"We are the monsters" — that's the premise for the genre of film known as body horror — movies that fixate on monstrous and grotesque changes to the body. There have been good body horror films and bad ones, but "The Fly" starring Jeff Goldblum and Geena Davis was perhaps the most consequential. The movie captured anxieties around bodily autonomy and physical decay, just as the AIDS epidemic was becoming catastrophic. Forty years later, Body Horror is back with films like "The Substance" and "Together." Producer Matthew Lazin-Ryder examines what these films reveal about our bodies, our minds and our sense of who we are.