Children often ask their parents why they yawn and most parents are at a loss to give answers other than because they are tired. Even the scientists have been asking that question for centuries and still don’t know all the answers.
Let’s review what the professionals have to say. First of all humans and other animals with backbones yawn. So don’t be surprised if you see your cat or dog yawn from time to time.
Now the scientists have come up with a new theory after researching the topic. It appears the function of yawning is to cool the brain. According to the research, when you begin to yawn you stretch your jaw muscles and that causes the blood to flow in the head, neck, and face. You then take a deep breath that forces the flow of blood and spinal fluid down from the head. Then the intake of cool air into the mouth will cool these fluids.
According to Andrew C. Gallup, PhD, a postdoctoral research associate at Princeton University, the whole process acts like a radiator that cools the hotter blood of the brain by introducing cooler air from the lungs and extremities. http://www.webmd.com/brain/news/20110923/why-we-yawn
If this theory holds true we will yawn more in cooler weather than warm weather so that we can get the cooler air to cool down the brain.
To test their theory the researchers went to Arizona in the hotter and cooler season. They showed people pictures of other people yawning and 45 percent of the people (80 subjects) yawned more when looking at the pictures in cooler weather. They also yawned more when they were out in the cooler weather for longer periods of time. The researched matched experiments they had previously done on birds and rats.
Not all researchers agree with this new theory thought they admit that changes in room temperature affects yawning. In hot weather we would need to yawn even more. Furthermore, the body has other cooling devices such as sweating.
As a result there are two schools of thought on this matter of yawning. One camp suggests that yawning is part of the body’s cooling system and therefore physiological while the other camp believes it is a social function or psychological function.
Yawning is contagious
We know that yawning is contagious. The researchers had to show people yawning in pictures to do their experiments on yawning. Still it is unclear why yawning is a social behavior. Although this examiner can see a host yawning as a clue for guests who have overstayed their welcome to go home!
Yawning is a primal instinct
According to Robert Provine, a professor of psychology and neuroscience at the University of Maryland, Baltimore County, "When you see someone else yawn, you don't think to yourself, 'Well, I'll yawn, too," says Provine. "It just happens -- it's instinctive, and it's a very primal aspect of human behavior that goes back to ancient herd mentality."
Yawning produces social cues
University of Geneva physician Adrian G. Guggisberg, MD who supports the social theory says yawning often shows signs of boredom and fatigue. Though it is not known yet why yawning produces social cues.
Is this another example of what came first the chicken or the egg, perhaps the brain cooling theory and social cue theory is part of the same mystery of yawning?