That an ecological crisis confronts humankind is now so central to our thinking that the notion that human beings adapt to their natural environment seems obvious. But ecological interpretations of world history are surprisingly recent. Sociologists, in attempting to classify societies, have looked increasingly to a people' s relationship with their natural environment and, provide food, clothing, and shelter. Human beings meet these needs in a wide variety of environments, including deserts, rain forests, grasslands, and so on. Such environments are part of ecosystem, complex web of interdependencies among organisms, communities of organisms, and the natural habitual. Some societal variation derives from the different demands made by different ecosystems. Customs and ways of life that would be adaptive in one ecosystem would be maladaptive in another. We confront a habitat and evolve a mode of existence not so much as lone individuals, but cooperatively as larger social units. Social organization and technology are our chief adaptive mechanisms. Social organization develops as we create stable, ordered relationships and become infused with common cultural traits. Much depends on whether or not our values, norms, beliefs and institutions favor or foreclose new avenues of adaption. Likewise, technology —the application of knowledge for practical ends allows us to harness and change aspects of our environment. In its broadest sense, technology entails the practical arts and skills of human society. As technology has become more advanced, we have gained access to greater amounts of non human energy (animal, water, fossil fuel, solar, and so on). In turn, new sources of energy have allowed our cultures to expand and change. Other changes follow as well. The author points out that differences in people's ways of life come from______.