When Can You Tell if a Baby Is Left or Right Handed
Correct and left-handedness in humans
Why exercise humans, virtually solitary among all fauna species, display a distinct left or right-handedness? Not even our closest relatives amidst the apes possess such decided lateral asymmetry, equally psychologists telephone call it. Notwithstanding about 90 per cent of every human population that has ever lived appears to accept been right-handed. Professor Bryan Turner at Deakin University has studied the inquiry literature on left-handedness and found that handedness goes with sidedness. So ix out of 10 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: blackness and white, up and down, left and right. It"s a system of signs that enables us to categorise phenomena that are essentially ambiguous.'
Inquiry has shown that in that location is a genetic or inherited element to handedness. But while left-handedness tends to run in families, neither left nor correct handers will automatically produce off-spring with the same handedness; in fact about six pct of children with two right-handed parents volition be left-handed. However, among two left-handed parents, mayhap 40 percentage of the children will also exist left-handed. With one right and one left-handed parent, 15 to 20 per cent of the offspring volition be left-handed. Even among identical twins who have exactly the aforementioned genes, one in half dozen 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 jell in the encephalon) had paralysis of the right half of their trunk. He noted that since the left hemisphere of the brain controls the right half of the body, and vice versa, the brain damage must accept been in the brain's left hemisphere. Psychologists now believe that amidst right-handed people, probably 95 per cent have their language centre in the left hemisphere, while v per cent accept right sided language. Left-handers, however, practice not show the contrary pattern but instead a majority also take 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, equally the brain evolved, one side became specialised for fine control of movement (necessary for producing speech) and along with this evolution came correct- hand preference. According to Brinkman, most left-handers have left hemisphere dominance but also some chapters in the right hemisphere. She has observed that if a left-handed person is brain-damaged in the left hemisphere, the recovery of voice communication is quite often ameliorate and this is explained past 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 female parent in the outset twelvemonth of life merely this could be one hand or the other. In humans, however, the specialisation in function of the two hemispheres results in anatomical differences: areas that are involved with the production of speech are ordinarily larger on the left side than on the correct. Since monkeys have non acquired the art of speech, one would not expect to meet such a variation but Brinkman claims to have discovered a trend in monkeys towards the asymmetry that is axiomatic in the homo brain.
Two American researchers, Geschwind and Galaburda, studied the brains of human embryos and discovered that the left-correct asymmetry exists before nascency. But as the brain develops, a number of things tin can impact it. Every encephalon is initially female in its system and information technology 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 dissimilar rates; the correct hemisphere develops starting time, and so the left. Moreover, a girl'south brain develops somewhat faster than that of a male child. Then, if something happens to the brain's evolution during pregnancy, it is more likely to exist affected in a male and the hemisphere more than likely to be involved is the left. The brain may become less lateralised and this in plow could outcome in left-handedness and the development of sure superior skills that take their origins in the left hemisphere such as logic, rationality and abstraction. It should be no surprise and so that amidst mathematicians and architects, left-handers tend to be more common and there are more than left-handed males than females.
The results of this inquiry may be some consolation to left-handers who have for centuries lived in a globe designed to adjust right-handed people. However, what is alarming, according to Mr. Charles Moore, a author and journalist, is the way the word "correct" reinforces its own virtue. Subliminally he says, language tells people to call up that anything on the right tin 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 paw, frequently develop a stammer as they are robbed of their liberty of speech". However, as more inquiry is undertaken on the causes of left-handedness, attitudes towards left-handed people are gradually changing for the better. Indeed when the champion tennis role player Ivan Lendl was asked what the unmarried thing was that he would choose in order to improve his game, he said he would like to become a lefthander.
Geoff Maslen
Questions one-seven
Utilize the information in the text to match the people (listed A-East) with the opinions (listed 1-vii) beneath.
Write the appropriate letter (A-E) in boxes ane-7 on your answer canvas.
Some people match more than than one opinion.
A Dr Broca
B Dr Brinkman
C Geschwind and Galaburda
D Charles Moore
Eastward Professor Turner
| Example | Answer |
| Monkeys practice not show a species specific preference for left or right-handedness. | B |
1 Man beings started to show a preference for right-handedness when they first developed language.
Reply: B Locate
2 Society is prejudiced against left-handed people.
Answer: D Locate
3 Boys are more than likely to exist left-handed.
Answer: C Locate
iv Later a stroke, left-handed people recover their spoken language more quickly than righthanded people.
Reply: B Locate
5 People who suffer strokes on the left side of the brain ordinarily lose their power of speech.
Answer: A Locate
6 The two sides of the encephalon develop different functions before birth.
Reply: C Locate
7 Asymmetry is a common feature of the human body.
Answer: E Locate
Questions 8-10
Using the data in the passage, consummate the table below.
Write your answers in boxes eight-10 on your answer sheet.
| Percentage of children left-handed | |
| I parent left-handed One parent right-handed | 8 |
| Both parents left-handed | 9 |
| Both parents right-handed | ten |
Questions 11-12
Choose the appropriate letters A-D and write them in boxes xi-12 on your answer canvas.
xi.A study of monkeys has shown that
A monkeys are not usually correct-handed.
B monkeys display a capacity for speech.
C monkey brains are smaller than human brains.
D monkey brains are asymmetric.
11. Answer: D Locate
12. Co-ordinate to the writer, left-handed people
A will often develop a stammer.
B have undergone hardship for years.
C are untrustworthy.
D are expert lawn tennis players.
12. Respond: B Locate
Source: https://mini-ielts.com/50/view-solution/reading/right-and-left-handedness-in-humans
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