The Contagious Yawn

It is said that we yawn when there is too much carbon dioxide and not enough oxygen in our blood. The brain stem detects this and triggers the yawn reflex. We inhale deeply, shooting a jolt of oxygen into the lungs and to the bloodstream. But why is yawning so contagious? Have you ever seen a person yawn, and then you start yawning and wonder why? I have and decided to do a little research on it. Here's one answer I found "If you're out late in some crowded dive, you're probably all tired, all warm under the collar, and all breathing the same stale air. You're probably all on the verge of a yawn, too, and the power of suggestion from seeing one person do it is enough to push everybody else over the edge." So if you yawn after seeing another person yawn, that means you were on the verge of a yawn to begin with and didn't notice? Some say we yawn because it's too warm in the room. Hmm...both are interesting points and makes perfect sense.
Here are some things to ponder:

• Why is it contagious even in the day time?
• Why do you yawn from just reading about yawns?
• If you see a animal yawn, will you yawn too?
• Will we ever know the TRUE reason as to why is contagious?