agriculture in Mesoamerica and in the Andes, giving a long timeline for the human-wrought changes in the environment before the arrival of the Europeans. William Denevan specifically argued against the "pristine myth" of lack of human impact on the environment prior to 1492. Indigenous land use before European contact Environmental historians have been criticized for what is called “recentism,” that is examining twentieth-century environmental issues. Works by archeologists and historians focusing on the colonial era in Latin America (1492-1825), which were not called “environmental history” at the time, are a rejoinder to that criticism. Human activity shaped the environment of Latin America long before the arrival of Europeans in the late 1400s. In central Mexico and the highland Andes, settled indigenous civilizations were created because indigenous groups could produce agricultural surpluses of native carbohydrates, maize and potatoes. These surpluses allowed for social differentiation and hierarchy, large settlements with monumental architecture, and political states that could demand labor and tribute from growing populations. There was significant altering of the natural landscape in order to create more arable and productive land. Agriculture in Mesoamerica (the region of central and southern Mexico and Central America), was characterized by intensive agricultural methods to boost their food production and give them a competitive advantage over less skillful peoples. These intensive agricultural methods included canals, terracing, raised fields, ridged fields, chinampas, the use of human feces as fertilizer, seasonal swamps or bajos, using muck from the bajos to create fertile fields, dikes, dams, irrigation, water reservoirs, several types of water storage systems, hydraulic systems, swamp reclamation, swidden systems, and other agricultural techniques that have not yet been fully understood. Maize was the center of the indigenous diet. Environmental factors are now considered crucial in the “collapse” when monumental architecture ceased to be erected in the southern Maya region. Deforestation was caused by human activity. Drought might have been a factor arising from the deforestation. By the time Spaniards began exploring Central America in the early sixteenth century, there were 600 years of jungle growth and only ruins of the monumental structures, but the human populations persisted in smaller numbers and scattered settlements, practicing subsistence agriculture. These decreased Maya populations proved more resistant to European conquest and consolidation than the their conquest of the Aztec Empire. The Maya people did not disappear, but adapted often more sustainably to nature. In the Andes, terracing of steep hillsides brought