Yawning doesn't always mean you are bored. Adelie penguins actually yawn as part of their wooing ritual. Couples face each other and the males stand with their beaks wide open and face towards the sky.
As for why people yawn... good question. Nobody really knows why we yawn. For a while scientists believed that you yawned when there was too much carbon dioxide and not enough oxygen in your blood. Part of your brain realized this and triggered you to yawn. As your mouth stretches you inhale deeply, sending a shot of oxygen to the lungs and into the bloodstream. That theory went out the window because nobody can prove it.
A Few Cool Yawning Facts
Humans of all cultures, nations and races yawn.
Olympic athletes often yawn before competition.
Reading about yawning will make you yawn.
Blind people yawn more after hearing an audio tape of people yawning.
55 percent of people will yawn within five minutes of seeing someone else yawn.
The average yawn lasts about six seconds.
Yawning has been observed in humans as early as the first three months after conception.
Psychotics rarely yawn.
Crocodiles, fish, birds and snakes (among other creatures) yawn, too.
The average yawn lasts about six seconds.
Yawns often recur at intervals of about one minute.
Yawning is NOT a response to an excess of carbon dioxide or a shortage of oxygen.
You often yawn because you’re stretching, but stretches are not always accompanied by yawns.
Yawns sometimes can be viewed as an indication that something is wrong inside the body. Frequent yawning can be one of the symptoms of brain lesions and tumors, hemorrhages, motion sickness, opiate withdrawal, encephalitis and chorea (an abnormal voluntary movement disorder).
Contagious yawning is thought to be an ancient way of communicating bedtime to the rest of a group of people.
A stifled yawn is never as enjoyable as a completed one.
