Endogenous change: on cooperation and water availability in two ancient societies

摘要

We propose and test the theory of endogenous change in societal institutions based on historical reconstruc-tions of two ancient civilizations, the Indus and Hohokam, in two water-scarce basins, the Indus Basin in the Indian sub-continent and the lower Colorado Basin in the southwestern United States. In our reconstructions, institutions are approx-imated by the scale of “cooperation”, be it in the form of the extent of trade, sophisticated irrigation networks, a central state or a loosely held state with a common cultural identity. We study changes in institutions brought about by changes in factors like rainfall, population density, and land-use-induced water resource availability, in a proximate manner. These fac-tors either change naturally or are changed by humans; in either case we contend that the changes affect the stability of cooperative structures over time. We relate the quantita-tive dimensions of water access by ancient populations to the co-evolution of water access and the socioeconomic and so-ciopolitical organizations. In doing so, we do not claim that water manipulation was the single most signi?cant factor in stimulating social development and complexity – this would be highly reductionist. Nonetheless, we provide a discussion with the aim to enhance our understanding of the complex-ity of coupled human–hydrological systems. We ?nd that scarcity triggered more complex cooperative arrangements in both Indus and Hohokam societies.