OR2B11 gene was switched off. No, OR2B11 is not a droid from Star Wars! Apparently, this gene is responsible for us detecting cinnamon aroma (cinnamaldehyde). There was also a 30% frequency for gene OR4E2 (fruity pear drops) and a 24% frequency for OR8K3 (menthol). Plus many others.

The researchers determined that on average there is a 30% difference in the make-up of active odour receptors between any two people. Which is a remarkable degree of variation. This explains why many people have aroma ‘blind-spots’, where they are unable to detect specific aromas such a sulphur or coconut, for example. There’s one other factor, however.

There's more to smell than the nose!

The 400 or so odour detectors that we each have are important, but they are only one component of the olfactory system. From each receptor the signal must travel through the olfactory bulb, and along a complex network to arrive at its destinations within the brain. But here’s the thing.

The experience of smelling is processed in so many different areas of the brain that’s it’s a task and a half to precisely figure out which bit does what. When we apply the possibility of genetic variability to the entire olfactory system, the implications for aroma detection variability become mind-boggling!

While we may think of some people as having a developed or highly trained sense of smell, the reality is that your genes will determine how well you can smell each individual odour. And the degree of variation between individuals is considerable. Having said that, science has demonstrated that it is possible to train your nose to an extent, but keep an eye out for that article later this year.

Embrace your freedom

What this information provides for each and every one of us is a free pass to say what we smell at tastings, without the need to ‘fit in’. It liberates us from the confines of right and wrong. And opens the doors to true expression. But it also unboxes a whole new puzzle.

If our thresholds for specific odour detection vary by 30% on average, how on earth can we agree on the smell (and therefore taste) of anything? Should we ally with those who have similar gene expressions? Even the very thought ventures into territory where no moral person would wish to tread.

The scientific approach that is applied to the sensory assessment of whisky in industrial settings, attempts to solve the problem through calibration. Assessors will calibrate their ‘noses’ using a selection of standardised aroma samples. For example, vanilla, butter, smoky, etc. Plus off-notes too. Although not without it’s drawbacks, this approach works very well for the purposes of consistency, quality, and spotting faults.

In at the deep end

For everyone else, calibration is shaped by experiencing odours in the wild, as part of the complex flavour amalgamations that erupt from the dram in your glass. Scotch whisky, being one of the most forthright flavour experiences on Earth, can therefore feel a little like being thrown in at the deep end for newcomers.

Hence, armed with the knowledge that our olfactory systems are more diverse than most people realise, we can go forth with a newfound sense of freedom. Take this opportunity to embrace our differences rather than challenge them. It’s the diversity, mystery and multifariousness of single malt whisky that brings us together. By embracing the same qualities in people, whisky becomes a vehicle for cohesion. And ultimately a vehicle for building better relationships and experiences.

Today Speyside, tomorrow the world! Join the crusade, together we can make the world a better place. Or at least enjoy a dram or two together.

If you know others who are passionate about whisky, flavour, and overthinking how we taste, invite them to the Flavour Crusaders newsletter today. We've only just started scratching the surface!