The Red Queen_ Sex and the Evolution of Human Nature - Matt Ridley [70]
Montagues and Capulets
It is time to introduce the great dichotomy. Sexual selection theory is split into two warring factions. There is no accepted name for each party. Most people call them ‘Fisher’ and ‘Good-genes’; Helena Cronin, who has written a masterful history of the sexual selection debate,24 prefers ‘good-taste’ and ‘good-sense’. They are sometimes also known as the ‘sexy-son’ versus the ‘healthy-offspring’ theories.
The Fisher (sexy-son, good-taste) advocates are those who insist that the reason peahens prefer beautiful males is because they seek heritable beauty itself to pass on to their sons, so that those sons may in turn attract females. The Good-geners (healthy-offspring, good-sense) are those who believe that peahens prefer beautiful males because the beauty is a sign of good genetic qualities – disease resistance, vigour, strength – and that these are the qualities that the females seek to pass on to their children.
Not all biologists admit to being members of one or other school. Some insist there can be a reconciliation; others would like to form a third party, and cry with Mercutio, ‘A plague on both your houses’. But none the less the distinction is as real as the enduring feud between Capulets and Montagues in Romeo and Juliet.
The Fisherians derive their ideas mostly from Sir Ronald Fisher’s great insight about despotic fashion, and they follow Darwin in thinking the female’s preference for gaudiness to be arbitrary and without purpose. Their position is that, especially on leks, females choose males according to the gaudiness of their colours, the length of their plumes, the virtuosity of their songs or whatever, because the species is ruled by an arbitrary fashion for preferring beauty that none dares buck. The Good-gene people follow Alfred Russel Wallace (though they do not know it) in arguing that, arbitrary and foolish as it may seem for a female to choose a male because his tail is long or his song loud, there is method in her madness. The tail or the song tells each female exactly how good are the genes of each male. The fact that he can sing loudly or grow and look after a long tail proves that he can father healthy and vigorous daughters and sons just as surely as the fishing ability of a tern tells his mate that he can feed a growing family. Ornaments and displays are designed to reveal the quality of genes.
The split between Fisher and Good-genes began to emerge in the 1970s once the fact of female choice had been established to the satisfaction of most. Those of a theoretical or mathematical bent – the pale, eccentric types umbilically attached to their computers – became Fisherians. Field biologists and naturalists – bearded, besweatered and booted – gradually found themselves Good-geners.25
Is Choosing Cheap?
The first round went to the Fisherians. Fisher’s intuition was fed into mathematical models and emerged intact. In the early 1980s three scientists all programmed their computers to play an imaginary game of females choosing long-tailed males and bearing both sons that had the long tails and daughters that shared the preference of their mothers. The longer the male’s tail, the greater his mating success, but the smaller his chances of surviving to mate at all. Their key discovery was that there exists a ‘line of equilibrium’ at any point on which the game can stop. On that line the handicap to a female’s sons of having a long tail is balanced exactly by the advantage those