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Studies on how men and women differ in their brain biology get too much attention and are used wrongly to draw conclusions about aptitudes for science, according to gender experts.

Although the male and female brain may differ in size, structure and function, there is no evidence that they translate to differences in behaviours or IQ, said neuroscientist Lise Eliot, from the Chicago Medical School in the United States, at a gender summit in London this month. Practice and experience is what matters most in how well people do whatever they do, including science.

"Brain differences [are] small, not binary, and of no known relationship to math, verbal, interpersonal, or any other higher cognitive ability," she said. “Even if we do see a (biological) sex difference in the brains it doesn’t mean it’s hardwired.”

“When you say ‘10 per cent smaller brain’ it [comes across] as if it affects the IQ, it affects a woman’s performance,”

Caroline Pule

Simplistic conclusions drawn from evidence of sex differences in biology can fuel overt or subtle beliefs that women and girls have less aptitude for science, adding to the obstacles that women in science face across the world.

According to Rana Dajani, associate professor of biology and biotechnology at the Hashemite University in Jordan, who also spoke at the conference, the challenge is to strike a balance between acknowledging biological differences without translating them into behavioural and social, or using them as a basis for discrimination.

Part of the problem is that studies which find differences between male and female brains often grab the headlines and get used to extrapolate to the wrong conclusions.
 
“Sex differences are sexy,” said Eliot, citing a report  picked up by more than 200 news outlets which suggested that “striking” differences in brain wiring could explain why men and women excel at different tasks. The problem was that the study failed to take differences in brain size into account, and looked specifically at a period in adolescence where the sexes differ the most – and a follow-up study disproved it.

The bias sometimes extends to the publishing of scientific results: in April this year, scientists wrote in the journal Nature that neuroimaging studies tend to over-report sex differences and under-report non-significant results.

Eliot added the example of research reporting sex differences in language function between the left and right hemispheres, which was based on about 30 participants and based its conclusions on differences in one of three tests. The research has been cited by others more than 1600 times, she said, but a meta-analysis later found there are no sex differences. One way to address simplistic conclusions is to ‘package’ this message so it’s easily understood, according to Caroline Pule, vice chair of the South African chapter of the Organisation for Women in Science in the Developing World (OWSD). She told SciDev.Net that this will help convey the evidence to counter people who fixate on biology to stick to beliefs about gender differences in aptitude for science.
 
“If it’s at the level that every man in [a] developing country can understand, it would really help break that stigma,” said Pule.

She gave the example of a study which shows that female brains are on average 10 per cent smaller. This is comparable or smaller to sex differences in size seen with other organs, and – just as hands of different sizes function just as well – does not lead to differences in IQ.  When scientists zoom in to look at brain structures, the differences virtually disappear.

“When you say ‘10 per cent smaller brain’ it [comes across] as if it affects the IQ, it affects a woman’s performance,” said Pule, adding that presenting the evidence in a way that’s easy to understand will help spread the right message beyond science circles.

Until people stop fixating on the biological to deny women’s aptitude in the sciences, the plasticity message needs to be pushed much harder, according to Eliot. Even the ability to see isn’t hardwired, she pointed out in a presentation that ran through several measures of brain structure and function. “Nature (genetics and hormones) and nurture (environment and experience) are inextricably interwoven from the first cell division,” she said, and synapses are very adaptable in the early years of age.
 
Learning to behave according to social norms of ‘boy’ and ‘girl’ is a potent influence whose full implications have yet to be fully explored, added Eliot – little research has tested how the brain itself might reflect gendered learning and social status in addition to biology. 

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