Asked in Yawning
Yawning

Why are yawns contagious?

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04/29/2014

Some people have a theory about why yawns are contagious, but it has since been proven incorrect. The theory goes like this... When you breathe, you take in carbon dioxide. Scientists used to think you yawned because you had too much Co2 in your body, and you yawned it out. When you yawn near someone else, scientists thought that they then breathed in the cloud of Co2 and then needed to yawn it out. And the theory was that when you are tired you take shallower breaths and so need to get rid of more carbon dioxide. This has recently been proven a false theory. However! When you talk to plants, it really does help them grow because you are giving out Co2 as you breath, which helps them to grow quicker.
They're contages as yawns contain a small amount of nicotien this erges people to yawn to get their fix.