“Not until the beginning of the 20th century did Europe's urban populations finally become self-sustaining: before then, constant immigration of healthy peasants from the countryside was necessary to make up for the constant deaths of city dwellers from crowd diseases.”

“We know from our recent history that English did not come to replace U.S. Indian languages merely because English sounded musical to Indians' ears. Instead, the replacement entailed English-speaking immigrants' killing most Indians by war, murder, and introduced diseases, and the surviving Indians' being pressured into adopting English, the new majority language.”

“It's striking that Native Americans evolved no devastating epidemic diseases to give to Europeans in return for the many devastating epidemic diseases that Indians received from the Old World.”

“(On the beginning of the mid-1990s' genocidal war in Rwanda:)Within six weeks, an estimated 800,000 Tutsi, representing about three-quarters of the Tutsi then remaining in Rwanda, or 11% of Rwanda's total population, had been killed.”

“...invokes the supposed stimulatory effects of their homeland's cold climate and the inhibitory effects of hot, humid, tropical climates on human creativity and energy. Perhaps the seasonally variable climate at hight latitudes poses more diverses challenges that does a seasonally constant tropical climate”

“In short, Europe’s colonization of Africa had nothing to do with differences between European and African peoples themselves, as white racists assume. Rather, it was due to accidents of geography and biogeography—in particular, to the continents’ different areas, axes, and suites of wild plant and animal species. That is, the different historical trajectories of Africa and Europe stem ultimately from differences in real estate.”

“One way to explain the complexity and unpredictability of historical systems, despite their ultimate determinacy, is to note that long chains of causation may separate final effects from ultimate causes lying outside the domain of that field of science.”