In Greek mythology, Charon or Kharon (English pronunciation: /'k?r?n/, /'k?r?n/; Greek ?????) is the ferryman of Hades who carries souls of the newly deceased across the rivers Styx and Acheron that divided the world of the living from the world of the dead. A coin to pay Charon for passage, usually an obolus or danake, was sometimes placed in or on the mouth of a dead person.[1] Some authors say that those who could not pay the fee, or those whose bodies were left unburied, had to wander the shores for one hundred years.
http://en.wikipedia.org/wiki/Charon_(mythology)
A pyre (Greek: ????, pyrá, from ???, pýr, fire), also known as a funeral pyre, is a structure, usually made of wood, for burning a body as part of a funeral rite. As a form of cremation, a body is placed upon the pyre, which is then set on fire.
Traditionally, pyres are used for the cremation of the deceased in the Hindu and Sikh religions, a practice which dates back several thousands of years.[1] Funeral pyres were also used in Viking culture, typically on floating boats, as well as by the Romans.[2]
http://en.wikipedia.org/wiki/Cremation_pyre
Personally, I believe the funeral pyre or cremation originated as a way to prevent the spread of disease from a corpse. It became a tradition associated with certain cultures or religions.