Pettäminen on geeneissä

Devotion and betrayal, marriage and divorce: how evolution shaped human love:

According to evolutionary psychology, it is "natural" for both men and women--at some times, under some circumstances--to commit adultery or to sour on a mate, to suddenly find a spouse unattractive, irritating, wholly unreasonable.

Many studies confirm the more discriminating nature of women. One evolutionary psychologist surveyed men and women about the minimal level of intelligence they would accept in a person they were "dating." The average response for both male and female: average intelligence. And how smart would the potential date have to be before they would consent to sex? Said the women: Oh, in that case, markedly above average. Said the men: Oh, in that case, markedly below average.

In our species, then, a female's genetic legacy is best amplified by a mate with two things: good genes and much to invest. But what if she can't find one man who has both? One solution would be to trick a devoted, generous and perhaps wealthy but not especially brawny or brainy mate into raising the offspring of another male. The woman need not be aware of this strategy, but at some level, conscious or unconscious, deft timing is in order.

Evolutionary psychologist Douglas Kenrick has suggested as much. According to his research, men who are shown pictures of Playboy models later describe themselves as less in love with their wives than do men shown other images. (Women shown pictures from Playgirl felt no such attitude adjustment toward spouses.)

To an evolutionary psychologist, such numbers are just extreme examples of a simple fact: the ultimate purpose of the wealth and power that men seek so ardently is genetic proliferation. It is only natural that the exquisitely flexible human mind should be designed to capitalize on this power once it is obtained.

Thus it is natural that a rising corporate star, upon getting a big promotion, should feel a strong attraction to women other than his wife. Testosterone--which expands a male's sexual appetite--has been shown to rise in nonhuman primates following social triumphs, and there are hints that it does so in human males too.

J. Paul Getty said, "A lasting relationship with a woman is only possible if you are a business failure."

Evolutionary psychologists have shown that the tendency of women to place greater emphasis than men on a mate's financial prospects remains strong regardless of the income or expected income of the women in question.

Not only does male social inequality favor divorce. Divorce can also reinforce male social inequality; it is a tool of class exploitation. Consider Johnny Carson. Like many wealthy, high-status males, he spent his career dominating the reproductive years of a series of women. Somewhere out there is a man who wanted a family and a pretty wife and, if it hadn't been for Johnny Carson, would have married one of these women. And if this man has managed to find another woman, she was similarly snatched from the clutches of some other man. And so on--a domino effect: a scarcity of fertile females trickles down the social scale.

Viewing serial monogamy as polygyny by another name throws a kink into the family-values debate. So far, conservatives have got the most political mileage out of decrying divorce. Yet lifelong monogamy--one woman per man for rich and poor alike--would seem to be a natural rallying cry for liberals.