It seems that a lot has happened since neuroscientist Robert Provine traced the history of laughter back to primates.

Social media consultant Dan Zarrella has detailed the mechanics behind the phenomenon of laughter. He has also explained how we can get a laughter epidemic of our own doing.

According to Zarrella, laughter acts as a form of collective catharsis or an expression of relief. He mentioned at least two example where this was seen:

• the Tanganyika Laughter Epidemic
• laughter in the Charismatic Christian Movement

In all cases, the laughter took place within a context of tension - people laughed as they underwent change. As is the case with yawning, the very sound of  someone laughing can induce you to laugh as well.

This, furthermore, creates a snowball effect that infects others until laughter spreads all over the place like a virus. Should you be interested in engineering your own outbreak of contagious laughter, Zarrella has this recommendation: just do it.

Find a particularly tense moment and a group of people, and start laughing. Then sit back and watch how quickly people catch on.