This paper presents a simulation of world-systems theory’s iteration model of early human societies. The polities modeled are composed of sedentary foragers and/or simple horticulturalists that rely upon basic subsistence technologies and display low levels of internal differentiation. World-systems theory’s iteration model integrates several processes of demographic regulation: environmental constraints, migration, intra-polity conflict, and inter-polity warfare. Computer simulation of this model reveals that different degrees of resource richness, land area, and initial population size have important effects on the average population levels and the behavior of interacting polities. A well-known ecological phenomenon, “the paradox of enrichment,” emerges when polities interact through warfare. Variations in the size and resources of local and regional areas, along with climatic variation, provide explanations of patterns of warfare in such systems. Finally, to make the iteration model compatible with other existing simulations of early human societal demographic regulation, we demonstrate that the ability of polities to regulate fertility has large consequences for both population sizes and inter-polity relations. A simulation of the world-systems iteration model would provide insights about how world-system dynamics produce selection pressures for the emergence of technological development, interpolity trade, and within-polity hierarchy, but these are subsequent steps. Our initial simulation holds technology and social organization constant in order to examine the demographic consequences of resource use and competition among polities for resources.