You Are My Natural Selection

Are there other examples of selective breeding by non-human eyes? Oh yes. Think of the dull, camouflaged plumage of a hen pheasant, compared with the splendiferous male of the same species. There seems little doubt that, if his individual survival were the only thing that mattered, the cock golden pheasant would 'prefer' to look like the female, or like a grown-up version of how he was as a chick. The female and the chicks are obviously well camouflaged, and that's the way the male would be too if individual survival were his priority. The same is true of other pheasants such as Lady Amherst's and the familiar ring-necked pheasant. The cocks look flamboyant and dangerously attractive to predators, but each species in a very different way. The hens are camouflaged and dull-coloured, each species in pretty much the same way. What is going on here?

One way to put it is Darwin's way: 'sexual selection'. But another way - and the one that better suits my primrose path - is 'selective breeding by females of males'. Bright colours may indeed attract predators, but they attract female pheasants too. Generations of hens chose to mate with bright, glowing males, rather than the dull brown creatures that the males would surely have remained but for selective breeding by females. The same thing happened with peahens selectively breeding peacocks, female birds of paradise breeding males, and numerous other examples of birds, mammals, fish, amphibians, reptiles and insects where females (it's usually females rather than males, for reasons we needn't go into) choose from among competing males. As with garden flowers, human pheasant-breeders have improved upon the selective handiwork of the hen pheasants that preceded them, producing spectacular variants of the golden pheasant, for example, although more by picking one or two major mutations rather than by gradually shaping the bird through generations of breeding. Humans have also selectively bred some amazing varieties of pigeons (as Darwin knew at first hand) and chickens, descended from a Far Eastern bird, the red jungle fowl Gallus gallus.

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