why do we yawn?
The yawn, the yawn is a strange and wonderful mystery. Everyone yawn's, kids, babies most mammals and even some reptiles. We humans even begin yawning in our mama's womb, around 11 weeks we can yawn. Yawing is contagious as most of us know, we yawn when we are bored or tired, but the question is, why do we yawn? And, what the heck is a yawn????? Their has been more theories about yawning then actual research, so nobody really knows why we yawn but lets look at some of the theories anyway.
Some research has shown that a part of the brain called the hypothalamus has an important part of our yawning. It has been shown that some neurotransmitters, like dopamine, excitatory amino acids, nitric oxide and neuropathies increase yawning if injected into the hypothalamus of animal. So what does this mean, who knows but it's interesting....Anyway most people assume that we yawn because our bodies are trying to rid its self of extra carbon dioxide and to take in more oxygen. According to this theory people yawn when there are bored or tired because they breathe more slowly. When your breath slows down less oxygen makes it to the lungs, as carbon dioxide builds up in the blood a message to the brain signal you to take a deep breath and a yawn is produced.
However, with this theory some research has actually disproved it; In 1987 some researchers testes this theory that high carbon dioxide causes yawning. Normally the air we breath is made up of about 20%oxygen, about 80% nitrogen and about .03% of carbon dioxide and a few other gases in very low concentrations. In the test performed by the researchers they gave college students different ratio of gases. The results we surprising, none of the changes caused more or less yawning.
Other tests done by researchers include testing through exercise; exercise obviously causes people to breath faster. However the number of yawns during the exercise was not different from the number of yawns before or after the exercise, their for it appears that yawning may not be due to the carbon dioxide levels in the blood and that yawning and breathing are controlled by different mechanisms.
So we are still wondering why we yawn, well other theories suggest that yawning is just as stretching, it increases the blood pressure and heart rate, and also flexes muscles and joints. Evidence that yawning and stretching may be related comes from the observations( that you ca try at Home) of people trying to prevent a yawn by clenching your jaws shut, the yawn is somehow unsatisfied, so basically the stretching of the jaw and face are necessary for a good yawn.
The theory about why yawns are contagious goes back to the beginning of man. some think and I agree that yawning could be contagious because of the behaviours of early mammals, one member of a group yawned to signal an event, and so all the mammals would also yawn. Over time and evolution it has evolved to just a natural part of the day, he yawns, you yawns and so on.
So now you know a little more about yawning, or maybe a little less...Ha, ha.... my final question is... How many times did you yawn during this article??? I bet it was at least once, because even reading about yawning can make us yawn....how strange is that. So hey if you got to....YAWN, it must be good for us...or we wouldn't do it so much....I yawned eight times while writing this article....