According to new research by Professor Adrian Furnham of University College London, men overstate how clever they are and women underestimate their own intelligence, although men and women tend to have the same IQ. He may have got a Third at college, she may have got a First, but forget it. It's called the "male hubris, female humility" effect and it's everywhere - at the office and in the home. It explains a lot.

Watch a woman loading the dishwasher. Up comes the male: "No, dear, the spoons have to go like this. And if you put the blender there and the plate here at least the door will shut. Silly old you."

She grits her teeth and, for the sake of domestic peace, lets him take over. That's " emotional intelligence", at which women are better than men.

Of course, it all depends on how you define intelligence. A narrow, old-fashioned definition relates merely to problem-solving: the wider, modern definition is kinder to women, including empathy and earlier language skills, at which women excel. Actually, he may be right about the blender, and she would be wise to let him rearrange the dirty dishes as he wishes, because men are better than women when it comes to spatial awareness.

But how important is that these days, other than making him better at parking or carrying big bits of furniture up the stairs? And who cares anyway?

Male hubris is useful enough outside the home. When it comes to getting through interviews, demanding promotion and getting the girl, confidence and a bit of swagger wins. Female humility? Well, it's useful in Darwinian terms, in as much as it tends to get her the man. Men in theory prefer to marry women less intelligent than they are, a little younger than they are, a little lower down the social scale.

The mating instinct tells a woman that humility pays off. So tuck in the chin, lower the eyes, and pretend. Here I am, take me, little helpless me. If he beats his chest like a gorilla over his promotion, and she declines hers because she feels she can't cope, her home life and probably her sex life will benefit. As will her children, in a contented home. Darwin wins again.

On the other hand, humility won't pay off in the work world because that's one of socialisation, not species instinct. It doesn't get you equal pay. The ones who get and accept the promotion are the minority of self-aware, bright young professional women who decline to show humility, and think themselves the equal of any man. In eschewing humility they have found their dignity. The trouble is, like their sisters, it's still hardwired into them to go on looking for Mr Right, the one who earns a little more than they, is a little older and richer and more socially secure (see Bridget Jones, not to mention Elizabeth Bennett).

She is following the Darwinian model, in fact, but where is this glorious man to be found? He isn't. They are asking too much. Today's woman, Professor Furnham tells us, proving his point, sees her grandfather as cleverer than her grandmother, but this need not be only prejudice. It may well be that she remembers him accurately. Grandpapa's tendency would have been to marry a sweet girl rather than a clever girl.

Moreover, he will have gone out to work and seen the world and brought home new ideas. She will have just slumped over the kitchen sink and lost IQ points. Same thing to a lesser degree with her father.

If today's man, boasting about his promotion, the speed of his car, the size of his bonus, his attractiveness to women, tosses his antlers and overestimates his intelligence and underestimates that of women, that's hardwired too. It's called sexism, and it's timeless. Yet while dismissing men as boasting, insensitive oafs, women do themselves no favours. They may be backed up by research - male self-esteem is certainly exaggerated (boasting); the higher the male IQ, the more Asperger-like the man (insensitive); poor emotional intelligence leads to behaviour hurtful to the female psyche (oaf!) - but comparisons remain odious.

Men live by testosterone, women are oestrogen-based. Men grunt a lot, women preen a lot. The male and the female IQ bell curves are different shapes - women tend to cluster in the middle, there are more males at the extremes.

This means there are more very clever men (that's why they get more Firsts at college than women) and very stupid men (that's why there are more men than women in police cells overnight).

Men single-task. Women multi-task; it's in their natures to do so, the better to look after the babies we were designed to have. Women pride themselves on this ability, but perhaps it is not so much of an advantage. Men focus better. In a world of their own, would women have invented television? I doubt it.

Men in groups get stupider - look at Iraq. Women in groups become more clever - look at women's self-help groups in Africa.

I suspect girls may be changing. Schoolgirls watching their male counterparts fail and their older sisters get jobs when their brothers can't, must surely come to the conclusion that women are the superior gender, and would answer Professor Furnham's questions differently. Unless - terrible thought - they are in rebellion against the work ethic.

Boys bunking off school and not bothering to pass exams might now be seen as a sign of intelligence and self-reliance while the girls just sigh and say, if only I had the courage, little me! As it is, I must just put my nose to the grindstone and work because, honestly, I'm just not very clever. I'll just have to get a job, because that's all I'm worth.

Perhaps this is why the L'Oréal 'Because I'm worth it'' advertisement works. Because we hope it's true.

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