Though both men and women seek general genetic quality, tastes may in other ways diverge. Just as women have special reason to focus on a man's ability to provide resources, men have special reason to focus on the ability to produce babies. That means, among other things, caring greatly about the age of a potential mate, since fertility declines until menopause, when it falls off abruptly. The last thing evolutionary psychologists would expect to find is that a plainly postmenopausal woman is sexually attractive to the average man. They don't find it: In every one of Buss's 37 cultures, males preferred younger mates (and females preferred older mates). The importance of youth in a female mate may help explain the extreme male concern with physical attractiveness. Women can afford to be more open-minded about looks: an oldish man, unlike an oldish woman, is probably fertile.
When it comes to assessing character--to figuring out if you can trust a mate--a male's discernment may again differ from a female's, because the kind of treachery that threatens his genes is different from the kind that threatens hers. Whereas the woman's natural fear is the withdrawal of his investment, his natural fear is that the investment is misplaced. Not long for this world are the genes of a man who spends his time rearing children who aren't his.
All of this sounds highly theoretical--and of course it is. But this theory is readily tested. David Buss placed electrodes on men and women and had them envision their mates doing various disturbing things. When men imagined their partner committing sexual infidelity, their heart rates took leaps of a magnitude typically induced by three successive cups of coffee. They sweated. Their brows wrinkled. When they imagined a budding emotional attachment, they calmed down, though not quite to their normal level. For women things were reversed: envisioning emotional infidelity--redirected love, not supplementary sex--brought the deeper physiological distress.
The logic behind male jealousy isn't what it used to be. These days some adulterous women use contraception and thus don't dupe their husbands into spending two decades shepherding another man's genes. But the weakening of the logic hasn't weakened the jealousy. For the average husband, the fact that his wife inserted a diaphragm before copulating with her tennis instructor will not be a major source of consolation.
The classic example of an adaptation that has outlived its logic is the sweet tooth. Our fondness for sweetness was designed for an ancestral environment in which fruit existed but candy didn't. Now that a sweet tooth can bring obesity, people try to control their cravings, and sometimes they succeed. But few people find it easy. Similarly, the basic impulse toward jealousy is very hard to erase. Still, people can muster some control over the impulse, and, moreover, can muster some control over some forms of its expression, such as violence, given a sufficiently powerful reason. Prison, for example.
This raises two final points. First, to say something is a product of natural selection is not to say that it is unchangeable. Just about any manifestation of human nature can be changed, given an apt alteration of the environment--though the required alteration will in some cases be prohibitively drastic.
Contrary to expectations, evolutionary psychologists subscribe to a cardinal doctrine of twentieth-century psychology: the potency of early social environment in shaping the adult mind. But if we want to know, say, how levels of ambition or insecurity get adjusted by early experience, we must first ask why natural selection made them adjustable. A guiding assumption of many evolutionary psychologists is that the most radical differences among people are the ones most likely to be traceable to environment.
Second, to say that something is "natural" is not to say that it is good. Nature isn't a moral authority, and we needn't adopt any "values" that seem implicit in its workings--natural selection's indifference to the suffering of the weak, for example, is not something we need emulate. But if we want to pursue values that are at odds with natural selection's, we need to know what we're up against. If we want to change some disconcertingly stubborn parts of our moral code, it would help to know where they come from. And where they ultimately come from is human nature, however complexly that nature is refracted by the many layers of circumstance and cultural inheritance through which it passes.
Excerpted from The Moral Animal: Why We Are The Way We Are (Pantheon) by Robert Wright. Copyright (C) 1994 by Robert Wright.
PHOTOS: The Jungle
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common goal,
evolution,
evolutionary explanation,
gene machine,
genetic differences,
human psychology,
infatuation,
infatuations,
knobs,
love,
lust,
passions,
raw lust,
sibling rivalry,
social environment,
spigots,
states of mind,
unconscious mind
