When did cannibals exist?

According to William Arens, an anthropologist at Stony Brook University in New York, "There is limited evidence for the possibility of cannibalism in prehistoric times," "It is two or three instances and all suggest they were isolated cannibalism, if it took place at all." However, Tim White, who in 1992 published evidence for cannibalism 800 years ago in southwest Colorado in the book Prehistoric Cannibalism at Mancos, refutes Arens' suggestion.
William Arens responded that White was seduced by the Holy Grail of cannibalism and failed to consider other explanations for the kind of perimortal bone trauma he encountered.

The jury is still out that cannibalism as a ritual practice ever existed. (Albeit no one doubts that it has been practiced under conditions of starvation or perversion.) Although much folklore abounds, no credible sighting of cannibalism by anthropologists exists. As the science writer, Martin Gardner noted in his book Did Adam and Eve Have Navels? Debunking Pseudoscience, that the skeptical case for why cannibalism is rare to non-existent it that the proposition of cannibalism often emerges from the imaginations of ethnographers and archaeologists, or it is rooted in scurrilous insults hurled between ethnic groups which have antagonistic relationships.

He cites the 1979 book by William Arens entitled The Man-Eating Myth which opened up the issue with a strong argument in favour of the belief that cannibalism has never been prevalent in any culture. Gardner notes that claims of institutionalized cannibalism have always been made by enemies, never the tribes themselves, and have usually proven hard to follow up. He refrains from taking sides but admits "My sympathies at the moment are with Arens."

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