REVIEWS

Your nose has been underrated

The Scent of Desire: Discovering our Enigmatic Sense of Smell by: Rachel Herz William Morrow, an imprint of HarperCollins, 2007 ISBN: 978-0-06-082537-9 Interview with Rachel Herz

The Scent of Desire by Rachel Herz is full of “aha” moments. The author’s goal is to have readers appreciate the sense of smell for the depth and richness it adds to our perception and well-being. To that end, she skillfully achieves her goal. You won’t underrate this sense again.

The book covers a wide ranging territory. As Herz says, “our sense of smell is integrally tied to our emotions, our memories, our behaviors and our health” (xvii). The raised-in-Canada author also discusses the little-known but debilitating condition anosmia, or the loss of the sense of smell, caused by injuries to the head where the smell centre intertwines with the emotion neural structures in the brain. This area, called the amygdala, is highly sensitive to scents:

“Brain imaging studies have shown that when we perceive a scent, the amygdala becomes activated, and the more emotional our reaction to the scent, the more intense the activation is” (p. 4).

This translates into big emotional reaction + smell = strong memory and emotion when smell is encountered again.

For most animals, smell is the main way to sense danger. Humans have learned to rely more on sight, but our sense of smell may still kick into action in very primal ways. Herz theorizes that “odors still evoke in us the remnants of this primeval survival code” (p. 14).

But there’s a lot more to smell than just staying away from danger. Smell is much more linked to desire, love and even longing. Herz discloses some of her favorite scents. One of them is skunk! She describes how this normally nasty scent is closely tied in her experience to a feeling of love. (You need to read this story on your own to fully appreciate it.)

This work prompts us to examine our own favorite smells for the memories and emotions they evoke. For me, the book reminded me of my childhood love of the smell of car exhaust. That smell brings back memories of my dad warming up the car in winter so that we could go somewhere much more interesting than the farm where we lived. Naturally, to this day, I still love the smell of exhaust, as poisonous and dangerous as it is, for the memory of that sweet promise of adventure.

You’d expect a book like this to expound on the virtues of this or that scent for health purposes. Herz does include a chapter on aromatherapy, but mainly to dismiss it. If you like a scent, chances are it will make you feel good when you smell it. But smells are so linked to experience that even a scent like lavender, which many claim has relaxation properties, may make you quite anxious if it was the scent your despised Grade 4 teacher used to wear as she rained torment upon you...(Are your ears burning, Mrs. Pollock?)

The book gets juicier and much more fun when Herz considers smell + sex and smell + gender. Here she considers the fascinating idea that we can smell prospective good partners (e.g. husbands). This is linked to our need to survive and to reproduce with men who have immune systems complementary to our own. We can smell this? Herz suggests we can. But then there’s the problem of cologne and perfume. Pretty much the olfactory equivalent of lying about your age or which writers you prefer to read.

Further, she settles the difference of which gender is able to smell better. It’s an answer that will make both genders feel good because sometimes we have a better sense of smell. Sometimes men do. I don’t want to give away the answer. Read the book to find out when we are better at detecting odors than our male counterparts.

A Scent of Desire is an interesting book that will get you talking to your friends and family about smells. Amazingly, people feel quite open discussing their weird and wonderful smells. Behind each revelation is a very unique reason that will leave you appreciating the fantastic way the nose guides us, despite getting very little notice.

GP: From reading your book, I understood that our sense of smell has been underrated compared to our other senses. Why do you think this particular sense has been somewhat ignored?

RH: Our sense of smell has been ignored for several reasons. First there’s the socio-historical problem of it having been denigrated to the base and animalistic during the Victorian era. The catch phrase being “civilized people don’t smell.” Then there is the problem that it is hard to study scientifically—or at least within the paradigms that had been developed to look at other phenomenon it was seen as more difficult to control and less rigorous because one can’t quantify or manipulate the stimulus (odor molecules) the way one can manipulate light (vision) or sound waves (hearing). The solution to this problem has simply been to develop new and different methods, but the acceptance of novel procedures and topics is slow and stubborn. Fortunately, the molecular and biochemical disciplines have been making enormous leaps in studying olfaction over the past two decades, and I expect psychological science to eventually catch up. Finally, there is the fact that people in general do not consider the sense of smell to have much usefulness to our lives especially when compared to other senses like vision, and therefore the impetus to study it has been weak. I hope that my book will help make everyone—laypeople and scientists alike—more aware of how important the sense of smell is and how valuable it is to study and discover.

GP: I remember during my pregnancies experiencing a greatly heightened sense of smell, and being able to smell things I hadn't noticed or been bothered by before. Have you heard of this experience from other women? Is there an evolutionary benefit to a heightened sense of smell for pregnant women?

RH: I have heard many women say this. But believe it or not, the hard data do not show any significant evidence that women’s sense of smell becomes physically more sensitive during pregnancy than at any other time, although their sense of taste does. During pregnancy, sensitivity to bitter taste in particular becomes heightened. This makes good biological sense, because bitter things tend to be poisonous. Returning to our sense of smell and why the scientific tests don’t correlate with anecdotal experiences, I think this is because though physical sensitivity does not change in absolute terms, psychological sensitivity to odors does change during pregnancy. When women are pregnant they are much more alert and attentive to their general environment and state. Increased attention can actually lead to increased sensitivity to scents. Therefore, the feeling that at various times odors are overwhelming is true, but this is not a constant change in the physiology of the nose, so laboratory tests don’t pick it up. The reason smells can be more bothersome to pregnant women is because the stronger something is the less pleasant it is—we experience this in all senses, loud noises, very bright lights, strong smells are all unpleasant. The heightened vigilance that occurs during pregnancy and greater wariness also influences the “interpretation” of scent to be more negative. Our sense of smell is highly influenced by context and expectation. Taken together, it seems that the psychological state of pregnancy is responsible for physical changes in the perception of certain odors at certain times.

GP: You describe the reduced smelling capacity of smokers. Do people enduring second-hand smoke have similarly reduced capacity?

RH: I do not know of any studies that have examined the impact of second-hand smoke on olfactory function. The reason why smoking reduces sensitivity to scents is because the chemicals in smoke are toxic to the olfactory receptors and kill or damage them. The fewer functioning olfactory receptors we have the less sensitive we are to smells (the less well we can smell). The good thing is that our olfactory receptors regenerate every 28 days, so a month after someone has quit smoking they can expect to have a fully functioning sense of smell. With respect to second-hand smoke I could imagine that if exposure were high and constant then it would be damaging to the olfactory receptors of the non-smoking noses around as well.

GP: The gender differences with regard to smell are fascinating! I think it's amazing that in some parts of our menstrual cycle, we are able to smell more effectively than our male partners and less effectively in other parts of the cycle. I've noticed, anecdotally only, that men often complain more about garbage-related smells in the home than women do. Could this be linked to the gender differences? Or is it more likely that men would just prefer not to take out the garbage?

RH: This is interesting to me—I’ve actually not heard this anecdotally or otherwise. My speculative explanation for the occasions where you know of this follows from the fact that people react negatively to odors that they do not think fit the context, situation, or environment. Men who complain about garbage odors in the home may be reacting to a feeling that their home should be cleaner and more pristine than it is. The women-folk should be doing more housework!

GP: Your hope in the book was to help people appreciate better their sense of smell, so you have covered a wide range of topics. Among the many aspects of smell that you described in the book, is there one that intrigues you more than others that you will look into more closely in your future research?

RH: There are many aspects of our sense of smell that fascinate me and I would love to look into all of them. If I had to pick just one for now, it will most likely be pheromones, the facts and fictions in the latest research, and how this area is influencing the fragrance industry and the hopes to be able to bottle an aphrodisiac.