阅读理解
Most people around the world are right-handed. This also seems to be
true in history. In 1799, scientists studied works of art made at different times
from 1,500 B.C. to the 1950s. Most of the people shown in these works are right-handed,
so the scientists guessed that right-handedness has always been common through history.
Today, only about 10% to 15% of the world's population is left-handed.
Why are there more right-handed people than left-handed ones? Scientists
now know that a person's two hands each have their own jobs. For most people, the
left hand is used to find things or hold things. The right hand is used to work
with things. This is because of the different work of the two sides of the brain.
The right side of the brain, which makes a person's hands and eyes work together,
controls the left hand. The left side of the brain, which controls the right hand,
is the centre for thinking and doing problems. These findings show that more artists
should be left-handed, and studies have found that left-handedness is twice as common
among artists as among people in other jobs.
No one really knows what makes a person become right-handed instead
of left-handed. Scientists have found that almost 40% of the people become left-handed
because their main brain is damaged when they are born. However, this doesn't happen
to everyone, so scientists guess there must be another reason why people become
left-handed. One idea is that people usually get right-handed from their parents.
If a person does not receive the gene (基因) for right-handedness,
he / she may become either right-handed or left-handed according to the chance and
the people they work or live with.
Though right-handedness is more common than left-handedness, people
no longer think left-handed people are strange or unusual. A long time ago, left-handed
children were made to use their right hands like other children, but today they
don't have to.
