The collapse of Classic Maya civilization in the Central Maya Lowlands and the disappearance of 90 percent of its population in the ninth century A.D. has been attributed to many causes: drought, epidemic, even a peasant revolt.

New research based on a multidisciplinary analysis of the Maya shows that only by looking at the interactions of the complex systems the Mayans were part of -- such as climate, trade, and agriculture -- do clues to the real history emerge.

Read the paper in PNAS (August 20, 2012, subscription required for full paper)

“There is no monolithic period of collapse but a lot of variability,” says co-author Jerry Sabloff, President of the Santa Fe Institute. “What we see are many variable patterns. The only way to explain the variability is to take a complex systems view.”

Sabloff and Arizona State University geographer B. L. Turner have woven together a complex, data-rich history of agricultural practices in the lowlands and the demands on ecosystem services that created a stressed environment that was ripe for trouble when one particular drought struck.

On top of that, overland trade routes had shifted to sea routes around the peninsula, isolating the interior cities. All these stresses led to conflicts, loss of control by the Mayan elite, and, ultimately, decisions by peasants to leave the Central Lowland cities and relocate on the coast or in the Northern Lowlands, where Maya civilization continued to flourish.

The analysis, published Aug. 20 in the Proceedings of the National Academy of Sciences, is in sharp contrast with theories that put most of the blame on individual, catastrophic drivers of change. In recent years, for example, many archaeologists have renewed their interest in the drought hypothesis, says Sabloff. That interest has been fueled by more and better paleoclimate data from the region. What that data show, however, is not a simple drought/collapse relationship, he says. Even cities that were water-rich, like Palenque, collapsed.

“It is true that we go through moments when certain drivers are emphasized much more than others,” agrees Turner. “But collapse of the Classic Maya is sometimes simplified to the point of misunderstanding.”

Adds Sabloff: “Understanding the complex cultural and environmental interactions that led to the decline in one key part of the Maya Lowlands and a flourishing in other parts clearly cannot solve modern-day problems, but we hope it can provide a useful context for today’s policymakers and planners as they grapple with similarly complex interactions.”

Read the Phys.org article (August 21, 2012)

Read the Arizona State University news release (August 21, 2012)