英语听力—环球英语 1366 Why Do I Yawn?

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　　Welcome to Spotlight 1. I’m Nick Page.
 
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　　And I’m Liz Waid. Spotlight uses a special English method of broadcasting. It is easier for people to understand no matter where in the world they live.
 
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　　Yawning 3. It is something that people everywhere do. It is a simple motion 4. Open your mouth extremely 5 wide. Pull air into your mouth. Your lungs expand to fill with fresh air. The muscles 6 near your stomach pull in. Your whole body feels a good stretch. Then you blow the rest of the air out.
 
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　　As you were listening, did you just yawn 2? That is another interesting thing about yawning. It is contagious 7. That is, when a person sees another person yawning, she may yawn too. Yawns 8 seem to move from person to person. In fact, we may only need to HEAR or SEE the word yawn to begin yawning.
 
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　　But why do we yawn? Is there a reason? Why is yawning contagious? These are some of the questions we aim to answer in today’s program. Today’s Spotlight is on yawning.
 
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　　Scientists all over the world have tried to understand why people yawn. Andrew Gallup is a behavioral biologist 9 at Princeton University. He studies how a person’s behavior and body are linked. He told Sciencenews.org:
 
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　　“Every single day, every person on the planet 10 yawns. But we have no idea why we do it.”
 
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　　A yawn seems like a simple thing. We do not even think about yawning when we do it. It is an involuntary action. People do not choose to yawn. It is a natural reaction of the body. But yawning is really very complex 11. It involves many parts of a person’s body. Yawning has a physical effect on our bodies. Studies have shown that yawning increases a person’s heart rate. His heart beats faster. Yawning increases the flow of blood in a person’s body.
 
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　　Scientists do have some theories about why people yawn. Some of the theories are social theories. One social theory about yawning is a very simple one. People yawn when they are tired or bored - that is, when they are not interested in what is going on around them. But many people yawn even if they are not tired. For example, even Olympic athletes may yawn when they are getting ready to compete. People do yawn when they are tired. But this cannot be the only reason why people yawn.
 
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　　Some scientists believe people yawn because our bodies have changed to do that through history. They say ancient people learned 12 to yawn over many years. People may have begun yawning as a way to quickly communicate with other people around them. For example, imagine you are a person living many thousands of years ago. Imagine you saw a dangerous animal, like a lion or tiger. If you made a sound, the animal might hear you. But, if you open your mouth wide into a yawn, you can communicate your message quietly. However, this theory does not really explain why people yawn. If yawns communicate danger, why do we yawn when we are tired?
 
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　　Other theories say people yawn for a particular physical purpose. For example, maybe yawning helps a person’s body to get more oxygen. Oxygen is one important gas in air. When we breathe, we pull oxygen into our lungs. It is necessary to make our bodies work. Could yawning mean a person is trying to get more oxygen?
 
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　　Robert Provine is also an expert on yawning. He led an experiment in 1987 to test this theory. He tested the theory on a group of college students. He wanted to discover if students yawned 13 more when there was less oxygen.
 
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　　Provine observed the students while they breathed different kinds of air. But it did not matter how much oxygen was in the air. Students all yawned at the same rate. He believes that yawning does not have anything to do with breathing. People do not yawn to get more oxygen.
 
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　　A more recent theory about yawning suggests people yawn to keep their brains cool. Andrew Gallup led a study to test this theory. Gallup studied 80 people in the winter, and 80 in the summer. He found that people were more likely to yawn in the summer than in the winter. He believes this is because it is more difficult for a person’s brain to stay cool in the summer. A cooler brain can work better. So, when it is hot, a person’s body begins a yawn. The yawn pulls in air to cool the brain.
 
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　　Is this the real reason people yawn? No one really knows for sure. People have been asking this question for thousands of years!
 
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　　But there is another mystery about yawning. Why is yawning so contagious? Doctor Catriona Morrison is a psychologist 14. She studies human behaviour. And she teaches at the University of Leeds. She told the BBC 15:
 
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　　“Contagious yawning is a very interesting behaviour. You do not need to see the yawn. You do not even need to hear the yawn. You can just read about it or think about it and it gets you going.”
 
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　　Doctor Morrison led a team of researchers to investigate 16 contagious yawning. Researchers used students for their experiment. Each student sat in a room with a secret researcher. The secret researcher yawned often. Researchers observed if the students yawned too - and how many times. After ten minutes, each student took a short test. In the test, the student tried to identify the feelings of another person. Doctor Morrison’s team discovered that the students who yawned were more likely to also understand another person’s feelings. This is the idea of empathy - being able to understand the way another person feels. Doctor Morrison told the BBC:
 
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　　“We believe that contagious yawning shows empathy. It shows that a person can understand another person’s body and mind.”
 
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　　Yawning is not very contagious for every person. People who have trouble feeling empathy will not yawn contagiously 17. And children do not experience contagious yawning until about age four. This is about the age when children develop the ability to feel empathy.
 
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　　The link between yawning and empathy is solid 18. Scientists have also taken pictures of people’s brains. These pictures show areas that are active when a person is reacting 19 to yawning. The same areas are active when a person is thinking about another person’s feelings.
 
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　　Yawning is just one of the amazing and strange things our bodies do. We may never know why people yawn, or why yawning is contagious. But one thing is sure. Many people think of a yawn as something rude. So if you must yawn, make sure you cover your mouth while you do it!
 
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　　The writer and producer of this program was Liz Waid. The voices you heard were from the United 20 Kingdom and the United States. All quotes 21 were adapted for this program and voiced by Spotlight. You can listen to this program again, and read it, on the internet at www.radioenglish.net. This program is called, ‘Why Do I Yawn?’
 
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　　You can also leave your comments on our website. And find us on Facebook - just search for Spotlight Radio. We hope you can join us again for the next Spotlight program. Goodbye.
 
　　*Some of the music in this program came from Podington Bear*