published: due to its bright green cover and influence, it has been nicknamed "The Green Bible". During the 1980s and 1990s he co-directed survey work at the Classic Maya site of Copán in Honduras. In 1985 he was elected to the National Academy of Sciences. Outside of the US, he also served as a Visiting Professor at the Instituto Nacional de Antropología e Historia, the National Autonomous University of Mexico and the National School of Anthropology and History in Mexico. Sanders' approach was influenced by cultural evolutionism, and laid particular stress on cultural ecology, emphasising the relationship between people and their surroundings, and seeking similarities in different cultures in their response to specific environmental conditions. As such, he saw the study of settlement patters in a society as key, and bound up the study of ecological and demographic developments. During his studies at Harvard, he developed the concept of the "central Mexican symbiotic region", referring to the network of symbiotic and mutually beneficial social and economic relationships that existed across a diversity of ecological zones in central Mexico prior to the Spanish conquest of the Aztec Empire. He argued that this area saw earlier and more acute urban development and state formation than other areas of Mexico, which he believed was the result of its physical geography: a semiarid climate which facilitated land clearance, variations in altitude meaning that it contained conditions suitable for growing maize, cotton and agave, and unpredictable levels of rainfall which spurred the development of irrigation and intensive agriculture. This in turn led to high population densities which could support more sophisticated agricultural techniques He died on July 2, 2008 in State College, Pennsylvania following a fall. References 1926 births 2008 deaths Historians of Mesoamerica Members of the United States National Academy of Sciences People from Patchogue, New York United States Navy personnel of World War II Harvard University alumni Pennsylvania State University staff 20th-century American anthropologists