Deforestation would have caused a decrease in crop yields due to soil erosion, loss of wood as a resource to construct fishing boats, among other things, and would have necessitated a halt to the construction of the moai erected around the island. Diamond hypothesizes that resource scarcity may have led to brutal civil war, creating a drop in population. He further hypothesizes that there were about 7,000 individuals pre-war, a number which fell to the 2,000 whom missionaries met when they showed up in the 19th century and conducted the first census of the island.