The authors assert that traditional sociological theories of human nature and society do not pay sufficient attention to the evolution of "big-brained hominoids," resulting in assumptions about humans' propensity for "groupness" that go against the record of primate evolution. When this record is analyzed in detail, and is supplemented by a review of the social structures of contemporary apes and the basic types of human societies (hunter-gathering, horticultural, agrarian, and industrial), commonplace criticisms about the de-humanizing effects of industrial society appear overdrawn, if not downright incorrect. The book concludes that the mistakes in contemporary social theory - as well as much of general social commentary - stem from a failure to analyze humans as "big-brained" apes with certain phylogenetic tendencies. This failure is usually coupled with a willingness to romanticize societies of the past, notably horticultural and agrarian systems