The nature/nurture debate about what makes us who we are has raged for the better part of this century. Like race, gender has become one of the most hotly contested pieces of territory in the war. The more information we have about brain function and the role of our genes, the harder it is to ignore the importance of nature in the construction of the self. "Biological determinist" explanations for all kinds of human behaviour are much in vogue, but mistrusted by feminists who fear that the aphorism "Biology is destiny" may once more become a reality.
Now, as scientists explore new scanning techniques that can monitor the the living brain, fresh evidence for sexual difference has emerged. "One of the most interesting things to develop in this field in the last decade is the technology to observe the inner workings of the brain," explains Jim Meyer, producer of Why Men Don't Iron. "When you compare male and female brains performing the same tasks, it is immediately obvious that something different is happening. What is open to debate are the implications of this, but it is now very hard to deny that there are differences in the way that male and female brains work."
Why Men Don't Iron is likely to raise a few feminist hackles. Provocatively, it claims that men are, quite simply, constructed to be better at anything that requires mechanical and spatial skills; the few women successful in fields like engineering and construction have brains that show distinct male characteristics. Women, meanwhile, have natural advantages when it comes to nurturing and childcare and men who go in for traditionally female professions like nursing have "female-pattern" brains. The research which supports this, carried out in the US and Britain, suggests that the "wiring" of male and female brains is different; the female brain is more interconnected and the two halves of the brain communicate more. Male brains are more compartmentalised and focussed; men tend to use one side of the brain at a time. This favours stronger mechanical and spatial skills; the "female pattern" scores highly for verbal skills.
This, says Jim Meyer, is highly significant when it comes to education; lessons in schools, with their emphasis on verbal skills, do not favour boys, who are less adept with languages. However, while males may not do as well as females at school, they more than make up for it later. The glass ceiling that holds down women's careers is a well-documented phenomenon. Why Men Don't Iron suggests this may be down to differing brain neurochemistry. Although both sexes secrete the hormone testosterone, men have higher levels and react to it differently; they experience a testosterone surge and a "high" when they compete and win. "Women do not react to testosterone in the same way," says Meyer. "In terms of competing, men may have a certain advantage. In the workplace this could help to explain why men strive to get to the top while women are more co-operative; they prefer to reach agreement rather than beat the competition." Other conclusions drawn by the researchers are that women are better able to tune into young children's needs and better at doing several things at once, while men have less well-developed social skills than women, are less empathetic, and have a lower tolerance for routine tasks (such as ironing, for instance).
Suggesting, however, that one sex has a prior disposition towards doing the ironing, is surely tiptoeing towards dangerously mysogynistic ground? "There is a natural fear of biological explanations because people have a tendency to misinterpret it as implying some kind of determinism," says Jim Meyer. "Some people think biological explanations may be misused to block social change or excuse unacceptable behaviour. In fact nothing in this research implies that one sex is inferior or superior, and no- one in the field is implying that biological factors are the only factors that influence behaviour, or that equal opportunities are not a perfectly reasonable expectation. But understanding our underlying biological tendencies may be important in understanding why we are different and helping understand each other."
The notion of biological difference certainly strikes a chord with some parents. New mother Jane Gerrard, 34, is a believer. "I asked if I could know the sex of my baby before it was born because I felt I'd need time to get over the news if it was a boy," she says. "I was delighted to hear I was having a girl. Boys are more difficult and boisterous and girls are able to entertain themselves and be constructive. It is shocking to make such a huge generalisation but I think my mother's generation believed they could bring up boys and girls to be the same and time has proved it just isn't true. Go to any nursery school: girls talk more to each other, boys like jumping around and hitting each other." Sue Parker, 26, is a solicitor. "I do think that I operate differently to my male colleagues," she says. "I am less interested in point-scoring. In meetings I am less aggressive; I've found that the best way to get attention is not to join in with any shouting that's going on but to actually drop my voice and that makes people listen. Men are more like bulldozers. Socially it's the same. Men talk at each other while women talk to each other."
Not all are convinced, however, that biology holds the key. Dr Richard Woolfson, child psychologist and author of An A-Z of Child Development (Souvenir Press pounds 10.99) agrees that boys and girls behave differently from a very early age. "This is generally accepted. But is the reason nature or nurture? If you look at the way that parents play with their young children, they tolerate more conflict from boys and they channel boys towards lively pursuits and girls towards more sedate ones - the parents do not do this consciously, but it's very difficult to untangle this kind of conditioning from other factors. And children take their cues from other children and copy those around them." It is easy, he says, to describe adult behaviour, but difficult to pinpoint where those behaviour patterns have sprung from. "I certainly don't want to knock this new research and I think it is very interesting, but as far as I'm concerned the jury is still out."
Olwyn Burgess, director of career management for Cepec Consulting, points out that there are many factors that influence women's progress in the workplace - in particular the perception that women should put family before career. "There is still a lot of sexism and the perception that women should be at home," she says. "Women who have families have to sacrifice too much to get to the top of the tree. A survey of middle managers published last year in Fortune magazine showed that men who state that they are going to take time out to spend it with their family are hitting a glass ceiling, just as women do."
Joan Smith, author of Different For Girls (Chatto, pounds 10.99) believes that programmes like Why Men Don't Iron are evidence that the notion of equality still provokes enormous resistence. "For centuries there was the assumption that men and women were different, though it was never very closely examined," she says. "Then about 200 years ago it emerged that women weren't very happy; they believed that they could be as good as men if they had the education. This led to great cultural anxiety; religious pamphlets in the early 1800s saying that God had made the sexes different, psychoanalytical explanations in the later nineteenth century. Now in the twentieth century we have these supposedly scientific notions." Even the title of the programme, she says, reinforces stereotypes. "Most people can't afford to have someone else do the ironing for them and so it is usually done by women, which is very convenient for men. Of course they'd like to think there is a valid underlying reason why this should be." In fact, she says, there is as much difference between individuals of either sex as there are between women and men. "Men do better in offices because they are male-dominated environments," she adds. "The world of work was set up to accommodate men, so of course men do better."
The attitude of Why Men Don't Iron is one of "vive la difference"; that men and women are equal in status but complimentary rather than being the same. Nevertheless it's hard not to feel just a weeny bit partisan. After all, a generation or two ago the career choices for women were nurse, teacher or secretary; it's galling to be told that in fact these are just the kinds of jobs we're programmed for.
'Why Men Don't Iron', the first documentary in the series of three is shown on Channel 4 on Tuesday at 9pm