Shaking hands seems like an innocuous enough gesture. It is commonly used upon meeting someone new, when greeting someone, when leaving, to offer congratulations, to express thanks, to complete a business agreement, and even to exhibit sportsmanship. Handshakes are like Leonardo da Vinci – they’re the Renaissance Man of silent communication. But why clasp hands? Why shake up and down after the hands are joined? Like most of the seemingly benign actions in our lives, the origin lies in our interest in self-preservation.
For most of history, offering an open hand as a form of greeting was a symbol of two things: (1) that you were unarmed, as holding a knife or any other small blade with an open, outstetched hand would be impossible; and (2) that you were coming in peace. The Romans, like they did with most things, enhanced this process and insisted on clasping forearms with their counterparts. A simple embrace of open hands did not satisfy their suspicion that you might be armed. What if you had a weapon concealed in your sleeve? The Romans were like TSA agents and the forearm embrace was their metal detector. If you’ve read your Julius Caesar, you can understand their paranoia. And as a final security measure, the Romans also felt it was necessary to shake violently while joined at the forearm with said counterpart. If there were any weapons particularly well-hidden, this not-so-gentle shake would jostle them loose and send them cascading to the floor below. It may seem excessive, but better safe than Caesar.