How did axis orientations of continents affect the success or non-success of human beings in various areas of the world, according to Guns, Germs, and Steel?
Diamond argues that Eurasia, which has the largest stretch of land oriented along an east-west axis of any landmass in the world, was more suited to the spread of agriculture than other landmasses. This is because regions along the same lines of latitude have similar climates. Domesticated crops that will do well in, say, Iran, will also do well in Portugal, because temperatures in the two areas are relatively similar. In North and South America, on the other hand, Mesoamerican domesticates had difficulty spreading into South America, because they had to spread through different climatic zones (like the Andes highlands, for example.) So Eurasian peoples had a major geographic advantage in terms of being able to develop agriculture.