Tackling the big issues of the day, it is surprising how much psychological research is devoted to this subject. The history of studying yawning began in the 1980s and has evolved into a large discipline in its own right. This has taken many a whacky angle, like trying to teach tortoises how to yawn for example. This research may have all been in vain though, as some leading researchers concluded that yawns are not contagious, they just happen to occur at the same time. For a history of the study of yawning, click here.
It is a common myth that contagious yawning is a sign of empathy. More recent research has suggested that contagious yawning is linked to perceptual sensitivity and not empathy. In otherwise, it is a the power of suggest rather than anything else. To read the study click here.