" But for years questions persisted about whether most cannibalism was religiously motivated and selective or culinary and routine. DNA suggests routine. Every known ethnic group worldwide has one of two genetic signatures that help our bodies fight off certain diseases that cannibals catch, especially mad-cow-like diseases that come from eating each other’s brains. This defensive DNA almost certainly wouldn’t have become fixed worldwide if it hadn’t once been all too necessary. "

― Sam Kean , The Violinist's Thumb: And Other Lost Tales of Love, War, and Genius, as Written by Our Genetic Code