Other Campuses: UC-Irvine study finds General intelligence equal between sexes
January 31, 2005
(U-WIRE) LOS ANGELES – The ability of females and males to use different brain structures in order to attain the same result once again proves the versatility and complexity of the human body.
Recently, there has been much controversy in the public sphere over the innate intellectual differences between the sexes. Though brain structure varies among the sexes, general intelligence has proven not to vary, researchers say.
In fact, comments made about such inherent differences by Lawerence Summers, the president of Harvard University, two weeks ago had media outlets scrambling. But scientists are now showing that such differences may not prove anything. A University of California-Irvine research group has found that while different brain regions related to intelligence were utilized, men and women yielded similar IQ scores.
“This particular research is asking the question, where in the brain is intelligence? And the answer is not that obvious,” said Richard Haier, leader of the research and professor of psychology in the Department of Pediatrics at UC-Irvine.
A November 2004 research paper in NeuroImage – a brain function journal – reported there is no one neuroanatomical structure pertaining to general intelligence. The study found women had more white matter than gray matter – the two general components of the brain – in areas of the brain related to intelligence.
“For example, (in a computer) the white matter is like the wiring. The more wiring, the faster the information can flow between brain areas. The gray matter is more like the processor,” Haier said.
“So imagine a computer with a very fast processor, gray matter, and a very high speed connection, white matter. … The combination of the two is very important,” he added.
The researchers found that men had about 6.5 times the amount of gray matter than women, and that women had about nine times the amount of white matter. In addition, 84 percent of the gray matter related to IQ in women was found in the frontal lobes while only 45 percent of this gray matter in men was found in this region of the brain.
More dramatically, 86 percent and zero percent of white matter was found in the frontal lobes in women and men, respectively. But these differences in the composition of the brain yield similar general intelligence in the sexes.
– Joie Guner
In a separate study of magnetic resonance imaging (MRI) scans, UCLA researchers found that female brains have increased folding compared to male brains.
“We are showing that cortical thickness, gray density and cortical density increase in female brains compared to male brains,” said Eileen Luders, one of the researchers of the study and a graduate research scholar in University of California-Los Angeles Prof. Arthur Toga’s laboratory.
The researchers who work in a laboratory of neuroimaging at the UCLA David Geffen School of Medicine also found increased gray matter density in women in the left hemisphere of the brain associated with language.
“Our results might support the hypothesis that this (greater folding in female brains) compensates for smaller brain size in females,” Luders said.
The researchers said they believe that the increased folding in female brains could explain why both sexes have similar results in general intelligence exams. Recently, the president of Harvard University said at an economics conference that there were innate differences in men and women that could explain why fewer women had math and science careers. He later clarified saying women can succeed in math and science.
But, data on the structural differences of the brain does not support conclusions based on sex pertaining to mathematic or scientific skill.
“The comments indicate that (Summers) is clearly not familiar with the latest neurological studies on males and females,” said Audrey Cramer, director of the Life and Physical Sciences Undergraduate Research Center and the Center for Academic and Research Excellence.
“There is a lot that is not known about the brain and to draw conclusions is premature at this time,” she added.
Many different components can lead to excellence in math and the variance in this capacity does not allow one sex to be deemed superior in intelligence to the other.
“The average man can’t do high-level math nor can the average woman. The difference is among people who can do very high-level math… (They) don’t differ even on the high end,” Haier added.
– Joie Guner