“We can put a man on the moon, but we do not understand what the function of yawning is,”
Gary Hack
University of Maryland School of Dentistry in Baltimore
http://news.nationalgeographic.com/news/2011/11/111115-yawning-mystery-brains-sinuses-health-science/

Have you ever experienced yawning so much that tears roll down your face? Do you yawn from boredom, lack of sleep, or as nonverbal communication? No one really knows. Researchers have many theories on why we yawn but the fact remains: WHY we yawn is still a total mystery. The only thing you will find, is that YOU will yawn reading about yawning. That leads us to fact one about yawning.

1. Yawning is an involuntary action that everyone does. Nearly every creature on the planet yawns, including snakes and fishes. http://news.bbc.co.uk/2/hi/6270036.stm

2. Yawning is contagious. (Okay, you probably already knew that) Chances are you will yawn if you see someone else yawn, see someone in a movie yawning, or even read about yawning. But did you know that the source of contagious yawning is a sign of empathy and social bonding?

Originally, scientists thought that contagious yawning was the result of a releasing mechanism – in other words, seeing someone yawn flipped the yawning-switch in the brain, and it makes you yawn. But it actually turns out that there is a correlation between the susceptibility for contagious yawning and self-reported empathy. Converging evidence for the empathy hypothesis comes from the fact that contagious yawning is absent in individuals with autism spectrum disorder.
http://scienceblogs.com/thoughtfulanimal/2010/07/14/yawn-yawn-yawn-yawn-yawn-conta/

3. Contagious yawning is a different story. Only humans, chimpanzees and possibly dogs have been shown to be affected by contagious yawning. http://news.discovery.com/human/health/yawning-social-behavior.htm

4. Fetuses begin yawning in the womb as early as 11 weeks after conception, said Robert Provine, a developmental neuroscientist at the University of Maryland, Baltimore County. http://news.discovery.com/human/health/yawning-social-behavior.htm

5. The average yawn last 6 seconds. http://www.thefactsite.com/2009/01/things-you-didnt-know-about-yawning.html

6. A man was sentenced to two months imprisonment for yawning outside the courtroom in Fiji. He successfully appealed. http://www.fijitimes.com/story.aspx?id=227294