People who have larger brains have better intellect, according to McMaster University's researchers. Neuroscientist Sandra Witelson led the study which also said that there were differences between women and men. The study which was published in the journal Brain also said, said that in women, verbal intelligence was clearly co-related with brain size, accounting for 36% of the verbal IQ score.
However, in men, this was true for right-handers only, indicating that brain asymmetry was a factor in men. The study involved testing of intelligence in 100 neurologically normal, terminally ill volunteers, who agreed that their brains be measured after death.
The findings revealed that spatial intelligence was also correlated with brain size in women, but less strongly. It said that in men, spatial ability was not related to overall brain size. These results, they said, suggested that women may use verbal strategies in spatial thinking, but in men, verbal and spatial thinking were more distinct.
Studies further revealed that brain size decreased with age in men over the age span of 25 to 80 years, but age hardly affected brain size in women. It was not known what protective factors, which could be genetic, hormonal or environmental, operated in women, they said.
They however said, it was still to be determined what nature's contribution was to this cerebral size relationship with intelligence.
"We're going to need to be careful if, in the future, we use MRI brain scans as a measure of ability in any selection process," said Prof. Witelson.