Its east–west major axis permitted many inventions adopted in one part of Eurasia to spread relatively rapidly to societies at similar latitudes and climates elsewhere in Eurasia. Its breadth along its minor axis (north–south) contrasts with the Americas’ narrowness at the Isthmus of Panama.
Even within Eurasia, there are North-South differences. India, for instance, is aligned primarily along longitude, not latitude. If environmental differences can account for a large portion of the variance between civilisations and societies, then we should see those effects in India. Do we? Is there variation between North and South India with regards to adoption of food production, writing, pottery, etc? Did South Indian societies change from hunting-gathering to agriculture later than those in the North? How did crops spread from North to South if the weather and climate conditions are so different?
