A new study has found that there genuinely are numerous subtle genetic differences between men’s and women’s brains.

The finding, made at Uppsala University in Sweden, and published in the journal PLoS Genetics, could help explain some of the differences in the way mental traits and skills are said to differ between the sexes. For example, women are generally considered more compassionate and better at empathising, whilst men are more prone to aggression and risk-taking.

These gender differences are widely accepted, but natural and social scientists have long argued about the extent to which they are rooted in our underlying biology, or whether they are learnt through social roles.

Hundreds of genes are switched on and off differently within the cerebral cortex, which is the grey matter involved in memory, thought, reasoning, attention and language.

The study showed that while there are no sex differences in general intelligence, and both sexes share the same basic genes, there are key differences in their expression or activity. Women tend to have stronger visual memories, while men are more proficient at visualising objects when rotated in space. It has been suggested that this may reflect the way men generally like to navigate by reading maps, whilst many women prefer to remember landmarks.

The study, led by Dr Elena Jazin, does not directly prove that any of these traits are related to differences in gene activity, but it does show a contrasting genetic architecture of male and female brains that could plausibly contribute.

The researchers said:

While the two sexes have the same basic genes, many of these are more active in the brains of only one sex. These gender-specific patterns of gene expression could affect many aspects of behaviour

Although this doesn’t prove we are programmed to think in a certain way, it leaves the possibility open. And the autors wrote:

The obvious question to follow is whether or not these signatures of sex in the brain have physiological significance for brain physiology and/or behaviour

Our results suggest that variation in expression of genes in the brain may be an important component of behavioural variation within as well as between species.

Dr Jazin also noted:

Knowledge about gender differences is important for many reasons. For example, this information may be used in the future to calculate medical dosages, as well as for other treatments of diseases or damage to the brain.

Professor Simon Baron-Cohen, of the University of Cambridge, who had suggested the existence of “empathising-type” and “systemising-type” brains commented:

This is a very original study, testing which genes are expressed differently in males and females across different primate species. It confirms the supposition that genetic sex differences are expressed not just in the secondary sexual characteristics in the body, but in the brain.

Finding genes that are conserved across species points to the evolution of these genetic sex differences, and finding them in the brain suggests that they may in part influence the way the mind works, and in part influence our behaviour.

The work could also explain sex variations in mental health and neurological diseases, such as depression and Alzheimer’s.

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Posted by Jonathan in Anthropology, Biology