When and how did gesture of clapping originated?

Clapping originally wasn't actually what we know now as "clapping". It actually originated in ancient Greece when theaters were not very popular. After every performance, most all (which was very few) audience members would pat the actors on the back as a sign of respect and praise, but eventually that became an arduous task, so people eventually began saying that one hand is the actors back, and the other hand is your hand and they would slap or "clap" it.