31. Not only was Eurasia by chance blessed with biological abundance, but the very __________ of the continent greatly promoted the spread of crops between distant regions. When the supercontinent Pangea fragmented, it was torn apart along rifts that just so happened to leave Eurasia as a broad landmass running in an east-west direction - the entire continent stretches more than a third of the way around the world, but mostly within a relatively narrow range of latitudes. As it is the latitude on the Earth that largely determines the climate and length of the growing season, crops domesticated in one part of Eurasia can be transplanted across the continent with only minimal need for adaptation to the new locale. Thus wheat cultivation spread readily from the uplands of Turkey throughout Mesopotamia, to Europe, and all the way round to India, for example. The twin continents of the Americas, by contrast, lie in a north-south direction. Here, the spreading of crops originally domesticated in one region to another led to a much harder process of re-adapting the plant species to different growing conditions. [3점]
* fragment: 조각나다 ** rift: 갈라진 틈
① isolation ② orientation
③ diversity ④ conservation
⑤ instability