Diamond recalls working at a farm owned by a Swiss man who had settled in America when he was a teenager. One of Diamond’s fellow farmhands was a Native American man named Levi, and Diamond had been surprised one day when he heard Levi drunkenly cursing the farmer. Up to this point, Diamond had believed what he and other white schoolchildren had been taught about the heroic conquest of the American West, yet he now perceived that Levi’s tribe of hunters and warriors had been robbed of its land. This reminiscence prompts the question of how European farmers managed to triumph over these warriors.

Diamond explains that, since the ancestors of modern humans diverged from the ancestors of great apes around seven million years ago, humans have, for the most part, fed themselves by hunting and gathering. It is only within the last 11,000 years that some have turned to food production. Crucially, food production was an indirect prerequisite for the production of guns, germs, and steel. Whether or not peoples on different continents became farmers and herders thus helps to explain the different development of their societies.

Agricultural societies prospered because the availability of more consumable calories led to a greater number of people within those societies.