Cannibalism--Cultural versus religous roots

Understanding Maori notions of tapu and utu have enlightened me as to why they were motivated to cannibalize although it has done little to explain how the practice originated as a punishment. It makes sense that they would have grave punishments for violation of tapu, but how do we explain the origin of those punishments? My first thought was that it was rooted in the Maori's complex web of religious figures and deities--not some law of sympathetic magic. There certainly is cannibalism in Maori folklore but there didn't seem to be anything significant or universal that would cause cannibalism to be so widely practiced. I thought that perhaps there would be some deity or character in Maori religion that engaged in cannibalism or did something to suggest it was appropriate but most of their deities were symbolic--a god for the fish, the sun, the water, the wind, etc.

When I think about deviating behavior that is accepting in American society it seems obvious why it is accepted. Jon Krakauer wrote a book called Under the Banner of Heaven where he goes into Mormon Fundamentalist Sects that committed terrible atrocities and makes the interesting point that the American legal system asserts that all people who are religious are insane--the only difference being that they assert that only when they have committed a deviating act and only in the presence of religious beliefs. When I ask myself why religous beliefs make deviating acts acceptable the only answer I can think of is that it is part of our culture. Some things simply evolve as social norms and it happens collectively in a passive way--there is no specific reason. Perhaps cannibalism evolved in a similar way, with its easy acceptance into Maori culture influenced by religion, but not caused by it.