Contagious? We Asked a Scientist"
by Teresa Carey
Why are yawns contagious? We asked a scientist
The average adult yawns 20 times per day. And when you feel a yawn coming on, it can be nearly impossible to suppress. But why does being around other yawners make you yawn?
PBS NewsHour asked a speech scientist, a sleep neurologist, a neuroethicist and a neuroscientist who studies brain circuits related to itching why yawns are contagious. They said the evolutionary value of collective yawning remains unknown, but may have something to do with the desire of an animal to protect the members of its tribe.
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There is no scientific consensus on why we yawn.
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Question
Use the passage to answer the question.
Which is the most effective way to separate the two sections at the blank line?
