Z. mays (maize) ultimately became the most important source of calories in Mesoamerica, particularly when combined with beans to create a critical protein source given the lack of animal protein. Maize is also the most visible cultigen in the paleoecological record. Molecular evidence puts the domestication of maize in the central Balsas of Mexico ∼7000 BC ( Matsuoka et al., 2002) and maize microfossils (starch and phytoliths) from Xihuatoxtal Shelter in this region indicate domestication, along with squash (likely

C. argyrosperma), by 6700 BC ( Piperno et al., 2009). BEZ235 Maize pollen and phytoliths in lake sediments and peri-coastal wetlands, suggest widespread dispersal through the lowland Neotropics of Mesoamerica between ∼5600 and 4500 BC ( Pope et al., 2001 and Pohl et al., 2007, Kennett et al.,

2010). The first appearance of maize pollen and phytoliths in paleoecological records from lakes and wetlands in the lowland Neotropics is coincident with increased charcoal flux, a reduction in tree pollen and the appearance of disturbance plant taxa (Jones, 1994, Pohl et al., 1996, Pope et al., 2001, Neff et al., 2006 and Kennett et al., 2010). Investments in niche construction (e.g., forest clearance; Smith, 2007) suggest that slash-and-burn farming contributed significantly to the diet (Kennett et al., 2010). This occurs by 5200 BC along the western periphery of the Maya region (Tabasco; CB-839 chemical structure Pope et al., 2001 and Pohl medroxyprogesterone et al., 2007) and is evident in the peri-coastal fringe of the eastern lowlands by 2000 BC (Pohl et al.,

1996). Slash-and-burn farming is well suited to the high net primary productivity and rapid regrowth of secondary forest in lowland tropical forests. The agricultural cycle tracks changes in rainfall linked to the position of the Inter-Tropical Convergence Zone (ITCZ; Haug et al., 2001). Forest plots are cleared and burned during the dry season (December–May) and maize is planted along with other crops (squash, gourd, pumpkin) just prior to the rains in May/June (Wilk, 1991). This primary crop is generally harvested in September. Second and even third crops can be planted in persistently moist soils along wetland margins or in relict river channels closer to the water table, and a mulching technique is sometimes used to produce a second crop in drier areas (matambre = hunger crop; Culleton, 2012) to hedge against potential shortfalls in the primary harvest. All of these techniques are methods of agricultural intensification that would be very hard to detect archeologically or within the paleoecological record. Long-term storage of grain is not an option in the Neotropics and cannot be used to reduce year-to-year variations in crop yield ( Webster, 1985). Dry conditions or unpredictable rains undermine food production. The Classic Maya also used a range of other crops and landesque cultivation systems (e.g.