The book brings together a group of authors who are addressing the nature and causes of warfare in simpler, tribal societies. The authors represent a range of different opinions about why humans engage in warfare, why wars start, and the role of war in human evolution. Warfare in cultures from several different world areas is considered, ranging from the Amazon, the Caribbean, the Andes, the Southwestern US, Southeast Asia, Polynesia, and Malaysia. To explain the origins and maintenance of war in tribal societies, different authors appeal to a broad spectrum of demographic, environmental, historical and biological variables. Competing explanatory model of warfare are presented with overlapping bodies of data offered in support of each model.