It’s unusual, but not impossible, to come across a female plumber or motor mechanic. Although the gender of medical students in the USA and UK is about equal, about 35% of all practicing doctors are female. There are only about 5-10% female neurosurgeons, whereas there are around 20-25% female neurologists and 40- 50% female psychiatrists. Why is this, and should it concern us? Should we press for legislation that insists on 50% female neurosurgeons? Or even plumbers? Should we limit the number of female psychiatrists to 50%?
To make an obvious point, men and women differ in what they want to achieve, their abilities and opportunities. Not all men would make acceptable plumbers. Why do people differ? The standard answer is that there is an interplay between genes and their environment: each man or women is born with a particular set of genes which may (or may not) bias his/her choices in life and thus his/her opportunities. Then the environment kicks in. if you are naturally good at music, you are likely to want to learn to play an instrument. But if you are born into a family with no access to music or musical teachers, then this ability may not fulfill its potential. You may never be that concert pianist; though you would never know whether, given every opportunity, you’d make the grade. So there are complex and changing factors that determine achievement for everyone.
Gender may be one. It’s fashionable – in some quarters – to deny that there are any overall differences between males and females. Biology, inconveniently, tells another story. Females have two X chromosomes, men only one X but a much smaller Y chromosome. The Y chromosome has one major function: during the earliest part of foetal life, it makes a testis from the primordial structure which, otherwise, will become an ovary. This then secretes testosterone, which has remarkable and long-lasting actions on the developing brain and widespread effects on behavior. There are other genes on the Y chromosome that may also contribute to 'masculinity'. Testosterone has enormous significance for the developing brain, which cannot be discounted. There are structural differences between male and female brains (see an earlier blog). The converse is also true: absence of testosterone may accentuate behaviors associated with 'femininity'.
Little boys play with trains and guns, and rush around (‘rough and tumble’ play): little girls play differently. There are those who ascribe this to social pressure: parents, they say, expect their children to play in this sex-differentiated way and reinforce the ‘correct’ behavior. But if you give toys to children of cultures than have never seen them, the boys still play with the train, the girls with the dolls. Little girls exposed to abnormally high levels of testosterone in the womb tend to play like boys; conversely, males who are genetically unresponsive to their own testosterone play like girls. That is not to say that parents have no influence on a child's behavior. As always, there is an interaction between biological propensity and socialization: neither acts alone. Denying the importance of either is wishful thinking, not logic.
If I say to you: ”most men are stronger than most women” you are unlikely to disagree, though we both know that there are some women who are stronger than some men, and that a man’s strength depends on many things, including his genes, age, diet, fitness and training. This illustrates the futility of taking up fixed positions in ‘nature/nurture’, ‘genes/environment’ debates when the interaction between them is what is interesting. The current focus on epigenetics makes this all the more obvious.
Gender differences in behavior also exist, though they overlap, just as muscular strength does. If you go to a car show, the majority of the crowd will be male: but at least some of the females there are not simply dutiful companions. They are there because they are interested, and nobody stops them going. But the fact that there are many more men says something important about sex differences. Those women who don’t go have probably chosen to stay away. Studies show that men are generally more interested in ‘things’ (eg machines) than women, whereas women are more interested in people (‘empathy’) than men. But it’s important to emphasize again that these qualities overlap: some women are more interested in machines than some men and so on. Is this all upbringing or social expectation? We should be prepared to accept biological as well as social determinants. We readily accept gender-related physical differences in muscles; the structure of the brain is also sensitive to testosterone (see footnote), so why is there such resistance to the notion of gender-related differences in behavior?
It is likely that gender differences may have been magnified by physical circumstances. Working down a mine, tilling a field, hunting a prey, throwing a spear - all require physical attributes that have limited them largely to men. But things are changing. Modern machines are directed by pressing a button or touching a screen. Modern weapons are fired, or drones launched or guided by computers that require no special muscular ability. Women are taking more prominent roles in political, industrial and military life. While this does not eliminate the reality of gender differences in behavior, we should beware of how much they have depended on factors that relate to differences in physical ability or accepted social role rather than motivation or cognitive gender-dependent behavioral characteristics. As the physical effort required for tasks that used to be gender-specialized become less dependent on muscles, it will be easier to observe true differences in gender-related abilities and aptitudes. Assuming, of course, that other obstructions have been removed. It is highly likely that they will still exist, though perhaps not in the more exaggerated forms we sometimes see today. Indeed, the development of new human activities, such as computer gaming, may reveal additional gender differences in behavior.
Humans have unrivaled abilities to recognize, compensate and modify gender differences by political or social means. If you were to examine the social role of female chimpanzee across the centuries, you would find little difference. Furthermore, female chimps in one forest behave much the same with respect to the males as in another. Behavioral changes do occur in non-human primates – they adapt their lives to their current environment – but this is fundamentally different from those that can happen in humans. The human brain gives us the unique ability to recognize and understand social interactions and their nature, and to decide, to a degree at least, how we want to them arranged. We make deliberate ethical or political decisions, which may not be in accord with biological destiny, as well as responding to the demands of the physical environment. The briefest examination of the very different roles of women in either the UK or the USA 200 years ago and today makes the point. And compare the current status of women in Western Europe and, say, countries such as Saudi Arabia. The roles of men and women in society, and the way they interact, has altered throughout the centuries, sometimes rapidly, at other times slowly, but also very variably in different societies. We cannot say this is ‘biological’ or ‘social’: the fact that the human brain has certain qualities and abilities (a biological fact) makes social evolution both possible and variable.
Gender equality is not a numerical state. We need to learn to be comfortable with the fact that most plumbers are male, and most nurses are female – with one major proviso: that anyone, irrespective of gender, with the motivation and ability to do something, or become something, has the opportunity to do so. Opportunity means a society that accepts that anyone can do anything, without hindrance due to gender, race, or circumstance, but that there will still be individual differences in ambition and ability. If that results in most surgeons being male, and most psychiatrists being female, then so be it. No quotas. Of course, it's obvious that we are not in that state: females, in however ‘advanced’ the country, do not always have equal opportunities. There are social pressures and biases. Repression of women is an historical and contemporary fact, and realization of this has resulted in the most significant socio-political movement of the twentieth century (the feminist movement). But to deny the existence of biological gender differences as a contributor to human variety is to deny and misunderstand one aspect of individuality. We must not confuse equality with similarity.
 For a fuller account, see Joe Herbert, Testosterone: sex, power and the will to win. Oxford University Press, 2015.