Putative Handshake Origin
.In The Left Stuff: How the Left-Handed Have Survived and Thrived in a Right-Handed World I came across an account of the origin of the handshake that I’d never encountered before and which I find quite interesting:
The Roman ritual of touching right hands—the precursor to the modern-day handshake—was originally intended to demonstrate that one was weaponless. It was allegedly promoted by the left-handed Julius Caesar, who could use it to conceal a weapon in his dominant hand.
—Roth, Melissa (2005), The Left Stuff, M. Evans and Company, p28.
Obviously too good a story to not be true!