A recent archaeological find in the Arctic revealed bones of a number of women and children which carried marks of ancient knives (probably flint), as well as having been split (for the marrow, no doubt), and afterwards neatly stacked. Probably the consequence of a raid by indigenous people of some sort. The Inuit and the forest people to the south seem to have a long history of conflict. The West Coast Haida practiced ritual cannibalism, the Caribes of Central America were greatly feared in the 16th century (remember Robinson Crusoe?). Africa, ditto; literature on the slave trade relates widespread cannibalism. Our taboos notwithstanding, cannibalism was probably more common than we realize. And since we're all related to some degree...