Most of us, for whom nature means either bad weather or a TV programme, live in a world of man-made colours: bright synthetic dyes which pep up our clothes; plastics and metals in ever more shrieking primaries; day-glos and fruit flavoured chromes; from the most dazzling items in our wardrobe to our plastic toys and accoutrements; from our visually alarming confectionery to the finish on certain meat products; even the perfect, irradiated red peppers and green apples piled up in our specially-lit fruit 'n' veg departments.
Colours are literally hardwired into the way we see and think about the world; our moods and pre-conscious desires. Marketers, in their simple wisdom, understand this and ramp up the pleasure principles. And they are right: colour is popular. People may have howled down Ted Turner when he colourised old black and white movies, but they've achieved higher ratings ever since, on cable.
As any good schoolchild knows, colour arises from the wavelengths of visible light which bounce off objects around us. Newton discovered the spectrum while refracting white (mixed) light through a prism. Red, long-wavelength light "bent" the most; violet the least. And then he got his white light back by passing the spectrum back through another prism. Neat, you have to admit.
Meanwhile, at the back of the human eyeball, there are two types of light-sensitive cells. "Rods" can respond to even a single photon, and so are useful for the cat's night vision. But much more light is needed to stimulate the three types of colour-sensitive "cones", each with their distinct photosensitivepigments; each peaking at the wavelength of either red, green or blue. (These we term the "primary" of colours of light, which mix in an additive way. With paint, however, the three primary colours are blue, yellow and red - because mixing them is based on subtractive logic, in that less light is reflected the more you mix: you eventually get dark, mucky brown.)
To "see" colour, signals from two or more types of cone must be compared and correlated. This processing actually begins in the eye, and separate packages of visual information (about colour, depth, form and motion) are sent in cascades of tiny voltages down the optic nerve, to the visual brain, right at the back of the head. There, they are unscrambled in a main central switchboard. Some neurons fire in response to red light and switch off with green, while others do the reverse. Others react similarly to blue and yellow - another pair ofcomplementary colours. (If this sounds baffling, try it. Stare at an intense red for a while, and then at a white surface, and you'll see an after-image of blue-green.) Colour information then ripples outwards, ending up in an area called V4 - two curved, bean-sized structures, one each side of the back-brain. Here, the real smarts of colour perception kick in.
The colour of an object is radically influenced by colours around it, as well as whether it is seen in artificial or natural light, daylight or twilight. Yet remarkably, the firing patterns of V4 neurons remain constant under very different lighting conditions. Its cells are locked into an interactional web ofstimulation, inhibition and competition - resulting in what we experience as a constant colour-perceptual state, updated every fraction of a second.
Another key mystery in neuropsychology is how vision and language link up. Although kids as young as four months show a preference for primary colours, they find it difficult to learn the names of colours until they are four or five. Darwin was so astounded by this that at one point he thought that his children were colour-blind. Again in the last century, Gladstone surmised from the scarcity and weirdness of colour terms in Homer (the "wine-dark sea", for instance), that the Greeks were colour-blind. But this was completely false - as is the notion, popular since the Renaissance, that classical Greek statuary was a colourless triumph of form over embellishment. Excavations have long shown that the Greeks decorated their architecture, friezes and statues in very vivid polychromy; the stone figures had detailed skin-tones, and great attention waspaid to lips, eyes and clothing.
In fact, anthropologists have discovered a consistent order in the development of colour terms in different languages. If there are only two colour words (as with the Dani hill tribes of New Guinea), these will be black and white. If three, red will arrive. Fourth and fifth will add either yellow or green. Six adds blue; seven, brown; and after that, all the purples and oranges, pinksand greys; and on to the full Dulux range of hickory, Marrakesh, kiwi crush, Union Village, and even a green called limbo.
Which brings us to the Great Eskimo Vocabulary Hoax. Contrary to another popular belief, Inuits do not have scores of words for "white" or "snow". That notion was first put about in 1911 by an amateur American linguist, Benjamin Lee Whorf. Catchy as it was, it led to successively inflated estimates in lists of Amazing Facts - all fitting in well with the Inuits' perceived exoticism: rubbing noses, swapping partners and chewing raw seal blubber.
Another fallacy is that colour vision is a perverse side-effect of our bulging intelligence, and that Rover, being a dog of little brain, sees only black and white. The truth is that mammals, other than primates, have two types of colour-sensitive cones: blue and yellow. Diurnal birds and surface-dwelling fish alsohave good colour vision - while insect eyes, though largely blind to red, often discern ultraviolet as a hue.
Display-wise, animals up and down the evolutionary tree use colour for individuality, camouflage, warning, mimicry, mood or courtship, such as the daft male Satin Bower Bird, who stockpiles blue objects in his nest to attract a lady. The eye itself independently evolved more than 40 times over thecourse of evolution, from clusters of photosensitive cells, pinhole eyes, curved reflectors and compound eyes, to the camera-lens eyes of vertebrae and octopuses.
Our own colour vision depends on two distinct sub-systems. The most recent evolved in primates about 30 million years ago. It overlaid a more ancient system of two types of cones: violet-blue and yellow-red. This is still the case with non-primate mammals and a "dichromatic" two per cent of human males. We share our normal "trichromatic" vision only with apes and Old World monkeys. It arose, like many evolutionary leaps, through a duplication and modification of agene on the X-chromosome which coded for the light-sensitive pigment in the middle, yellow-green area of the spectrum.
"Full-colour" red-green vision is a definite advantage to fruit-eating monkeys, who need to pick out fruit against foliage. The seeds of some tropical trees are still dispersed exclusively by monkeys. With bees and flowers in mind, the theological worry is that our colour vision, and indeed the entire primatelineage might all just have been a device invented by fruiting trees to go forth and multiply.
Humanity may have come a long way since, yet at some pre-linguistic level, we still mimic natural colour-codes to signal everything from traffic lights to toxic waste and radioactivity. Meanwhile, our symbolic and heraldic "languages" are largely inherited accretions of history and culture. For example, untilthe modern age, many dyestuffs were precious and came to signify rank and royalty (it took 12,000 crushed shellfish to create 1.5 grams of the secret Tyrian Purple of the Phoenicians). White linen, until the 17th century, was available only to the rich, and while white is an attractive quality in teeth,eyes and salt, it has become the apotheosis of modern washing-powder.
Otherwise, white tends to be associated with space, unity, virginity, permanence, sovereignty - but all that is largely conventional. In many cultures, including our own, white often symbolises mortality (white lilies, for instance), and indeed it was a colour of mourning in Europe until the 11th century.
Although officially no colour at all, black is psychologically powerful, with predominantly deathly associations. Since the 14th century, Christianity has used it to variously signify evil, mourning, renunciation, primordial darkness, corruption, unconsciousness, chaos and witchcraft. Modern English words are mired in cultural prejudice, but even in many African cultures, black is an unlucky colour. Mind you, Egyptians connected black with rebirth, resurrection; Qabalists associated it with understanding; and to Mayans it symbolised the death of an enemy. Meanwhile, in haute couture, black is a "contouring colour" (it saws inches off your silhouette), so for two centuries it has been chic in Europe.
Ecological green has been an Irish flag standard since at least as far back as Owen Roe O'Neill (early 17th century). More ancient associations, along with envy, include the supernatural, and loss of virginity - as in giving a maid "a green gown", presumably from the long grass. Constable was the first modern painter to make great use of green. It's hard to know what humour Kandinsky was in, however, when he described it as a "fat self-satisfied cow". But traditionally it's unlucky, and green cars are extremely unpopular.
As the colour of arterial blood, red has immediate associations: rage, red alert, or (with black), violent power. It also has a hot sexy side, even though, as a precious pigment, it was historically associated with wealth and royalty. It's also a common colour in the British military, from poppies to redcoats. And whatever about communism, in the Russian language, "red" and "beauty" were always expressed, until the 16th century, by the same word.
Blue, in various forms, was also precious (sapphire, lapis lazuli, turquoise, aquamarine, azurite, ultramarine), and it replaced gold in sixth-century iconography as an emblem of the Virgin Mary. It still has high-class connotations (blue blood, blue chip; in fact over 50 per cent of business suits are blue), but it's also the conventional colour of night (from film to painting), of vice and melancholy, from the blues to Picasso's blue period.
Yellow really arrived in European art with vivid new cadmium pigments in the early 19th century. Turner immediately deployed them in his vortices of sun colours, and later, Van Gogh burst into sunflowers, and wrote madly to his brother about citrus and other shimmering colour fields, and not least his "yellow house". But again, yellow has wildly negative associations, maybe because of jaundice, urine, yellow fever - indeed quarantine is often signalled by a yellow flag. And when Hitler forced Jews in 1930s Germany to wear yellow stars, he was merely continuing a long tradition going back to 1271, when King Edward forced Jews to wear a yellow taffeta strip as soon as they were seven years old.
Scientist-philosophers have long dreamed up more abstract theories: from Newton's mechanistic seven-colour spectrum (analagous to the musical scale); to Goethe's visionary Farbenlehre in 1810, on everything from after-images to howour brains construct colours (it was expanded on by Schopenhauer).
And art, of course, has always thrown up its great colourists: Titian; Monet's Rouen Cathedral series; Seurat's "chromoluminarism", dots of pure colour that he hoped would spectrally mix in the eye; and on to Mondrian's "neo-plasticism"and Kandinsky's great repository of colour ideas, The Spiritual in Art. Then there was Josef Albers's obsessive, life-long demonstrations of complementary colour schemes; the more intuitive colour excitement of de Kooning; the theoretics of Jasper Johns, Sol Le Witt and Frank Stella to the work of Brigid Riley.
It is hard to imagine art or life without colour, but the great case-history neurologist, Oliver Sachs, describes "cerebral achromatosia" in a 65-year-old artist called Jonathan I. The man spent his earliest days with Georgia O'Keeffe in New Mexico, painted Hollywood backdrops in the 1940s; and went on from Abstract Expressionism in NYC in the 1950s, to more commercial art direction. After a brain-damaging accident, he experienced a world seen only in shades of grey. Not only had his paintings become utterly meaningless to him, but he couldno longer remember colours, except empty words. People looked "like animated grey statues", and his appetite was ruined by the dirty, stained look of food. Colour TV was an "unintelligible hodge-podge" and flesh looked "rat-coloured" -he found sexual intercourse with his wife impossible.
In time, after suicidal bouts of depression, he adjusted. He took to exploring cities at night, driving and walking, when the "violent contrasts" of daylight seemed less irksome. He found solace in benighted diners, where "the darkness comes into the places . . . transforming them into night places". After anepiphany, viewing a loud red sunrise (which to his mind's eye, like that of a blackand-white photocopier, must have seemed apocalytic), he has finally gone back to making, and showing, paintings: anguished, angry, apocalyptic canvases, always in black and white. According to Sachs, they're very, very interesting.
Further reading: Colour Art & Science: edited by Trevor Lamb and Janine Bourriau, Cambridge University Press; Colour & Culture by John Gage, an astonishing work of scholarship, Thames & Hudson; An Anthropologist on Mars, Picador Warm. Thanks to the staff of NCAD Library.
