Rafael Wittek: Resource competition and violent conflict Johnson and Earle 1987), does not incorporate the crucial variables of the other two perspectives. None of them takes into consideration that different types of social orga- nization may solve the problem of scarcity in different ways. This one-dimensional point of view has still another consequence, as it obscures the fact that causal relation- ships may exist between the central variables of the different approaches. If this should be the case, statistical tests denying this fact may easily produce false correlations or may even be unable to unmask existing ones. Technically spoken, a distinction has to be drawn between (1) the causal relation- ships of the independent variables pertaining to the three approaches, and (2) the cau- sal effect these independent variables have on violent conflict. Causal relationships between the independent variables The central independent variables of the three approaches are population density, food Stress and social stratification (see Table 1). A bundle of hypotheses exists about the causal relationships between them, which will be briefly discussed below. Table 1. Independent variables SCCS Variable Quellen Source 64 Population density 1 = 1 per 5 sqm 5 = 26-100 Murdock & Wilson 1972 (persons per sqm) 2=1per1-5sqm 6 = 101-500 3 = 1-5 7 = over 500 4 = 1-25 678 Food stress 1 = food constant Sanday 1981 2 = occasional hunger 3 = periodic or chronic hunger 4 = starvation 270 Class stratification 1 = absence among free men Murdock 1967 2 = wealth distinctions 3 = elite 4 — dual (hereditary aristocracy) 5 — complex (social classes) Population density and social stratification. Among evolutionary theorists it is a com- monly shared view that rising population densities lead to social stratification (Johnson and Earle 1987: 16-18; Dumond 1972; McNetting 1972: 235; Hammel and Howell 1987: 147). According to these studies, population growth, which is viewed to ? an inherent trait of human und animal populations alike, causes population pres- Sure. Human societies face this situation by intensifying their production. This allows the generation of surplus, which is the basis of stratification. A positive relationship tween the two variables can be expected even if rising population densities are not Valid as a measure of scarcity, as suggested by some scholars.* According to a hypothe- ee * For à more lengthy discussion of this topic see Wittek 1990: 56-58.