It is as true today as it was hundreds of years ago: hunger, political conflicts and violence can plunge a society into chaos. This fate also befell the Maya metropolis Mayapan. An important trigger for their collapse was probably the lack of rain.
The decline of the ancient Mayan capital Mayapan in the 13th and 14th centuries was probably largely caused by a long-lasting drought. This not only led to hunger, but also aggravated political conflicts, which in turn led to violent clashes, as an international research team reports in the journal "Nature Communications". The team emphasizes that understanding the complex connections between climatic and social developments is also essential with a view to current climate changes.
Mayapan was located on the Yucatán peninsula in present-day Mexico and was the political center of the Maya culture there between around 1100 and 1450. Influential noble families worked in the city, in the center of which numerous temples and pyramids were built. The 4.2 square kilometer area of Mayapan was surrounded by a 9.1 kilometer long wall. It demarcated the city from the outside and probably served to protect the residents. 12 gates directed visitors in and out of the city. About 15,000 to 20,000 people lived in Mayapan, tending orchards, growing corn or trading.
But the city has long been politically unstable and marked by conflict and declining population. The unrest reached its peak in the 15th century and eventually led to the city's decline. In order to understand the reasons for this, the interdisciplinary research team led by Douglas Kennett from the University of California examined indications of climatic changes, including by analyzing cave minerals, such as in stalagmites. The researchers looked for records of acts of violence in historical documents and examined human remains for signs of violence.
"By combining climate data with historical sources and archaeological finds, a surprisingly detailed picture emerges of the Maya society in Central America 800 years ago," explains co-author Norbert Marwan from the Potsdam Institute for Climate Impact Research (PIK). "And that shows that even then, a changing climate had a significant impact on human civilization."
The population of the city grew accordingly from the year 1100, with peaks in population density around 1200 and 1350. After that, the population shrank and around 1450 was only very small. The researchers also examined mass graves from different periods. In two graves from the late 14th century they found remains of numerous people who had died violent deaths and were buried with shattered pottery. Some of their bones had been chopped up and burned. The researchers interpret them as victims of conflicts between political groups. They found similar traces in another grave from after 1400.
The decline in population and the violent clashes came at a time when the data showed that there was a drought. "Our data show that institutional collapse is associated with drought and conflict within the city," the researchers write. The system was vulnerable due to the strong dependence of corn cultivation on rainfall. There were therefore hardly any possibilities for irrigation and no larger storage facilities for the grain. Conflicting interests of the politically leading families have exacerbated the problems.
Regarding current climate changes, the researchers point out that food insecurity, social unrest and drought-induced migration are already concerns in parts of Mexico and Central America. "Our transdisciplinary work highlights the importance of understanding the complex relationships between natural and social systems, particularly when assessing the role of climate change in exacerbating domestic tensions and factionalism in areas where drought is leading to food insecurity."