In November 2013 a study was published in the journal ‘Proceedings of the National Academy of Sciences of the USA’ titled, ‘Sex differences in the structural connectome of the human brain’. Now if you don’t know what a connectome is, don’t worry, the term was only coined in around 2005. It refers to a map of neural connections in the brain, and it exists as a way of trying to connect the physical structure of the brain with its function. Fancy new terminology aside, the purpose of the study was to measure structural connections within the brains of just below 1000 young people (aged 8 to 22) and their results showed some interesting differences. Using a technique called diffusion tensor imaging (an MRI technique that measures the restricted diffusion of water) they found that after the age of 13 there were significant differences in how the brains of men and women were connected. In the study men’s brains were found to connect more within a given hemisphere. and women’s had great cross connectivity (seen below the connectome maps published, showing the male brain in blue and the female brain in orange:
As you can see, the male brain shows more longitudal connections whilst the female brains shows more transverse connections.
The abstract for the study states, ‘the results suggest that male brains are structured to facilitate connectivity between perception and coordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes’, having earlier noted that ‘Males have better motor and spatial abilities, whereas females have superior memory and social cognition skills’.
The publication of this paper resulted in a number of excitable and fairly familiar newspaper headlines:
The Telegraph announced boldly ‘Brains of men and women are poles apart’, (demonstrating once and for all that broadsheets aren’t immune to headline puns) telling us that women’s brains are set up to have better memories (for anniversaries!) and gauge social situations better while men’s brains coordinate their actions with their senses, so can navigate better (not to mention be better at parking cars).
The Independent declared these differences, ‘could explain why men are ‘better at map reading”.
The Belfast Telegraph gets the prize for the best reporting on this, by first reminding us that ‘men are from Mars, women are from Venus’ before going on to declare that the study has shown ‘men and women’s brains are wired in completely different ways, as if they were species from different planets.’
With the possible exception of the Belfast Telegraph (who seem to have got themselves hopelessly overexcited), you can’t place too much fault on the reporting here. It is a clear cut case of ‘science says’, and in this case has the benefits of a peer reviewed journal to back it up. The study itself made reference to differences in male and female behaviours, stating that men have better ‘motor and spacial abilities’ whereas women show, ‘superior memory and social cognition’. Unfortunately, whilst this paper may make that claim, the preceding study (of which the participants of this study were a subset) does not back that up (abstract here ). Of the 26 behavioural measures made for comparison (for example executive control, memory, reasoning, spatial processing, sensorimotor skills, and social cognition), 11 showed sex differences that were non existent, or as small as 53:47 (the expected sex outperforming the opposite only 53% of the time), Even in those areas where the differences are meant to be the greatest (spatial or social awareness) the performance difference was only 60:40-a measurable and noticeable difference for sure, but hardly enough to declare difference species.
My problem is not with this study or with their results, but rather with the way the conclusions have been drawn, and with the extrapolations. They have shown interesting differences in how men’s and women’s brains connect with themselves, but then rather than taking any further interesting steps, drilling down further into the data, they have attached some male/female stereotypes and called it job done. One of the authors has even suggested that the ‘hard wired’ differences found could explain the ‘gut feelings’ that women demonstrate more than men, and which makes them good mothers (‘intuition’ and ‘mothering’, or indeed ‘nurturing’ was not in fact measured in this study).
There could be other reasons than ‘men are better at map reading’ for the differences observed. Men’s brains are frequently bigger than women’s brains, the difference in the wiring could be due to physical necessity (there are also studies on this).
Then there’s the most interesting part of the study that has been the least discussed: the structural differences are not observed in a significant manner until after age 13. And we have to ask ourselves why. One of the proposed explanations is that this is the approximate average age for the development of secondary sexual characteristics. There are massive changes in the body, hormones flooding everything, the logic seems to be that the brain changes at this time too. However there is a better explanation, and one less routed in speculation. See, there’s this thing called neuroplasticity. It refers to the changes in neural pathways and synapses due to changes in behaviour or environment. Literally as you learn, your brain changes shape. Then we have to bear in mind that gender as a social construct is learned. It is taught. Little girls aren’t born liking pink. They are taught that girls like pink, and that they are a girl, therefore they then like pink. You put those two things together and what you end up with is the possibility that, rather than being innate, related to the release of hormones at puberty, the structural differences in the brains are programmed in by telling girls that boys are boisterous and girls play nice, that boys are good at maths and girls are caring, that boys build things and girls decorate them. But no mention is made in the study of any consideration of gendered activities in their subjects, or indeed any activities that may (and in fact do) influence how our brains are wired.
If you take this into account, the claim that ‘sex differences are hard wired’ seems a little less proven than it was before.
I am very fond of saying ‘peer reviewed journal or it didn’t happen’. But we have to be able to treat even these studies critically. Their data may be fixed and immutable (tho that is not always the case) but the conclusions have more room for movement. And the people making those conclusions are not immune from sexism.
The study may have shown that men and women’s brains connect differently. But it hasn’t shown why. And it hasn’t shown that the differences are innate. It has shown they are learned. ‘Men and women are taught to be different’ is a less interesting conclusions perhaps, but it is a more truthful one.
Post script: If you are interested in this subject, may I recommend the very excellent Delusions of Gender by Cordelia Fine. Her article on this study was also very useful to me.