"Good To Eat" by Marvin Harris and Aztec cannibalism

He tries very hard, and fails, to NOT say the unusual preponderance (for large states that need slaves and tax-payers) of cannibalism after battles for the Aztecs was NOT from the the lack of domesticated animals.  Lack of these meant that the best way to get the grain back to the capital along with some extra sorely-needed protein was to have an occassional war with the outer provinces that rebelled.  And that rebellion was built into the system because provinces knew their grain harvests might have to be marched by prisoners to the capital, and then the prisoners eaten for their protein.  Without the wheel, killing was minimized until the capital was reached. Religion being the mechanism of the procedure should carries no more weight in trying to discover "why" than it did for the middle east cultures despising pig as soon as forest disappeared, and hindus considering the cow sacred as soon as population exploded (it's more efficient for milk and plowing than eating).  The whole point of the book is to show that odd thoughts do not lead to odd food taboos, but that society-wide food production efficiency solutions lead to intelligent taboos.  A thing he finds strange is women in poor countries tabooing protien and certain foods during pregnancy, but it takes him a few pages to say "it might be because it leads to smaller children and smaller adults who need less protein and fewer calories".