Our brains are wired differently. Are we born like this, or is it something that develops with time? 

Researchers from the University of Pennsylvania and the Children’s Hospital of Philadelphia published a study suggesting that male and female brains are wired differently. But their claims made in the media suggesting that these differences are ‘hardwired’ and could explain some of the stereotypical behavioural differences between the sexes are what really caused a ruckus.  

As Professor Dorothy Bishop, a neuroscientist at the University of Oxford, explains, the study shows small differences in the way parts of the brain talk to each other. ‘It’s revealing possible differences in connectivity between males and females that may well be interesting, she says. In women, scans showed slightly greater connectivity between the brain’s two hemispheres, while in men, there is slightly increased connectivity within each hemisphere. These results represent the average man and woman – some women, for example, will have more internal connections than some men.  

But what about the suggestion that these differences are hardwired? ‘Hardwiring to a lot of people implies that you’re talking about something that’s there from birth,’ says Bishop. However, as the study’s youngest participants were eight years old, it was impossible to determine whether males and females are born with different brains from this study alone.  

In order to really understand the differences, we need to know how our experiences – growing up as girls or boys – affect our brains. For example, if girls are taught to like dolls, does this affect their brain development? Unsurprisingly, though, getting babies or toddlers to remain still in a brain scanner is not easy. 

Despite some claims that these results could explain so-called ‘women’s intuition’ and why men are said to be better at map reading, the study does not link neural wiring and behaviour directly. The participants did take behaviour tests, which highlighted slight sex differences, but there is no proof that these are due to differences in brain connectivity. Saying that one caused the other is like saying, ‘I’m out of jam. I saw you eating some jam the other day, therefore you ate my jam.’ It is a seductive argument, but not something that is necessarily true. 

Did you know?
The average human brain weighs around 1 100-1 500 grammes

Brain facts  

1. Women’s brain’s typically have more white matter than men’s.  

2. Men usually have bigger brains. Could size, rather than gender, explain the wiring differences?  

3. If the corpus callosum – the bundle of nerve fibres connecting the two hemispheres – is severed, links between vision, reasoning and speech are impaired 

By: Hayley Birch
Photography by: Ragini Verma, PHD, Proceedings of the National Academy of Sciences

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