Humans have always faced the threat of extinction. This book takes a broad perspective of the ‘extreme’ conditions of human existence and survival to examine how extremes have forced humans to change and how such extremes have determined the nature of society. This volume in The Evolution of Human Sociality series is the fourth (and final) book in a collaborative research project between primatologists and anthropologists. In seeking to understand human sociality, twenty-one authors focus on states of extremity and the ways in which they are perceived and confronted by humans and primates. The contributors consider, among other topics, the 'extremes' of urbanization and the disappearance of village societies; the 'extremes' of climate change, the Anthropocene, and the extinction of the human species; the 'extreme' of human birth; the 'extreme' of the absence of mothers for infant chimpanzees; and the ‘extreme’ of radiation disaster. On a more theoretical level, the book illustrates what happens at the moment when humans and primates choose their actions to survive under the pressure of extremes, as well as the mechanisms at the ‘tipping’ points of their action selection.