The Fields Under the Forest

[A] Large parts of the Amazon basin were long described as untouched, on the reasonable ground that the soil is poor and could not have supported a dense population. The reasoning was sound and the premise was wrong. Scattered through the forest are patches of dark, fertile earth, metres deep in places, containing charcoal, broken pottery, fish bones and the residues of household waste, and still farmed today by people who value them above anything else nearby. [B]

[C] These patches were made, not found. Charcoal from low, smouldering fires holds nutrients in the soil instead of releasing them, and repeated additions of waste over centuries built a medium that still outproduces the surrounding ground today. [D] The finding does not by itself prove a large population, since a small one could in principle have worked the same plots for a very long time. What settles the matter is the arrangement: the patches occur where settlements would be expected, along rivers and at junctions, and they thin out where nobody would have lived. The forest, on this reading, is not a wilderness that people happened to enter but the overgrown surface of a landscape that was cleared, farmed and eventually abandoned, and the trees that make it look untouched are part of what the abandonment produced.