History unfortunately does repeat itself.
Two thousand years ago the Romans laid siege to Carthage, killing more than half of the city's residents and enslaving the rest.
Hitler attempted to annihilate the Jews in Europe. In 1994 the Hutus turned on the Tutsis in Rwanda. The Khmer Rouge killed a quarter of Cambodia's population. After the breakup of Yugoslavia, Serbs slaughtered thousands of Bosnians at Srebrenica in July of 1995.
Last year when Buddhists attacked Rohingya Muslims in Myanmar many people were shocked to hear that mass killings still occur in the 21st century. But they do – and there's growing evidence that these events follow familiar patterns. And if they do, we should be able to see them coming.
"Genocides are not spontaneous," says Jill Savitt, acting director of the Simon-Skjodt Center for the Prevention of Genocide at the U.S. Holocaust Memorial Museum in Washington, D.C. "In the lead-up to these types of crimes we do see a consistent set of things happening."
Since 2014 the Holocaust Museum along with scholars from Dartmouth have mapped the conditions that precede a genocide. They built a database of every mass killing since World War II. Then they went back and looked at the conditions in the countries where the killings occurred just prior to the attacks. And now they use that computer model to analyze which nations currently are at greatest risk.