Why Are Some People Left-handed?
Research has shown that 90% of people naturally use their right hands for most tasks. But hundreds of millions of people usetheir left hands. Then why are some people left-handed? Scientists have been trying to answer that question for many years.A study done in 1992 found that men are more likely to be left-handed than women. It also found that Asian or Hispanicpeople are less likely to be left-handed than white people, black people or North American Indians. Some cultures acceptpeople who do things mostly with their left hands. Others do not.
Scientists want to know the reason for left-handedness because it is closely linked to mental problems and languagedifficulties. One idea about the cause of left-handedness is the genetic theory. It says that people are right- or left-handedbecause of genes passed to them by their parents. For example, it has been shown that the handedness of adopted childrenis more likely to follow that of their birth parents than their adopted parents. Other evidence of genetic involvement can befound in some families. One famous example is the left-handed members of the present British royal family. These includeQueen Elizabeth II, Prince Charles and Prince William.
Another idea is that right-handed people are born with the gene for it. But about 20% of people do not have the right-handedgene. These people could be either left- or right-handed. This idea may explain why two babies who have the same genesuse different hands. In 18% of identical twins one twin is right-handed, and the other is left-handed. Probably both twins lackthe right-handed gene so each has a chance to be either right- or left-handed.
Some scientists believe that the cause of handedness could include both genetics and development. Questions:
1. What is the passage mainly about?
2. Which of the following topics is discussed in more detail in the passage?
3. What did the speaker want to convey by an example of the present British royal family?4. What conclusion can you draw from the passage?
Does Being Left-handed Affect One's Life?
There are approximately 30 million left-handed people in the United States, and several hundred million more around theworld. Most right-handed people have never even considered the possibility that there might be any serious issues affectingleft-handers. Even among all of these left-handed people, there are many different opinions about what these issues are andwhich issues might be most important to them.
Some left-handers think that being left-handed is a positive factor in their lives, and they feel that there are no serious issuesaffecting them. Others think that being left-handed is not a significant factor and has not affected their lives one way or
another. There are also some left-handers who have no opinion and have never given any thought to what being left-handedhas meant to them. But th
e majority of left-handed people find that being left-handed is at least a small disadvantage and a minor source of frustrationin their lives.
There are many things that right-handed people take for granted that are quite difficult for left-handers. These include manybasic skills like learning to write, learning to use scissors and other hand tools and utensils, and learning various crafts andother activities. Sometimes left-handers are puzzled by equipment designed for right-handers, and other times they are
confused by instructors and instructions geared toward teaching right-handers. For some left-handed people this amounts tooccasional difficulties and minor inconveniences. For other left-handers it is a lifetime full of failures and frustrations that maylead to much more serious problems.
Questions:
1. What is the speaker's attitude toward left-handers?
2. What can be inferred from the passage about right-handers?
3. How do the majority of left-handers feel about their left-handedness?
Left-handedness and Right-handedness in Babies
Approximately 90% of people in the world are naturally right-handed. Why is this so, and are we born one way or the other?The answer to this question is rather complicated.
In babies and young children, no single side becomes dominant until around the age of eight. At 12 weeks, babies usuallyuse both hands equally, but by 16 weeks, they mostly use the left hand for touching. By 24 weeks, they have changed againand start using both hands. Then at 28 weeks, they become one-handed again, although this time it is the right hand that isused more. At 32 weeks, they start using both hands again. When they reach the age of 36 weeks, there is another change,with most babies now preferring to use the left hand. Between 40 and 44 weeks, the right hand is once again more used. At48 weeks, babies switch to using their left hands again, and then between 52 and 56 weeks, the right hand takes over. There are further changes still. At 80 weeks, the right hand loses control, and both are used again equally. When the youngchild reaches the age of two, the right hand takes over again, but between two and a half and three years, both hands areused equally. Things finally become stable at around four years and stay the same until, by the age of eight, one hand isstrongly dominant over the other.
Statements:
1. At 12 weeks, both hands become dominant. 2. By 24 weeks, right hand becomes dominant. 3. By 36 weeks, left hand becomes dominant.
4. Between 40 and 44 weeks, both hands become dominant. 5. At 48 weeks, left hand becomes dominant.
6. Between 52 and 56 weeks, both hands become dominant. 7. At 80 weeks, both hands become dominant. 8. At the age of two, right hand becomes dominant.
9. Between two and a half and three years, both hands become dominant. 10. By the age of eight, one hand is strongly dominant over the other.
Brain Organization and Handedness
Scientific studies during the 1970s and early 1980s suggested that differences in left- and right-handers' patterns of brainorganization may be associated with differences in skills, abilities, and perhaps even personalities. In the large majority ofright-handers, about 98 or 99 percent, speech is controlled by the left side of the brain.
The right side of the brain, however, is usually used for recognizing and remembering faces and understanding relationshipsin space. In left-handers, it is difficult to know exactly their patterns of brain organization. About 65 to 70 percent of left-handers have speech controlled by the left side of the brain, which is also true of right-handers. But in 30 to 35 percent of left-handers speech is controlled by the right side of the brain. In some left-handers, both sides of the brain are capable ofcontrolling speech.
Left Face
Are you considering whether to take piano lessons in order to pursue a career in the music world? Don't look at your fingers.Look at your face and determine whether you're left-faced or right-faced. Most talented musicians are left-faced. They includesingers, composers, conductors, and even country music artists. Beethoven, Tchaikovsky, Liszt, and many others were left-faced.
Just as most of us are either left-handed or right-handed, everybody has a more dominant and flexible side of the face. This isdetermined before birth. It has a link to the dominant side of the brain. Left-faced people are more able in the right side of thebrain. One of the specializations of the right half of the brain is the understanding of music. The left half, on the other hand,specializes in language and numbers, among other things.
Right-faced people may not make beautiful music, but they may become mathematicians, scientists, and good speakers.Most American presidents were right-faced.
To determine whether you are one of the ten percent of people who are left-faced, look in the mirror and see which side ofyour face is larger, more flexible, and has deeper dimples and a higher eyebrow. If you are a right-faced person, you may notbe interested to study music. But if your child is left-faced and shows a great interest in music at an early age, you had bettersend him or her to a music school as soon as possible.
Questions:
1. According to the passage, what might be considered a suitable profession for a right-faced woman? 2. What does the passage say about the human brain? 3. Which of the following is not true?
4. What would be a reasonable suggestion to a right-faced person who wants to study music?
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