New research from Erasmus University indicates that men may have larger brains than women.
The university, which operates in the Netherlands, published the results of the study in the journal Intelligence. Researchers looked at nearly 900 magnetic resonance imaging (MRI) scans of men and women in order to assess brain size; they also asked participants to complete IQ tests and memory tests.
The study’s results will be controversial, because researchers found that men outperform women on general IQ tests by 3.75 points, on average. The men also had brains that were on average 14 percent physically larger than the women’s.
“We found that men’s brains are larger than women’s, and our analysis suggests this is the reason for lower average general intelligence across a range of tests,” said lead author Dr. Dimitri van der Linden.
“We are aware of previous research suggesting women’s brains are better organised or process information more efficiently, but we did not look at this in our study.”
However, researchers noted that while men outperformed their female counterparts in most measures of intelligence, women did significantly better in memory tests.
Does this mean that men are smarter than women?
Well, no; it’s important to note that IQ tests are controversial to begin with, and many scientists believe that IQ is a poor measure of general intelligence. Social roles may also affect the development of intelligence.
For instance, women are underrepresented in STEM fields (science, technology, engineering, and mathematics) in certain countries, including the United States.
In other words, the Erasmus University study does not prove that sex fundamentally affects intelligence, and several scientists dispute the notion that a physically larger brain is necessarily more capable than a smaller brain.
“This is a well-researched study,” said Dr. Joseph Devlin, head of experimental psychology at University College London, in an interview with MetroUK, “but the evidence is not strong enough to prove that larger male brains are more intelligent than smaller female brains, which makes it a leap of faith, using a measure of general intelligence which has little basis.”
A different study, performed at the University of Edinburgh and led by psychologist Stuart Ritchie, showed that women have significantly thicker cortices than men. Thicker cortices are associated with higher general intelligence and cognitive intelligence. But cortical thickness also varied much more among men than among women.
That study would seem to dispute the findings of the Erasmus University research.
Ultimately, scientists have difficulty using anatomical differences between brains to show intelligence, simply because intelligence is so complex. Proving a genetic component—for instance, that gender determines brain capabilities—is even more difficult.
“Men and women’s brains are different,” said Dr. Devlin, “and we know spatial navigation is slightly better in men than women, while women tend to have a better vocabulary. But we should be skeptical of claims that men are smarter than women, especially when there is little to no evidence for that and lots of evidence to the contrary.”
Brain size might not be the magical indicator that researchers hoped for; nevertheless, it is a fascinating look into the biological differences that separate the sexes.