After years of heated dialogue, plus endless books, articles, debates, do men and women understand each other any better? It would seem not, according to a recent survey carried out at Harvard Medical School where college students were asked to share their thoughts about the opposite sex. The American magazine Psychology Today called the results "depressingly familiar". Both sexes came up with three main stumbling-blocks in the way of perfect accord. We put these questions to experts and non-experts alike.

Men ask:

Why do women need romance and love in order to have sex?

Why are women so emotionally unstable?

Why do women make such a big deal out of "trivial stuff" like remembering birthdays?

Women ask:

How can men have sex with you when they don't love you?

Why are men so afraid of their emotions?

Why don't men remember important things like birthdays and anniversaries?

Our panel:

Dr Pamela Wells and Dr Robin Russell, who both lecture in the psychology department of Goldsmith's College and specialise in the field of relationships and marriage; Phil, architect, 31; Joe, journalist, 31; Richard, accountant, 33; Niamh, social worker, 29; Annick, student, 28; Michelle, occupational therapist, 34; Ross, recruitment consultant, 32; Alison, computer programmer, 30; Helen, recruitment consultant, 31; Louise, student, 27

Why do women need romance and to be in love in order to have sex?

Candlelight dinners, red roses, little love notes - why should men have to bother with such nonsense? They still say they just don't understand why women want to be wooed.

According to Dr Robin Russell, the strenuous and prolonged chat-up is a legacy of primeval times when sex meant a definite possibility of pregnancy. "Women who get pregnant stand to risk far more than the men who get women pregnant, so women are much more cagey about establishing relationships," he explains. "They want to be reasonably confident that the man will hang around and help with childcare, so they want a degree of commitment before sex."

Modern man is unconvinced. "It's the same mentality that makes my wife unwrap her Christmas presents really carefully. I just tear the paper off and get to the gift," said Phil.

Not all men are unromantic. "Well, why shouldn't women expect sex with love? It's the ideal," said Joe. "But," he added pragmatically, "you don't really expect everything in life to be ideal all the time." And not all women fall for the hearts-and-flowers routine. "Sex is a bigger deal for women than men, and men just don't get that. But I'm not sure about needing romance. The love thing isn't essential, as long as nobody lies about it," said Niamh. "Women have worked out that sex without love is less fulfilling. Although there's no reason why it shouldn't be fun," said Annick.

And then there are the strictly practical reasons. "Women need some kind of insurance policy that they won't be discussed and evaluated afterwards by the boyfriend and his mates. We hope that love might mean a bit of respect," said Michelle. Or you can take the direct approach. "Women are fundamentally less honest than men," snapped Ross.

Why are women so emotionally unstable?

Some would hotly contest this sweeping generalisation, but it seems there is some evidence to prove that when it comes to posturing and vapouring, women are the more skilled sex. "If you take the neuroticism score on an Eysenck personality test, women do tend to score higher than men, and in standard questionnaires women's depression scores are twice as high as men's," said Dr Russell. "So there is good evidence to suggest that women are likely to experience the types of things that some would consider to demonstrate emotional instability. Some women also suffer from PMT, and as a male you tend to feel you might get your head bitten off, so that would contribute to the male impression of female instability."

Both men and women subscribe to the notion of hormonal mood swings. "It's hormones! Once a month, I get so depressed," said Alison. "It is partly hormonal, but I think the main reason is the brainwashing that has gone on in women's magazines for years, expecting them to be perfect at everything and beautiful," suggested Joe.

Predictably, though, women point out that men are also far from perfect. "Humans are emotionally unstable, not women," said Michelle. "This kind of sexist nonsense makes me despair. All the world's biggest dictators and general baddies are men, and if that doesn't show male emotional instability, I don't know what does," added Helen.

Men, indeed, are not entirely well-adjusted either. "They are more likely than women to be alcoholic, or criminal, or schizophrenic," pointed out Dr Russell. But empathy is not always forthcoming. "God knows why women are emotionally unstable. If they'd only calm down enough to discuss it we might all get somewhere," said Ross.

Why do women make a big deal out of trivial stuff like remembering birthdays?

Forgetting your partner's birthday or your anniversary is a considerable gaffe, as, indeed, is expecting her to take over remembering your family's significant dates. According to Dr Russell, however, women don't really mind pp'ing cards to people they've never met. "Women are more actively social," he said. "They express their emotions much more readily, and they are much more into personal relationships. Even amongst lab rats, the males are more exploratory than the females; it's one of the typical enduring sex differences that men go off alone, while women stick close to home and do the social interaction. Men are more the lone athlete/traveller/risk taker figure, women are more social."

No such hi-falutin' reason, said Richard. "They want lots of presents on their birthdays!"

It is the collective-card syndrome that really annoys. "Women don't mind remembering their own family's birthdays, it's when they find they've taken on remembering all their husband's family's as well that it gets too much. Men are just too dim to cope with the concept of looking at next week's diary, spotting a birthday and dropping into the card shop," said Michelle. And Helen adds: "There's nothing trivial about remembering signposts in your life. It's just pure selfishness to ignore them if it upsets your partner."

Or is it men that are devious? "Women know how important family ties are," said Annick. "Men only remember when they want something, like their mum to do their washing or their dad to lend them some money."

How can men have sex when they aren't in love?

Eugh. Imagine doing it just for the sake of it, with any old passing person of the opposite sex with an obliging nature. But they do, they do, said Dr Pamela Wells. "Men don't have to be as choosy as women when it comes to sexual partners; they tend to be less discriminating. If they can pass on their genes without any further commitment, they will. Also women are limited in the number of children they have, while in principle one man could father thousands of children, if not millions, so women have to be more careful to get it right."

So, explain yourselves. "Because they can!" and "Because women let them!" and "Because they can!" came a chorus from Phil and Joe and Michelle. Let's be realistic about this - "Well, if they get the chance, I suppose they aren't going to say no," said Annick. But then again, who would? "Ooh, men sleep with women they don't love because they want to have sex, I should think. What a stupid question. Women sleep with people they don't love too, you know," said Helen.

And, pointed out Richard, the route to being an uncaring shag-machine is not necessarily an easy one. "It's a revenge thing," he said. "Most men get rebuffed for years and years before they get anywhere, so when they find they can, they want to do it with everyone."

Why are men so afraid of their emotions?

Strong, silent, macho: the spirit of the Marlboro cowboy lives on in many a male breast. Why? "One of the things you can predict from an evolutionary basis is male/male competition," said Dr Wells. "Females are a valuable resource for males and are worth competing for. A man has to be strong, cunning and dominant in order to compete, so it's not in his interests to show signs of weakness or fear."

Or could it be that what one might mistake for callousness is simply a dignified reserve? "Men are not afraid of their emotions, they just don't wallow in them the whole time like hippos in mud," said Ross.

"It's not that men are afraid of their emotions, they just like to remain in control of them," added Richard.

Not everyone sees this as a disadvantage. "Thank God they are afraid of their emotions. There's nothing more annoying and disconcerting than a man in tears," said Michelle.

"I wish I could meet a man who was a bit more afraid of his emotions, frankly. These days they moan and whinge quite as much as the girlies do," observed Louise.

"They aren't, in my experience! Men are human too," said Helen.

Why don't men remember important things like birthdays and anniversaries?

What else can possibly be on their minds? In fact, they are biologically programmed never to drop into the greeting-card shop. "Women are more evolved in terms of keeping the social networks going," said Dr Pamela Wells. "In stone-age times you would really have needed that close network for childminding and help, and woman's role in keeping the social network intact has persisted."

Or could it be "because their brains are too full of sports statistics" (Alison's theory). Or too full of themselves, perhaps? "Men are so absorbed with themselves, anything that doesn't concern them personally just doesn't happen," said Phil. "And birthdays and anniversaries are trivial. Oh, all right then, they're important. But I have even more important things to think about."

But the favourite theory is that simple laziness plays a big part. "It's because their wives will do it for them," said Joe.

"It's because they are selfish gits who expect to get lots of stuff on their own birthdays but can't be bothered to reciprocate," said Louise.

But don't give up, said Michelle. "They do remember, especially if you remind them. You have to be prepared to train a man, it's just as big a responsibility as getting a puppy."