A Natural History of the Senses

by Diane Ackerman

  One of Gilbert’s colleagues, George Preti, staged an experiment in which ten women had the sweat of other women applied under their noses at regular intervals. It took three months for the women to begin menstruating at the same time as the women whose sweat they were smelling. A control group, daubed with alcohol instead of sweat, didn’t change their cycles at all. Clearly, a pheromone in sweat affects menstrual synchrony, which is why women in dorms or close girlfriends so often menstruate at the same time, a phenomenon known as the McClintock Effect (after Martha McClintock, the psychologist who first observed it). There appear to be other effects. When a man gets involved with a woman for any length of time, his facial hair starts to grow faster than it did before. Women who are cloistered away from men (in a boarding school, say), enter puberty later than women who are around men. Mothers recognize the odor of their newborn children, and vice versa, so some doctors are experimenting with giving children bursts of their mother’s odor, along with the anesthetic, during operations. Babies can smell their mother entering a room, even if they can’t see her. In J. M. Barrie’s Peter Pan, children can even “smell danger” while they sleep. Mothers of school-age children can pick out T-shirts worn by their own child. This is not true for fathers, who do not recognize the smell of their infants, but men can determine whether a T-shirt has been worn by a male or a female. Pheromones do affect people. But how much? Do pheromones trigger vigorous responses in us as they do in moths or beavers, or do they figure in the cascade of our sensory awareness no more significantly than ordinary visual or hearing cues? If I see a handsome man with beautiful blue eyes, am I having a “visualmone,” as one researcher called it dismissively, or is it just that blue eyes excite me because they register as attractive in the culture, time, and context of my life? Blue eyes, “baby blues,” remind us a little of Caucasian newborns, and fill us with protectiveness. But in some African cultures they would be thought ghoulish, icy, and unattractive.

  Science fiction has often frightened us with humans as automatons, driven by unknown forces, their minds a sort of dial tone. Suppose pheromones at times secretly cancel our powers of choice and decision? The idea alarms. We don’t like to lose control, except on purpose—during sex or partying or religious mysticism or doing drugs—and then only because we believe we’re just fractionally more in control than we’re not, or at least that such control will return to us quickly. Evolution is complex and at times amusing, so much of an adventure that few of its whims or obbligatos frighten me. Our apparent need for violence does, but not the possibility that we might be having elaborate, if subtle, conversations with one another through pheromones. Free will may not be entirely free, but it certainly is willful, and yet it seems as if there is a good deal of stretch in it. Such masterly ad-libbers as human beings know how to revise on almost any theme. If there’s one thing at which we really excel, it is at pushing limits, inventing strategies, finding ways to sidestep the rudest truths, grabbing life by the lapels and shaking it soundly. Granted, it tends to shake back, but that never stops us.

  NOSES

  When we crawled or flopped out of the ocean onto the land and its trees, the sense of smell lost a little of its urgency. Later, we stood upright and began to look around, and to climb, and what a world we discovered spread out before us like a field of Texas bluebonnets! We could see for miles in all directions. Enemies became visible, food became visible, mates became visible, trails became visible. The shadow of a distant lion slinking through the grass was a more useful sign than any smell. Vision and hearing became more important for survival. Monkeys don’t smell things as well as dogs do. Most birds don’t have very sophisticated noses, although there are some exceptions—New World vultures locate carrion by smell, and seabirds often navigate by smell. But the animals with the keenest sense of smell tend to walk on all fours, their heads hanging close to the ground, where the damp, heavy, fragrant molecules of odor lie. This includes snakes and insects, too, along with elephants (whose trunks hang low), and most quadrupeds. Pigs can smell truffles under six inches of soil. Squirrels find nuts they buried months earlier. Bloodhounds can smell a man’s scent in a room he left hours before, and then track the few molecules that seep through the soles of his shoes and land on the ground when he walks, over uneven terrain, even on stormy nights. Fish need olfactory abilities: Salmon can smell the distant waters of their birth, toward which they must swim to spawn. A male butterfly can home in on the scent of a female that is miles away. Pity us, the long, tall, upright ones, whose sense of smell has weakened over time. When we are told that a human has five million olfactory cells, it seems like a lot. But a sheepdog, which has 220 million, can smell forty-four times better than we can. What does it smell? What are we missing? Just imagine the stereophonic world of aromas we must pass through, like sleepwalkers without headphones. Still, we do have a remarkably detailed sense of smell, given how small our organs of smell really are. Because our noses jut out from our faces, odors have quite a distance to travel inside them before we’re aware of what the nose has probed. That’s why we wrinkle up our noses and sniff—to move the molecules of smell closer to the olfactory receptors hidden awkwardly in the backmost recesses of the nose.

  SNEEZING

  Few pleasures are as robust as the simple country pleasure of sneezing. The whole body ripples in orgasmic delight. But only humans sneeze with their mouths open. Dogs, cats, horses, and most other animals just sneeze straight down their noses, with the air bending a little at the neck. But humans huff and tremble in an anticipatory itch, draw in a big gobful of air, contract the ribs and stomach like a bellows, and violently shoot air into the nose, where it stops short, blasts the general area, and sometimes sprays messily out of the nose and mouth all at once. This wouldn’t matter too much if our lungs blew air out gently during a sneeze. But researchers at the University of Rochester have found that a sneeze expels the air at eighty-five percent the speed of sound, fast enough to scour bacteria and other detritus from the body, the sneeze’s goal. Human noses have a hairpin turn way at the back of the nasal passages, which makes the whole process of breathing more taxing, and inhaling odor molecules more difficult. There is no direct path for the air to follow in a sneeze. We have to open our mouths. If we sneeze closed-mouthed, the air thunders around the cavities and passages in our heads, looking for a way out, and can hurt our ears. There are many theories about why our noses are so poorly designed; in the last analysis, it probably has to do with the evolution of our biggish brains and the cramped space in our skulls, and to permit stereo vision. Bedichek suggests that the design didn’t become awkward until we “swarmed into those congested areas we call ‘cities.’ Here the nose has had forced upon it suddenly a function it was never intended to perform, namely, screening out dust and grit while at the same time being subjected to intolerable odors of municipal filth, and finally to fumes from the vast chemical laboratory the modern city has become.” The seventeenth-century poet Abraham Cowley states the point as a rhetorical question:

  Who that has reason, and his smell,

  Would not among roses and jasmine dwell,

  Rather than all his spirits choke

  With exhalations of dirt and smoke?

  A tickle is all it takes. Or the sun. Some people, like me, inherit a genetic oddity that causes them to sneeze when confronted by bright light. I’m afraid this syndrome has been given the overly cute acronym of ACHOO (autosomol dominant compelling helio-ophthalmic outburst). If I feel a sneeze hovering, all I have to do is look at the sun to bring on the explosion, a light apocalypse.

  SMELL AS CAMOUFLAGE

  Though it’s April, we’ve had snow in Ithaca for weeks, or so my neighbor tells me—I was in Manhattan, a maritime climate. Now I find that small mute deer prints lead right up to the door and the huge windows, dart across the frozen pool sparkling with rime, then meander through drifts to twin apple trees and ice-claggy fruit. So they have learned how to walk on water, browse the fragrant marvels t
ucked beneath the surface of the world, even how best to come and go in a season oblique with bullets and ice. Did they search for me, where I used to pause, reflecting in the glass? What if, later this spring, the frozen pool plays tricks and sags beneath their hooves, then folds up over them, and I do not hear their underwater screams? What if, like the snow, I have drifted too far? Craving the dialect of cities, I forgot the way deer steal into the yard with their big hearts and fragile dreams. I wasn’t here to follow their gaunt, level eyes, or the staggering poetry of their hooves.

  Often, I see them browsing in the yard, but when I slip outside for a closer look they smell my strong human scent, amble down to the fence, and leap back into their pandemonium of green. This summer I intend to disguise myself as a conifer or a mushroom. A recent issue of Field and Stream tells me how: To fool deer and rabbits, take something without much tannin (yellow birch, pine, mushrooms, hemlock, wintergreen, or some aromatic conifer, for example) and dry it for a week or two. Chop it up, then fill a jar half full of it. Add 100-proof vodka. Filter through a Melitta filter. Put in an atomizer. Apply liberally to bury your human smell. Let your thoughts mushroom.

  ROSES

  I am holding a lavender rose called “Angel Face,” one of the twenty-five rosebushes planted around my house. For the first few years, the deer that frequent my yard would steal in at dawn and eat all the buds and succulent new growth. Once they ate the bushes right down to the dirt, leaving only small knobs that looked like the velvet of incipient antlers. I am used to embezzlers in the garden. The first summer of the grape arbor, I watched two vines evolve from flowers to succulent purple fruits, sense-luscious and nearly bursting with fragrance. Each day, I watched them, waiting until the perfect moment of ripeness, imagining how it would be to roll the grapes around on my tongue, fresh, sweet, and quenching. One day the grapes’ purple sheen changed to a taut, robust iridescence, and I knew the next morning would be the earliest day to pick. Such knowledge was not reserved for me alone. When I awoke, I found every single grape sucked dry, the skins littering the ground like tiny purple prepuces. This scene, left by raccoons, has repeated every autumn ever since, despite cages, cowbells, barbed wire, and other “deterrents,” and frankly I’ve given up on grapes and raccoons. The roses pose a trickier problem.

  I love the deer as well as the roses, so I decided to use smell as a weapon—after all, plants do it—and sprinkled a mixture of tobacco and naptha around the rosebushes. It worked, but made the air raunchy and caustic. Unless you crave the smell of baseball players at winter camp, their mouths full of chewing mess, their pockets full of mothballs. This year I have another plan: lavender. Deer hate its strong nose-scrubbing smell; I’ve ordered dozens of bushes to plant around the roses and day lilies, hoping they’ll make an olfactory fence when the deer come calling. Still, we’ll divide the spoils. I have left them the luxuriant raspberry bushes, which I no longer try to harvest, and the twin apple trees. The raccoons get the grape arbor, the rabbits get the wild strawberries. But the roses are sacrosanct, because they so drench my senses with exquisite smells. The most expensive perfume in the world, and one of the enduring classics, Joy, is a blend of two floral notes: jasmine and lots of rose.

  Roses have tantalized, seduced, and intoxicated people more than any other flower. They’ve captivated homeowners, swains, flower addicts, and sensuists since the ancients. In Damascus and Persia, people used to bury jars of unopened rosebuds in the garden, and dig them up on special occasions to use in cooking—the flowers would open dramatically on the plates. In Jean Cocteau’s film version of the fairy tale Beauty and the Beast, all the mischief and magic begins when a man picks a rose for his daughter, her sole desire among a sea chest of riches. Long ago, Europeans raised a tough mongrel rose that was loud, obvious, and very hardy, and whose fragrance could embalm a statue. But, in the 1800s, they began importing elegant Chinese tea roses, which smelled like fresh tea leaves when crushed, and also frost-delicate, ever-blooming Chinese hybrids with bright yellow to red flowers. Breeding the hybrid Chinas with the European roses as carefully as racehorses, they produced subtle and sophisticated offspring roses, charmed into a seemingly endless array of colors, shapes, and scents. They called them “hybrid tea roses.” Since then, over twenty thousand varieties have been bred, and at one time the rose’s fragrance was nearly lost through overbreeding. Fragrance seems to be a recessive trait in roses, and two deeply fragrant parents may produce a petal-perfect but smell-less offspring. Now the trend is toward perfumed roses, thank heavens. The most popular hybrid tea in the world is “Peace,” a stunning multicolored pastel with sunset hues that shriek at noon, grow muted at sunset, and record all the other phantoms of light during the day. Its egg-shaped buds open into large, pale-yellow ruffles with translucent tips that are often flushed with pink. And it smells like sugared leather dipped in honey. Of all my roses, “Peace” seems to have an almost human complexion and human moods, depending on the moisture and light of each day. An experimental rose, it was named on May 2, 1945 (the day Berlin fell), at the Pacific Rose Society in Pasadena, because “this greatest new rose of our time should be named for the world’s greatest desire—Peace.” Many presidents have had roses named after them (Lincoln’s is blood red, John Kennedy’s pure white), and there are wittily named roses to honor movie stars or celebrities (Dolly Parton’s is flamboyantly pungent, with knockout-sized blossoms). Though roses symbolize beauty and love, their colors, textures, shapes, and smells are difficult to describe. “Sutter’s Gold,” one of my favorite hybrid tea roses, produces a flat ruffled flower of yellow petals tinged in apricot, fuchsia, and pink, with a fragrance like sweet wet feathers. The floribundas, thoroughly modern roses, cascade with flowers all summer long. “The Fairy” has hardly any scent, but is a constant explosion of dainty pink flowers from spring until winter, despite light snowfalls. Roses were already considered ancient when the Greek botanist Theophrastus wrote about “the hundred-petaled rose” in 270 B.C. Fossilized wild roses have been dated as far back as forty million years ago. The Egyptian rose was what we now call the cabbage rose, renowned for its many petals. When Cleopatra welcomed Mark Antony to her bedroom, the floor was covered in a foot and a half of such petals. Did they use the floor, and make love in a swamp of soft, fragrant, shimmying petals? Or did they use the bed, as if they were on a raft floating in a scented ocean?

  Cleopatra knew her guest. Few people have been as obsessed with roses as the ancient Romans. Roses were strewn at public ceremonies and banquets; rose water bubbled through the emperor’s fountains and the public baths surged with it; in the public amphitheaters, crowds sat under sun awnings steeped in rose perfume; rose petals were used as pillow stuffings; people wore garlands of roses in their hair; they ate rose pudding; their medicines, love potions, and aphrodisiacs all contained roses. No bacchanalia, the Romans’ official orgy, was complete without an excess of roses. They created a holiday, Rosalia, to formally consummate their passion for the flower. At one banquet, Nero had silver pipes installed under each plate, so that guests could be spritzed with scent between courses. They could admire a ceiling painted to resemble the celestial heavens, which would open up and shower them in a continuous rain of perfume and flowers. At another, he spent the equivalent of $160,000 just on roses—and one of his guests smothered to death under a shower of rose petals.

  Islamic cultures found the rose a more spiritual symbol, one that, according to the thirteenth-century mystic Yunus Emre, is supposed to sigh “Allah, Allah!” each time one smells it. Mohammed, a great devotee of perfume, once said that the excellence of the extract of violets above all other flowers was like his own excellence above all other men. Nonetheless, it was rose water that went into the mortar for his temples. Roses mix unusually well with water, making fine sherbets and pastries, so the flower has become a delicate staple in Islamic cooking as well as being much used to scent apparel. Hospitality still demands that a guest in an Islamic household be sprinkled with rose water a
s soon as she or he arrives.

  Rosaries originally consisted of 165 dried, carefully rolled-up rose petals (some of which were darkened with lampblack as a preservative) and the rose was the symbol of the Virgin Mary. When the crusaders returned to Europe, their senses sated by the exotic indulgences they discovered among the infidels, they brought attar of roses with them, along with sandalwood, pomander balls, and other rich spices and scents, plus a memory of harem women, sensual and languorous, who awaited a man’s pleasure. The scented oils the knights returned with became instantly fashionable, suggesting all the wicked pleasures of the East, as seductive and irresistible as they were forbidden. Pleasures as sense-bludgeoning as a rose.

  THE FALLEN ANGEL

  Smells spur memories, but they also rouse our dozy senses, pamper and indulge us, help define our self-image, stir the cauldron of our seductiveness, warn us of danger, lead us into temptation, fan our religious fervor, accompany us to heaven, wed us to fashion, steep us in luxury. Yet, over time, smell has become the least necessary of our senses, “the fallen angel,” as Helen Keller dramatically calls it. Some researchers believe that we do indeed perceive, through smell, much of the same information lower animals do. In a room full of businesspeople, one would get information about which individuals were important, which were confident, which were sexually receptive, which in conflict, all through smell. The difference is that we don’t have a trigger response. We’re aware of smell, but we don’t automatically react in certain ways because of it, as most animals would.

  One morning I took a train to Philadelphia to visit the Monell Chemical Senses Center near the campus of Drexel University. Laid out like a vertical neighborhood, Monell’s building houses hundreds of researchers who study the chemistry, psychology, healing properties, and odd characteristics of smell. Many of the news-making pheromone studies have taken place at Monell, or at similar institutions. In one experiment, rooms full of housewives were paid to sniff anonymous underarms; in another study, funded by a feminine hygiene spray manufacturer, the scene was even more bizarre. Among Monell’s concerns: how we recognize smells; what happens when someone loses their sense of smell; how smell varies as one grows older; ingenious ways to control wildlife pests through smell; the way body odors can be used to help diagnose diseases (the sweat of schizophrenics smells different from that of normal people, for example); how body scents influence our social and sexual behavior. Monell researchers have discovered, in one of the most fascinating smell experiments of our time, that mice can discriminate genetic differences among potential mates by smell alone; they read the details of other animals’ immune systems. If you want to create the strongest offspring, it’s best to mate with someone whose strengths are different from yours, so that you can create the maximum defenses against any intruder, bacteria, viruses, and so on. And the best way to do that is to produce an omnicompetent immune system. Nature thrives in mongrels. Mix well is life’s motto. Monell scientists have been able to raise special mice that differ from one another in only a single gene, and observe their mating preferences. They all chose mates whose immune systems would combine with theirs to produce the hardiest litters. Furthermore, they did not base their choices on their perception of their own smell, but on the remembered smell of their parents. None of this was reasoned, of course; the mice just mated according to their drive, unaware of the subliminal fiats.