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 UC 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 0 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.
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 UCLA Professor 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.