Food is the urgent and recurrent need of individuals and ofsociety. It dictates their activities in relation to their landat every stage of economic development, fixes the locality ofthe encampment or village, and determines the use. Ofthe territory from which sustenance h drawn. The lengthof residence in one place depends upon whether thesprings of' its food supply are perennial or intermittent,while the abundance of their flow determines how large apopulation a given piece of land can support.