A Tunisian protester holds a baguette while taking to riot police in January 2011. Martin Bureau/AFP/Getty Images hide caption toggle caption Martin Bureau/AFP/Getty Images The Salt Can Riots Be Predicted? Experts Watch Food Prices October 2, 2012 High food prices have often been cited as a factor behind mass protest movements. But a group of researchers say food prices can actually be used to predict when social unrest will occur. And according to their mathematical modeling, we've hit the threshold for more waves of riots.