This book explains the origins of what we generally refer to as "Human Nature." Despite the tremendous variation in human behavior, there are several distinct traits that are common to our species in general and, in fact, common to all species. These include dominance and submission, aggression, territoriality, altruism, loyalty to family and group, mistrust of strangers and sex drive along with all of our automatic bodily functions such as heartbeat and respiration. These functions and traits can be all lumped together under one heading that we refer to as the "Instinct of Survival" and originate in a small and very ancient part of our brain often called the "Primitive Brain Stem." My purpose in exploring these facts relating to human behavior is to inform the reader as to the natural origins of what are often completely illogical, unreasonable and destructive emotions that result in war, hatred, violence, bigotry and destruction. The alternatives of peace, cooperation, reason and constructive action are simply decisions we all can make.