One of the biggest barriers to equality is crumbling, thanks to a study that blows away the misconception that male and female brains are distinct.
Based on detailed and careful analysis of core features seen in scans of more than 1400 female and male human brains, Israeli researcher Daphna Joel and colleagues demonstrated that most are unique mixes or “mosaics” of features previously thought to be either “male” or “female”. A brain that is not a mix was found to be extremely rare.
The result is a major challenge to the entrenched misconceptions typified by the “men are from Mars, women are from Venus” hokum. My hope is it will be a game-changer for the 21st century.
Crucially, it means the power of neuroimaging to explore and explain the links between brain and behaviour can at last come into its own, freed from the constraints of preconceived stereotypes. Our understanding of sex-related brain differences will move beyond simple and outdated dichotomous thinking.
Knowing the controversy associated with such declarations, the authors have been very careful to use a range of different datasets from different laboratories and to investigate the veracity of their findings using more than a single neuroimaging measure.
Their paper adds to similar discussions in neuroscience, as well as to the canon of recent research findings that previously “well-established” sex differences in brain structures turn out to be false when careful analytical techniques are applied.
And it gels with the broader idea that the biology of sex differences is not what we thought. A news feature in Nature last year proclaimed: “Sex redefined: the idea of two sexes is simplistic”, reporting data showing that, even in the most fundamental aspects of sexual differentiation, including chromosomes, cells and genital anatomy, thinking in simple male/female terms is no longer tenable.
What’s more, for several years, psychologists have been saying that, in terms of cognitive skills and personality characteristics, the “two” sexes are much more similar than different. Just knowing whether someone is male or female is a very poor predictor of almost any kind of behaviour.
Most recently, researchers showed that, on over 100 different behavioural measures, male and female scores could not be reliably (or accurately) grouped into two distinct categories.
Joel’s paper is also timely. In the US, the National Institutes of Health, the world’s largest biomedical research institution, has mandated the inclusion of both sexes in preclinical and clinical research and some European funding is predicated on inclusion of sex and gender factors at all stages of the research process.
An outcome of this is likely to be an increased emphasis on statistically based sex “differences”, which may be misinterpreted as evidence of the kind of non-overlapping dichotomies that this latest research contradicts. Many researchers point out that these statistical categories are at best fallacious and at worst possibly harmful.
This is a controversial area and can lead to firmly entrenched positions. But the latest data must make neuroscience researchers re-examine how they design and interpret their research, the conclusions they draw and importantly how they are communicated.
Continuing to think in terms of simple male-female dichotomies is flying in the face of the evidence and will lead to poor research and misleading findings. To paraphrase the title of a key paper in this area, men are not from Mars or women from Venus, we are all from Earth.
Gina Rippon is a professor of cognitive neuroimaging at Aston University in Birmingham, UK
(Image: Aston Brain Centre, Aston University)
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