Dr. Melanie Joy is a Harvard-trained social psychologist and bestselling author who gives us unique insights into our most self-destructive habit: meat consumption. So, why do we do it? Processed meat is officially listed as a carcinogen by the World Health Organization. It's also a leading contributor to another of America's biggest killers, heart attacks. That doesn't seem to phase people. Why not? Find out in this short, but eye-opening, video. Carnism.org