The tests that show if you've got a male or female brain: The answer may surprise you - and explain your personality

Sit down for a moment. Relax. Then clasp your hands together so your fingers entwine — don’t overthink it! Now look at your thumbs. Which one is on top — the left one or the right?


If you are a man, the odds are it will be the left; if you are a woman, it is more likely to be the right. Now unfold your hands and take a look at your fingers, in particular your index finger (next to your thumb) and your ring finger (next to your little finger).

This is the stuff of jokes and self-help books — but it is also shown to be true through science. The question is, do these tendencies result from nature — with the biological gender we are born with deciding our interests and personalities — or do they result from nurture, with society and upbringing creating the differing ways that men and women behave?

The BBC series Horizon asked Professor Alice Roberts and me to investigate. We started from very different positions.

Alice thinks apparent brain differences between the sexes have been exaggerated by how our culture treats boys and girls. In the programme she carries out fascinating tests to prove her point, such as dressing up little boys as girls and vice versa and watching how people treat them.

Almost immediately, the girls start rough-housing and playing with trucks, while the boys are treated far more gently by the adults around them.

She argues that parents’ unconscious actions — such as being gentler with girls and letting boys behave more roughly — often mould children into men and women who embody gender stereotypes.

While I agree that lots of wild generalisations about men and women are bandied around, I also think there may be something in claims that our fundamental biology influences how we behave.

Professor Simon Baron-Cohen, an expert on the brain who I visited at Cambridge University, has done a lot of pioneering work on this. He believes, broadly, that people of whatever gender fall somewhere along a ‘systemiser’ to ‘empathiser’ spectrum.

Systemisters are people who enjoy breaking down and analysing systems.

They are more likely to become train spotters or computer scientists.

They are what he has called ‘male brained’ — as these qualities occur most frequently, but far from exclusively, in men.

Empathisers, on the other hand, are more typically ‘female’ brained as they are more typically women.

Although there are exceptions, most men — when tested — come out as more ‘systemising’ than ‘empathising’, while for women it is the other way round.

A number of studies have shown that the greater the difference between the length of the ring finger and the index finger, the more ‘male’ your brain is likely to be.

As you can imagine, this is a controversial area of science. Professor Baron-Cohen does these studies because he is interested in autism, which he describes as an extreme version of the male brain — more interested in systems and often struggling with empathy.

A while ago, when I was making a programme called Pleasure And Pain, we did a survey where we asked people which of the sexes they thought was better at tolerating pain — 81 per cent of women said ‘women’, while a mere 11 per cent thought men were the tougher breed.

Although men were more inclined to give themselves the benefit of the doubt, the majority, 54 per cent, still agreed ‘women’ were more stoical. But is this right?

One way to find out is to get male and female volunteers to take part in a cold water immersion test.

This is a standard pain test widely used because it causes acute pain without doing any long-term damage (as long as you don’t do it for more than 15 minutes).

In this test, you put your hand in a bucket of ice-cold water and see how long you can keep it there before the pain becomes intolerable.

I’ve done it a couple of times and oddly enough after the initial shock it doesn’t actually feel cold; below about 3 degrees Celsius your pain receptors overwhelm your temperature receptors so you are no longer able to tell if the water is hot or freezing.

All you know is that it is incredibly painful.

When this test is done in a laboratory setting, men almost always outlast women. This may be pure machismo, but Professor Jeff Mogil of McGill University, Montreal, thinks there is more to it.

A couple of years ago, I was in a large military hospital in Afghanistan, filming a series called Frontline Medicine for the BBC. I saw a number of soldiers, male and female, with serious head injuries.

I was told that the women were likely to make a better recovery than the men.Why? It may be, in part, because women have higher levels of progesterone.Progesterone is best known as a female hormone, involved in the menstrual cycle and pregnancy, but it is also important for the development of neurones — the cells that carry messages in the brain.

Animal studies and a few small human trials have shown that giving progesterone soon after suffering a brain injury improves survival and recovery.

This, I think, is why researching gender differences is worth doing.

It is not because it will help us understand why men struggle to remember their children’s birthdays or why there are fewer female darts players, but because it may help us find more effective ways to tackle disease.