Rise and fall of city states tied to stormy weather

Changeable weather may have been a major force in the success and failure of agrarian states in Mexico and Peru, according to climate and archaeological records.

For a new study, researchers looked at climate records for central Mexico gleaned from a stalagmite collected from Juxtlahuaca Cave in the state of Guerrero. They also looked at the climate record preserved in the Quelccaya ice cape in the Cordillera Vilcanota portion of the Peruvian Andes.

In both cases the climate records are based on oxygen isotope measurements on datable layers of ice or stalagmite cave deposition and show annual changes in rainfall and temperature for 2,000 years in Mexico and 1,800 years in Peru.

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