Cannibalism

"And the men who were with them there for the first time were eager to do the like. Thus, although we are born neither good nor bad, we become one or the other; and having formed habits, we are with difficulty drawn from them. But when irrational animals fell short, these bastard men tasted also human flesh. For it was not a long step to the consumption of flesh like their own, having first tasted it in other forms.