����� Perhaps the most basic theme of human history has been man's increasing need for food and the effort he has expended in producing it. The intensity of this effort and its wide variance over the earth has been increasingly studied by both economists and geographers. The former have been especially concerned with the theoretical considerations of those factors which determine the distribution patterns of intensity;1 geographers have been empirical, striving to discover the actual intensity patterns as they exist and the reasons for their existence. Both, however, have increasingly complemented the other, for the distribution of intensity is a product of economic "laws" and the physical environment, as well as historical circumstance.