One aspect of social stratification that the film illustrates is its arbitrariness. This is most apparent when Joaquin Phoenix's character, a war photographer, inquires about the tribal membership of two Rwandan women at his hotel bar. One identifies as Tutsi; the other identifies as Hutu. Phoenix's character confesses that he cannot tell them apart.
The division of the Hutus and the Tutsis into distinct groups—the latter with social and economic privilege, and the former without—was the product of Belgian colonial rule. Supposedly, Hutus and Tutsis could be distinguished based on certain physical characteristics. Hutus were said to have been darker and shorter, while Tutsis were said to be taller and lighter-skinned, or closer to European ideals of beauty. As a result of being the "favored" group, the Tutsis were granted rights and privileges that were not allocated to the Hutus. Many of them also enjoyed their loftier social position, which fostered resentment among Hutus. The stratification between Hutus and Tutsis was designed to oppress both groups, making it less likely that they would rise up against the Belgians.
After the collapse of colonial rule in what was formerly the Belgian Congo, Hutus seized power in a military junta and exacted revenge on the Tutsi population. They justified their victimization of Tutsis by dehumanizing them, referring to them as "cockroaches." Thus, social stratification between the groups devolved from one group supposedly being of superior humanity to another group not being at all human.
Whites in the film—including Phoenix's American correspondent, Nick Nolte's Canadian UN peacekeeper, and a French priest who runs an orphanage—occupy a complex position. They are outsiders who neither understand the genocidal conflict nor the world's indifference to it, but they are also privileged members of societies that have traditionally benefited from sectarian violence in Africa, as well as from the racism that planted the seeds of the conflict. What is ironic is that their whiteness—which gave them great power in colonial-era Africa—rendered them powerless in a post-colonial nation that was grappling with how to identify itself.