Do you have a male or female brain?

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).

It can be quite subtle, but in men the ring finger (measured from the crease where it joins the hand) is likely to be longer than the index finger. In women the two fingers are typically the same length.

Strangely enough, your hands give clues to what is sometimes called ‘brain sex’ — the way your brain reflects your gender.

Of course, we all have different skills and interests, but some are considered more typically male, and occur more commonly in men, while others are described as more typically female, and occur more commonly in women.

According to popular mythology, men tend to be more obsessed by things such as cars and obscure facts. You find men in pubs discussing the top speed of a car they are never going to drive, let alone own. They cling to the TV remote control. They like spending time in sheds.

Women, on the other hand, are said to be better at empathy and understanding what another person is feeling or needs. In an emotional crisis, they are more likely to offer sympathy.

If you are a man you may be surprised to learn that there are more than 400 different human emotions. If you’re a woman you probably knew that already.

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 SBS One 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.

While Professor Baron-Cohen accepts social pressures are important in influencing choices and behaviour, his studies suggest the hormones babies are exposed to in the womb can also shape the brain. Higher levels of testosterone in utero, for example — as measured in long-term studies that took samples from pregnant women then followed their children from birth — are associated with offspring who are less empathetic but better at some mental skills later in life.

In other words, more testosterone during pregnancy produces babies with a more male brain (we’re not yet sure why some mothers produce more testosterone).

(dailymail.co.uk)