This argument is very popular in the evolutionary psychology world. They want us to know, to see, to believe that primitive people (and primitive people usually have brown skin) are, statistically speaking, more violent than civilized ones (people who tend to have white skin). The argument, which Diamond repeats in his new and generally bad book The World Until Yesterday, is that though each Tribal-level battle has low casualties, as a whole (meaning, at the expanded scale of a war), they have higher death rates than state-level (or formal) conflicts. As a consequence, primitive people are more violent than civilized people. Yes, the bombing of Hiroshima killed thousands people in space, but tribal people are far more destructive over time. This is the argument evolutionary psychology types draw so much satisfaction from for reasons that are essentially racist. And racist not because the claim is factually wrong or right (in both case it is really meaningless), but because the claim is there to begin with. The very presence of the claim, the need to make it, the fact that there is a social and political niche for its appearance to fill; the fact it can't go away, the fact of its insistence, and the fact that its related to other claims that are more obviously racist. You have to see the space, and not what appears, as the problem.