Guns, Germs, and Steel | Study Guide

Jared Diamond

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Guns, Germs, and Steel | Part 2, Chapter 10 : The Rise and Spread of Food Production (Spacious Skies and Tilted Axes) | Summary



Diamond begins Chapter 10 by comparing the major axes of the continents. While the Americas and Africa are mostly on a north-south orientation, the Eurasian continent is longest on its east-west axis. This is important because if only a few regions developed agriculture based on geographic factors, the transport of the practice of agriculture was also shaped by geographic features. For example, it appears that in the Americas, many of the founder crops had multiple origination points, while in the Middle East, the cultivation of peas came from a single source. This shows the agricultural development in Mesoamerica was a local, geographically limited affair, while in the Middle East, a single development could very quickly spread over the entire region.

Crops from the Fertile Crescent spread very quickly across western Asia into Europe and parts of Africa. This rapid pace of expansion was because of Eurasia's east-west continent axis. Locations on the same latitude share the same seasons and the same hours of the day, and they also tend to have similar climates, rainfall, biomes, and habitats. For example, Portugal, northern Iran, and Japan all have similar climates, although they span the east-west extremes of the continent. Imagine trying to go north-south and growing Mexican corn in Canada; the plants would not survive the harsh winters and short growing seasons. By 2,000 years ago, Fertile Crescent crops dominated food production "from the Atlantic coast of Ireland to the Pacific coast of Japan." The ease of east-west travel for crops is also true for livestock and animals.

Diamond next compares this ease of transport with conditions in Africa and the Americas. While some crops and livestock were successfully used in North Africa and Ethiopia, none could breach the tropical jungles of sub-Saharan Africa to reach the more temperate zones in South Africa. In the Americas only a few crops, such as Mexican corn, spread to other regions; llamas, sunflower seeds, and other crops and animals were not brought out of their local origination sites. There were climatic and geographic variations within all of these examples, but the dramatic changes along north-south continental axes were at times insurmountable. This was true for other types of knowledge and technology transfer as well. For example, the wheels and writing developed in Mesoamerica never reached the Andes. As Diamond concludes, "No waves of native grain ever stretched from the Atlantic to the Pacific coast of North America, from Canada to Patagonia, or from Egypt to South Africa, while amber waves of wheat and barley came to stretch from the Atlantic to the Pacific across the spacious skies of Eurasia."


Chapter 10 is a crucial chapter in Diamond's overall argumentative picture. Indeed, the spatial axes of the continents can be considered the defining insight of Diamond's study. Why did the Spanish defeat the Incas at Cajamarca? While the Incas were not able to share their insights, inventions, crops, and animals with Mesoamerican societies because of geographic barriers, the people of the Iberian Peninsula benefited from millennia of exchanging plants, animals, and information, which was only made possible because of the latitudinal and geographic similarities with other, more developed parts of the Eurasian continent.

This chapter concludes the second part of the book, in which Diamond almost exclusively focuses on prehistory and geographic and botanical factors. In the next section, Diamond shows how the plant and animal husbandry he discusses in the first section go on to immediately cause the creation of the "guns, germs, and steel" that made conquest possible and had dramatic impacts for human societies on all parts of the globe.

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