Between the uncoordinated activities of individuals and the formally organized activities of governments and international organizations lie the oldest forms of social organization: families, clans, tribes, and other social units held together by such bonds as solidarity, obligation, duty, and love. These sociocultural systems have undergone considerable change throughout human history, yet informal groups connected by these bonds still exist and the bonds still influence behavior independently of governments and markets. Sociocultural systems are important in terms of global change in two ways. Some long-lived social units, whose survival may be threatened by global change, have developed ways of interacting with their environments that may be adaptable by others as strategies for response. Also, informal social bonds can have important effects on individual and community responses to global change and on the implementation of organized policy responses.
Indigenous peoples that were not tightly integrated into world markets have developed technological and social adaptations that often maintain their subsistence in reasonable balance with the local environment. The adaptations of Sahelian peoples to an environmental regime of recurrent drought is one example. A parallel example can be found in the indigenous economic systems on the Amazon, which for at least 500 years have used the ecosystem's material in ways that do not threaten its long-term productivity (Hecht and Cockburn, 1989). The Amazon's indigenous people are a major repository of practical environmental knowledge about sustainable use of resources (Moran, 1990; Posey, 1983). Slash-and-bum cultivation with adequate fallow periods allows for the recovery of vegetation in tropic moist forests (Uhl et al., 1989), attracts game animals to crops (Linares, 1976; Balée and Gély, 1989), and provides a well-balanced, varied diet (Baksh, n.d.). Local agroforestry systems, which combine "the production of crops including tree crops, forest plants and/or animals simultaneously or sequentially on the same unit of land" (King and Chandler, 1978), mimic tropical ecosystems, protecting the soil from leaching and erosion while replicating the natural succession of plant growth over a period of years, and are a model for modern systems of agroforestry. Some such systems can give per