We look into the evidence from primatology and archaeology to find the roots of human cannibalism in nature or nurture. Along the way we find shadows our own dual nature between sexy hippy bonobos and hawkish war chimps; learn how homo sapiens slept with their food, visit a stone age cave of nightmares in Britain; and join the debate over what seems to have been a short-lived fad for eating humans among the Ancestral Pueblo.