The civil war begins at the same time there are changes in the diet. The Island's bird life seems to have disappeared as does evidence of people eating porpoise and tuna. The wood carvings were made by starving people. Had the population overexploited natural resources? It seems there is a simpler answer - the felling of the last tree.
A parable for the world?
John Flenley's studies of pollen from lakebeds shows Easter Island was once covered with palms. Yet the Dutch in 1722 described an island without trees. The disappearance of tree pollen coincides with the civil war. The society relied on wood to make canoes. Treeless, their ability to fish for food was limited.