Differences between male and female brains are hard to define, and may be due to either nature or nurture, or both.
MEN and women are different. But some people believe men are from ‘Mars’ and women are from ‘Venus’, and that this explains why men never ask for directions and women are confused by maps, or why men excel at science, maths and technology and women in caring professions, such as nursing and teaching.
Economist Larry Summers thought so. In January, 2005, the then president of Harvard University provocatively said that men succeeded in science and engineering because they had “intrinsic aptitude”.
He was denounced as a sexist and resigned the following year. But now scientists (male and female) are wading into this controversial debate and asking if the differences between the sexes are nature, nurture or a combination of the two.
Are these differences hardwired into our physiology or learned behaviour? A BBC Horizon TV programme recently examined the science behind brain differences and the evidence it uncovered pointed towards biology. The programme-makers referred to the work of psychology professors, Melissa Hines and Gerianne Alexander, as proof.
In 2002, these scientists conducted a study involving vervet monkeys. They chose monkeys because it’s impossible to find children who have not been exposed to the gender expectations of society.
The scientists gave the monkeys a choice of ‘male’ toys, such as cars, ‘female’ toys, such as dolls, or ‘neutral’ toys, such as books and stuffed animals. They expected no difference between the toys the monkeys chose and were surprised when the males overwhelmingly chose boys’ toys, while females chose dolls.
“Our findings suggested that what defined ‘boy’ toys and ‘girl’ toys was not dictated by society, but may be due to visual cues that attract boys and girls in different ways,” says Dr Alexander.
The pair speculated that the female choice might be because female primates (and humans) do most of the childcare. They also suggested that boys were attracted to objects that encouraged movement and activity. These offered opportunities for rough, active play and for early training, for a boy who would grow to be a hunter.
A BBC online poll, called Sex ID, suggests the stereotyped differences between male and female brains might be true. More than 200,000 people from 53 countries completed this questionnaire to determine the gender typicality of their brains.
The results found that men were better at shape-sequencing tasks, while women were better at reading emotions.
However, there was much crossover and complaints that expectations played a part in the test. Because women are often told that they aren’t good at spatial awareness, this can’t help but influence them when they are asked to complete these tasks.
Professor of psychopathology, Simon Baron-Cohen, has other biology-based theories.
Over the past 20 years, he has measured testosterone levels in fluid taken from the wombs of pregnant women and tested the children at regular intervals afterwards.
He found that being exposed to higher levels of testosterone in the womb enhanced spatial ability. Children who had higher pre-natal levels were faster at finding specific shapes within an overall design.
This is a trait more commonly associated with men than with women.
Professor Baron-Cohen speculates that it’s all to do with hormones, and especially the male hormone, testosterone, which ultimately separates the boys from the girls.
Brain-scanning has highlighted other differences between male and female brains. One is that men’s tend to be bigger than women’s.
But before men congratulate themselves on this, size isn’t everything. Connections are what matter in brains.
Dr Ragini Verma and professor of psychology Rubin Gur, of the University of Pennsylvania, have explored this. They scanned the brains of 900 people, who ranged in age from eight to 22, and saw striking differences between males and females.
Male brains showed stronger connections between the front and back of the brain. “The back of the brain perceives and processes information, while the front of the brain acts upon that information,” says Professor Gur.
“Stronger connection between the front and back would suggest a greater facility between perception and action. This would be a positive asset for someone who needs to respond quickly to changing situations, someone like a hunter.”
In females, the connections were stronger between the right and left hemispheres. This may explain why women are usually better at multi-tasking and at emotional tasks.
However, although these differences were obvious in adult brains, they didn’t exist at all in children’s. They only emerged between the ages of 13 and 18, suggesting they are either caused by hormones or, alternatively, driven by social pressure.
Dr Carol Linehan, of the School of Applied Psychology at University College Cork, leans towards the latter. “While our biology enables us to do certain things and behave in certain ways, I think the sheer variety of what we can accomplish using the same basic physiology shows there is a huge role for nurture,” she says.
“Take athletes, for example. They are born with the potential to run fast or jump high, but it takes teams of coaches, trainers and nutritionists, and years of training, to get them there. It’s nature to start with, but it’s layered-over with nurture.”
There’s no escaping the pressure of socially imposed gender expectations, says Dr Linehan. “The moment a baby is born, the first question is whether it’s okay, the next is whether it’s a boy or girl,” she says. “From that moment on, our culture, society and history start to socialise us into particular gender roles. Biology is only a tiny part of the puzzle.”
She questions the reliability of brain scans. “Our brains are fantastic at learning and adapting,” she says.
“If we scan the brains of a 25-year-old man and a 25-year-old woman, can we be sure the differences are the result of biology or the results of brains adapting over time, to sex differences or to 25 years of living and learning in the culture we find ourselves in?”
Even Professor Gur says that this may be the case. “Brain anatomy is established through a combination of biochemical processes that are under genetic and environmental control, so some effects can be attributed to environment,” he says.
“For example, a lifelong stressor can influence the volume of some brain structures.”
Scientists and academics continue to argue over the nature-nurture influence on brain development and have yet to explain why men appear to have come from ‘Mars’ and women to have zoomed in from ‘Venus’.
While this research continues, Dr Linehan urges everyone — parents, teachers, career-guidance counsellors, employers and society in general — to become more open-minded.
“Every time you make an assumption, ask yourself if you would make the same assumption of the other gender,” she says. “Our basic biology may predispose us to certain things, but we are not predetermined by biology. We are thinking, acting human beings.
“We are all capable of more than we realise.”
Brain teaser quiz
Is your brain stereotypically male or female? Complete our quiz to find out. (Adapted from the book The Essential Difference by Professor Simon Baron-Cohen)
If someone is upset by something you’ve done, can you usually understand why?
A: Yes, usually very quickly
B: No, I’m often confused.
You’re explaining something to someone but they are struggling to understand it. Is it easy for you to describe it in a different way?
A: Yes, I do it almost without thinking.
B: No, I usually find there’s only one clear way to look at things.
How quickly do you notice when someone wants to join a conversation you’re having?
B: It can often take me a long time. I’m usually immersed in the conversation I don’t notice anything.
Do you like taking the lead when it comes to work projects?
A: No, I’m more of a team player.
B: Yes, I find I’m a natural leader.
Did you like maths at school?
A: I had to study hard but I usually passed.
B: It was easy enough to pass and I did well in the subject.
How do you feel when you have to look after other people?
A: It’s nice to feel needed but it’s hard if they become a burden.
B: Suffocated; I can’t wait to escape.
There’s an electrical problem at home. What do you do?
A: Call your regular electrician.
B: Try to fix it yourself first.
When it’s time for you to buy a new car or computer, do you want as much information as possible about its specific capacities?
A: I don’t bother with that kind of detail.
B: Of course.
Do you find it easy to read maps?
A: I actually find this quite difficult.
B: I can’t understand why anyone would have a problem with this.
If you’re discussing something you believe in strongly, how would you describe your attitude?
A: I can almost always tell if I’m being too forceful
B: I often go too far. It’s hard to tell when enough is enough.
If you chose more As than Bs, you have a ‘female’ brain. You are more in tune with your emotions and better able to empathise with others.
If you chose more Bs than As, you have a ‘male’ brain. You are better at systematic thinking and at spatial awareness.
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