Chinese Cave Graffiti Agrees With Site's Drought Ev

This is Scientific American 60-Second Science. I'm Cynthia Graber.Got a minute?
Historical instances of dramatic societal upheaval have been attributed to changes in climate.
Now a cave in China has been shown to contain both physical evidence for specific periods of drought and written records of the hardships, in the form of graffiti by people suffering from those droughts.
The findings are in the journal Scientific Reports.
During the past 500 years, people made regular pilgrimages to the Dayu Cave in the Qinling Mountains of central China.
During seven of the visits, the oldest one going back to the year 1520, pilgrims left messages on the cave walls related to droughts.
Researchers were able to link those graffiti, which contain dates, to physical evidence of the water shortages.
For example, lack of water caused changes in ratios of stable isotopes in specific layers of cave formations, such as stalagmites.
The site has thus provided the first known case of historical and geological records existing in the same cave.
Cambridge University earth scientist Sebastian Breitenbach is a co-author of the study.
He says that records found in caves and lakes in the last decade reveal possible links between climate change and the downfall of several Chinese dynasties, including the Tang and Ming.
He also notes, "Things in the world are different from when these cave inscriptions were written,
but we're still vulnerable to these events, especially in the developing world."
Thanks for the minute, for Scientific American 60-Second Science. I'm Cynthia Graber.