home range sufficient to live their whole lives within. We build garden fences, but even our homes are often shared with lodgers or fellow apartment dwellers, and most of our lives are spent on some form of common ground, at work, shopping, traveling, entertaining ourselves: People live in groups.
None of this is much help, then: Most people live in monogamous societies, but this may only tell us what democracy usually prescribes, not what human nature seeks: Relax the antipolygamy laws and it flourishes. Utah has a tradition of theo-logically sanctioned polygamy and in recent years has been less forceful about prosecuting polygamists, so the habit has reemerged.
Although the most populous societies are monogamous, about three-quarters of all tribal cultures are polygamous, and even the ostensibly monogamous ones are monogamous in name only.
Throughout history powerful men have usually had more than one mate each, even if they have had only one legitimate wife: However, that is for the powerful: For the rest, even in openly polygamous societies, most men have only one wife and virtually all women have only one husband: That leaves us precisely nowhere. Mankind is a polygamist and a monogamist, depending on the circumstances.
Indeed, perhaps it is foolish even to talk of humans having a mating system at all: They do what they want, adapting their behavior to the prevailing opportunity.'
WHEN MALES POUNCE AND FEMALES FLIRT
Until recently, evolutionists had a fairly simple view of mating systems based on the essential differences between males and females:
If powerful men had their way, women would probably live in harems like seals; that is certainly the lesson of history. If most women had their way, men would be as faithful as albatrosses.
Although research has modified this supposition, it is nonetheless true that males are generally seducers and females the seduced: Humanity shares this profile of ardent, polygamist males and coy, faithful females with about 99 percent of all animal species, including our closest relatives, the apes.
Consider, for example, the question of marriage proposals: In no society on earth do they usually come from the woman or her family. Even among the most liberated of Westerners, men are expected to ask and women to answer: The tradition of women asking men on Leap Year ' s Day reinforces the very paucity of their opportunities: They get one day to pop the question for every 1,460 that men can do so. It is true that many modern men do not go down on one knee but 'discuss ' the matter with their girl-friends as equals: Yet even so, the subject is usually first raised by the man. And in the matter of seduction itself, once more it is the male who is expected to make the first move. Women may flirt, but men pounce:
Why should this be? Sociologists will blame it on conditioning, and they are partly right. But that is not a sufficient answer because in the great human experiment called the 1960s much conditioning was rejected yet the pattern survives: Besides, conditioning usually reinforces instinct rather than overrides it.
Since an insight of Robert Trivers 's in 1972,' biologists have had a satisfying explanation for why male animals are usually more ardent suitors than females and why there are exceptions to the rule.
There seems to be no reason why it should not also apply to people. The gender that invests the most in creating and rearing the offspring, and so forgoes most opportunities for creating and rearing other offspring, is the gender that has the least to gain from each extra mating. A peacock grants a peahen one tiny favor: a batch of sperm and nothing else. He will not guard her from other peacocks, feed her, protect a food supply for her, help her incubate her eggs, or help her bring up the chicks. She will do all the work.
POLYGAMY AND THE NATURE OF MEN
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Therefore, when she mates with him, it is an unequal bargain. She brings him the promise of a gigantic single- handed effort to make his sperm into new peacocks; he brings just the tiniest—though seminal—contribution: She could choose any peacock she likes and has no need to choose more than one. At the margin, he loses nothing and gains much by mating with every female who comes along; she loses time and energy for a futile gain. Every time he seduces a fresh female, he wins the jackpot of her investment in his sons and daughters. Every time she seduces a fresh peacock, she wins a little extra sperm that she probably does not need. No wonder he is keen on quantity of mates, and she on quality.
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 one another 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.'
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.'
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 exceptions. In sea horses the female has a sort of penis that she uses to inject eggs into the male's body, neatly reversing the usual method of mating.
