One of the most common confusions about evolutionary psychology concerns this issue of conscious motivation. Evolutionary theory says organisms are "designed" by natural selection to get their genes into the next generation. But that doesn't mean they pursue this "goal" consciously. For example, the impulse of lust exists because during evolution, individuals with genes conducive to sex--such as genes for lust--out-reproduced individuals with genes not conducive to sex. But this lust succeeds in getting genes into the next generation regardless of whether the individuals experiencing it are conscious of its "purpose." Indeed, early-20^th-century anthropologist Bronislaw Malinowski reported that when he happened upon the Trobriand Islanders, they hadn't yet grasped the connection between sex and reproduction. But they were doing a great job of both. (Some subsequent anthropologists have found Malinowski's claim incredible, but no one has disproved it.)

So too with the fact that Bob Dole, and men generally, find women of childbearing age more sexually attractive than women of post-reproductive age. During evolution, men who focused their romantic overtures on young-looking women out-reproduced men who focused them on old-looking women. So over the generations, genes conducive to an aesthetic preference for young flesh spread through the population. But, like lust, this aesthetic preference can accomplish its "goal" of genetic proliferation without anyone being consciously aware of the goal. Bob Dole almost certainly didn't think, "Hey, this prospective wife appears to be of reproductive age, whereas my present wife isn't." In fact, he probably wasn't interested in having kids at all. He and Elizabeth never did have kids, at any rate.

Does this fact, that people sometimes choose not to have offspring, discredit the very premise of evolutionary psychology? If you're asking this question--as many of evolutionary psychology's critics have--then the previous two paragraphs have failed in their mission. During human evolution there was no contraceptive technology, so impulses such as lust and romantic love were sufficient to goad our ancestors into producing children; then, once the children materialized, genetically based impulses of parental love ensured that our ancestors would take good care of these endearing little vehicles of genetic transmission. Thus there was no reason for natural selection to build in a conscious desire to have offspring.

Of course, aspects of the modern environment--in particular, contraceptive technology--can frustrate this Darwinian logic, and keep lust from translating into offspring. More to the point, we can consciously choose not to slavishly follow various aspects of natural selection's agenda, including reproduction itself. That's the difference between us and all other organisms.

If you would like a longer primer on evolutionary psychology--and more discussion of various common confusions about it--you might try some online excerpts from my book, The Moral Animal. Of particular relevance to the issues of polygamy and promiscuity are the excerpts from Chapter 2, "Male and Female," and Chapter 3, "Men and Women."