My colleagues and I have done a survey of 13,000 students on more than 17 campuses, and we found that while sex in college has always been a bit more casual, "hooking up" has pretty much replaced other traditional forms of dating.

It's like what you might call Goldilocks' dilemma in the old fairy tale. Young men see women as "less than" or "better than," but never their equals. And studies indicate that equality is the best foundation for a healthy relationship.

Many guys see relationships with women as a zero-sum game: If she wins, he loses. Marriage is the ultimate contest: Her job is to get him to capitulate to marriage. So many men see marriage as the "end of freedom," the end of boyhood. That's why bachelor parties are supposed to revel in that boyish irresponsibility "one last time." So many guys figure, "Why rush into something that means basically that you'll be a prisoner forever?"

Guys constantly talk about pornography in two ways: as revenge and as reassurance. When you live in a world in which beautiful, sexy women are all around you, in the same classes, on the same athletic field, competing for the same jobs, then the pornographic world - the world in which women thrill to male sexual desire - reassures men that although they may feel "one down," they're still entitled to women's bodies.

Some of the worst elements of Guyland rest on the twin pillars of men's silence and women's compliance.

Ironically, survey after survey shows that married men are happier and healthier than unmarried men. Oh, and they also have more sex.

Many boyfriends or close male friends seem so different when they are by themselves, as opposed to when they are with a bunch of other guys. I think it has to do with the desperate desire on the part of guys to be seen as a "real guy" - a real man, a man's man.