Why most of the greetings involve showing of hands?
Like for example, the handshake, hands and bowing for the chinese and the hand touching and reaching back to touch the heart for the muslim.
Perhaps, it is so because when you meet a stranger and you can see both of his hands, they can't be hiding any weapons. Therefore, you can rest at ease and make friends.
Then the Eskimos rub noses cause so damn cold and they cover everything up except for their eyes area.