<< News >> Smithsonian scientists connect climate change, origins of agriculture in Mexico
Submitted by coldrum on Thursday, 21 June 2007 Page Views: 943
Pre-ContactNew charcoal and plant microfossil evidence from Mexico’s Central Balsas valley links a pivotal cultural shift, crop domestication in the New World, to local and regional environmental history.Agriculture in the Balsas valley originated and diversified during the warm, wet, postglacial period following the much cooler and drier climate in the final phases of the last ice age. A significant dry period appears to have occurred at the same time as the major dry episode associated with the collapse of Mayan civilization, Smithsonian researchers and colleagues report in the Proceedings of the National Academy of Sciences online.
The Balsas valley is one of the most likely sites for the domestication of corn (Zea mays) from its wild ancestor, teosinte (Zea mays ssp. parviglumis) because populations of modern teosinte from that region are genetically closest to maize. As the lakes formed beginning around 10,000 B.P., they became magnets for human populations who exploited the fertile soils and rich aquatic resources the lakes contained. The researchers found prehistoric pottery sherds and other artifacts in sediments at the edges of the lakes. At one lake, phytolith data shows that maize and squash were probably planted at the fertile edges by 8000 B.P. Pollen from teosinte is indistinguishable from that of maize, but Zea pollen is consistently present in the cores since the end of the last ice age.
Pollen and phytoliths from weeds associated with crop plants become plentiful in the cores at roughly 6300 B.P Charcoal associated with agricultural burning practices also is abundant at that time. Between 1800 B.P. and 900 B.P., a major drying event occurred, corresponding to the time when a drought occurred in the region of the Classic Mayan civilization.
For more, see Eureka Alert.
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