In this important book, Princeton sociologist Walter L. Wallace suggests that human species survival is now threatened. The time has come, therefore, for human societies to add the forecasting provided by computer simulations of human socio-cultural phenomena to both population size controls - recommended by Thomas Malthus - and natural selection and migration mechanisms - proposed by Charles Darwin - to serve the continued survival of living species. To this end, Wallace offers interpretations of six classical theories that address the issue of human species survival, including those of Karl Marx, Emile Durkheim, Max Weber, Thomas Malthus, Charles Darwin, and Ibn Khaldun.Specifically among the classical sociologists: Emile Durkheim focuses on human societies and proposes a moderate amount of division of labour - when supported by a cooperation-ensuring morality - as a mechanism whereby societies, and, by implication, Homo sapiens as a species, can maintain itself without migration. Karl Marx also focuses on human societies, but unlike Durkheim who concentrates on how such societies maintain themselves, Marx concentrates on how the physical behaviour characteristics that are innate to and socio-culturally taught to the human participants in those societies contribute to that maintenance - again, without migration.Max Weber concentrates on how the psychical behaviour characteristics innate to and those socio-culturally taught to the human participants in human societies contribute to the maintenance of human societies - and thereby of the human species - again, without migration. Professor Wallace argues that considering the work of these classical theorists can make a profound difference in the future survival of the human species.