Academic IELTS Reading Practice - 11 - Right and Left Handedness in Humans
You should spend about 20 minutes on Questions 1-12 which are based on Reading Passage 11 below:
A Dr Broca
B Dr Brinkman
C Geschwind and Galaburda
D Charles Moore
E Professor Turner
Right and Left Handedness in Humans
Why do humans, virtually alone among all animal species, display a
distinct left or right-handedness? Not even our closest relatives among
the apes possess such decided lateral asymmetry, as psychologists call
it. Yet about 90 per cent of every human population that has ever lived
appears to have been right-handed. Professor Bryan Turner at Deakin
University has studied the research literature on left-handedness and
found that handedness goes with sidedness. So nine out of ten people are
right-handed and eight are right-footed. He noted that this distinctive
asymmetry in the human population is itself systematic. “Humans think
in categories: black and white, up and down, left and right. It”s a
system of signs that enables us to categorize phenomena that are
essentially ambiguous.’
Research has shown that there is a genetic or inherited element to
handedness. But while left-handedness tends to run in families, neither
left nor right handers will automatically produce off-spring with the
same handedness; in fact about 6 per cent of children with two
right-handed parents will be left-handed. However, among two left-handed
parents, perhaps 40 per cent of the children will also be left-handed.
With one right and one left-handed parent, 15 to 20 per cent of the
offspring will be left handed. Even among identical twins who have
exactly the same genes, one in six pairs will differ in their
handedness.
What then makes people left-handed if it is not simply genetic? Other
factors must be at work and researchers have turned to the brain for
clues. In the 1860s the French surgeon and anthropologist, Dr Paul
Broca, made the remarkable finding that patients who had lost their
powers of speech as a result of a stroke (a blood clot in the brain) had
paralysis of the right half of their body. He noted that since the left
hemisphere of the brain controls the right half of the body, and vice
versa, the brain damage must have been in the brain’s left hemisphere.
Psychologists now believe that among right-handed people, probably 95
per cent have their language centre in the left hemisphere, while 5 per
cent have rightsided language. Left-handers, however, do not show the
reverse pattern but instead a majority also have their language in the
left hemisphere. Some 30 per cent have right hemisphere language.
Dr Brinkman, a brain researcher at the Australian National University
in Canberra, has suggested that evolution of speech went with
right-handed preference. According to Brinkman, as the brain evolved,
one side became specialized for fine control of movement (necessary for
producing speech) and along with this evolution came righthand
preference. According to Brinkman, most left-handers have left
hemisphere dominance but also some capacity in the right hemisphere. She
has observed that if a left-handed person is brain-damaged in the left
hemisphere, the recovery of speech is quite often better and this is
explained by the fact that left-handers have a more bilateral speech
function.
In her studies of macaque monkeys, Brinkman has noticed that primates
(monkeys) seem to learn a hand preference from their mother in the first
year of life but this could be one hand or the other. In humans,
however, the specialization in (unction of the two hemispheres results
in anatomical differences: areas that are involved with the production
of speech are usually larger on the left side than on the right. Since
monkeys have not acquired the art of speech, one would not expect to see
such a variation but Brinkman claims to have discovered a trend in
monkeys towards the asymmetry that is evident in the human brain.
Two American researchers, Geschwind and Galaburda, studied the brains
of human embryos and discovered that the left-right asymmetry exists
before birth. But as the brain develops, a number of things can affect
it. Every brain is initially female in its organization and it only
becomes a male brain when the male foetus begins to secrete hormones.
Geschwind and Galaburda knew that different parts of the brain mature at
different rates; the right hemisphere develops first, then the left.
Moreover, a girl’s brain develops somewhat faster than that of a boy.
So, if something happens to the brain’s development during pregnancy, it
is more likely to be affected in a male and the hemisphere more likely
to be involved is the left. The brain may become less lateralised and
this in turn could result in left-handedness and the development of
certain superior skills that have their origins in the left hemisphere
such as logic, rationality and abstraction. It should be no surprise
then that among mathematicians and architects, left-handers tend to be
more common and there are more left-handed males than females.
The results of this research may be some consolation to left-handers
who have for centuries lived in a world designed to suit right-handed
people. However, what is alarming, according to Mr. Charles Moore, a
writer and journalist, is the way the word “right” reinforces its own
virtue. Subliminally he says, language tells people to think that
anything on the right can be trusted while anything on the left is
dangerous or even sinister. We speak of lefthanded compliments and
according to Moore, “it is no coincidence that lefthanded children,
forced to use their right hand, often develop a stammer as they are
robbed of their freedom of speech”. However, as more research is
undertaken on the causes of left-handedness, attitudes towards
left-handed people are gradually changing for the better. Indeed when
the champion tennis player Ivan Lendl was asked what the single thing
was that he would choose in order to improve his game, he said he would
like to become a lefthander. [ Geoff Maslen ]
Questions 1-7
Use the information in the text to match the people (listed A-E) with the opinions (listed 1-7) below. Write the appropriate letter (A-E) in boxes 1-7 on your answer sheet. Some people match more than one opinion.
Use the information in the text to match the people (listed A-E) with the opinions (listed 1-7) below. Write the appropriate letter (A-E) in boxes 1-7 on your answer sheet. Some people match more than one opinion.
B Dr Brinkman
C Geschwind and Galaburda
D Charles Moore
E Professor Turner
Example
Answer
Monkeys do not show a species specific preference for B
left or right-handedness.
Monkeys do not show a species specific preference for B
left or right-handedness.
- Human beings started to show a preference for right-handedness whent hey first developed language.
- Society is prejudiced against left-handed people.
- Boys are more likely to be left-handed.
- After a stroke, left-handed people recover their speech more quickly than righthanded people.
- People who suffer strokes on the left side of the brain usually lose their power of speech.
- The two sides of the brain develop different functions before birth.
- Asymmetry is a common feature of the human body.
Questions 8-10
Using the information in the passage, complete the table below. Write your answers in boxes 8 10 on your answer sheet.
Using the information in the passage, complete the table below. Write your answers in boxes 8 10 on your answer sheet.
Percentage of children left-handed
One parent left-handed
One parent right-handed ........(8)........
One parent right-handed ........(8)........
Both parents left-handed
.........(9)........
Both parents right-handed
.......(10).......
Questions 11-12
Choose the appropriate letters A-D and write them in boxes 11 and 12 on your answer sheet.
Choose the appropriate letters A-D and write them in boxes 11 and 12 on your answer sheet.
11 A study of monkeys has shown that
A monkeys are not usually right-handed.
B monkeys display a capacity for speech.
C monkey brains are smaller than human brains.
D monkey brains are asymmetric.
A monkeys are not usually right-handed.
B monkeys display a capacity for speech.
C monkey brains are smaller than human brains.
D monkey brains are asymmetric.
12 According to the writer, left-handed people
A will often develop a stammer.
B have undergone hardship for years.
C are untrustworthy.
D are good tennis players.
A will often develop a stammer.
B have undergone hardship for years.
C are untrustworthy.
D are good tennis players.
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