This interdisciplinary analysis of humanity's propensity to warfare develops a thesis that certain evolved behaviours (such as inclusive fitness) have interacted over time with environmental factors (such as limited resources) to create a propensity to warfare. This theory is applied to several case studies which leads to a redefinition of the concepts of nationalism and patriotism. The authors consider their approach as radical, not only challenging contemporary theories of warfare but showing why existing peace initiatives are inept. They regard the book as a scientific inquiry as opposed to a political one; they aim to avoid moralizing, seeking only to communicate "what is", not "what ought to be" about human nature. The moral which they do advocate here is that behaviours and institutions which are outfoxing humanity's efforts to prevent nuclear annihilation, should be abandoned.