2017年5月6日雅思阅读真题+题目+答案：Being Left-handed in a Right-handed World

2017年5月6日雅思阅读真题+题目+答案：Being Left-handed in a Right-handed World

The world is designed for right-handed people. Why does a tenth of the population prefer the left?

A The probability that two right-handed people would have a left-handed child is only about 9.5 percent. The chance rises to 19.5 percent if one parent is a lefty and 26 percent if both parents are left-handed. The preference, however, could also stem from an infant’s imitation of his parents. To test genetic influence, starting in the 1970s British biologist Marian Annett of the University of Leicester hypothesized that no single gene determines handedness. Rather, during fetal development, a certain molecular factor helps to strengthen the brain’s left hemisphere, which increases the probability that the right hand will be dominant, because the left side of the brain controls the right side of the body, and vice versa. Among the minority of people who lack this factor, handedness develops entirely by chance. Research conducted on twins complicates the theory, however. One in fivesets of identical twins involves one right-handed and one left-handed person, despite the fact that their genetic material is the same. Genes, therefore, are not solely responsible for handedness.

B Genetic theory is also undermined by results from Peter Hepper and his team at Queen’s University in Belfast, Ireland. In 2004 the psychologists used ultrasound to show that by the 15th week of pregnancy, fetuses already have a preference as to which thumb they suck. In most cases, the preference continued after birth. At 15 weeks, though, the brain does not yet have control over the body’s limbs. Hepper speculates that fetuses tend to prefer whichever side of the body is developing quicker and that their movements, in turn, influence the brain’s development. Whether this early preference is temporary or holds up throughout development and infancy is unknown. Genetic predetermination is also contradicted by the widespread observation that children do not settle on either their right or left hand until they are two or three years old.

C But even if these correlations were true, they did not explain what actually causes left-handedness. Furthermore, specialization on either side of the body is common among animals. Cats will favor one paw over another when fishing toys out from under the couch. Horses stomp more frequently with one hoof than the other. Certain crabs motion predominantly with the left or right claw. In evolutionary terms, focusing power and dexterity in one limb is more efficient than having to train two, four or even eight limbs equally. Yet for most animals, the preference for one side or the other is seemingly random. The overwhelming dominance of the right hand is associated only with humans. That fact directs attention toward the brain’s two hemispheres and perhaps toward language.

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Questions 1-5

Reading Passage has seven sections A-G.

Which section contains the following information?

Write the correct letter A-G in boxes 1-5 on your answer sheet.

1  Preference of using one side of the body in animal species.

2  How likely one-handedness is born.

3  The age when the preference of using one hand is settled.

4  Occupations usually found in left-handed population.

5  A reference to an early discovery of each hemisphere’s function.

Questions 6-9

Look at the following researchers (Questions 6-9) and the list of findings below.

Match each researcher with the correct finding.

Write the correct letter A-G in boxes 6-9 on your answer sheet.

List of Findings

A Early language evolution is correlated to body movement and thus affecting the preference of use of one hand.

B No single biological component determines the handedness of a child.

C Each hemisphere of the brain is in charge of different body functions.

D Language process is mainly centered in the left-hemisphere of the brain.

E Speech difficulties are often caused by brain damage.

F The rate of development of one side of the body has influence on hemisphere preference in fetus.

G Brain function already matures by the end of the fetal stage.

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