Right_and_left-handedness_in_humans-Vocabulary_Exercise

Right and left-handedness in humans

display a distinct left or righthandedness? Not even

relatives among the apes possess such decided lateralasymmetry, as psychologists call it. Yet about 90 per cent of every human

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 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 categorise phenomena that are essentially ambiguous.'

2.Research has shown that there is 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.

3.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 right-sided 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.

4.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 specialised for fine control of movement (necessary for producing speech) and along with this evolution came right-hand 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 specialisation in function 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.

5.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 organisation 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.

6.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 left-handed compliments and according to Moore, `it is no coincidence that left-handed 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 to improve his game, he said he would like to become a left-hander.

Vocabulary and Phrases:

I.Word Detective: Use the following clues to find the

words from the article that correspond to the descriptions

(definitions). Paragraph numbers are given to you.

adj.easy to perceive; especially clearly outlined (Para. 1)

adj.situated at or extending to the side(Para. 1)

v.place into or assign to a category (Para. 1)

adj.occurring among members of a family (Para. 2)

n.the immediate descendants of a person(Para. 2)

n.evidence that helps to solve a problem(Para. 3)

n. something a little different from others of the same type (Para.

4)

n. superior development of one side of the body (Para. 4)

adj.characterized by elegance or refinement or accomplishment (Para. 4)

adv.at the beginning (Para. 5)

adj.stemming from evil characteristics or forces; wicked or dishonorable (Para. 6)

II.Coping with technical terms (words in the category of brain science): Use the dictionary to learn these words

below.

lateral, lateralize

asymmetry, systematic,

handedness

sidedness

power of speech

stroke

paralysis

hemisphere

anatomical

embryo

secrete(v. )

hormone

stammer

III．List of words/phrases with little or without context clues: evolution, evolve

ambiguous

identical twins

reverse pattern

vice versa

compliment

IV．This article discusses the factors that contribute to the handedness in human beings. What cause/effect signal words are used in Para.1, 2, 3, 4, 5?

1 X found that handedness goes with sidedness.

2 Research has shown that there is genetic or inherited element tohandedness.

3 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.

4 Y has suggested that evolution of speech went with right-handed preference.

5 The recovery of speech is quite often better and this is explained by the fact that left-handers have a more bilateral speech function

5 (T)hespecialisation in function of the two hemispheres results in anatomical differences.

6 The brain may become less lateralised and this in turn could result in left-handedness.

V. Other sentence structures and phrases that are noteworthy:

1.Attitudes towards left-handed people are gradually changing

for the better.

2.But while left-handedness tends to run in families, neither

left nor right handers will automatically produce off-spring with the same handedness.

VI. More Exercises:

1.McKinnon estimated the sided/ lateral movement

of the bridge to be between four and six inches.

2.Healthreformfocused on

information asymmetry/symmetry betweendoctors

and patients.

3.Thisproblemcries out for a long-term , open-minded,

systematic/unsystematic search.

4.The books are marked/categorized into beginner

and advanced.

5.His reply to my question was somewhat

clear/ambiguous.

6.Husbands and wives of British nationals do not

automatically/mechanically gain citizenship.

7.She wore the different/identical dress on both

occasions.

8.A hint/ clue in a crossword or game is information

which is given to help you to find the answer to a

question.

9.I understood in general what she was talking about,

but some of the fine/ nice details were beyond me.

Multiple choice:

1.The firm soon achieved complete ________in the

marketplace.

(A) advantage

(B) dominance

(C)control

(D)influence

2.________ reports say that seven people have died,

though this has not yet been confirmed.

(A)Initial

(B)First

(C)Introductory

(D)Beginning

3.Our stomach ________ digestive juices when the

time for meals comes.

(A)discharge

(B)secrete

(C)eliminate

(D)produce

4.When her mother died, she found ________in her

religious beliefs.

(A)relief

(B)consolation

(C)consolidation

(D)grief

5.I have read many books, perhaps they influenced me

________.

(A) subliminally

(B) purposely

(C)intentionally

(D)consciously

6.There is something ________at the back of that

series of crimes.

(A) dangerous

(B) bad

(C)sinister

(D)disturbing