Laughter just might be the most contagious of all emotional experiences. What's more, it is a full-on collaboration between mind and body. Although laughter is one of the distinguishing features of human beings, little is known about the mechanisms behind it.
Scientists do know that laughter is a highly sophisticated social signaling system, helping people bond and even negotiate. Interestingly, most social laughter does not result from any obvious joke.
Laughter is not limited to communicating mirth. It can be triggered by embarrassment and other social discomforts.
Although laughter is not generally under voluntary control, yukking it up has numerous health benefits: It releases tension, lowers anxiety, boosts the immune system, and aids circulation. Contagious convulsions are anything but frivolous.