The Island of the Colorblind

R.L. Stevenson writes about pigs in his memoir of Polynesia, In the South Seas:

The pig is the main element of animal food among the islands… Many islanders live with their pigs as we do with our dogs; both crowd around the hearth with equal freedom; and the island pig is a fellow of activity, enterprise, and sense. He husks his own cocoa-nuts, and (I am told) rolls them into the sun to burst…It was told us in childhood that pigs cannot swim; I have known one to leap overboard, swim five hundred yards to shore, and return to the house of his original owner.

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It was striking how green everything was in Pingelap, not only the foliage of trees, but their fruits as well – breadfruit and pandanus are both green, as were many varieties of bananas on the island. The brightly colored red and yellow fruits – papaya, mango, guava – are not native to these islands, but were only introduced by the Europeans in the 1820s.

J.D. Mollon, a preeminent researcher on the mechanisms of color vision, notes that Old World monkeys ‘are particularly attracted to orange or yellow fruit (as opposed to birds, which go predominantly for red or purple fruit).’ Most mammals (indeed, most vertebrates) have evolved a system of dichromatic vision, based on the correlation of short- and medium-wavelength information, which helps them to recognize their environments, their foods, their friends and enemies, and to live in a world of color, albeit of a very limited and muted type. Only certain primates have evolved full trichromatic vision, and this is what enables them to detect yellow and orange fruits against a dappled green background; Mollon suggests that the coloration of these fruits may indeed have coevolved with such a trichromatic system in monkeys. Trichromatic vision enables them too to recognize the most delicate facial shades of emotional and biological states, and to use these (as monkeys do, no less than humans) to signal aggression or sexual display.

Achromatopes, or rod-monochromats (as they are also called), lack even the primordial dichromatic system, considered to have developed far back in the Paleozoic. If ‘human dichromats,’ in Mollon’s words, ‘have especial difficulty in detecting colored fruit against dappled foliage that varies randomly in luminosity,’ one would expect that monochromats would be even more profoundly disabled, scarcely able to survive in a world geared, at the least, for dichromats. But it is here that adaptation and compensation can play a crucial part. This quite different mode of perception is well brought out by Frances Futter-man, who writes:

When a new object would come into my life, I would have a very thorough sensory experience of it. I would savor the feel of it, the smell of it, and the appearance of it (all the visible aspects except color, of course). I would even stroke it or tap it or do whatever created an auditory experience. All objects have unique qualities which can be savored. All can be looked at in different lights and in different kinds of shadows. Dull finishes, shiny finishes, textures, prints, transparent qualities – I scrutinized them all, up close, in my accustomed way (which occurred because of my visual impairment but which, I think, provided me with more multi-sensory impressions of things). How might this have been different if I were seeing in color? Might the colors of things have dominated my experience, preventing me from knowing so intimately the other qualities of things? 

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