I have an uncle. Or, perhaps I should say I had an uncle, and that is just the point. He cheated on my aunt -- his wife of many years -- and she has thrown him out. They are getting a divorce. Apparently, this wasn't his first indiscretion -- my aunt forgave him a former dalliance some years ago. Her self-respect just won't let her do it a second time, and I certainly understand that. The thing is, I know how, and I know why, my uncle could do what he did. Just as I know how and why Elliot Spitzer pitched himself off his rising political star into an abyss of humiliation, and John Edwards did much the same -- to name only very recent and prominent protagonists in this dreadfully common tale. The short answer for Spitzer, and Edwards, and my uncle and all the others (surveys suggest that over 20 percent of American husbands cheat on their wives, and under-reporting is suspected) is: six million years of evolutionary biology. And it helps to deal with it, because the better we understand our impulses, the more likely we are to be masters of them. And let's face it, we have a way to go. For all the mystique we drape over it -- the perfume and fashion, cologne and coquetterie, the conventions of courtship and the rituals of romance -- sex is about biology. It is the means, procreation the end.
Natural selection is as simple-minded as it is brilliant in its engineering; it simply favors whatever perpetuates itself. There is no better example of a trait well suited to propagate itself then the impulse to propagate. Consider two potential ancestors, Y and X. Y is keen to procreate; X couldn't care less.
Y follows his inclinations (the male pronoun is intentional), and the result is many little Y's, each inheriting the parental tendency. Soon, there are descendants of Y, and Y-like behavior, in all directions.
We have at least one very good real-world demonstration of this. According to a study published in 2003 in the American Journal of Human Genetics, Genghis Khan, the 13th century Mongol warlord, has passed on his genes to roughly a half percent of the entire current population of the globe. No real need to talk about how.
Now back to the alternative ancestor, X, who, disinterested in sex, has none. There are, thus, no descendants of X, and none to inherit X's native chastity. The non-procreative make decidedly poor ancestors.
Now, let's deal with sex differences, which have more to do with X's and Y's (of the chromosomal variety) than Mars and Venus. Men and women are running different genetic programs.
If the reason any impulse tends to prevail is that it fosters its own survival, then it stands to reason that men and women would stand apart in their attitudes about sex -- with, thankfully, the occasional opportunity and cause to meet in the middle.
Women bear the full biological burden of the procreative act. And to survive this requires sanctuary, security and stability. So, as a general rule, women are choosy. There's a lot at stake. Biologically, men bear no procreative burden whatsoever. You can bet Ghengis did not dote on his haphazard progeny. Love 'em, leave 'em, repeat is the program that maximizes male reproductive success. These divergent biological imperatives result in divergent attitudes as we pass biology through the filter of culture. As for men, it has perhaps never been summed up more succinctly than by Billy Crystal in "When Harry Met Sally." I simply commend the movie to you, but will say no more, or risk sleeping on the couch for the next week or two. A birthday card I saw recently summed up the situation for women. A group of attractive women was gathered around a birthday cake, and saying: "Sex! Sex! Definitely, sex!" Inside, it read: "Which would you rather give up -- sex, or chocolate?" The card was funny -- but equally funny to the point of absurd is the very notion of such a card for men! That tells us something. Women are no more immune to primitive biological programming than men, of course. Ladies, when you eat that cake knowing you shouldn't, you have some insight into the philandering of men. The behaviors are by no means comparable in consequence, but they are cousins in origin. They are both behaviors that may not be in our best interest, motivated by primitive drives hard-wired into the various manifestations of human appetite.
I make this comparison only in the hope of helping us understand ourselves and one another a little bit better. I am by no means an apologist for male infidelity. To my male readers, I note that we are all hard-wired just the same way. But, gentlemen, who we are is how we behave. Those of us privileged to march under the banners of love and loyalty and familial devotion have more than ample cause to be something greater than the sum of our biological parts. The frequency with which men succumb to the temptation of infidelity -- across all cultures -- may more be testimony to the depths of biological programming than to shallowness of character. But on the other hand, love and loyalty are a higher calling than the primitive impulses encoded in our genes. If lust is best explained by probing the depths of our biology, trust is only earned by rising to the heights of our greater potential. DNA is not destiny. Our genes notwithstanding, we each get to choose. Dr. David L. Katz can be reached at www.davidkatzmd.com.