Shared narratives (myths) are necessary for social cohesion. But unquestioned myths are dangerous. Each generation inherits anew the same genetic heritage from our Stone Age ancestors and culturally transmitted myths from more recent generations. Some of these myths intensify the problematic aspects of our genetic heritage, notably our species' tendency to form antagonistic groups that sometimes dehumanize each other with horrific consequences.. We must carefully evaluate our myths and the emotions they arouse, especially now, when we have the means to wipe ourselves out.