早稲田国際教養 2008年 大問1 He thinks, she thinks.

Recent research may provide some clues to a long-standing paradox. Men's brains are bigger than women's ― about 100 grams heavier on average ― even when their larger proportional size is factored into the equation. Brain volume is correlated with intelligence, according to a 2005 study, yet both sexes score about the same on IQ tests.


Even though women's brains are smaller, they have some 1) distinct advantages that may level *1 the playing field. Women have more gray matter ― areas of nerve cell bodies. Studies consistently show that women surpass men on verbal and memory tasks, and the superior temporal cortex, one of the brain areas responsible for language, is 29 percent larger in females. Blood flow is about 15 percent higher in the female brain, which offsets the cognitive losses of aging, and women's nerve cells are also more tightly packed together, which suggests that they may function more efficiently.


An analysis of human brain tissue, for example, conducted by Sandra Witelson and her colleagues at the Michael G. DeGroote School of Medicine at McMaster University, revealed that women's nerve cells were 11 percent denser than men's in a region of the temporal cortex that is involved with language processing, comprehension, and memory. "Little girls develop language skills earlier than boys, and they're ( a ) discriminate between speech sounds," says Witelson.


This may be part of the reason why women do better in school― ( b ) because they're conditioned to please people or to sit in a chair quietly. According to behavioral studies, even in kindergarten and first grade, girls are more articulate than boys, their handwriting is neater, and they're quicker at answering questions, says Louann Brizendine, a researcher at the University of California at San Francisco and author of The Female Brain. ( c ), this pattern appears to become more obvious: Females now outnumber males in college, and more women go on to graduate.


The male brain, by contrast, is filled with more white matter, which consists of longer nerve fibers that communicate with more distant regions of the brain. White matter also contains fibers from nerves that block the transmission of information in the cortex, which enhances local processing. The white matter may be what gives men their ability to focus intently on work and tune out distractions, ( d ) their clear-cut superiority when it comes to reasoning about physical objects and locations, says Ruben Gur, a psychologist and director of the Brain Behavior Laboratory at the University of Pennsylvania in Philadelphia. ( e ), then, that men still dominate fields like architecture, organic chemistry, physics, and brain surgery. There are only a handful of female chess grandmasters, and girls are less likely than boys to sit for hours playing video games.


Men are faster at mentally rotating an object ― imagining what something looks like from a different perspective ― and have an internal compass that enables them to look up at the sun to figure out directions. Women, on the other hand, rely on landmarks ― turn right at the church, turn left after the fire station ― to find their way around.


Because it takes hundreds of thousands of years for the genetic evolution of natural selection to occur *2, these sex differences in navigation strategies probably have their roots in the Stone Age. Women most likely watched the kids and worked close to home, using familiar sights to find their way back. Men, meanwhile, were hunters and ventured into unknown territory in search of food. ( f ), they figured out where they were by estimating the distance they had already traveled and their orientation in space.


Over the millennia, men and women apparently evolved different mental pathways to get around, and men mastered the use of geometric cues to navigate unfamiliar territory. In a 2000 German study, for example, men sped through a three-dimensional virtual-reality maze much faster than women, averaging two minutes and 22 seconds compared with three minutes and 16 seconds for women.


Brain imaging techniques revealed that men found their way out of the maze using the left hippocampus, a memory storage region that also governs mapping of the physical environment. Women used their right parietal and prefrontal regions, which are linked to visual identification and reasoning. The women's use of the prefrontal region, say researchers, suggests that they relied on landmarks and pictured the objects in their minds, while the men used both landmarks and geometric cues, like shapes and angles, to escape the maze.


These skills may have enabled men to navigate distant lands across unmarked desert sands and vast unexplored oceans. In one famous 1916 incident, New Zealand native Frank Worsley, a member of the Antarctic expedition led by explorer Ernest Shackleton, relied almost solely on his internal compass to save the lives of 28 men lost on an island in the Antarctic.


Worsley set off from the remote island in a 22-foot lifeboat across the South Atlantic Ocean, eventually traveling 800 miles to one of the South Sandwich Islands near the tip of South America, where there was a whaling station where they could get help. Worsley had only been able to take sightings of the sun four times during the stormy 17-day trip, and the rest had been based on his internal compass.


The way males and females handle their anger or emotionally upsetting situations ― women may feel sick to their stomach, while men tend to act out ― may also stem from fundamental differences in how their brains have evolved.


A 2002 study using MRI scans showed that brain areas keeping aggressive behavior under control were relatively larger in women than in men. Female brains had a significantly greater volume than males of orbital frontal cortex *3, the seat of cool-headed decision making behind the forehead, in proportion to the amygdala, a more primitive, almond-shaped structure deep inside the brain that excites us by stimulating the survival instinct and getting the adrenaline flowing.


The implication here is that in an emotionally intense situation, women are more able to control their tempers. ( g ) they have a bigger braking mechanism than males, women will try to defuse a volatile situation rather than explode.


We need look ( h ) the latest in (2) celebrity bad behavior for an example. When Paris Hilton was arrested on suspicion of drunk driving in the early morning hours last September, she was "cooperative," according to police sources. But alcohol suppresses the frontal cortex, ( i ) one's ability to control anger or aggression. Like when Mel Gibson was stopped by police for the same reason, and he completely lost his temper.


When Larry Cahill and his colleagues at University of California at Irvine conducted a series of experiments to track sex differences in the brain's ability to store memories, they came to similar conclusions. Researchers found that the amygdala, which also processes emotional memories, acts differently in men and women. In one study, volunteers were shown a series of extremely violent films while their brain activity was measured using a PET scan.


To process the most disturbing material, men fired up the amygdala's right hemisphere, which is more in tune with the outside world and communicates with regions that control sight and motor coordination. Women, on the other hand, activated the left hemisphere, which concentrates more on the body's inner environment and is connected to the insular cortex, where information gained from the senses is translated into emotional experiences, and to the hypothalamus, the master regulator of certain basic functions.


"When men are presented with a strong emotional stimulus, part of the motor system is activated, ( j ) may be why men try to resolve the situation by taking action," says Witelson. "But in women, the hypothalamus is activated, which controls digestion, so it may not be surprising that when a woman is really upset, she feels sick and can't sleep."


We also know that the brain's right hemisphere extracts the essence of a situation, the central idea, while the left side considers the finer points and tracks the details. Consequently, this right-left amygdala division may also illuminate why women remember every painful detail of an argument they had on their honeymoon ― where they were, what they were wearing, the time of day ― while their husbands barely recall the fight.


[Adapted from Linda Marsa, "He thinks, she thinks," Discover Magazine, July 2007]


(1) Choose the best word or phrase to put in each space (a) ~ (j). No answer can be used more than once.
A as well as B because C better able to D even though E in all likelihood F it's not merely G little wonder
H no farther than I over time J reducing K which


(2) Choose the best way to complete each of these sentences, which relate to the underlined words in the passage.
1 The fact that women have some (1) distinct advantages that may level the playing field suggests that
A) a deeper understanding of how men's and women's brains function has led to greater equality between them.
B) evolutionary changes in the brains of men and women have decreased over the years.
C) inequality between men and women can be explained by differences in the way their brains function.
D) overall, men are more intelligent than women but other advantages women have over men equalize their relations with one another.
E) the smaller size of a woman's brain does not mean she is intellectually inferior to men.


2 The writer uses the example of, (2)celebrity bad behavior to
A) emphasize that differences in brain function do not apply to people in all professions.
B) explain that a bigger braking mechanism in women does not result in more rational behavior.
C) illustrate that when drunk, differences in brain function between men and women lessen.
D) reinforce the argument that women are better than men at handling difficult situations.
E) suggest that women are more likely than men to get away with improper behavior.


(3) Which of the following agree with statements in the text? Mark your answers true or false.
a. Although a woman's brain is smaller compared to a man's, in many ways her brain is more efficient than a man's.
b. Because the results of IQ tests are similar, biological differences in their brains cannot explain behavioral differences between men and women.
c. Differences in the way the amygdala functions in men and women help explain why men learn languages more easily than women.
d. Increased amounts of white matter in men's brains explain their strong desire to get along with others.
e . Sex differences in navigational ability seem to be the result of thousands of years of experiencing different sex roles in society.
f . The fact that men can better remember the details of an argument with their wives, suggests that their right hemispheres are more developed than in women.
g. Women are more likely to feel physical discomfort than men when presented with a disturbing situation.


*2:for S to do「Sが~する(こと)」

*3:greater volume of orbital frontal cortex