(This is a guest post by Gary Feinman)
Published in the journal Science, Medina-Elizalde and Rohling’s (2012) quantitative analysis of Terminal Classic period Maya (AD 800-1000) climatic shifts is a welcome refinement of the extent of a late 1st millennium episode of climatic change. Yet the authors' speculations regarding the fall of inland Maya settlements (the so-called Maya Collapse) is fraught with failures in logic and limitations in hypothesis evaluation that too often are characteristic of natural scientists delving naively into the causes and complexities of societal change. Even more problematic is the repeated license given by one of the world’s premier science journals to this kind of disciplinary overreach at a time when extremely few articles by archaeologists are offered this broadly visible platform.
Medina-Elizalde and Rohling begin with the premise that drought precipitated the collapse of these inland centers. But, when finding precipitation declines of only 40%, they do not reconsider their presumed causality, instead inferring that the Maya polities were so fragile that even the estimated rainfall declines were enough to generate collapse. These findings then underpin their policy warning that even minor climatic shifts may fatally endanger contemporary states facing present climatic shifts.
Left entirely unconsidered in their historical reconstructions of causality are the numerous other factors, from warfare to shifts in pan-Mesoamerican exchange patterns, that have been advanced as keys to the fall of the Classic Maya states. The consideration, evaluation, and elimination of alternative hypotheses are central to truly scientific inquiry, and their absence from this work only reinforces the preconceived bias that the prehispanic Maya were not sufficiently ingenious to respond to natural environmental fluctuations. It is crucial to recognize that Maya polities in northern Yucatán and coastal Belize, some of the driest parts of the Maya domain, thrived during and after the decline of inland settlements and populations.
Also problematic are the advanced policy implications. While I share concerns about anthropogenic environmental and climatic changes that hazard the modern world, the authors’ perspectives view humans as incapable of forging effective responses to external perturbations. And yet, those of us dedicated to understanding our species’ history recognize that we have repeatedly established cooperative networks at various scales to address and forestall similar challenges. If modern societies fail and fall, the responsibilities will be borne in part by our cooperative, competitive, and leadership networks and arrangements rather than merely the consequence of declines in rainfall.
At its current best, contemporary archaeological practice strives for serious evaluations of the causes and consequences of social actions and change. Repeatedly we have seen that through history rarely have climatic perturbations alone been both the proximate and ultimate causes of significant shifts in human settlement and catastrophic upheavals in political organization (e.g., Middleton 2012). Given the problems faced by our species today, the publishers of Science ought to lend their weighty profile and give greater voice to those of us endeavoring to understand the repertoire of behaviors that humans and their social groupings have derived and innovated to address the suite of challenges that they have faced. Many of those historical episodes may bear key insights for addressing the hazards and challenges that we as a species and a society face today.
Medina-Elizalde, Martín, and Eelco J. Rohling
2012 Collapse of Classic Maya Civilization related to modest reduction in precipitation. Science 335:956-959.
Middleton, Guy D.
2012 Nothing lasts forever: environmental discourses on the collapse of past societies. Journal of Archaeological Research 20. In press (available online).
Gary M. Feinman
The Field Museum