In early 2002, a woman walking her dog in the woods adjacent to Tri-State Crematory in the Appalachian town of Noble, Georgia, found a human skull. Arriving investigators discovered body parts scattered all over the woods, and when they entered the crematory compound, they immediately called in FEMA.
What they encountered on the premises was a confusion of cadavers rotting in various holding crypts and earthen pits. A coffin left in the crematory yard contained a green-black stew of human bones. The scene was beyond grim: corpses jellying into dreadlocks of waxen gray material, fermented fat and muscle twisted around moldy bones. A skull and torso were found floating in the compound’s lake. In all, 334 sets of remains were found, some of which still bore toe tags.
The incinerator at Tri-State was in working order, and the manager, Ray Brent Marsh, couldn’t say why he had stockpiled the bodies. (“Not for lack of a desire to give those answers,” he said at his plea hearing, “but the lack of the answer.”) But where Marsh’s mess was a tragedy for the families of the dead, the United States Armed Forces saw an opportunity. There was a practical application for all that decay — specifically for the compounds known as putrescine and cadaverine, both of which smell like their names suggest.
Soldiers are exposed to death in its many stages — from the just-before wound, when an exploded abdomen leaks the odors of digestion, to the weeks-later smell of advanced decomposition. Many of the men and women thrust into these experiences were coming home unhinged, so the U.S. military was prompted to deploy, for the first time, scent as a training tool.
Pamela Dalton, of the Monell Chemical Senses Center in Philadelphia, remotely coordinated the odor-gathering effort at Tri-State as part of a program funded by the Department of Defense. “Volunteers collected samples of the air,” she explains. “I don’t think I’ve ever smelled anything more disturbing in my entire life.” Dalton works on olfactory strategies to treat (or preempt) post-traumatic stress disorder, her goal being to hinder the associative power of common war-zone odorants by inuring soldiers to them. Diesel fuel is one of the smells that can send a veteran around the bend. The same goes for cordite. And the smell of death, of course, is a reliable trigger.
“It’s a lot easier to associate a negative emotion with an odor,” Dalton told me. “That happens almost with one trial, where positive associations take a lot longer, sometimes two to three pairings.” If you smell a corpse in a well-lit room while watching war imagery with virtual-reality glasses, you may be less vulnerable to those sensory stimuli when you experience them in a war zone. The military wanted to create soldiers who wouldn’t come apart when an I.E.D. ripped off the leg or pierced the skull of someone nearby.
But there was another battlefield use for the samples collected at Tri-State. “I did some work around 1997,” Dalton told me, “to see if there was a ‘universal malodor’ that caused people from any culture to leave an area.” She explained that a certain branch of the military had “wanted to know if there was a single odor or set of odorants that would produce this effect.” The answer, Dalton said, was a nonlethal biological agent — she called it “a chemical, but not a chemical weapon” — known as Stench Soup. In one test trial, volunteers fitted with heart-rate and gastric-motility monitors were seated in a room into which Dalton pumped the odorant. They were told to turn down a dial when the stench became unbearable. In another test trial, volunteers were asked to drink a milkshake while smelling Stench Soup. Most couldn’t.
“What we realized rather quickly,” Dalton told me, “was that if [the odor] was going to transcend culture, it had to be something that had biological significance, and that’s why we focused on things like vomit. . . . We worked on our own formula for human feces. We did a rotting-sewage odor, rotting meat.” Stench Soup works on the principle that something truly repulsive needs to have something nice in it to make the olfactory mucosa want more. Said Dalton, “Combining these unpleasant formulas with . . . a floral or a fruity odor was what made the thing so disgusting none of us could stand it.”
Dalton sent me a sample. It arrived in a cloudy vial covered with some sort of sticky plastic wrap, which was suspended inside a glass specimen jar filled with Styrofoam peanuts, which in turn was sealed in a Ziploc bag. There was a little beige stir bar inside the vial. I recruited my downstairs neighbor and we went out to the alley behind the house. I closed the vial as soon as I opened it. The alley reeked all the way out to the street, at least twenty feet from where we stood. A passerby stopped and peered in. The vial had been open for fewer than three seconds.
Historically speaking, science has been charged not with intentionally producing bad odors but with eliminating them. The traditional approach to dealing with the ambient smells of a city has been to mask its odors — of sewage and waste, or death and contagion — with some more agreeable scent. Alain Corbin’s history of France’s relationship to scent, The Foul and the Fragrant, describes the events of March 23, 1782, when a group of experts in chemistry and hygiene were summoned to Paris’s Hôtel de la Grenade, a hospital on Rue de la Parcheminerie. Medical students were said to have been discarding body parts in the cesspool. The smell was legendary. That day, Antoine Lavoisier, the Duc de La Rochefoucauld, and others came to test a new antimephitic, a substance meant to neutralize miasmas. (For centuries, physicians believed that miasmas — vapors carrying noxious particles — were the cause of communicable diseases, from bubonic plague to cholera to malaria. The theory held till the middle of the nineteenth century, when germs began to be better understood by science.) At some point during the test of the stench neutralizer, a cesspool cleaner was overcome by the fumes and fell in. He was soon pulled out but did not survive. A ventilation inspector who inhaled the dying man’s breath while trying to administer mouth-to-mouth resuscitation shouted, “I am a dead man!” and fell into a fit, foaming at the lips. He survived, but not, Corbin notes, without suffering “after-effects.”
Ancient Rome, to take another example, was filthy, despite (or perhaps because of) its grandeur. A main artery of the Eternal City was the Cloaca Maxima, an open sewer that carried waste into the Tiber River. As Europe grew, many cities had open sewers running through their streets. Well into the nineteenth century, horrific bouts of cholera spread via the presence of fecal matter in both the air (dried and pulverized and lofted upward as dust) and the water.
In early modern cities, malodors migrated from sewers to a sociocultural equivalent: poor people — the pongy masses who couldn’t afford to mask the odors of the body with perfume or neutralize the stench of the neighborhoods where they lived. Ragpickers were particularly shunned, because their work took them to the city dumps. Prostitutes were considered repugnant for the obvious reason that they were more exposed to infection than most people, and specifically because they were exposed to a lot of semen — the aura seminalis being a powerful odorant when put in contact with the female sexual orifice. Homosexuals, too, were tainted by their association with excessive amounts of semen, as well as by the perception of anal sex as unclean. Nasty smells were like grave sins; they were associated with the dire consequences of bad behavior.
The perfume of certain flowers brought by the living to a wake for the dead provided a respite from the smell of putrefaction. The smell of corruption was an aspect of the nightmare set in motion by Eve’s conversation with the serpent. No wonder some of the earliest attempts to produce pleasant smells came straight out of religious practice. The presence of incense indicated class and power, and it also suggested cleanliness — all of which were evidence of the holy. The word “perfume” is derived from the French parfumer (“to scent”), which comes from the Latin per fumare (“to perfuse with smoke”). For Buddhists, the smoke of a censer purified the place of worship and summoned buddhas and jikikoki, the souls of dishonest incense dealers condemned after death to subsist on incense smoke. In Christianity, prayers were commixed with the smoke of frankincense and myrrh. For a brief moment, the smells of dirty transient life could be supplanted by something sweeter.
All of which is to say that good smells do often signal good things. A strong antiseptic odor likely attracted the Aborigines of Australia to eucalyptus. Its derivative, eucalyptol, was used as a remedy for congested airways, intestinal disorders, and topical infection, and has been observed, in at least one controlled environment, to kill leukemic cells. The Bundjalung of what is now New South Wales found tea-tree oil to be effective in fighting coughs and colds as well as fungal invasions, hemorrhoids, and urinary-tract infections. Native to Asian tropical forests, “green leaf,” or patchouli, has long been taken to ease anxiety and treat snakebite. The oil of the cedars of Lebanon is reported to slow male-pattern balding. Rosemary quiets rheumatism. Cannabis relieves pain.
One of the most popular cure-alls in premodern Europe was also the continent’s first alcohol-based perfume. It was called Hungary water. Most likely developed by a court alchemist during the late 1300s, it supposedly cured gout, epilepsy, headache, lethargy, memory loss, toothache, deafness, and a host of other maladies. According to an unsigned nineteenth-century article in London’s Saturday Review, the recipe was fairly simple:
Take of aqua vitae, four times distilled, three parts, and of the tops and flowers of rosemary two parts: put these together in a close vessel: let them stand in a gentle heat fifty hours and then distill them. Take one dram of this in the morning, either with your food or drink, and let your face and the diseased limb be washed with it every morning.
The remedy, according to another medical writer, included this important step: “Breathe in with your nose.” Hungary water, in other words, would do double duty as a medication and a scent, and it remained the most popular perfume among European aristocrats for the next 400 years.
What eventually supplanted Hungary water was the introduction, in Germany, of eau de cologne, adapted from an old monk’s recipe by Giovanni Paolo Feminis, an Italian merchant, in the early years of the eighteenth century. Eau de cologne was composed of neroli oil, bergamot, lavender, and rosemary. It could be splashed on the face to freshen up or taken internally for swollen gums and indigestion — and it also eased early-morning jitters. French soldiers used this aqua admirabilis because the smell of something nice covered the odors of war and overpopulation resulting from the march of empire. The recipe’s path through Europe is a matter of debate among historians of perfumery. By some accounts, the heirless Feminis, before dying in 1736, passed his recipe to his great-nephew Giovanni Maria Farina, who sold it to a German banker named Wilhelm Mülhens. By other accounts, Mülhens acquired the recipe more or less the way Feminis had: as a gift from a monk. In either case, Mülhens opened in 1792 a shop called 4711, named for its address, where he sold “la véritable Eau de Cologne.” The scent’s popularity grew, enhanced by the French troops who had brought it back to Paris after occupying Cologne during the Seven Years’ War. (Napoleon is said to have used as many as sixty bottles a day.) Many were encouraged to enter the business and trade in eau de cologne under the name Farina. 4711 is still available, and to this day is quite inexpensive, although now it’s touted in advertisements as Das Wunderwasser.
Concurrently with the opening of Mülhens’s first shop, the French town of Grasse was emerging as the birthplace of modern perfume. This development was the product of a strange symbiosis. Grasse was originally famed for its tanneries; tanneries famously stink. But since the village was also blessed with the ideal climate in which to grow many types of sweet-smelling flowers and herbs, the local jasmine, rose, and lavender were deployed to help cover the animal odors of the tannery. Taking this symbiosis one step further, Grasse began manufacturing scented gloves, which were already in use throughout Europe. When an onerous leather tax made the glove trade unprofitable, Grasse remade itself as a town of perfumers. The smells of Hungary water and eau de cologne persist, but they are now re-created synthetically in a laboratory.
The processing of smells begins in the olfactory bulb. Humans have two of these bulbs above the sinuses, peninsular areas of whitish-gray tissue about the size of a raindrop, one per nostril. They run above the skull’s cribriform plate, a thin piece of bone that separates the nasal cavity from the brain, and they receive information from the olfactory epithelium, a group of 15 to 20 million sensory neurons in the upper regions of the nose, each of which sends an axon through the cribriform plate to one of the olfactory bulbs. Here is one of the few spots where the sensory structures of the human central nervous system come directly into contact with the outside world.
Beyond these anatomical nuts and bolts, however, our knowledge of the mechanisms of smell is extremely fuzzy, riddled with indeterminacy because it is based on someone’s say-so, and the caprices of subjectivity make the sense of smell particularly hard to analyze. Some humans are more gifted in this area than others, and some people learn to use what is native to them with astonishing results. Helen Keller, for example, could tell what a person did for a living by the smell of his or her clothes.
Nonhumans are better equipped. Houseflies can detect odor with their antennae. Salmon are able to sniff out their ancestral spawning streams from thousands of miles away. Physiology is a limiting factor for humans, with our mere 15 to 20 million sensory neurons (some breeds of dog have as many as 200 million), but the limitation is not merely physiological. Unlike animals for whom smell is a crucial means of figuring out what’s what, for us the sense is peripheral, almost frivolous. Odor pertains to the uncontrollable and the contagious, to kitsch and camp. It is the profane; the animal, base nature, the fart — all of these intermingled with what W. H. Auden called “the unmentionable odor of death.”
In the modern science of smell, fragrance molecules are routinely engineered to make something that smells bad (many lotions and detergents reek in their untreated state) smell like nothing at all. In the federally regulated world of marketing-speak in the United States, this manipulation is expressed as the difference between “fragrance free” (meaning no scent has been added) and “scent free” (meaning a scent has been added to neutralize the original scent of the product). Other molecules are designed to make you think of sex, or to get you relaxed enough to forget you can’t afford a new car.
ScentAir is one of a handful of companies catering to the unwitting consumer’s easily manipulated sense of smell. ScentAir sells the smell of a place, and “it” can smell like anything you want. The company’s promotional material trots out a plate piled high with some idiot Proctor & Gamble alum’s notion of the Proustian madeleine. “Nobody has ever asked you to stop and hear the roses,” the company’s website reminds visitors. “Think about one of your favorite memories and there’s an excellent chance there’s a smell attached to it.” The idea is to create a signature scent for a business, so that people will come to associate that smell with a predictable, repeatable, deliverable experience. Brand recognition becomes synesthetic reality. (Less subtle, perhaps, was the introduction back in 2008 of Flame, a discontinued men’s fragrance marketed by Burger King that made the wearer smell like a flame-broiled Whopper.)
In marketing circles, this is scent’s golden moment. The smells of everyday life, once dominated by butchered meat and offal, manure and unwashed people, have been transformed into something like elevator music. Coincidentally, Muzak (the elevator-music company) has been the exclusive distributor of ScentAir since 2004. As a result, Westin hotels now smell and sound the same wherever you go. In theory, your brain finds this pleasing, because — like an incense-infused hall of worship — its scent requires none of the vigilance necessary for sussing out a new environment. Omni Hotels and a variety of big-name retailers (Samsung, Sony, Victoria’s Secret) have also discovered the advantages of scent branding, which is now used to invigorate workouts at gyms and to prevent bad behavior in parking garages.
Alex Moskvin of BrandEmotions, a division of International Flavors & Fragrances, describes what he calls “the DNA” of a brand. “It’s important for companies like ours to understand the emotional communication of the fragrance and to have a point of view on that,” he said in a 2005 interview with Fast Company. “We want to capture a smell that makes people feel part of the club.” Most people want to belong to this club. After all, Napoleon belonged to it.
It’s one thing to synthesize the smell of a hamburger, a shopping mall, even rotting flesh, but the smell of a place is more complex, and a thousand times more elusive. Still, there are certain constants. The smell of rain is one of them. It is associated with the calm of nature, a cleansing force, even a kind of sanctity. The smell of soil is another — though it is hard to separate that scent from the water that unlocks it. In 1964, I. J. Bear and R. G. Thomas, two Australian chemists, published a paper in Nature about the smell of rain on parched clay. They called this odor petrichor, from the Greek petra (stone) and ichor, the bloodlike fluid that courses through the veins of the gods of Greek mythology. According to Bear and Thomas, the substance they identified was universal, and it was responsible for the pleasant odor that rises from the ground just after the first raindrops touch desert clay following a dry spell.
Since the time of ancient Egypt, doctors, alchemists, and perfumers have captured scents through enfleurage — trapping odorant in a prepared substrate, usually animal fat — for use in unguents, salves, and perfume. In the case of petrichor, the substrate is mineralogical rather than lipid — mostly clay and rock and hardpan — which makes the collection of petrichor extremely complicated and expensive.
Although the smell of rain is intensely desirable (many people list it among their favorites), attempts to create synthetic petrichor — sometimes called petite pluie in the perfume industry — are fairly rare, and always failures. That is because petrichor, as described by Bear and Thomas, tells a terrestrial ghost story. Like the smell of death and disease in the plaster walls of a nineteenth-century morgue (that’s why they’re tiled or coated with semi-gloss paint today) or the fish stink in an open container of spoiled milk, the ambient odors of any given environment are absorbed from the air by anything porous and stored there. The matrix we call air is filled with an ever-changing bouquet of terpenes and volatile lipid- and carotenoid-derived compounds released during processes of decomposition, metabolism, and growth. A balanced ecosystem has a more delicate bouquet than the overcrowded streets of eighteenth-century Paris, but petrichor and the malodor of premodern Europe are close olfactory cousins. They both describe the world encountered there; they tell an olfactory story of place.
To produce other coveted scents, the easiest route recently has been laboratory synthesis. Natural oud, or gaharu, is a resin common to several species of agarwood tree. It is the tree’s immune response to a particular kind of fungus, and it is in great demand, typically exceeding $50,000 a kilogram. A decent approximation of the same scent has been produced in a laboratory for a fraction of the cost. Likewise, the compounds 5,7,7-trimethyloctanenitrile and 2-nonenenitrile (“iris nitrile”) smell like iris butter, but they don’t cost tens of thousands of dollars per kilogram, like the sweetly violetlike note that develops when the oil in iris rhizomes has been aged five years and then recovered through steam distillation.
The smell of a place at a particular moment could be said to follow the same rules as any perfume, but with a far greater degree of complexity. Typically, a perfume is composed of some head notes (bright smells that dissipate quickly), heart notes (heavier molecules that define the overall smell), and a bottom note (a smell such as sandalwood, which doesn’t dominate a fragrance but may stay on your clothes for days). On a midsummer afternoon after a light rain, the smell of my block in Brooklyn might include petrichor as a heart note. But that would only be the simplest part: there would be head and heart notes of gasoline, rotting food, fallen leaves, pollen, flowers, car exhaust, a great variety of feces from organisms sharing the space, and perhaps bottom notes from the soil, grime, and soot ground into pavement, with an occasional contribution from the East River when the wind is right. My own Wythe Avenue smell-of-rain moment would compare to an isolated attempt at synthetic petrichor about as well as a Big Ten marching band to a tin whistle.
If we were to succeed in creating a generic after-rain scent, it would be an olfactory representation of cycles of regeneration — in other words, it would be the smell of life and death and everything in between. But because it would be a perfume, it would be bound to miss the mark. In the end, perfume is all about masking the smells of nature with the smell of something above and beyond nature, where nothing bad happens.
The duplication of an odor, however, is extremely complicated. For example, Forest Fresh Little Tree air freshener doesn’t smell very much like the resin on bark, much less the smell of sunlight hitting that resin (heat and humidity speed molecular activity, thereby intensifying odors). There are no duff or humus smells from the forest floor, and no vanillin from rotting wood. Your brain says “pine forest” because it has been lulled into a stupor by the fake smells of the marketplace. It recognizes the evergreen note, but it doesn’t worry too much about the imposter odor.
Fragrance manufacturers are in the smell-décor business. Everything is a caricature, designed for the lowest common denominator. When you smell peach gummy candy, it is an idealized cartoon peach. If you want pine, you get Little Tree. Jennifer Lopez’s Glow by JLo is a sort of anime version of freshly washed skin. The lobby at Macy’s will feature a few vials of liquid that are the smell equivalent of a bodice-ripper. Specificity and nuance raise the common denominator and diminish marketability.
The kings and queens of popular culture — whether Ralph Lauren or the Olsen twins — leave their mark on the olfactory mucosa of the unwary consumer. The descriptive briefs that serve as a road map for a new scent are studies in nonsense. Tom Ford wants “fresh cherry wood licked by a green-hot oxygen fire in a Balinese temple.” Marc Jacobs imagines “a blossoming daffodil floating on an ocean of smoky Siberian snows.”
With its purchase of Quest International, a fragrance and flavor company, in 2006, Givaudan cemented its position as the world’s largest producer of flavors and fragrances, with a valuation of about $4 billion. Roman Kaiser, a chemist, was the director of natural scents and a distinguished research fellow at Givaudan for three decades, until he retired in 2011. His improbable name came up again and again while I was searching for someone to explain the odor of place.
Kaiser’s work took him all over the world. He flew above the canopies of rainforests in a dirigible, collecting samples in glass bulbs designed to create a vacuum around the scent source. He then reconstituted the natural scents he found on those expeditions. He was not seeking ways to re-create such rare odors as agarwood or oud — that work was already being done by his lab. Kaiser was being paid to find new scent molecules, not better examples of known ones.
One of the many natural wonders Kaiser, who has published two books, writes about is Chlamydomonas nivalis, or watermelon snow, a pinkish-green algae that grows on glaciers. The pink color comes from a package of carotenoid in each cell — the pigment is needed to capture sunshine and for UV protection. C. nivalis grows on snow in the summer months at the two-mile-high range in the Alps, the Sierra Nevada, and the Andes (where Darwin saw it and called it “red snow”). When stepped on, the compressed snow turns the color of watermelon pulp and emits a faint odor that more or less matches the smell of that fruit. In Scandinavia, they call it “blood snow.” Kaiser sent me a sample of his synthetic version. The smell was as advertised.
Another curiosity Kaiser likes to talk about is a common plant whose vinelike aerial roots are recognizable throughout lower Amazonia. Philodendron solimoesense is about the thickness of a thumb and can grow to a length of sixty feet. Kaiser first encountered it when, dead-ended in heavy growth, he was forced to cut a couple of the vines. For the first few seconds, a flood of water poured from the severed vines. “But then, I could hardly believe,” Kaiser wrote in Meaningful Scents Around the World, an account of his travels and discoveries, “the most transparent and crispest grapefruit scent, embedded in woody notes, entered my nostrils.”
He made a perfume based on this odor, Air de Philodendron, which is the fragrance he generally wears. Its head note is derived chemically from the smell of the severed vines in the Amazon basin, shot through with other citrus notes and a hint of cassis. From there, it bounces through a space filled with what smells to me like lily of the valley (very difficult to reproduce) and jasmine, and then it settles into a woody bottom composed of darker musk notes wrapped around wacapou (a tree native to French Guiana), sandalwood, Virginia cedar, and a touch of frankincense.
Kaiser’s role was to find new notes for professional noses to use in the service of those wizards of place — whether Tom Ford and Marc Jacobs or the anonymous overseer of the Westin hotel empire. Kaiser’s distinction is that he re-created things found in nature that fall on the dirty side — stuff that is decidedly antiperfume, like dirt and fungus and mold — not to mask the real but to mimic it.
When I asked Kaiser whether he could truly manufacture the smell of an entire place with all its constituent elements, from the pretty to the profane to the mundane, he paused. Then he quickly walked me through an olfactory analysis of place, a biome he had studied on the Mediterranean coast. It was June, he began, and the location was Liguria, in northern Italy.
There are two main Pinus species in Liguria, Pinus pinaster and Pinus maritime, and both contribute resinous, musky, woody notes to the olfactory environment. “This is very basic,” he said. “And these notes are from resin that has been exposed to the sun — very typical for this environment.”
“That takes care of the pine species,” he continued, “and now it depends really very much on where we are. On the Ligurian coast, you will also find a lot of two Pistacia species: Pistacia terebinthus and Pistacia lenticus. Both give off a very characteristic, green, slightly citrus note, reminiscent of galbanum — think of cut bell pepper. And now two important floral notes in June. There is broom, Spartium junceum, a very rich aromatic floral scent a little bit related to orange blossom; and a honeysuckle species, Lonicera implexa, which emits, especially between six and ten in the evening, a strong, very tender, rather white floral scent that would harmonize all these notes into something very attractive.
“The dynamics change over the span of a day, and according to the time of year. If you would like to study a place, you can’t just trap the scent that is in the air close to your nose,” he explained. “Instead, you have to divide this entire olfactive environment into different building blocks. You have to establish an inventory, make a ranking: most important, less important, and medium important scent sources. Trap them individually. Investigate the most important ones, and afterward reconstitute the whole thing.”
I couldn’t help but wonder what this place-in-a-bottle would cost. The kings of yore were able to smell sweet and look great because they had enormous wealth, but their notion of smelling nice was to wrap themselves in a cloud of expensive scent. That ability to banish the odors of early Europe was valuable. Now the smell of rotting cadavers is valuable, because the average deployed soldier costs the government $531,427 annually. The smell of a random place along the Ligurian coast is not worth very much, and it has no health benefits (unless there is some boost in mental health spurred by wonder). You would need to capture and analyze the air at least 3,000 times to replicate the smell of a full day, I speculated to Kaiser. He considered my proposed methodology excessive, but said that the samples would cost about $800 a pop. The total would come to $2.5 million. And it would still be a sketch, an approximation.
All this made me think that it is enough to take in my genius loci in real time: the dry garbage smells mixed with the pee of drunkards and the dog shit and the toxic soil packed between the knuckled roots of the Callery pear trees — everything that contributes to the smell of my here and now. Neither Roman Kaiser’s dirigible nor Pamela Dalton’s nonlethal bioweapon can top the smell of noon on July 1, 2013, on a stoop on Wythe Avenue on the south side of the Williamsburg neighborhood of Brooklyn. I don’t need $2.5 million to have the experience, and if a modern-day king came strolling by holding hands with the Pope, well, I’m afraid my block would still smell like shit.