Decline of Early Mesoamericans Due to Climate Change

The drastic decline of a group of early Mesoamericans from the region around Canton was due, at least in part, to climate change, according to a new study.

Cantona was one of the largest cities in pre-Columbian Mesoamerica, located near present-day Mexico City, with a population of 90,000 inhabitants. And by 1150 AD, this population was completely wiped out, and researchers are just beginning to understand why.

Described in the journal Proceedings of the National Academy of Sciences, researchers discovered evidence of a drought in the Cantona region between 500 and 1150 AD, around the same time the early Mesoamericans were wiped out.

"We found that Cantona's population grew in the initial phases of the drought, but by 1050 AD long-term environmental stress (the drought) contributed to the city's abandonment," researcher Susan Zimmerman, of the Lawrence Livermore National Laboratory, said in a statement. "Our research highlights the interplay of environmental and political factors in past human responses to climate change."

In order to figure out what the climate was around this time, researchers studied sediment samples from a nearby crater lake called Aljojuca, focusing on cores in the last 3,800 years (even though the cores cover the last 6,200 years). From these samples, they analyzed pollen, stable isotopes, and elemental concentrations, all which serve as proxies of past climatic and environmental conditions. Then, after radiocarbon dating and age models, they found evidence of a centennial-scale arid interval between 500 and 1150 AD.

So while past climate change events such as this drying period aren't entirely to blame for the downfall of the early Mesoamericans from the Cantona region, this study indicates that it at least played an important part.

"Our results suggest that climate change played a contributing role in the site's history," Zimmerman concluded.

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