In a never-ending quest to plumb the mysteries of men, women and sex, the journal Human Nature has published a study that minces no words in concluding that women "have higher standards" when engaging in a one-night stand.

Sure, sure, we've all heard the evolutionary argument: With the dangers of prospective childbirth and years of child care hanging in the balance, women would be expected to be choosier than men about whom they will mate with. Bound by no such commitments and keen to maximize the propagation of their DNA, men will mate, shall we say, more indiscriminately.

But do we ever tire of hearing the details? We do not.

So here's how they play out in the latest study. A total of 427 men and 433 females from universities in the United States, Germany and Italy were asked to imagine their response to a request by a member of the opposite sex to: a) go out on a date; b) go home with the requestor; and c) go to bed with him or her.

The person making the invitation could be "moderately unattractive," "somewhat attractive" or "exceptionally attractive," and the research participant was asked for his or her answer under each of these permutations.

Across the board, men were more likely to accept any and all of the invitations than were women. There were a few national differences among the men: the German men were most reticent about going out or going home with any of the imagined women, and Italians were least discriminate about doing anything with anyone. American men were more likely than their German counterparts to go to bed with a woman. But they weren't quite as randy as the Italians.

As a group, the men also showed a preference for a somewhat or exceedingly attractive woman over a moderately unappealing one. But as long as a woman was at least somewhat attractive, then men were equally ready to go off with her. Extraordinary beauty was not required to secure their willingness to go out, go home or go to bed with a woman extending the invitation.

Not so women. For female respondents who agreed they would go to bed with a man, only the best would do. While they were equally likely to go out with a moderately handsome man than with an exceptionally handsome specimen, the women respondents were far more likely to accept only the exceptionally attractive man's invitation to his home or his bed.

"While men are not entirely insensitive to their requestor's attractiveness, women have higher standards and are more likely to engage in casual sex with an exceptionally attractive man than with a less attractive man," said the study's author, psychologist Achim Schuetzwohl of Britain's Brunel University. The differences among men appear to reflect "culural differences in sexual morals and preferences," he added.

But the difference between men and women when it came to a roll in the hay? Human Nature, apparently.

Still not tired of reading about sexual differences between men and women? You couldn't do better than the latest Kinsey report, published in the April 2008 Archives of Sexual Behavior.

-- Melissa Healy