The Red Queen_ Sex and the Evolution of Human Nature - Matt Ridley [66]
His racial theory was almost certainly a red herring5 but the notion of selective mate choice was not. Darwin wondered if the selection by females of a ‘breed’ of males was the reason that so many male birds and other animals were gaudy, colourful and ornamented. Gaudy males seemed a peculiar result of natural selection since it was hard to imagine that gaudiness helped the animal to survive. In fact, it would seem to be quite the reverse: gaudy males should be more conspicuous to their enemies.
Taking the example of the peacock, with its great tail decked with iridescent eyes, Darwin suggested that peacocks have long tails (they are not actually tails, but elongated rump feathers that cover the tail) because peahens will only mate with peacocks that have long tails. After all, he observed, peacocks seem to use their tail when courting females. Ever since then the peacock has been the crest, mascot, emblem and quarry of sexual selection.
Why should peahens like long tails? Darwin could only reply: because I say so. Peahens prefer long trains, he said, because of an innate aesthetic sense – which is no answer at all. And peahens choose peacocks for their tails rather than vice versa because, sperm being active and eggs passive, that is usually the way of the world: males seduce, females are seduced.
Of all Darwin’s ideas, female choice proved the least persuasive. Naturalists were quite happy to accept the notion that male weapons, such as antlers, could have arisen to help males in the battle for females, but they instinctively recoiled at the frivolous idea that a peacock’s tail should be there to seduce peahens. They wanted, rightly, to know why females would find long tails sexy, what possible value they could bring the hens. For a century after he proposed it, Darwin’s theory of female choice was ignored while biologists tied themselves in furious knots to come up with other explanations. Darwin’s contemporary, Alfred Russel Wallace’s preference was initially that no ornaments, not even the peacock’s tail, required any explanation other than that they served some useful purpose of camouflage. Later he thought they were the simple expression of surplus male vigour. Julian Huxley, who dominated discussion of the matter for many years, much preferred to believe that almost all ornaments and ritual displays were for intimidating other males. Others believed that the ornaments were aids to females for telling species apart, so that they chose a mate of the right species.6 The naturalist Hugh Cott was so impressed by the bright colours of poisonous insects that he suggested that all bright colours and gaudy accessories were about warning predators of dangers. Some are. In the Amazon rainforest the butterflies are colour-coded: yellow and black means distasteful, blue and green means too quick to catch.7 In the 1980s a new version of this theory was adapted to birds, suggesting that colourful birds are the fastest fliers and are flaunting the fact to hawks and other predators: I’m fast, so don’t even think of trying to chase me. When a scientist put stuffed male and female pied flycatchers out on perches in a wood, it was the dull females that were attacked first by hawks, not the colourful males.8 Any theory, it seemed, was preferred to the idea of female preference for male beauty.
Yet it is impossible to watch peacocks displaying and not come away believing that the tail has something to do with the seduction of peahens. After all, that was how Darwin got the idea in the first place: he knew that the gaudiest plumes of male