Introduction

BEING A SMELL EXPERT has its ups and downs. In my professional life I’ve attended secret perfume planning meetings in corporate suites with spectacular views of Central Park. But I’ve also sat at a conference table and sniffed defrosted samples of used feminine hygiene products.

I’ve traveled to London, Zürich, Paris, and Cannes, staying at the best hotels and eating at the finest restaurants. I’ve also traveled to Cape Girardeau, Missouri, to evaluate the scent of carefully aged cat feces.

I have air-kissed fashion celebrities and sniffed the scalps of elderly ladies being shampooed in a mock salon.

I was among the first people to smell Elizabeth Taylor’s White Diamonds, but also one of the first to sniff purified 3-methyl-2-hexenoic acid—the aromatic essence of ripe, unwashed armpits.

These experiences are not unusual in the fragrance industry: people there sniff for a living and create scents for everything from perfume to kitty litter. What is unusual is that I’m a sensory psychologist, trained in evolutionary theory, animal behavior, and neuroscience. I’m a rational, evidence-based guy working in the most frothy, fashion-driven, marketing-heavy business outside of Hollywood.

The sense of smell portrayed in the mainstream media (“Seven Ways to Drive Him Wild with Your Perfume!”) is far different from the way scientists see it (“Multivariate Analysis of Odorant-Induced Neural Activity in the Anterior Piriform Cortex”). The magazine version—breezy and chatty—sails merrily past new discoveries just emerging from the laboratory. The official scientific version—formal, dense, and dry—hides some very cool new stories.

I know people are fascinated by the hows and whys of odor perception. When they find out I’m an expert, they bombard me with questions. The answers are often weirder than they could have imagined. The new science of smell is making us rethink everything from wine tasting to Smell-O-Vision. So it’s time for a fresh look at odor perception and how it plays out in popular culture.

Where to begin? With a simple question: How many smells are there? The answer leads to psychology (“How do you count smells?”), technology (“How do you take apart a complex odor?”), and secrets of the trade (“How do you become a perfumer?”).

In the chapters that follow, I take up other simple questions—What makes for a good sense of smell? Do bad odors make us sick? Can subliminal smells make us do things against our will?—and follow them to some strange and unexpected places. Welcome to my world. Breathe deep and enjoy.