Thursday, September 03, 2009

Are brains sexed?

From this fascinating interview of Catherine Vidal, neurobiologist and Research Director at the Institut Pasteur:

Let’s start with a very direct question: is the brain sexed?

The scientific answer is, paradoxically, yes and no. Yes, because the brain controls the reproductive functions. Male and female brains are not identical, in every species, including our own, because sexual reproduction involves different hormone systems and sexual behaviours, which are controlled by the brain.

But the answer is also no, because when we look at the cognitive functions, it is cerebral diversity which reigns, independently of gender. For thought to emerge, the brain needs to be stimulated by its environment. At birth, just 10 % of our 100 billion neurons are inter-connected. The 90 % of remaining connections will be constructed progressively depending on the influence of the family, education, culture and society. In this way, during its development, the brain integrates external elements associated with its owner’s personal history. We call this cerebral plasticity; which is why we all have different brains. And the differences between individuals of one and the same gender are so great as to outweigh any differences between the genders.

In fact, behind your question is the fundamental problem of the degree to which behaviour is innate and to which it is acquired – an essential question that philosophers and scientists have been debating for centuries. This remains an ideologically-charged subject, which the media adore.

The interview appears in the April issue of, devoted to gender issues in science and technology.