Sexy science: Why being a Samantha may simply be down to the time of the month

SEX AND THE CITY is at a cinema near you this week and I reckon that part of the fun of watching, for women anyway, is deciding which of the four main characters you identify with. Maybe you're a Carrie, a Charlotte or a Miranda, but can any woman truly own up to being a Samantha?

She has her momentary lapses, but Samantha is essentially a man-eater who is into sex, lots of sex, and with no emotional involvement. Do such women really exist?

Well, such men certainly exist and it's easy to see why, biologically speaking. Men who have spread themselves about a bit have had more children, and so passed on their genes for these tendencies to future generations.

It's no surprise that surveys show men generally have a more positive attitude than women to casual sex.

For women, on the face of it, it looks like they'd be best off being choosy and coy about sexual partners, otherwise they might get left holding the baby. But for many women, desire and chemistry gang up, temporarily at least, and obliterate any concern about a sensible relationship. Why would a woman do it?

For one thing, she might be able to get genetic benefits for her child should she get pregnant – it could be that a woman is more likely to be able to snare a high-quality guy for no-strings-attached sex than for a long-term relationship.

Another reason for a quick fling could be to suss out a man's potential for being "the one" before investing too much emotionally. So are some women naturally promiscuous?

Anne Campbell, professor of psychology at Durham University, figured that if women are adapted – designed by natural selection – for casual sex, then they are likely to have positive feelings about such relationships.

To check this out, she recruited 998 men and 745 women through a Channel 4 TV programme, all of whom claimed to have had one-night stands, and quizzed them on how they felt about the experience.

Campbell reports in the latest issue of the journal Human Nature that, following a one-night stand, men are more likely than women to want their friends to hear about it, to feel successful because other men found their partner desirable and to feel greater sexual satisfaction.

Women generally felt less positive the morning after, but said they didn't feel disappointed that the relationship didn't come to anything more, suggesting they weren't attempting to test out a potential long-term partner.

A lot of them, however, said they felt "used". Typically, a woman reported being blanked or ignored by the man, making her feel that he didn't want to have a "public" relationship with her and that she wasn't good enough.

My friend Alex has had her share of one-night stands and her analysis of morning-after behaviour seems to square with this.

She says: "The problem with men is that they're big-headed and they're scared that women will want commitment when all they really want is for the guy to be friendly and acknowledge that they had fun together."

If women often feel bad after casual sex, it prompts the question – why do it? The timing of such encounters could give a clue.

Steven Gangestad, of the University of New Mexico, carried out research showing that women are more likely to desire a fling around the time of month when they're likely to get pregnant, although there's no suggestion that this is a conscious decision. Not only that, but they show a shift in preference to very masculine-looking men who are likely to have good genes that could get passed on to children.

What is clear is that, like Samantha, a lot of women like having a lot of sex with a lot of different partners. It could be that nowadays, with easy availability of contraception, not to mention women's increasing financial independence and the resulting lack of reliance on a man to "look after" her, a modern woman is freer than ever to pursue her sexual desires.

It doesn't mean we've gone off meaningful relationships, though. Even Samantha got into monogamy by the end of the SATC series. Wonder if she can hang in there in the movie…