Groups in mind : the coalitional roots of war and morality

War is older than the human species. It is found in every region of the world, among all the branches of humankind. It is found throughout human history, deeply and densely woven into its causal tapestry. It is found in all eras, and in earlier periods no less than later. There is no evidence of it having originated in one place, and spread by contact to others. War is reflected in the most fundamental features of human social life. When indigenous histories are composed, their authors invariably view wars-unlike almost all other kinds of events-as preeminently worth recording. The foundational works of human literature-the Iliad, the Bhagavad-Gita, the Tanakh, the Quran, the Tale of the Heike-whether oral or written, sacred or secular-reflect societies in which war was a pervasive feature. Wherever in the archaeological record there is sufficient evidence to make a judgment, the traces of war are to be found. It is found across all forms of social organization-in bands, chiefdoms, and states. It was a regular part of hunter-gatherer life wherever population densities were not vanishingly low, and often even in harsh and marginal habitats. The existence of intergroup 191