As a child survivor of the Holocaust, Paul Valent's life's work has been an investigation into the reasons why humans - who have the capacity to love and care for each other - too often hate and hurt each other instead. Over eight decades, utilising major investigations into how the brain works, he comes to understand the workings of his own mind, the minds of patients, victims, and - eventually, with courage and sensitivity - the minds of perpetrators. Valent reveals how the bulk of our brains conceals a mindset evolved in our jungle heritage, its challenges and traumas. He then describes how this mindset manifests itself in today's world, in violence that ranges from bullying to war, and includes the Holocaust and other genocides.