2.1.3 General Principles
Rather than managing plants and animals to achieve a spatially focused concentration of food energy, which is the strategy of agriculturalists and pastoralists, hunter-gatherers must depend on the natural distribution patterns in time and space of the resources on which they depend. In circumstances in which there is a natural concentration of resources in time and space, sedentism is encouraged, so that people and their possessions do not have to keep shifting from place to place. Even if temporary, sedentism is likely to be attractive to HG societies for many reasons: (1) it confers many social benefits; (2) it allows long-term storage of food energy to be an option, thereby increasing future security; (3) it reduces the direct energy expenditures involved in walking, carrying infants, and transporting possessions from one residential base to another; and (4) it reduces the indirect costs of high mobility, such as higher infant mortality, less equipment, and smaller energy stores, if all food must be carried. However, unless food energy sources are spatially concentrated, sedentism also reduces the accessible territory to a local area, which is soon likely to become overexploited. In arid areas, water may also become scarce. The HG lifestyle can be seen as the outcome of a perpetual compromise between the various costs of mobility (many of them measurable as energy costs) and the costs of sedent- ism. The disadvantages of sedentism will become energy costs once carrying capacity is exceeded, because when hunting yields decline and other resources are depleted, labor productivity will fall. As a result, people must work for longer periods, and/ or journey times from home base to food source must increase, so as to compensate.