What Is The Origin Of The Handshake?

Shaking hands or some kind of embrace, using the arms or hands is common place throughout the world, not just within western civilisations.
It has developed from the days when people used to live in very small, isolated communities, hunting for food and not really coming into contact with outsiders.
When a stranger appeared, he was usually perceived as some kind of a threat, so in order to diffuse any aggression, the stranger would make some indication that he was not bearing arms. Since most people are right handed and would use the right hand to carry arms, a waving of the right arm and hand would indicate that he was unarmed.
As time progressed, within the Middle Ages and the use of daggers etc, the handshake started to evolve as a sign that no weapons were concealed under clothes.
Women were not usually viewed as a threat, so women did not shake hands: this has only recently evolved.

Dates back to the day of the Neanderthal when they would grab each other's testicles to validate manliness.

The handshake is one of the most important social customs which has emerged in the history of human civilization. It is also part of our everyday non verbal communication. The origins of the handshake are bit difficult to ascertain, because it originated before any written recordings of history. The oldest form of handshakes was practiced by the Egyptians. It was a ritual practiced amongst the rulers; they would shake hands with the statues of the Egyptian Gods. This symbolised the transfer of power from the gods to the current ruler. The modern handshake may have originated in the medieval Europe, where knights would clasp each others hands to show that they have not carried any concealed weapons. There was a minimum level of trust that is if this ritual was performed it meant that they had come in peace.