Just to add some fun historical perspective – If one desires endless (and fascinating) lessons about widespread cannibalism among North American natives, one need only read Francis Parkman, the great 19th-C historian. His examples, of course, deal w/ Eastern 17th-C and 18th-C tribes – blood chilling for the reader, but presented, correctly I believe, as proud (and power-giving) achievements from the perspective of the natives. Often, his documentation comes through the first-hand reports of French Jesuit missionaries, whose journeys into the deep forests provided plenty of believable material to share about native life & culture – believable, even if their first objective was not to collect anthropological material like scientists. (I don’t recall Parkman discussing cannibalism due to famine, but it no doubt took place, even in Eastern forests of plenty.) An interesting counterpoint would be the journals of Lewis and Clark, capable (not trained) anthropologists of the Western tribes. Beyond the range of the Sioux, it’s difficult to imagine cannibalism among most of the early 19th-C tribes they met and studied – not even by the starving Shoshone (Snake) Indians.

The overall impression is, naturally, that cannabilism – whether to appease hunger or improve one’s warlike prowess – is highly dependent on cultural mores that change through time and space. The long life of Anasazi culture, one can only suspect, went through periods that both encouraged and discouraged it.