Brain scans open ugly old debate

NETHERLANDS: Research into human IQ - long one of the most controversial areas of science - has produced a new set of suitably awkward results.

Men’s average IQ is four points above women’s because they typically have bigger brains.

Scientists used the latest scanning techniques to measure the brain volumes of 896 people, who were also subjected to a battery of intelligence tests.

‘‘We found that the average IQ of men was about four points above that of women,’’ said Professor Dimitri van der Linden, of Erasmus University in Rotterdam. ‘‘So if men had an average score of 100, women would score 96.’’

The controversial finding is the latest twist in a debate that goes back decades and has powerful political implications.

In the 19th century the view that women’s smaller brains made them less intelligent was used to justify denying rights such as voting and property ownership.

This historical bigotry means that today even conducting such research has become awkward because the discovery of IQ differences between genders, races or other groups is so politically charged.

Van der Linden said his view was that such disagreements were best resolved by high-quality data, so he and his colleagues used detailed MRI scans of people aged between 22 and 37 to measure the volume of their brains, the areas of their cerebral cortex - associated with conscious thoughts and actions - and other factors. They also measured IQ.

They found that men had an average brain volume of 1.2 litres compared with 1 litre for women. The surface area of men’s cerebral cortex was 1850 sq cm against 1630 sq cm for women.

A key finding was that in both men and women, people with bigger brains had slightly higher IQ scores. - Sunday Times