By nature, humans are a social species. Our brains are wired from birth with programs that were crucial to our distant ancestors. Infants come equipped with a basic repertoire of social skills. And yet, as history has shown, there is a dark side to the human brain. The evidence is overwhelming that throughout our history as a species, relations between individuals and societies have been destructive as well as positive. As series host Roger Bingham explains: "We are living in the Space Age with brains from the Stone Age. We need to ‘tune’ our psychology, to figure out how to turn up the volume on ancient instincts like cooperation and turn down the volume on instincts like organized aggression." (58 minutes)