Includes bibliographical references and index.

Contents: Introduction: Three simple truths about revenge and forgiveness -- Putting vengeance and forgiveness back into human nature -- Revenge is a problem : counting the costs -- Revenge is a solution : three evolutionary hypotheses -- The retribution solution : the evidence for adaptation -- Family, friendship, and the functions of forgiveness -- The forgiveness instinct -- The forgiving brain -- To promote and to maintain friendly relations : making forgiveness happen -- From neurons to nations -- Divine forgiveness and righteous revenge -- Homo ignoscens.