By JOHN TIERNEY
New York Times

Thanks to psychologists at the University of Texas at Austin, we can at last count The Whys of Mating. After asking nearly 2,000 people why they'd had sex, the researchers have assembled and categorized a total of 237 reasons - everything from "I wanted to feel closer to God" to "I was drunk." They even found a few people who claimed to have been motivated by the desire to have a child.

The researchers, Cindy M. Meston and David M. Buss, believe their list, published in the August issue of Archives of Sexual Behavior, is the most thorough taxonomy of sexual motivation ever compiled. This seems entirely plausible.

Who knew, for instance, that a headache had any erotic significance except as an excuse for saying no? But some respondents of both sexes explained that they'd had sex "to get rid of a headache." It's No. 173 on the list.

Others said they did it to "help me fall asleep," "make my partner feel powerful," "burn calories," "return a favor," "keep warm," "hurt an enemy" or "change the topic of conversation." The lamest may have been, "It seemed like good exercise," although there is also this: "Someone dared me."

Dr. Buss has studied mating strategies around the world - he's the oft-cited author of "The Evolution of Desire" and other books - but even he did not expect to find such varied and Machiavellian reasons for sex. "I was truly astonished," he said, "by this richness of sexual psychology."

The best news is that both men and women ranked the same reason most often: "I was attracted to the person."

The rest of the top 10 for each gender were also almost all the same, including "I wanted to express my love for the person," "I was sexually aroused and wanted the release" and "It's fun."

No matter what the reason, men were more likely to cite it than women, with a couple of notable exceptions. Women were more likely to say they had sex because, "I wanted to express my love for the person" and "I realized I was in love." This jibes with conventional wisdom about women emphasizing the emotional aspects of sex, although it might also reflect the female respondents' reluctance to admit to less lofty motives.

The results contradicted another stereotype about women: their supposed tendency to use sex to gain status or resources.

But then, men were also more likely than women to say they'd had sex because "I was slumming." Or simply because "the opportunity presented itself," or "the person demanded that I have sex."

To make sense of the 237 reasons, Dr. Buss and Dr. Meston created a taxonomy with four general categories:

Physical: "The person had beautiful eyes" or "a desirable body," or "was good kisser" or "too physically attractive to resist." Or "I wanted to achieve an orgasm."

Goal Attainment: "I wanted to even the score with a cheating partner" or "break up a rival's relationship" or "make money" or "be popular." Or "because of a bet."

Emotional: "I wanted to communicate at a deeper level" or "lift my partner's spirits" or "say 'Thank you.' " Or just because "the person was intelligent."

Insecurity: "I felt like it was my duty" or "I wanted to boost my self-esteem" or "It was the only way my partner would spend time with me."

Having sex out of a sense of duty, Dr. Buss said, showed up in a separate study as being especially frequent among older women. But both sexes seem to practice a strategy that he calls mate-guarding, as illustrated in one of the reasons given by survey respondents: "I was afraid my partner would have an affair if I didn't."

That fear seems especially reasonable after you finish reading Dr. Buss's paper and realize just how many reasons there are for infidelity. Some critics might complain that the list has some repetitions - it includes "I was curious about sex" as well as "I wanted to see what all the fuss was about" - but I'm more concerned about the reasons yet to be enumerated.

For instance, nowhere among the 237 reasons will you find the one attributed to the actress Joan Crawford: "I need sex for a clear complexion." (The closest is "I thought it would make me feel healthy.") Nor will you find anything about gathering rosebuds while ye may (the 17th-century exhortation to young virgins from Robert Herrick).

excerpted from:
"The Whys of Mating: 237 Reasons and Counting"
By JOHN TIERNEY
© New York Times July 31, 2007