It is puzzling that societies, which reached such a high level of development, have disappeared suddenly. It has been argued that overexploitation of environmental resources has played a role in causing the collapse of such societies. In this paper we propose an explanation for the pattern that overexploitation seems more common in ancient societies that built larger structures.

This explanation is based on the well-studied sunk cost effect in human decision making: Decisions are often based on past investments rather than expected future returns. This leads to a tendency not to abandon something (e.g. settlements) if much has been invested in it, even if perspectives are dim. Empirical examination suggests that sunk-cost effects leading to similar declines in resiliency are visible in the histories of prehispanic Puebloan societies.

A stylised model is used to illustrate under which condition collapse of societies can be expected. Finally, we discuss the consequences of these insights for current societies.

About Marco Janssen
Marco Janssen is presently at the Dept of Spatial Economics, Vrije Universiteit Amsterdam but will as of February 2002 start a position in Indiana, USA at the Center for the study of institutions, populations and environmental change. Dr Janssen is also on the board of the Resilience Alliance.