The spectre of social collapse is raised by economic crises, frustrated aspirations for increased prosperity and the growing realisation that we are facing unprecedented climatic shifts and related environmental impacts. End-of-the-world stories have gripped the imaginations of the public, and popularisations have made extensive but uncritical use of dramatic cases of past socio-ecological system ‘collapse’—warnings that have proved impossible to use in planning for future adaptive management and provide little effective material for the development of sustainability.
A major challenge is to develop scientifically valid approaches for comparison between detailed regional cases that can identify recurring or rare patterns in human ecodynamics; separate case-specific patterns of response and outcome from factors that seem to cross-cut local conditions; and provide a secure scientific basis for a global approach to the study of human ecodynamics on the millennial scale.
The Casa Grande ruins in the Sonoran desert of the south-western USA. This ‘Great House’ was built in the early fourteenth century, but has been abandoned for about 500 years. Radical transformations happened to the ancient culture of the Phoenix basin between the mid-fourteenth and mid-fifteenth century AD, at a similar time (but for very different reasons ) as the end of Norse settlement Greenland.
My Leverhulme Study Abroad Fellowship has enabled me to build on knowledge gained and links forged in previous research in the North Atlantic to develop new understanding of global human ecodynamics through the exchange of ideas, data and models with colleagues researching prehistoric societies of the south-western USA.
This connection has great potential because we are addressing similar questions of long-term human ecodynamics, resilience and transformation involving similar sized populations, over similar timescales, and utilising world-class empirical data sets. Crucially, there are also major contrasts in physical environments and human societies. Socio-ecological systems of medieval North Atlantic communities include provisioning systems based on domestic animals, the extensive utilisation of wild resources (such as birds, fish and marine mammals), iron tools, ships and the development of trade based on bulk commodities. Environmental stresses were delivered by cold, wet, storminess, disease and volcanic eruptions. The prehistoric south-western USA was radically different: subsistence, for example, was based on arable production; there were no domesticated mammals for eating, transport, labour or manure production; no access to marine resources; no iron tools and environmental stresses were most notably delivered by drought. This combination represents an outstanding opportunity to understand generic questions of resilience, change, environmental impacts and the long-term consequences of decision making. It also provides opportunities to identify early warning signals of threshold-crossing events. With long-term perspectives it is possible to say what happened next and search for evidence of critical slowing down (increasing recovery times after perturbations) and flickering between alternate states, phenomena known to be key indicators of approaching thresholds.
During my fellowship I have had great opportunities to discuss with colleagues in Iceland, New York, Arizona and Washington State, how decisions that develop rigidity, promote hierarchy, conformity or connectedness can determine the nature of subsequent change in the face of environmental or cultural stressors. The path dependencies resulting from choices are crucial and can only be assessed with a long (century-scale) time perspective that can track the consequences of different decisions, paths chosen and conjunctures. We are not Vikings or Neolithic farmers, but utilising both the North Atlantic and south-western USA cases provides a great opportunity to develop generic understandings of long-term human ecodynamics relevant to both understanding the past and planning for the future.
Professor Andy Dugmore
University of Edinburgh