The Red Queen_ Sex and the Evolution of Human Nature - Matt Ridley [88]
In more human terms, men can father another child just about every time they copulate with a different woman, whereas women can bear the child of only one man at a time. It is a fair bet that Casanova left more descendants than the Whore of Babylon.
This basic asymmetry between the genders goes right back to the difference in size of a sperm and an egg. In 1948 a British scientist named A. J. Bateman allowed fruit flies to mate with each other at will. He found that the most successful females were not much more prolific than the least successful, but the most prolific males were far more successful than the least prolific males.6 The asymmetry has been greatly enhanced by the evolution of female parental care, which reaches its zenith in mammals. A female mammal gives birth to a gigantic baby that has been nurtured inside her for a long time; a male can become a father in seconds. Women cannot increase their fecundity by taking more mates; men can. And the fruit fly rule holds. Even in modern monogamous societies, men are far more likely to have lots of children than women are. For instance, men who marry twice are more likely to sire children by two wives than women who marry twice are to have children by both husbands.7
Infidelity and prostitution are special cases of polygamy in which no marriage bond forms between the partners. This puts a man’s wife and his mistresses in different categories with respect to the investment that he is likely to make in his children. The man who can sufficiently arrange his business affairs to make time, opportunity and money available for supporting two families is as rich as he is rare.
Feminism and Phalaropes
The rule that parental investment dictates which gender will attempt polygamy can be tested by looking at its anomalies. In sea horses, the female has a sort of penis which she uses to inject eggs into the male’s body, neatly reversing the usual method of mating. The eggs develop there and, as the theory predicts, it is the female sea horse that courts the male. There are about thirty species of birds, of which the phalaropes and jacanas are the best known examples, in which the small dowdy male is courted by the large, aggressive female and in every single one of them it is the male that broods the eggs and rears the chicks.8
Phalaropes, and other seducer-female species, are the exceptions that prove the rule. I remember watching a whole flock of female phalaropes badgering a poor male so hard he almost drowned. And why? Because their mates were quietly sitting on their eggs for them, so these females had nothing better to do than look for second mates. Where males invest more time or energy in care for the young, females take the initiative in courtship, and vice versa.9
In mankind, the asymmetry is clear enough: nine months of pregnancy set against five minutes of fun. If the balance of such investment determines sex roles in seduction, then it comes as no surprise that men seduce women rather than vice versa. This fact suggests that a highly polygamous human society represents a victory for men, whereas a monogamous one suggests a victory for women. But this is misleading. A polygamous society represents, primarily, a victory for one or a few men over all other men. Most men in highly polygamous societies are condemned to celibacy because, remember, sex ratios are equal.
In any case, no moral conclusions of any kind can be drawn from evolution. The asymmetry in