Until recently, scientists thought cannibalism was a rare response to starvation or other extreme stress. Well-known cannibals like the praying mantis and black widow were considered bizarre exceptions. But now, we know they more or less represent the rule. Bill Schutt shows how cannibalism can promote the survival of a species by reducing competition, culling the weak, and bolstering the strong. Lesson by Bill Schutt, animation by Compote Collective.