The problem of recognizing the reality of the male sex drive was brought home to me in a rather amusing experience I had some years ago. I was writing a paper weighing the relative influence of cultural and social factors on sexual behavior, and the influence consistently turned out to be stronger on women than on men. In any scientific field, observing a significant difference raises the question of why it happens.

We had to consider several possible explanations, and one was that the sex drive is milder in women than in men. Women might be more willing to adapt their to local norms and contexts and different situations because they aren't quite so driven by strong urges and cravings as men are.

When I brought this up in the paper as one possible theory, reviewers reacted rather negatively. They thought the idea that men have a stronger sex drive than women was probably some obsolete, wrong, and possibly offensive stereotype. I wasn't permitted to make such a statement without proof, which they doubted could be found.

And when I consulted the leading textbooks on sexuality, none of them said that women had a generally milder desire for sex than men. Some textbooks explicitly said that that idea was wrong. One, by Janet Hyde and Richard DeLamater, openly speculated that women actually had a stronger sex drive than men, contrary to what I thought.

Two colleagues and I decided to see what information could be gleaned from all the published research studies we could find. This meant a long process of slogging through hundreds of scientific journal articles reporting scientific studies of sexual behavior.

One colleague, Kathleen Catanese (now a professor of psychology at a Midwestern college) started out as a strong feminist with the party-line belief that there was no difference in sex drive. The other, Kathleen Vohs (now a professor of ), was undecided. My hunch was that men had the stronger sex drive. Thus, at the outset, we held an assortment of views, but we all decided we would just follow the data and revise our opinions as the evidence came in.

The task was considerable, and I at least was nagged by the that this point was so obvious that no one would want to publish our research. One colleague heard we were reviewing the literature to see whether men wanted sex more than women, and she commented acidly, "Of course they do. Everybody who's ever had sex knows that!" Well, everybody, apparently, except the expert researchers on sexuality and authors of textbooks.

There is no single, clear measure of sex drive. So we approached the problem like this: Imagine two women (or two men for that matter), such that one of them has truly a stronger sex drive than the other. What differences in preferences and behavior would you expect to see between the two of them?

For example, the one with the stronger sex drive would presumably think about sex more often; have more fantasies, desire, and actual sex more often; have more partners; masturbate more often; and devote more effort to having sex than the other. The reverse is quite implausible. That is, it is hard to imagine the woman with a weaker sex drive having more frequent than the woman with the stronger sex drive.

And so we searched for studies that compared men and women on these types of behaviors.

After months of reading and compiling results, the answer was clear. There is a substantial difference, and men have a much stronger sex drive than women. To be sure, there are some women who have frequent, intense desires for sex, and there are some men who don't, but on average the men want it more. Every marker we could think of pointed to the same conclusion. Men think about sex more often than women do. Men have more sexual fantasies, and these encompass more different acts and more different partners.

Men masturbate more than women, much more. is considered by sex researchers to be one of the purest measures of sex drive because it is not much constrained by external factors (such as the need to find a partner or the risk of or disease). Some people say that women feel guilty about masturbation, but that's not what the data say, at least not anymore.

In fact, it's mainly the (few) nonmasturbating men who associated masturbation with . Nonmasturbating women generally say they just don't feel any inclination to do it. They don't need guilt to resist the impulse, because they aren't resisting, because they don't have the impulse.

There's plenty more. Men take more risks and incur more costs for sex. (Remember President Clinton.) Men want sex more often than women, whether one is talking about young couples or people who have been married to the same person for 40 years. Men also want more different partners than women want, and men like a greater variety of sex acts than women do.

Men initiate sex often and refuse it rarely. Women initiate it much more rarely and refuse it much more often than men. Given an opportunity for sex, men leap at it, while women say no. One classic study sent student research assistants out on campus to approach fairly attractive people (of the other ) at random with the line, "I've been noticing you around campus and I think you're attractive. Would you like to go to bed with me tonight?" More than three-quarters of the men said yes. Not a single woman did.

Women find it easier than men to go without sex. An adult woman who is between relationships can easily go for months, sometimes even years, hardly thinking of sex and not minding if she doesn't have it. Men go nuts without sex (or at least some do). A man who loses his girlfriend will often start masturbating by the next day or two.

Even when both men and women make a heartfelt, sacred vow of chastity, the men find it much harder to keep than the woman. Catholic priests have much more sexual activity than the nuns, even though both have committed themselves to the single standard of complete abstinence and have backed this up with a sacred promise in the context of the most important beliefs and values in their lives.

In short, pretty much every study and every measure fit the pattern that men want sex more than women. It's official: Men are hornier than women.