Yawning is usually the act of a person inadvertently opening his mouth when he wishes others would shut theirs.
Yawning is contagious to dogs as well as humans
Dogs often yawn when confused.
Psychopaths are often immune to contagious yawning due to a lack of empathy. They're also less likely to be startled.
The average person yawns about 250,000 times over the course of their life and babies in the womb even do it as early as 12 to 14 weeks.
Yawning is such that our cautious ancestors, when yawning, blocked the way to the entrance of evil spirits by putting their hands before their mouths. We find a reason for the gesture in the delicacy of manner which forbids an indecent exposure.

An estimated 55% of people yawn after reading the word "yawn."
Yawning is, when accompanied by stretching, called 'Pandiculation'
The average person yawns about 250,000 times in a lifetime.