Abstract
Agricultural practice is largely dictated by natural environment and the technological requirements of the principal crops cultivated. Yet the inherent characteristics of an individual farming system, in particular whether production methods tend to be intensive or extensive, will affect not only the associated agricultural technology but also the organization of the economy and society. Here a brief historical survey of four of the world's most important crop complexes is presented. Both the agricultural technology and the economic relations associated with important crop plants are outlined, hoping to identify not only their chief characteristics but also their potential for change.