TURN YOUR NOSE UP
Been wedded to the same floral eau de toilette for more than a decade? Or do you hold fast to fragrance recommendations from a beauty-mad pal? Well, don’t. Because as you’re about to find out, scent is a complicated beast, personal to you and ever-changin
Catch a whiff of the science behind scenting your body
My relationship with hyacinths is complicated. Every February, I eagerly await the early bloomers, desperate to fill my home with their fresh velvety scent – for each room to have its own pink, violet and white centrepiece. They signal the end of winter, new beginnings and hope. And yet, catching a whiff of them unprepared fills me with a sense of poignancy. My long-held attachment to hyacinths stems from them being a staple of my childhood home, the happy dynamic of which broke down after my parents separated; it’s why their smell has the power to draw to mind a tangle of blissful early childhood memories and the emptiness of the emotional vacuum that followed. My husband, on the other hand, is not only unmoved by the fragrance of hyacinths, he finds it distinctly ‘urine-like’.
Such is the subjectivity of scent. The same aroma will elicit different reactions from person to person, just as the same perfume will sit differently on each individual’s skin. Unlike any other area of beauty – the prescriptive and unchanging nature of your foundation shade or repeat-order dry-skin solutions – fragrance is mercurial, with your sense of smell shifting throughout your life. Which is why an exploratory approach to fragrance, and discarding the notion of a lifelong ‘signature’ scent, has the potential to unlock emotions, happy memories and uplifting feelings with every spritz.
SMELL THE ROSES
Why is it that scent is so idiosyncratic? For the most part, you’re looking at pure biology. While your eyes have just two main types of receptors (rods and cones), your sense of smell uses around 400, all of which sit in the roof of the nasal cavity, a large air-filled space above and behind the nose. These olfactory receptors work by recognising and memorising all the many different elements that combine to make up an odour, which is why your nose houses so many.
Take rose, for example; your scent receptors don’t simply learn a singular ‘rose’ scent. They recognise olfactory units that combine to create that umbrella smell, and some of these characteristics will then be used to recognise other flowers or perfumes. ‘This mechanism of olfactory learning is a process called pattern recognition,’ explains Ioannis Kontaris, head of neuroscience research at fragrance company Givaudan.
‘As you smell more and more different smells in your environment, you build a sort of library and can recognise patterns and make connections between the fragrance fragments in that library.’ What’s perhaps most interesting is that this olfactory learning continues throughout your life, so you’re always learning to smell and appreciate scent in different ways as time goes on. And with such a large number of receptors, the way people interpret their signals can vary widely. ‘Slight genetic differences can mean these receptors behave differently from person to person,’ says Tim Jacob, emeritus professor of biosciences at Cardiff University.
The physiological placement of these receptors is another thing that sets smell apart from your other senses. Holed up in your nasal cavity, they have a direct line via the olfactory bulb to the brain’s limbic system, which deals with memory, association and emotion. ‘That the olfactive system is so closely linked to the limbic structures in the brain means that odour memory is highly emotional,’ explains psychologist Dr Céline Manetta, consumer science research fellow at International Flavors & Fragrances. ‘This short, intense connection between nose and brain is why when you learn to memorise an odour, you instinctively memorise all the contextual elements that were present, too – the people, the place, the atmosphere, the situation – it’s what makes odour memory so personal.’
LEARNING FROM EXPERIENCE
Think for a second about your go-to mascara. It’s likely to be your favourite because of the results you get when you use it: long-lasting, lengthening, waterproof. In fact, the majority of products in your beauty arsenal earn their place because they deliver – but fragrance is different. There’s no anti-ageing promise and no claims to hydrate or smooth. The choice of what to spritz is powered solely by what you can smell and how that makes you feel. In short, your preference for smell is largely down to the associations it holds to other things entirely. ‘A study published in the journal Chemical Senses suggests that if you make negative associations with an odour when you first smell it, your future evaluation defaults to
negative,’ says Dr Manetta. ‘So, if you catch a whiff of eugenol (the antiseptic that smells like cloves) during a bad experience at the dentist’s, the next time you smell it, perhaps in another cosmetic product, you’d react negatively purely for that reason.’ Equally, as Kontaris explains, associations can be positive. ‘We run experiments exposing people to isovaleric acid – a chemical compound that smells similar to strong cheese and sweaty socks. Half of the participants are told the smell is emanating from a delicious cheese; the others are told they’re smelling dirty socks. The former always report loving the scent far more than the latter.’
These preferences for smell based on positive association begin as early as when you’re still in the womb. A French study of hours-old newborns showed that those whose mothers had consumed an aniseedheavy diet in pregnancy showed they recognised and appeared to enjoy the smell of aniseed.
So powerful can these associations be that Professor Jacob has developed his own sensory therapy device (kodobio.com), which uses positive smell stimuli to help lower stress and treat anxiety and depression.
TAKE IT PERSONALLY
It isn’t just your memory bank that accounts for the unique way you react to fragrance. Fluctuations in your hormones can affect your sense of smell, too. ‘We’re still not sure
‘The short, intense connection between nose and brain is what makes odour memory so personal’
of the exact mechanism, but women at their most fertile — when oestrogen peaks in the menstrual cycle — have a more acute sense of smell,’ says Professor Jacob. These natural fluctuations in fragrance preference can even be disturbed if you’re on the pill. ‘Women taking the oral contraceptive pill don’t have the smell sensitivity of naturally cycling women,’ adds Professor Jacob. Suddenly, there’s a reason why that perfume you doused yourself in during your teens isn’t quite so attractive now you’re older and have different hormone levels. It’s all down to evolution – women are programmed to sniff out a partner based on his natural fragrance, which ideally indicates he has a markedly different immune system to give potential offspring better immune diversity.