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

amounts (.01 percent), was responsible for 95 percent or more of the cooked-artichoke smell. The chemical at the heart of John Muir’s Sierra smellscape turns out to be 1-hexen-3-one.
    Hexenone has been fingered as a key aroma in aged milk, cream, and butter; it also has a starring role in linden honey and fresh raspberries. This illustrates that a complex stew of volatile molecules can smell a lot simpler than what is implied by its lengthy ingredient list; one chemical can dominate an entire bouquet. Another lesson: abundance is not a reliable clue to odor impact; in this case, a single molecule from a single plant provides the aromatic background for an entire ecosystem And finally, it shows that a talented fragrance chemist can find the single molecule responsible for John Muir’s poetic impressions of the Sierra Nevada foothills.
     
    F ROM THE WHISPERED fragrance of a single exotic blossom, it is but a step to capturing an entire smellscape. No one had a surer grasp of the grand scale of the American smellscape than Walt Whitman.
    The conceits of the poets of other lands I’d bring thee not,
    Nor the compliments that have served their turn so long,
    Nor rhyme, nor the classics, nor perfume of foreign court or indoor library;
    But an odor I’d bring as from forests of pine in Maine, or breath of an Illinois prairie,
    With open airs of Virginia or Georgia or Tennessee, or from Texas uplands, or Florida’s glades…
    —W ALT W HITMAN,
Leaves of Grass
    Pine forest or prairie, seashore or bayou, the essence of the ambience is there for the taking. To carry it away, all you need is a pump and a trap. To reproduce it is not trivial—it’s a matter of money and determination—but it is firmly within our technological grasp. We can re-create the scent of coyote mint and pennyroyal and Sierra Mountain Misery. We can project them into your living room or office cubicle. Imagine them unspooling in slow transitions—a diorama for the nostrils—while you listen to Muir’s afternoon on the Feather River, or to Whitman’s ode to the American outdoors. What would you like to smell? For myself, I’d vote for the sea breeze at Point Reyes and the scent of the redwoods at Big Sur.
     
    I N HIS 1947 MEMOIR
Speak, Memory
, the novelist and butterfly expert Vladimir Nabokov recounts a moment from one of his summertime collecting trips:
    Unmindful of the mosquitoes that coated my forearms and neck, I stooped with a grunt of delight to snuff out the life of some silver-studded lepidopteran throbbing in the folds of my net. Through the smells of the bog, I caught the subtle perfume of butterfly wings on my fingers, a perfume which varies with the species—vanilla, or lemon, or musk, or a musty, sweetish odor difficult to define.
    Scented butterflies are not exotic or rare. The Green-veined White, for example, is common throughout Europe and in parts of the United States, where we call it the Mustard White. To the British lepidopterist George Longstaff, its “strong and distinct” odor resembled lemon verbena. Back in 1912, he wrote: “It is curious that to this day so few persons are practically acquainted with the scent of the Green-veined White. When, at the Brussels Conference, in 1910, I caught a male
G. napi
in the beautiful garden of the Congo Museum, and demonstrated the scent to half a dozen entomologists present, none of these gentlemen had perceived the scent before, though at least one of them was a very eminent observer.” The situation hasn’t changed much in the last hundred years. No current field guides mention the scent of the Green-veined White—or of any species, for that matter. The fussy “butterflies through binoculars” crowd discourages physical contact with actual insects, but there are plenty of Mustard Whites in the Rocky Mountains, and you don’t have to be as brutal as Nabokov. Go ahead and catch one for yourself. Sniff and release.
    In Longstaff’s field notes, one finds an astonishing