"Yawning is extremely contagious -- 55% of people who witness someone yawn will yawn within five minutes. If a visually impaired person hears a tape of someone yawning, he or she is likely to yawn as well. Face it, the likelihood of you making it to the end of this answer without looking like one of these gaping maws is unlikely.
Although the contagious nature of yawning is well established, we know less about why this is so. Researchers are currently giving the topic some serious attention. One theory suggests it's a holdover from a period in evolutionary history when yawning served to coordinate the social behavior of a group of animals. A recent study postulates that contagious yawning could be part of the "neural network involved in empathy."
While the mystery of contagious yawning has yet to be solved, perhaps researchers are closing in on an answer. On the other hand, given the subject matter, we wouldn't blame them for falling asleep at the wheel. In the meantime, give the "yawn challenge""
Source(s):
http://ask.yahoo.com/ask/20050623.html
