Population estimation on the basis of social organization is one of the least accurate of the methods we shall examine. At best, we can only infer in general terms how high populations were at various levels of societal complexity. It is obvious that a people supported by a hunting, fishing, and gathering technology would be smaller than a group living by intensive irrigation agriculture. The basic differences in the population characteristics of primitive, agricultural, and industrial economic systems have long been a subject of investigation of historical demographers. In the present chapter we shall review some recent developments in the study of social structure and population size, then examine applications of the method to Incaic Peru.

Robert L. Carneiro has documented a relationship between the number of organizational traits of a society and the size of the group. As societies become larger they become structurally more complex. The relationship is direct, but structural complexity does not increase as rapidly as population. Indeed, for Carneiro, growth provides the very impetus for societal development. “The pressure brought about by the quantitative increase of like units leads inevitably to a critical point at which the system must either fission or advance to new levels of organization by undergoing a qualitative transformation.” D. E. Dumond goes so far as to suggest that population is the independent variable and that any change in social organization is dependent on population size.