Drought destroyed ancient civilizations 

Researchers analysed stable carbon isotopes in ancient barley grains from archaeological sites spanning between 10,000 and 500 BC in the region and found signs of several droughts that may have afflicted agricultural settlements there. 

“There may be some textual evidence saying the inhabitants of these sites were involved in a war with another city-state. But with the data on their agricultural background, we can more precisely define the parameters that led to either collapse or resilience of societies,” says Simone Riehl from the University of Tübingen, Germany, who led the research.

Riehl and her colleagues analysed the ratio values of stable carbon isotopes in barley grains from 33 archaeological and 13 modern sites that humans occupied at various periods. The ratio values of the carbon isotopes reflect times of reduced water availability and signal evidence of drought stress. 

The researchers found severe drought stress signals in barley grains extracted from the archaeological sites lying along the banks of Euphrates and Khabur rivers in addition to sites in northwestern and western Syria between 2,500 and 1,600 years ago. 

Faced with drought, local people grew grains using river-derived irrigation or cultivating grains that grew without irrigation. 

The results provide clues to how agricultural societies performed under fluctuating climatic conditions, which has implications for risk assessment in regions of endangered food security today, he adds. 

The study, according to Ellery Frahm from the University of Minnesota, US, provides “a new, millennia-spanning foundation for research that explores links between environment and society.” 

The drought stress, around 4,000 years ago, at Tell Mozan and other human settlements in Syria may have forced humans to abandon urban centres, eventually leading to the fall of the Akkadian empire, adds Frahm.  

The findings by Riehl and her colleagues published in PNAS¹ suggest that the historic climatic changes in the region forced people to invent new strategies to maintain agriculture and their economies. This may help better understand the ongoing crisis in war-torn Syria that was hit by a severe drought between 2007 and 2010² .

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