Dozens of countries have suffered through civil conflicts in the past few decades. The humanitarian consequences have been staggering: 3 million civilian deaths in Congo and hundreds of thousands more in Rwanda, Sierra Leone, and Sudan. The direct human impacts for survivors are enormous, and there may be lasting economic setbacks for whole societies.

Likewise, the regional spillover effects are devastating for neighboring countries faced with refugees, lawlessness on their borders, and the illicit trade in drugs and arms that often proliferate in conflict zones.

But what causes this instability, and what can be done about it? Recent research shows…