What is the origin of the Pharisees and Sadducees?

I understand that Sadducees were upper-class wealthy men who made up the Jewish aristocracy. Pharisees came from all economic classes but were distinguished by their rigid adherence to behaviour as interpreted from the Torah. They were prominent during the time of Jesus, but when did these two groups first arise, and which came first? Perhaps the Old Testament can shed light on this; for example do they go back to the time of Moses, or perhaps to the time of Zadok the priest? What is the origin of the Pharisees and Sadducees?