SCIENCE IN THE NEWS #2078 - DigestBy StaffThis is Bob Doughty.And this is Steve Ember with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in Science. Today, we tell why some people are left-handed. We tell about a link between a sleep problem and high blood pressure. And we tell about rising temperatures in the United States.
Why are some people are left-handed? Scientists have been trying to answer that question for many years. Research has shown that ninety percent of people naturally use their right hands for most tasks. But hundreds of millions of people use their left hands. A study done in Nineteen-Ninety-Two found that men are more likely to be left-handed than women. It also found that Asian or Hispanic people are less likely to be left-handed than white people, black people or North American Indians.
Some cultures accept people who do things mostly with their left hands. Others do not. For example, in some countries eating with the left hand is considered an insult to others. In the past, some parents and teachers forced left-handed children to use their right hands instead.Scientists want to know the reason for left-handedness because it is closely linked to mental problems like schizophrenia and language difficulties. One idea about the cause of left-handedness is the genetic theory. It says that people are right or left-handed because of genes passed to them by their parents.
For example, it has been shown that the handedness of adopted children is more likely to follow that of their birth parents than their adopted parents.
Other evidence of genetic involvement can be found in some families. One famous example is the left-handed members of the present British Royal Family. These include the Queen Mother, her daughter Queen Elizabeth the Second, the Queen's son Prince Charles and his son Prince William.Amar Klar at the National Cancer Institute in Washington D. C. believes right-handed people are born with a gene for it. But, he says, about twenty percent of people do not have the right-handed gene. These people could be either left or right-handed.
Doctor Klar wants to find this gene. He plans to test the genes of members of one-hundred families in which at least one parent is right-handed and two of the children are left-handed. He will look for markers in the DNA to see how often the children have the same markers as the parents.Stanley Coren of the University of British Columbia in Canada thinks the reason for left-handedness is linked to fetal development. This idea says left-handedness results from damage to a fetus during or before birth. One cause of such damage could be an unusual position of the fetus in the mother's uterus. Another cause could be unusual levels of chemicals in the uterus. Doctor Coren says this damage could explain why a larger percentage of left-handed people have mental and health problems.Both these ideas have been offered to explain a situation that has been a mystery to scientists for a long time: how can two babies who developed from the same egg and have the same genes use different hands? In eighteen percent of identical twins, one twin is right-handed and the other is left-handed.
One possible answer is that both twins lack the right-handed gene, so each has a chance to be either right or left-handed. Another possible answer is that the difference is the result of damage caused by both babies being in a crowded uterus.
Still other scientists say handedness could have more than one cause which could include both genetics and development.Experts also link left-handedness to artistic and athletic ability as well as extremely high intelligence. They say a great number of left-handed people were famous political leaders, artists, scientists or athletes.
These include the political leaders Alexander the Great and Napoleon Bonaparte. The musicians Sergei Rachmaninoff and Ludwig Van Beethoven. The artists Michelangelo, Leonardo da Vinci and Pablo Picasso. The scientist Albert Einstein. And the baseball player Babe Ruth.
Other experts say every American president in the last twenty-five years has been at least partly left-handed, except for Jimmy Carter. They are Gerald Ford, Ronald Reagan, George Bush and Bill Clinton.
However, some left-handed people were famous criminals. They include Billy the Kid, Jack the Ripper and the Boston Strangler.Much interesting information about left-handedness can be found on the Internet computer network. The address is www. lefthandpublishing. com.
((MUSIC BRIDGE))You are listening to the Special English program SCIENCE IN THE NEWS on VOA. This is Steve Ember with Bob Doughty in Washington.
American scientists say they have found the strongest evidence yet linking a breathing problem called sleep apnea to high blood pressure. They published the study in the Journal of the American Medical Association.
People with sleep apnea briefly stop breathing while they sleep. Sleep apnea can cause a tired feeling and head pain. Researchers at the Johns Hopkins University School of Public Health organized the new study. It involved more than six-thousand adults.The researchers found that people who stopped breathing the most during sleep were more likely to have high blood pressure. Even people with moderate levels of sleep apnea had a higher risk of high blood pressure. High blood pressure increases the risk of heart attack, stroke and kidney disease. Sleep apnea is more common among people who weigh too much. However, the study found a link between sleep apnea and high blood pressure in people of all weight groups.
Experts say people with high blood pressure who become sleepy during the day should be tested for sleep problems. It is not clear yet if sleep apnea causes high blood pressure. The researchers at Johns Hopkins plan to study that next.
((MUSIC BRIDGE))Weather experts say this spring was the warmest in the United States in the past century. They say the average temperature across the United States between March and May was about thirteen degrees Celsius. That reportedly is two-tenths of a degree higher than the old record.
Officials with the National Climatic Data Center announced the findings. The center is part of the National Oceanic and Atmospheric Administration.The new report says more than sixty-four percent of the United States was much warmer than normal during the three-month period ending in May. It says less than one percent of the country was much cooler than normal. The weather experts add that thirteen of the past sixteen spring seasons in the United States have been warmer than normal.
The report says average weather conditions across the United States mainland were drier than normal during the three-month period. This was only the third spring since Nineteen-Eighty-Nine that the country received less rainfall than normal.The National Climatic Data Center also reported above average temperatures in many other areas during this period.
Some of the warmest conditions were observed from Kazakhstan south across Afghanistan, Pakistan and Iran. The report says these areas have received little if any rainfall during the past three months. Higher than normal temperatures were noted in much of central and eastern Europe and northern Africa.
However, cooler than normal conditions were observed across large areas of Australia, South Africa and South America. Parts of South Africa and Australia also had a lot of rain and flooding during this period.
This Science in the News program was written by Nancy Steinbach and George Grow. It was produced by George Grow. This is Bob Doughty.And this is Steve Ember. Join us again next week for more news about science in Special English on the Voice of America.