垂直的文明 · CIVILIZATION GOES VERTICAL
An Empire Built Up a Staircase — South America · The Andes
安第斯山脉沿南美脊背绵延约 7,000 公里，是陆地上最长的山脉。印加人不与坡度为敌——他们在层层叠叠的气候带上耕作，用道路把约两百万平方公里连成一体，缔造了前哥伦布时代美洲最大的帝国。
沿安第斯山坡上行，你会像旅人穿越国度一样穿越气候带——低处种玉米，高些种土豆，近雪线便是放牧羊驼的草场。安第斯先民在此驯化了土豆，学会同时利用每一道海拔，于是一条山谷便能自给。印加人用数千公里的石砌道路，把这些垂直的世界串连起来。
The Andes run ~7,000 km down the spine of South America, the longest mountain range on land. The Inca didn't fight the slope — they farmed it in stacked climate zones and tied ~2 million km² together with roads, building the largest empire of the pre-Columbian Americas.
Go up an Andean slope and you pass through climates the way a traveller passes through countries — maize low down, potatoes higher, then pasture for llamas near the snow. Andean peoples domesticated the potato here and learned to use every band of altitude at once, so a single valley could feed itself. The Inca laced these vertical worlds together with thousands of kilometres of stone road.