Reviewed this book for my own Assent to Truth. David Barash the primary author Like sociologist Herbert Spencer applies Darwin's evolutionary principles of animals to the psychology of human behavior. The premise is that Man is not dissimilar to animal predilection based on sensual need, survival, whereas the human intellect identifies a difference of moral good v sensual satisfaction and survival instinct. If that awareness exists in the human psyche it radically differentiates Man. In consequence Barash's psychological assessment is tailored to his own personal predilection rather than fact.