How did the handshake originate?

In primitive life the hand was probably a symbol of power and strength.So when the hand was extended to someone, it could have represented good will, since it showed that the person was not armed or ready to fight. The hand was an important symbol in early religions, probably as a mark of power. The Greeks prayed to their gods with raised hands. Presenting the hands palm to palm was at one time the way an inferior person paid respect to a superior one. Among the Arabs, it was customary at one time to kiss the hand of a superior.The early Greeks held out the right hand when they wished to indicate friendship to a stranger. And while we shake hands without thinking, we are really carrying on a custom that has been handed down to us from ancient times.