Did climate change cause these ancient civilizations to collapse?

“Droughts didn't always impact societies in the past,” says archaeologist Kyle Bocinsky, one of the authors of the study. “There were plenty of times in which the Pueblo people did just fine in the face of pretty dramatic climate downturns. But we also found that a combination of social organization, inequality and climate change did prompt revolutions in Pueblo society, and not just once, but four times in the Pueblo past between 8500 and 1400.”  http://www.globalpost.com/article/6764863/2016/04/24/did-climate-change-cause-these-ancient-civilizations-collapse
Article courtesy of the Global Post by Elizabeth Stockman and Alexa Lim