In international relations, unlike the natural sciences, there are few fundamental principles or laws. The world map, however, reveals at least one iron law of global politics: human territoriality. Almost every inch of the globe is partitioned into exclusive and bounded spaces that “belong” to specific groups of humans. Any that is not—such as Kashmir, Jerusalem, and the South China Sea—remains hotly contested. Throughout history, territory has led to recurrent and severe conflict. States are prepared to go to war, and individuals are prepared to die, even over land with little intrinsic value. While such behavior presents a puzzle for international relations theory, a broader evolutionary perspective reveals that territorial behavior has the following three characteristics: (1) it is common across the animal kingdom, suggesting a convergent solution to a common strategic problem; (2) it is a dominant strategy in the “hawk-dove” game of evolutionary game theory (under certain well-defined conditions); and (3) it follows a strategic logic, but one calibrated to cost-benefit ratios that prevailed in our evolutionary past, not those of the present. These insights generate novel predictions about when territorial conflict is more or less likely to occur in international relations.

Since 1990, negotiated settlements have become the preferred means for settling civil wars. Historically, however, these types of settlements have proven largely ineffective: civil wars ended by negotiated settlement are more likely to recur than those ending in victory by one side or the other. A theoretical and statistical analysis of how civil wars end reveals that the type of ending influences the prospects for longer-term outcomes. An examination of all civil war endings since 1940 finds that rebel victories are more likely to secure the peace than are negotiated settlements. A statistical analysis of civil wars from 1940 to 2002 and the case of Uganda illustrate why rebel victories result in more stable outcomes. Expanding scholarly and policy analysis of civil war termination types beyond the current default of negotiated settlement to include victories provides a much larger set of cases and variables to draw upon to enhance understanding of the conditions most likely to support long-term stability, democracy, and prosperity.

From 1940 to 2000, Islam was involved in a disproportionately high number of civil wars compared with other religions, such as Christianity or Hinduism. To help explain the overrepresentation of Islam in these wars, this article introduces a theory of “religious outbidding.” The theory holds that embattled political elites will tender religious bids when they calculate that increasing their religious legitimacy will strengthen their chances of survival. In combination with three overlapping factors—the historical absence of an internecine religious civil war similar to the Thirty Years’ War in Europe, proximity of Islam's holiest sites to Israel and large petroleum reserves, and jihad (i.e., defense of Islam as a religious obligation), religious outbidding accounts for Islam's higher representation in religious civil wars. The article includes a statistical analysis of the role of religion in civil wars and tests the logic of the argument of religious outbidding in the case of Sudan's two civil wars.