A Natural History of the Senses (37 page)

Without light, could you or I see? Without light and water, could life exist at all? It’s hard to imagine living without light. The most frightening dark I remember was when scuba-diving in an underwater cave in the Bahamas. We carried flashlights, but at one point I turned mine off and just sat in the darkness. Later, when I climbed up out of the cave and stepped into the blinding light of a hot Bahamian day, the sun was burning from ninety-three million miles away, yet felt like fresh sandpaper on my arms and legs. At exactly 4:00
P.M
. it rained briefly, as it did each day at that time. The wet roads looked shiny. Not so the stone walls. Light waves hitting a smooth, flat surface bounce back evenly, making the surface shine. If the surface is rough, the light waves scatter in different directions, not as many will return to our eyes, and the surface doesn’t look shiny. It takes only a little light to stimulate the eye—a candle burning ten miles away will do—and a moonlit night, especially after a snowfall, will flood the eye with reflections, shapes, and motion. Astronauts in orbit around Earth can see beneath them the wakes ships leave in the oceans. But when we’re in the forest under a low cloud cover, and night falls like a black sledgehammer, there are no light rays to bounce back at the eyes, and we don’t see. As Sir Francis Bacon noted slyly in his essay on religion, “All colours will agree in the dark.”

Even people who have been blind since birth are greatly affected by light, because, although we need light to see, light also influences us in other subtle ways. It affects our moods, it rallies our hormones, it triggers our circadian rhythms. During the season of darkness in northern latitudes, the suicide rate soars, insanity looms in many households, and alcoholism becomes rampant. Some diseases, including rickets, result in part from children receiving too little sunlight; children are active creatures, and need the vitamin D that light produces to keep them healthy. Other malaises, like Seasonal Affective Disorder (SAD), which leaves many people feeling depleted and depressed in the winter months, can be corrected by daily doses of very bright light (twenty times brighter than average indoor lighting)
for about half an hour each morning. Some lingering low-level depression can be cured by changing a patient’s sleep schedule so that it parallels the season’s periods of light and dark more closely. Most years, Ithaca, New York, has only two seasons, both of which are wet—hot wet and cold wet—so it tends to be overcast much of the time. Bright light doesn’t stream in through the picture windows at sunrise. Anyway, my bedroom windows are thickly curtained, and I sleep in a room dark enough to please a star-nosed mole. Although I go speed walking for fifty minutes every day, regardless of season or weather, I find that I feel much more energetic, and generally happier, if I do my winter walkabouts in early or midmorning, and do them every single day without fail; in summer, it doesn’t seem to matter when I work out, or even if I occasionally miss a day.

Light therapy is being used to help people with psoriasis, schizophrenia, and even some forms of cancer. The pineal gland, or “third eye,” as it’s been mystically labeled, seems to be intimately involved with our sense of season, of well-being, the onset of puberty, the amount of testosterone or estrogen we produce, and certain of our more subtle seasonal behaviors. Testosterone is at its highest in men during early afternoons (around 2:00
P.M
.) in October, I suppose because a child conceived then would be born during the summer and have a greater chance of survival. Of course, men don’t all wait for that one climactic autumn month to make love, rising through a crescendo of libido in September and an only slightly dwindling mania as they near Christmas.

One of the hallmarks of our species is our ability not only to adapt to our environment, but also to change the environment to better suit us. We withstand the cold reasonably well, but we don’t let its extremes bully us into migrating; we just build shelters and wear clothes. We respond to sunlight, and we create light for times when there is little or no sun. We use the energy of fire, and we create energy. Most of this we like to do outside our bodies, unlike other creatures. When we want to light up the world around us, we build lamps. Many insects, fish, crustaceans, squids, fungi, bacteria, and protozoa bioluminesce: They throb with light. The angler fish even
hangs a glowing lure from its mouth, which attracts prey. A male firefly flashes its cool, yellow-green semaphores of desire, and if the female, too, is randy, she flashes back her consent. They look hot and bothered, twinkling through a summer’s night like lovers drifting from one streetlamp to the next. Their light comes from the blending of two chemicals, luciferin and luciferase (lucifer means “shining”). If you row through Phosphorescent Bay off the southwestern coast of Puerto Rico, at night, you’ll leave a trail of glowing auroras in the water and see cool fire dripping from your oars; it comes from microscopic invertebrates, which live in the water and secrete a luminous fluid whenever jostled. James Morin, a marine biologist at UCLA, has been studying rice-grain-sized crustaceans of the genus
Vargula
, which he’s nicknamed “firefleas.” There are thirty-nine known species, and they use light not only for courtship, but also to alarm their enemies. When they light up, they become more visible, but so does the predator, which in turn becomes easier to spot by an even larger predator. During courtship, each species flashes its own dialect of light. Far brighter than fireflies,
Vargulae
glow with an intense brilliance. “If I put a single fireflea on my fingertip and squashed it, I could read a newspaper from the light for about ten minutes,” Morin explains. Sailors tell about ships trailing fire from their sterns. They don’t mean St. Elmo’s fire (an atmospheric phenomenon that can strike a mast and ignite it with a cool, crackling, eerie green glow), but a moon-bright glitter swirled up on the water as the ship passes through tiny luminous lives.

Around Halloween, stores begin to sell necklaces, wands and other plastic items that glow coolly in the dark. Based on bioluminescence, they contain luciferins, and work the same way as a firefly’s glow. But, for extra sparkle, a trick or treater might also chew wintergreen Lifesavers. If you stand in the dark and crush one between your teeth, it will spill blue-green flashes of light. Certain substances (some quartzes and mica, even adhesive tape, when it is yanked off specific surfaces) are
triboluminescent;
they give off light if you rub, crush, or break them. Broken wintergreen fluoresces and broken sugar gives off ultraviolet light; the combination—in candies that
contain both sugar and oil of wintergreen—produces tiny bolts of blue-green lightning. Try this parlor game: Step into a closet with a mouthful of wintergreen Lifesavers and a friend and wait for sparks to fly.

At twilight, pink wings tremble along the hilltops, and purple does a shadow dance over the lake. When light hits a red car on the streetcorner, only the red rays are reflected into our eyes, and we say “red.” The other rays are absorbed by the car’s paint job. When light hits a blue mailbox, the blue is reflected, and we say “blue.” The color we see is always the one being reflected, the one that doesn’t stay put and get absorbed. We see the rejected color, and say “an apple is red.” But in truth an apple is everything
but
red.

Even though it’s sunset and the quantity, quality, and brightness of light have all diminished, we still perceive the blue mailbox as blue, the red car as red. We are not really cameras. Our eyes do not just measure wavelengths of light. As Edwin Land, inventor of the Polaroid Land Camera and instant photography, deduced, we judge colors by the company they keep. We compare them to one another, and revise according to the time of day, light source, memory.
*
Otherwise, our ancestors wouldn’t have been able to find food at sunset or on overcast days. The eye works with ratios of color, not with absolutes. Land was not a biologist, but a keen observer of how we observe, and his theory of color constancy, proposed in 1963, continues to make sense. Every college student at one time or another has asked what it means to
know
something, and whether there are simple perceptual truths that people share. We watch
color
television because our ancestors had eyes cued to the ripening of fruit; and they also had to be wary of poisonous plants and animals (which tend to be brightly colored). Most people can identify between 150 and 200 colors. But we do not all see exactly the same
colors, especially if we’re partly or completely color-blind,
*
as many people are—men in particular. A blue ship may not look the same when viewed from opposite sides of a river, depending on the landscape, clouds, and other phenemona. The emotions and memories we associate with certain colors also stain the world we see. And yet, how astonishing it is that we do tend to agree on what we call red or teal or cream.

Not all languages name all colors. Japanese only recently included a word for “blue.” In past ages,
aoi
was an umbrella word that stood for the range of colors from green and blue to violet. Primitive languages first develop words for black and white, then add red, then yellow and green; many lump blue and green together, and some don’t bother distinguishing between other colors of the spectrum. Because ancient Greek had very few color words, a lot of brisk scholarly debate has centered around what Homer meant by such metaphors as the “wine-dark sea.” Welsh uses the word
glas
to describe the color of a mountain lake, which might in fact be blue, gray, or green. In Swahili,
nyakundu
could mean brown, yellow, or red. The Jalé tribespeople of New Guinea, having no word for green, are content to refer to a leaf as dark or light. Though English sports a fair range of words to distinguish blue from green (including azure, aqua, teal, navy, emerald, indigo, olive), we frequently argue about whether a color really should be
considered
blue or green, and mainly resort to similes such as grass green, or pea green. The color language of English truly stumbles when it comes to life’s processes. We need to follow the example of the Maori of New Zealand, who have many words for red—all the reds that surge and pale as fruits and flowers develop, as blood flows and dries. We need to boost our range of greens to describe the almost squash-yellow green of late winter grass, the achingly fluorescent green of the leaves of high summer, and all the whims of chlorophyll in between. We need words for the many colors of clouds, surging from pearly pink during a calm sunset
over the ocean to the electric gray-green of tornadoes. We need to rejuvenate our brown words for all the complexions of bark. And we need cooperative words to help refine colors, which change when they’re hit by glare, rinsed with artificial light, saturated with pure pigment, or gently bathed in moonlight. An apple remains red in our minds, wherever we see it, but think how different its red looks under fluorescent light, on the shady branch of a tree, on a patio at night, or in a knapsack.

Color doesn’t occur in the world, but in the mind. Remember the old paradoxical question: If a tree falls in the forest, and no one is around to hear it, does it make a sound? A parallel question in vision: If no human eye is around to view it, is an apple really red? The answer is no, not red in the way we mean red. Other animals perceive colors differently than we do, depending on their chemistry. Many see in black and white. Some respond to colors invisible to us. But the many ways in which we enjoy color, identify it, and use it to make life more meaningful are unique to humans.

In the Hall of Gems at the Museum of Natural History in New York, I once stood in front of a huge piece of sulfur so yellow I began to cry. I wasn’t in the least bit unhappy. Quite the opposite; I felt a rush of pleasure and excitement. The intensity of the color affected my nervous system. At the time, I called the emotion wonder, and thought: Isn’t it extraordinary to be alive on a planet where there are yellows such as this? One of today’s “color consultants” might tell me instead which chakra, or energy center, the yellow was stimulating. The therapeutic use of color has become faddish of late, and, for a price, all sorts of people will help you “learn what colors your body needs,” as one guru puts it. Recent books decree the only and perfect colors to make you look beautiful or cure your flagging spirits. But scientists have known for years that certain colors trigger an emotional response in people. Children will use dark colors to express their sadness when they’re painting, bright colors to express happiness. A room painted bubble-gum pink (known in hospitals, schools and other institutions as “passive pink”) will quiet them if
they’ve gotten obstreperous. In a study done at the University of Texas, subjects watched colored lights as their hand-grip strength was measured. When they looked at red light, which excites the brain, their grip became 13.5 percent stronger. In another study, when hospital patients with tremors watched blue light, which calms the brain, their tremors lessened. Ancient cultures (Greek, Egyptian, Chinese, Indian, and others) used color therapies of many sorts, prescribing colors for various distresses of the body and soul. Colors can alarm, excite, calm, uplift. Waiting rooms in television studios and theaters have come to be called greenrooms, and are painted green because the color has a restful effect. Dressing baby boys in blue and girls in pink has a long history. To the ancients, a baby boy was cause for celebration, since it meant another strong worker and the carrying on of the family name. Blue, the color of the sky where the gods and fates lived, held special powers to energize and ward off evil, so baby boys were dressed in blue to protect them. Later, a European legend claimed that baby girls were born inside delicate pink roses, and pink became their color.

Some years ago, when I had taken a job directing a writing program in St. Louis, Missouri, I often used color as a tonic. Regardless of the oasis-eyed student in my office, or the last itchlike whim of the secretary, or the fumings of the hysterically anxious chairman, I tried to arrive home at around the same time every evening, to watch the sunset from the large picture window in my living room, which overlooked Forest Park. Each night the sunset surged with purple pampas-grass plumes, and shot fuchsia rockets into the pink sky, then deepened through folded layers of peacock green to all the blues of India and a black across which clouds sometimes churned like alabaster dolls. The visual opium of the sunset was what I craved. Once, while eating a shrimp-and-avocado salad at the self-consciously stately faculty club, while I gossiped with an anorexic and hopped-up young colleague, I found myself restless for the day to be over and all such tomblike encounters to pale, so I could drag my dinette-set chair up to the window and purge my senses with the
pure color and visual tumult of the sunset. This happened again the next day in the coffee room, where I stood chatting with one of the literary historians, who always wore the drabbest camouflage colors and continued talking long after a point had been made. I set my facial muscles at “listening raptly,” as she chuntered on about her specialty, the Caroline poets, but in my mind the sun was just beginning to set, a green glow was giving way to streaks of sulfur yellow, and a purple cloud train had begun staggering across the horizon. I was paying too much rent for my apartment, she explained. True, the apartment overlooked the park’s changing seasons, had a picture window that captured the sunset every night, and was only a block away from a charming cobblestone area full of art galleries, antique stores, and ethnic restaurants. But this was all an
expense
, as she put it, with heavy emphasis on the second syllable, not just financial expense, but a too-extravagant experience of life. That evening, as I watched the sunset’s pinwheels of apricot and mauve slowly explode into red ribbons, I thought:
The sensory misers will inherit the earth, but first they will make it not worth living on
.