Why do we... shake hands?

In the world of Rome's Revolution, Rei is always saying something that Rome has no clue what he means. Many of our colloquial expressions and actions require a cultural context to make any sense at all.

When Rei first met Fridone in Part 2 of Rome's Revolution, a form of this method of greeting had survived the 13 century gap. Here is that little scene:

     “Beo, this is Rei. He saved me and perhaps the whole world. He is mau emir.”
     Fridone reached out with his arm and Rei extended his. Fridone grabbed a hold of it in a peculiar way and pulled him down toward him and gave him a hug, which Rei allowed. Then Fridone pushed him back and turned to Rome. “He is mandasurte, also? He certainly does not look like a Vuduri.”

So today's question is: Why do we shake hands?

The origin of this tradition is very simple. In the olden days, people walked around armed and killed each other whenever possible. Before guns, there were knives. If a person was concealing a weapon, they couldn't very well show it to you. So reaching forward with an open hand was meant to signify that you were not armed or at least not immediately ready to kill the person you were greeting.

A more exotic method would be the forearm grip so you could check for knives up the sleeve but this has fallen out of favor, leaving only the firm handshake in its place.

The 35th century Vuduri were unfamiliar with this custom. None of them would think to try and conceal a weapon because their minds are all inter-connected and you would just know. Thus Rei brought this tradition to them, and they adopted it, without really knowing the reason.

Tomorrow, why do we say gesundheit when someone sneezes?