Papua New Guinea (PNG) has been the site of a great deal of scientific work, and a fair amount of interdisciplinary debate, within the broad field of historical ecology, which encompasses the study of indigenous society-environment relationships over different time periods. However, this in itself provides no guarantee that scientists engaged in such debate will have a greater influence on the formulation of environmental conservation policies in a state where indigenous decision makers now hold the levers of political power. Five environmental policy paradigms which have emerged in the course of public debate about environmental conservation in PNG over the past half century; the wildlife management, environmental planning, biodiversity conservation, ecosystem assessment, and carbon sequestration paradigms. Each paradigm has framed a distinctive form of interdisciplinary debate about indigenous society-environment relationships within a contemporary political framework. However, a further connection can be drawn between the role of interdisciplinary debate in an evolving national policy framework and the history of scientific debate about the nature of indigenous society-environment relationships in the pre-colonial era. This connection places a distinctive emphasis on the relationship between indigenous agricultural practices and management of the national forest estate for reasons which are themselves a contingent effect of the nature of European colonial intervention over the course of the last century and a half. This particular bias in the relationship between historical ecology and environmental policy has lasted down to the present day. PNG's environmental policy problems are unlikely to have any rational or sensible solution in the absence of a better scientific understanding of the complexity of indigenous society-environment relationships. Scientists need to understand the complexity of the environmental policy process as a historical process in its own right in order to work out which policy problems offer both the scope and the incentive to sustain specific forms of interdisciplinary debate that are likely to produce better policy outcomes.