CHILE: The enormous carved heads known as moai are the most recognizable monuments created by the Polynesian civilization that settled Rapa Nui (Easter Island) around A.D. 1000. It turns out the sculptures were also instrumental in boosting agricultural productivity there. Analysis of soil samples taken near the island’s main quarry indicates that quarrying activity caused phosphorous and other beneficial substances to enrich the adjacent slopes. This allowed the Rapa Nui settlers to grow sweet potatoes, bananas, and taro there, even when conditions were less favorable elsewhere on the island.