Science nas given humans many amazing devices and useful bits of knowledge. We know so much about our bodies and how to stay hea
lthy, for example. We also know how to make machines and devices that make life easy for
us. Scientists dedicate their lives to knowledge, but even with a
lifetime commitment, sometimes scientists fail to find all the answers. One mystery that still remains unsolved is why
we yawn-what makes us yawn and
what purpose it serves.
Recent studies suggest that we yawn when we get tired as a way to encourage our brains. The theory is that yawning helps cool the brain, allowing it to
work more efficiently. According to WebMD's article about these studies, when you yawn, your jaw muscles get stretched, increasing blood flow to your
neck face, and head. Also a deep breath during the yawn forces spinal fluid and blood down from the brain. The cool air then cools down these fluids.
Other scientists believe, however, that yawning is a form of communication. This theory attempts to explain why yawning seems to spread from person to
IS person. This kind of behavior is called *contagious yawning" and carries with it a possible social
message. Scientists are not yet sure what exactly the
message is, but they believe people who have more social empathy are more likely to start yawning when they see someone else yawning.
Scientists will continue to investigate the mystery of the yawn. Is it a leftover behavior from before humans had language? Was it a "Hey, I'm sleepy. Let's
go to sleep" message? Or is it really just a way to keep our brains cool? While this is behavior still is largely a mystery, one thing is certain: you are probably
fighting the urge to yawn right about now.
According to the text, what is one purpose of the yawn?
TO encourage the brain
O To find all the answers
O To wake up the body
O To exercise facial muscles
