Understanding long-term human ecodynamics through the lens of ecosystem collapse

Most research on long-term human ecodynamics examines changes in the size and structure of human populations, often in relation to climate change. Here we offer an alternative perspective that draws on recent progress in conservation science, examining the causes and consequences of ecosystem collapse. We identify human actions that can cause abrupt transformation of ecosystems, in relation to key mechanisms and underlying theory. Such ecosystem collapse can in turn affect human societies by altering flows of ecosystem benefits to people. In this way, human ecodynamics can be understood by separately analysing the dynamics of social and ecological sub-systems, which are reciprocally linked. Ecosystem collapse represents a perturbation of these sub-systems, and provides insights into the mechanisms underlying their respective dynamics. We illustrate this approach through four case studies, which examine the spread of agriculture during the Holocene. Four key knowledge gaps emerge through consideration of these case studies: the linkages between social and ecological sub-systems, and how these change over time; the presence of feedbacks between these sub-systems; the relationships between local- and regional-scale collapse; and the relationships with ecological recovery. Increased research on ecosystem collapse could help clarify the relative influence of environmental degradation on societal dynamics, while providing insights into resilience and sustainability. Given the outstanding societal importance of ecosystem collapse, such research could also strengthen the relevance of historical sciences to the contemporary world.