Credit: Mark Robinson
Ancient Amazonian communities fortified valuable land they had spent years making fertile to protect it from conflict, excavations show.
Farmers in Bolivia constructed wooden defences around previously nutrient-poor tropical soils they had enriched over generations to keep them safe during times of social unrest.
These long-term soil management strategies allowed Amazonians to grow nutrient demanding crops, such as maize and manioc and fruiting trees, and this was key to community subsistence. These Amazonian Dark Earths, or Terra Preta, were created through burning, mulching, and the deposition of organic waste.
It was known that some communities built ditches and embankments, known locally as a zanja, around their settlements, which had suggested to act as a defensive structure. The examples from Bolivia were specifically constructed to also enclose the enriched soil and this is the first evidence of an additional fortification built in the ditch, demonstrating how important communities felt it was to protect their investment in the land.