This page gives the true history of Rock, Paper, Scissors. It was once a game where you held out from zero to five fingers, and the winner was decided by who had the lowest number-- with the exception that five beat zero. The numbers 1 through 4 were redundant (playing 2, 3, or 4 is a strategic mistake) so the game was reduced to only the throws 2 (scissors), 5 (paper) and zero (rock.) The game was originally invented in China, was popular in Japan by the 1700s, and was virtually unknown in the West in the late 1800s (judging by books of children's games) but commonly known in Europe and the U.S. by the early 1900s.
Here is some additional history: