We present evidence that the intensity and endurance of civil wars and conflicts can depend on the social structures of the societies involved. More specifically we argue that ‘segmentary lineage societies’ will tend to experience conflict which is more violent, of larger scale and more enduring that societies which feature different types of kinship systems. We investigate this by coding for 145 African ethnic groups whether or not they were historically organized as segmentary lineages and show that indeed such groups are prone to conflict along these lines. We show that the results are robust to a number of potential confounders such as historical political centralization, the importance of Islam and contemporary development outcomes. We argue that the causal connection works through the fact that in a segmentary lineage society it is easier to mobilize fighters and solve the collective action problem. The argument can help to explain the incidence and nature of conflicts in
the Sahel and the Horn of Africa as well as the Middle East.