However, high productivity also allows other non-farmers to be supported. Those who farm the most productive land grow and store more food. Those on less productive land may need to borrow from them during bad seasons. Therefore, one segment of the population can exert power over another segment. However, resources other than land are also required for farming.
Irrigation systems are complex and require a cooperative effort to build and maintain.
Often, a centralized authority will supervise the distribution of water and the maintenance of its system of delivery. Because water is often more limited than farmland, those who manage the water have control over those who need it. This might be how Teotihuacan in central Mexico was able to achieve dominance over its neighboring communities. The next several chapters build on the concept that culture operates as a system, a network of inter-related components, such as social organization , politics , beliefs , settlement patterns , and economics . Once again, economies are the kind of thing that archaeologists like to examine simply because the material-based data we recover are conducive to its study.