At last there’s proof of what we’ve always suspected – physiologically and behaviourally men and women are different. Vivienne Parry reports
Friday February 10, 2006
Marianne Legato, professor of clinical medicine at Columbia University, and one of the foremost experts in gender differences, has been at the forefront of this revolution in understanding, which encompasses not just behavioural variations between men and women – universally acknowledged – but gender specific differences in physiology. These are not trivial, but of life-or-death importance.
Take, for instance, the human heart. Women’s hearts are smaller, which our alien might anticipate, as women are on average smaller than men, but the musculature of their hearts is less elastic. Women are also more likely than men to develop early beats or abnormal ones (arrhythmia), probably because of the profound influence of their hormones; In men, exercise is often a trigger for abnormal heart rhythms, whereas the precipitating factor in women is more likely to be hormonal change. However, the oft repeated tale that you can tell the sex of an unborn baby by the rate of its heartbeat (less than 140, a boy, more than this, a girl) is not true.
Even the clinical symptoms of heart attacks vary between the sexes. Crushing chest pain is the one we know best, but one in five women having a heart attack will experience it as upper abdominal pain, shortness of breath, nausea and sweating. Such departures from "normal" symptomatology have led to women being sent home from casualty, their heart attacks initially diagnosed as panic attacks.
Much of this was unknown until the 1990s because most of the information on the cardiovascular system came from studies done exclusively on men. Why was this? Partly because of the assumption that men and women must be the same, partly because it was thought that women (and especially those who might become pregnant during the period of research) needed to be protected and finally, for financial reasons; women’s fluctuating cycles meant many more of them had to be included in trials than men to ensure that the hormonal bias of their menstrual cycles was erased.
As a result, the drugs that were developed to treat men’s heart problems sometimes made women’s problems worse. Many of these drugs work by prolonging the time the heart takes to relax after each beat, but in women, whose hearts take relatively longer to relax than men’s, they can trigger extra beats.
Men and women also process medicines in different ways – women clear some drugs from their systems more quickly and may need higher doses to have the same therapeutic effect, particularly just before a period when rising levels of hormones temporarily speed drug clearance rates.
Thanks to these important differences, clinical drug trials are now expected to include female subjects, something that was certainly not the norm 20 years ago, when nearly all medicines were tested on fit young men. It has led to some interesting anomalies – did you know for instance that some of the painkilling drugs used in labour on maternity wards have never formally been tested in women? Yes, labour drugs were tested on men.
As people have begun to compare the sexes, it has been realised that the variations between men and women are not confined to one body system, but range across them all. Women have stronger immune systems, for example, making them less likely to succumb to infection but more likely to suffer from auto-immune diseases, such as rheumatoid arthritis and multiple sclerosis. This may also be the reason behind another strange-but-true gender fact – men are more susceptible to parasitic infections than women. But there are many examples. Bile from the female liver is different to bile from a male one – the reason gallstones are more common in women. Food takes longer to pass through a woman’s gut than a man’s. Women’s skin is more prone to wrinkling than men’s.
In her book Why Men Don’t Remember and Women Never Forget, Legato focuses on the many gender variations in brain anatomy and function, relating them to the behaviours we observe so often in our partners. In doing so, she creates a bridge of understanding across the gulf of incomprehension that undoubtedly exists between the sexes.
For instance, women’s complaint that men never listen … and men’s claim that women never stop talking. Well, we would stop, wouldn’t we, if they got it the first time? And how about that other frequently offered male phrase – "I’m not a mind reader"?
Legato helps to explain the differences in how the way each sex listens and what they hear. Men’s ability to process language and understand what is said to them starts to diminish from the age of about 35, whilst women preserve this function until they are menopausal. Decoding the meaning of the spoken word is easier for women. For a start, both halves of their brains are involved, while in men it is only the left side. There is more. Much communication relies on what is unsaid, on facial expression and other nonverbal cues. Women are able to correctly interpret a wider range of facial expressions than men, giving them an empathy advantage. Women also have better memories for the spoken word, meaning that they do tend to retain the points of an argument that men have, perhaps wisely, long since forgotten.
Legato outlines a communications strategy to correct this imbalance. One of the key points is for women to say what they mean – verbally, not with a look which men are poor at interpreting: "If you’re asked what’s wrong and you say nothing, chances are that he is going to believe you. It doesn’t mean he doesn’t care. In fact, the opposite is true. When men are upset they tend to go it alone. The result is that they will respect your implicit instruction to leave you alone."
It would, however, be wrong to think of there being a male-type brain or a female-type brain. There is a continuum with a large overlap in the middle which, fortunately, gives us both analytical women and sensitive men. Knowing that there are these differences is akin to acquiring a toolkit, so that instead of exasperation, each sex can adapt ways of communication, adopting, as Legato says, the best that each has to offer and forging stronger relationships as a result.
As for men’s and women’s bodies, how about a prediction? Gender-specific medicine will become a growing speciality as research uncovers key points of difference which, if used correctly, will mean better treatments and understanding for both sexes
· Dr Marianne J Legato’s new book Why Men Never Remember and Women Never Forget is published by Rodale at £7.99. To order a copy with free UK p&p call the Guardian Book Service on 0870 836 0875 or go to guardian.co.uk/bookshop