Does the brain have a sex?
People celebrated Women's Day on 8 March, paying homage to the strengths and skills of women the world over. However, while differences exist between men and women, the question about the similarity of their brains continues to pique people's interest. In an interview to be published shortly in the magazine research*eu, Dr Catherine Vidal, neurobiologist extraordinaire and Director of Research at the Institute Pasteur in France, talks about the brain, and the differences between male and female brains. When research*eu asked whether differences exist, Dr Vidal replied, 'The answer, both scientifically and paradoxically, is yes and no. Yes because the brain controls the reproductive functions'. She explained: 'The brains in males and females are not identical, and that is for all species including ours. Sexual reproduction involves hormonal systems and different social behaviours, which are controlled by the brain.' However, Dr Vidal noted, the answer is also no because 'if we consider the cognitive functions, it is primarily the brain's diversity that reigns independently of the sex'; she added that 'indeed, for thought to emerge, the brain must be stimulated by the environment'. According to Dr Vidal, only 10% of our 100 billion neurons are interconnected at birth and the remaining 90% of the connections are built gradually, based on the influences of family, education, culture and society. During the developmental process, the brain integrates external components that are linked with the history of each influence. 'This is called brain plasticity,' she said. 'That is why we all have different brains. And differences between individuals of one sex are so important that they will prevail over those between the sexes.' Dr Vidal remarked that there is also a fundamental problem of determining which behaviours are innate and which are acquired. 'It is a key issue that has been discussed with philosophers and scientists for centuries,' she was quoted as saying. 'Even today, it is a subject that is steeped in the ideology and the media revels in that.' With respect to how the media claims that cerebral specialisation differs between males and females, Dr Vidal said: 'Theories on hemispheric differences between the sexes in language are at least 30 years old. They have not been confirmed by recent studies of brain imaging that allow us to see the living brain at work. These theories were often based on observations conducted on very small samples.' According to Dr Vidal, 'they continue to cite those studies while the contemporary scientific reality is quite different.' Therefore, the meta-analysis, based on the conclusions of all experiments published in scientific literature, and covering several hundred men and women, show that 'there is no statistically significant difference between the sexes in the hemispheric distribution of language areas,' as she explained. The locations of the language areas vary considerably from one individual to another. 'This variability outweighed the possible variability between the sexes,' Dr Vidal remarked. The Institute Pasteur Research Director also rejected the theory that male brains are more suitable to abstract reasoning, especially mathematics. 'Two important studies published last year in the magazine Science illustrated this,' she said. In the first one, data collected in 1990 showed that boys performed statistically better than girls in maths, but the same survey commissioned last year showed that the girls did just as well as the boys. 'The results are simply due to the development of science education and the growing diversity of scientific fields.' The second study, conducted last year with a sample of 300,000 in 40 countries, showed that the current socio-cultural environment is conducive to gender equality. 'More girls are getting good test scores in maths,' Dr Vidal highlighted. 'In Norway and Sweden, the results are comparable, and in Iceland, the girls beat the boys.' It should be noted, however, that the boys beat the girls in Korea and Turkey. Dr Vidal underlined that the major research breakthrough in neurobiology is brain plasticity. 'Is is no longer tenable to invoke the biological differences between the sexes to justify the different distribution of men and women in society,' she was quoted as saying. Dr Vidal's comments are backed up by a newly published study in the journal Psychological Bulletin. While some people may think that most women do not chose careers in maths-intensive fields because they lack mathematical ability, the study, which analyses 35 years of research on sex differences in maths, shows that they choose not to study maths because they want the flexibility to raise children, or because they prefer less maths-intensive fields of science. The idea that it is because they lack the ability is wholly unwarranted. Meanwhile, as Dr Vidal pointed out, people's mindsets are also different today. 'If the Nobel Prize in Physiology or Medicine 2008 was jointly awarded to Luc Montagnier and his [female] main collaborator, Françoise Barré-Sinoussi, it is [because] attitudes are changing,' she commented.
Countries
France