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loser's wife over his shoulder and take her away are at one extreme; Cyrano de Bergerac, who hoped to seduce Roxanne with words alone, is at the other. But in between there are thousands of permu-tations: A man can " win" a woman by competing with other men, or he can woo her, or both.
The two techniques—wooing and winning—are equally likely to sieve out the "best" male. The difference is that whereas the first technique will select dandies, the second will select bruis-ers. Thus, bull elephant seals and red deer stags are big, armed, and dangerous. Peacocks and nightingales are aesthetic show-offs.
By the mid-1980s evidence had begun to accumulate that, in many species, females had a large say in the matter of their mating partner: Where males gather on communal display arenas, a male 's success owes more to his ability to dance and strut than to his ability to fight other males."
It took a series of ingenious Scandinavians to establish that female birds really do pay attention to male plumes when choosing a mate. Anders Moller, a Danish scientist whose experiments are famously clever and thorough, found that male swallows with artificially lenghtened tails acquired mates more quickly, reared more young, and had more adulterous affairs than males of normal length. 12 Jakob Hoglund proved that male great snipe, which display by flashing their white tail feathers at passing females, could be made to lure more females by the simple expedient of having white typing-correction fluid painted onto their tails:" The best experiment of all was by Malte Andersson, who studied the widow bird of Africa. Widow birds have thick black tails many times the lengths of their bodies, which they flaunt while flying above the grass.
Andersson caught thirty-six of these males, cut their tails, and either spliced on a longer set of tail feathers or left them shortened. Those with elongated tails won more mates than those with shortened tails or tails of unchanged length:" Tail-lengthening experiments in other species that have unusually long tails have similarly boosted male success:"
So females choose: Definitive evidence that the female preference itself is heritable has so far been hard to come by, but it
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the Red Queen
would be odd if it were not. A suggestive hint comes from Trinidad where small fish called guppies vary in color according to the stretch of water they inhabit: Two American scientists proved that in those types of guppies in which the males are brightest orange in color, the females show the strongest preference for orange males. 16
This female preference for male ornaments can actually be a threat to the survival of the males: The scarlet-tufted malachite sunbird is an iridescent green bird that lives high on the slopes of Mount Kenya where it feeds on the nectar of flowers and on insects that it catches on the wing. The male has two long tail streamers, and females prefer the males with the longest streamers. By lengthening the tail streamers of some males, shortening those of others, adding weight to those of a third group, and merely adding rings of similar weight to the legs of a fourth, two scientists were able to prove that female-preferred tail streamers are a burden to their bearers. The ones with lengthened or weighted tails were worse at catching insects; the ones with shortened tails were better; the ones with only rings on their legs were as good as normal."
Females choose; their choosiness is inherited; they prefer exaggerated ornaments; exaggerated ornaments are a burden to males. That much is now uncontroversiaclass="underline" Thus far Darwin was right.
DESPOTIC FASHIONS
The question Darwin failed to answer was why: Why on earth should females prefer gaudiness in males? Even if the "preference"
was entirely unconscious and was merely an instinctive response to the superior seduction technique of gaudy males, it was the evolution of the female preference, not the male trait, that was hard to explain.
Sometime during the 1970s it began to dawn on people that a perfectly good answer to the question had been available since 1930. Sir Ronald Fisher had suggested then that females need no better reason for preferring long tails than that other
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THE PEACOCK S TALE
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females also prefer long tails. At first such logic sounds suspiciously circular, but that is its beauty. Once most females are choosing to mate with some males rather than others and are using tail length as the criterion—a big once, granted, but we'll return to that—then any female who bucks the trend and chooses a short-tailed male will have short-tailed sons. (This presumes that the sons inherit their father 's short tail.) All the other females are looking for long-tailed males, so those short-tailed sons will not have much success: At this point, choosing long-tailed males need be no more than an arbitrary fashion; it is still despotic. Each peahen is on a treadmill and dare not jump off lest she condemn her sons to celibacy. The result is that the females ' arbitrary preferences have saddled the males of their species with ever more grotesque encumbrances. Even when those encumbrances themselves threaten the life of the male, the process can continue—as long as the threat to his life is smaller than the enhancement of his breeding success: In Fisher 's words: " The two characteristics affected by such a process, namely plumage development in the male and sexual preference in the female, must thus advance together, and so long as the process is unchecked by severe counter-selection, will advance with ever-increasing speed. "i '
Polygamy, incidentally, is not essential to the argument.
Darwin noticed that some monogamous birds have very colorful males: mallards, for example, and blackbirds. He suggested that it would still benefit males to be seductive and so win the first females that are ready to breed, if not the most, and his conjecture has largely been borne out by recent studies. Early-nesting females rear more young than late-nesting ones, and the most vigorous songster or gaudiest dandy tends to catch the early female. In those monogamous species in which both males and females are colorful (such as parrots, puffins, and peewits) there seems to be a sort of mutual sexual selection at work: Males follow a fashion for picking gaudy females and vice versa. 19
Notice, though, that in the monogamous case the male is choosing as well as seducing. A male tern will present his intended with fish, both to feed her and to prove that he can fish well
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enough to feed her babies. If he is choosing the earliest female to arrive and she is choosing the best fisherman, they are both employing eminently sensible criteria. It is bizarre even to suggest that choice plays no part in their mating: From terns to peafowl, there is a kind of continuum of different criteria. A hen pheasant, for example, who will get no help from a cock in rearing her young, happily chooses to ignore a nearby cock who is unmated to join the harem of a cock who already has several wives: He runs a sort of protection racket within his territory, guarding his females while they feed in exchange for sexual monopoly over them: The best protector is more use to her than a faithful house-husband: A peahen, on the other hand, does not even get such protection: The peacock provides her with nothing but sperm: 20