When asked to describe one memorable regret in their lives, a recent large survey found the most common qualm amongst a nationally representative poll of North Americans, involved ''romance''. This covered love, sex, dating or marriage.

Romantic remorse includes divorce, marrying the ''wrong person,'' an affair, not pursuing someone special, casual sex with the wrong partner, losing one's virginity too early or too late. Women were more likely than men to describe a romantic regret.

These findings have now inspired a team of psychologists to conduct the largest and most in-depth study to date on sexual regret. The team was led by Professor Martie Haselton, and the research was conducted through her lab at UCLA, with Andrew Galperin as lead author, and including co-authors David Buss and Gian Gonzaga, amongst other colleagues.

The authors of the study, due to be published in the academic journal Archives of Sexual Behaviour, were particularly interested in whether men and women would experience substantially different sexual regrets, reflecting fundamental contrasts between men's and women's romantic experiences.

The investigation was based on evolutionary theory - that sexual drives evolved to pass on our genes as much as possible to future generations. This - some proponents of the theory argue - becomes a primary biological imperative - driving our sex lives - but perhaps often below conscious awareness.

Our brains evolved to cope with survival in ancient environments, so modern day sexual strategy, the contention is, remains an echo of how our ancestors played the game of love. Each time an ancestral man had sex with a different fertile partner he could potentially produce new offspring. But adding more sex partners for ancestral women did not increase their child production, as it did for men.

These ancient sexual strategies do not yield the same reproductive advantages in the modern world, where - for example, contraception is commonly used - but it seems our 'neanderthal' brains continue to guide behaviour to this day.

Evolutionary theory therefore predicts women will evolve a different sexual strategy to men, emphasising quality over quantity. Previous surveys confirm women remain much more selective than men in choosing sleeping partners, whereas men are more open than women to casual sex, desiring more numerous sexual liaisons.

One of the unique aspects of this study, in our opinion, is that it tackles the problem that in the arena of erotic encounters, those taking part in research surveys are not always entirely honest. Asking instead what you mourn in your romantic career, may be an innovative and more accurate way of illuminating our normally secret sex lives.

The authors of this new study on sexual regret predicted that, in line with evolutionary theory, women more than men, will regret poorly chosen sexual actions (doing something and later wishing they hadn't). Men more than women will bemoan poorly chosen sexual inactions (not doing something yet later wishing they had).

Previous research is in line with these predictions; women were more likely than men to regret their first act of sexual intercourse. Women were more likely to rue losing their virginity too early and having premarital sex, whereas men were more likely than women to resent not losing it early enough, and not having more premarital sex.

In one part of this latest investigation, participants were asked about their top five life regrets, top five regrets from the past few years, top five action and inaction regrets, and top five romantic/sexual action and inaction regrets.

None of the 39 sexual action regrets were more common for men than for women, and only one of the 30 sexual inaction regrets was more common for women than for men. This remorse was 'not engaging in sexual activity with someone only because I did not want to appear promiscuous'; 16% of women in comparison to 8% of men reported this lament. Women are more likely than men to worry about appearing promiscuous.

The top three most common regrets in women's top five lists of regret were in descending order: Lost virginity to 'wrong' partner - 24% of women cite this as a top five regret, in contrast to only 10% of men. Then came 'Cheated on past or present partner' - 23% of women put this as a top five regret in comparison to 18% of men. Third was - 'Relationship progressed ''too fast'' sexually' - 20% of women put this as a top five regret, while this only applied to 10% of men.

Sexual actions involving a lack of commitment will be those that women are particularly likely to repent, was predicted by the authors using evolutionary theory, before conducting the study. Sure enough, action regrets in the context of uncommitted sex generally dominated women's top five lists. These included having a one-night stand, sex with a stranger and sex with someone who falsely promised commitment.

The top three most common regrets in men's ''top five'' lists in descending order were - 'Too shy to indicate sexual attraction to someone' - 27% of men cite this as top five regret, in contrast to 10% of women. Next came - 'Was not more sexually adventurous when young' - 23% of men in comparison to 7% of women. Third became - 'Was not more sexually adventurous when single' - 19% of men in distinction to 8% of women.

Women's top frets also included having sex with a physically unattractive partner; women (17%) were more likely than men (10%) to list this as one of their strongest regrets. This result might seem counterintuitive; men tend to place a greater premium than do women on physical attractiveness in potential mates. However, it's actually consistent with previous psychological research on romance.

First, women substantially increase their standards for physical attractiveness for casual sex partners. On the other hand, men dramatically lower all their standards when indulging in 'short-term mating', including ideals for physical attractiveness. So, men are less likely to bemoan casual sex with a physically unattractive partner.

Men's aggregated ''top five'' list of sexual laments largely consisted of inaction regrets. These include missing casual sex opportunities, not having sex early enough in a relationship, staying in a bad relationship and missing sexual opportunities as a result, and wasting effort pursuing someone whom they thought would have sex with them, but did not.

The contrasting pattern in regrets lead to a theme emerging between the genders; in essence, whereas women regretted being ''led on'' romantically, men were more upset at being ''led on'' sexually.

In the study entitled 'Sexual Regret: Evidence for Evolved Sex Differences', men and women reported similar rates (56%) of having engaged in casual sex. But women reported more numerous and more intensely felt sexual action regrets than men did, particularly regrets involving ''casual'' sex.

Men reported more numerous and stronger sexual inaction regrets than women did, particularly regrets involving failure to engage in casual sex or the pursuit of a relationship that delayed sexual activity or precluded better sexual opportunities.

Compared to heterosexual women, both lesbian and bisexual women reported less sexual action contrition, and reported more sexual inaction regret. In other words, lesbian and bisexual women appeared a bit more like men, than did heterosexual women in their pattern of sexual regret.

The authors of the study, Andrew Galperin, Martie Haselton, David Frederick, Joshua Poore, William von Hippel, David Buss and Gian Gonzaga, argue this pattern of regrets could be explained by the fact that women who have sex with women do not worry about pregnancy.

Plus, a particularly sobering point for men to consider, the authors contend women who have casual sex with women, could experience greater sexual satisfaction than women who have casual sex with men.