Free What the Nose Knows: The Science of Scent in Everyday Life by Avery Gilbert Page B

and safety. Tiger’s view—essentially a biologized version of “women spend more time cooking”—will not be received warmly in some quarters. Yet it’s hard to see how a cultural explanation can explain sex differences in two-week-old infants.
     
    W ITH AGE, OLFACTORY performance begins to deteriorate. The first signs of decline are detectable in the early forties—at least under laboratory conditions—and the pace accelerates in the sixties and seventies. Interestingly, the rate of decline varies with the odor. Rose and banana, for example, are easily perceived until people are in their seventies, while mercaptans (the natural-gas warning odor) show a drop among people in their fifties. Some age-related smell loss can be traced to the nose itself—the accumulated wear and tear of infections and minor blows to the head. Some of the loss is traceable to the brain. For example, odor identification ability depends on how much short-term memory the test requires. Because short-term memory declines with age, elderly people score better when the odor test is presented in a simple yes/no format than in a multiple choice format that requires more memory capacity. In any case, decline is not inevitable; a given seventy-five-year-old may outperform a given twenty-five-year-old. Perfumers, in fact, usually get better with age. Experience and skill more than compensate for any dimming of acuity that comes with age. I know of no fragrance house with a mandatory retirement age for perfumers.
     
    T O THE AVERAGE person it seems obvious that smoking must dull the sense of smell. Surprisingly, the evidence is equivocal. Some studies find adverse effects of smoking but many, including several recent ones, do not. One, an Australian study of 942 people, found that having a smoke within fifteen minutes of smell testing put a temporary dent in performance. Other than that, “smoking did not reduce olfactory performance or self-assessment of olfactory ability in this group, contrary to previous findings.” The National Geographic Smell Survey reported mixed results. For example, smokers found the artificial musk scent of Galaxolide more intense than did nonsmokers, but the reverse was true for the musky-urinous smell of androstenone. Pleasantness ratings for the skunky-smelling mercaptan sample were higher among smokers, but so were their ratings for rose and cloves. It’s possible that smokers become sensitized to some odors and desensitized to others. In any case, minor effects of smoking observable in clinical testing may have little appreciable impact on everyday smell function. Indeed many perfumers, including the best in the business, have smoked like chimneys.
    So strong is the conventional wisdom about the negative effect of smoking that researchers worry when they fail to confirm it. Take the case of a large population-based study in Skövde, Sweden. It linked decreased olfactory performance to several factors including being older, being male, and having nasal polyps. Smoking was not one of the factors. Similarly, diabetes and nasal polyps predicted complete anosmia, but sex and smoking did not. The authors didn’t find that smoking
improved
odor perception; they merely failed to find that smoking harmed it. One can see them bracing for a wave of politically correct indignation when they say, “The lack of a statistically significant relationship between olfactory dysfunction and smoking may be controversial.”
    Blind Faith
    When, at a party, I own up to being an expert on the sense of smell, I get peppered with questions. (I don’t mind this—if I’m not in the mood for Q&A, I tell people I’m “in the chemical business” and the conversation grinds to a halt.) People often ask about smell ability. Who is better: men or women? perfumers or normal people? Curiously, one comparison doesn’t come as a question but as an assertion. Wineglass in hand, someone will inform me in earnest tones that “blind people have