The drought theory is still controversial among some archeologists who believe a combination of overpopulation, an internecine struggle for control among the nobles, a weak economic base, and a political system that didn't foster power-sharing led to the Maya's collapse. One hypothesis suggests the Maya people themselves were responsible for their downfall as a result of environmental degradation, including deforestation.
Defenders of the climate change theory, however, say the droughts sparked a chain of events that led to the demise of the Maya. "Sunny days, in and of themselves, don't kill people," said Richardson B. Gill, author of The Great Maya Droughts: Water, Life, and Death. "But when people run out of food and water, they die."
Living on the Edge
In their twilight days, the Maya were a society in deep trouble, according to the authors of the new study. Densely populated cities strained resources. Agricultural production became crucial in order to feed the people. "They were living on the absolute edge," said Hoag.
While the Maya had learned to live with shorter droughts, the study indicates that a more subtle, long-term drying trend was ongoing during the collapse. The three specific droughts may have been what pushed the Mayan society over the edge.
"Not only did the Maya have to face an intense climatic catastrophe, but the duration was something that they had never experienced before," said Hoag. "If they had stayed for another two years, they may have survived. But how could they know that the drought would end?"
Learning from the Past
Other human societies have succumbed to climate swings. In Mesopotamia, a canal-supported agricultural society collapsed after a severe 200-year drought about 3,400 years ago. With wetter conditions, civilizations thrived in the Mediterranean, Egypt, and West Asia. Ten years after their economic peak in 2,300 B.C., however, catastrophic droughts and cooling hurt agricultural production and caused regional collapse.
Other societies, however, have survived past climate changes by changing their behavior in response to environmental change. About 300 years after the Mayan collapse, the Chumash people on California's Channel Islands survived severe droughts by transforming themselves from hunter-gatherers into traders.
Experts say the Maya collapse could serve as a valuable lesson today to societies in Africa and elsewhere that are vulnerable to droughts. When droughts strike, they can trigger a chain reaction beginning with crop failures, leading to malnutrition, increased disease and competition for resources, and ultimately causing warfare between nations and sociopolitical upheaval.
"We can handle climate change if we're prepared for it," said Hoag. "The Maya were not prepared."
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