Smell

A few comments on the physiology, psychology, and culture of aroma from Diane Ackerman’s A Natural History of the Senses .

Like many writers, Ackerman links smell and memory: “Nothing is more memorable than a smell. One scent can be unexpected, momentary, and fleeting, yet conjure up a childhood summer beside a lake in the Poconos, when wild blueberry bushes teemed with succulent fruit and the opposite sex was as mysterious as space travel; another, hours of passion on a moonlit beach in Florida, while the night-blooming cereus drenched the air with thick curds of perfume and huge sphinx moths visited the cereus in a loud purr of wings; a third, a family dinner of pot roast, noodle pudding, and sweet potatoes, during a myrtle-made August in a Midwestern town, when both of one’s parents were alive. Smells detonate softly in our memory like poignant land mines, hidden under the weedy mass of many years of experience. Hit a tripwire of smell, and memories explode all at once. A complex vision leaps out of the undergrowth.”

She comments on the difficulty of using words to describe smells: “When we use words such as smoky, sulfurous, floral, fruity, sweet, we are describing smells in terms of other things . . . . Smells are our dearest kin, but we cannot remember their names. Instead we tend to describe how they make us feel” with words like disgusting, intoxicating, sickening, pleasurable, delightful, revolting. She thinks this is hard-wired in our brains, where the locus of smell is distant from the locus of language. Smells connect to objects and situations not to words. This is one of the reasons smells are so potent: We know them but “we cannot utter their names.” Smell is a mystic sense.

One aspect of the phenomenon of smell is that it is direct, “the most direct of all our senses.” There is a very physical, direct link to the world in smells: “When I hold a violet to my nose and inhale, odor molecules float back into the nasal cavity behind the bridge of the nose, where they are absorbed by the mucosa containing receptor cells bearing microscopic hairs called cilia. Five million of these cells fire impulses to the brains olfactory bulb or smell center. Such cells are unique to the nose . . . . the neurons in the nose are replaced about every thirty days, unlike any other neurons in the body, they stick right out and wave in the air current like anemones on a coral reef.” We are extraordinarily sensitive to smells: “We need only eight molecules of a substance to trigger an impulse at a nerve ending, but forty nerve endings must be aroused before we smell something.”

What we smell is evaporation, volatility, living energy, or death: “Many things we encounter each day – including stone, glass, steel, and ivory – don’t evaporate when they stand at room temperature, so we don’t smell them. If you heat cabbage, it becomes more volatile . . . and it suddenly smells stronger.” Scents send messages, including sexual messages, but they aren’t always delivered immediately. Fortunately, “Most smells will glow for a while, where a wink may vanish before it’s seen, a flexed muscle may imply too many things, a voice startle or threaten.”

“Odor greatly affects our evaluation of things, and our evaluation of people.” We smell fruit in the market. We recoil instinctively from the alcoholic breath of a drunk on the street, or someone who has strong bodily odors.