ABSTRACT
The Beginnings of Maize Agroecosystem Historically, seeds for a maize agroecosystem were sown 8,000 years ago, in the Pacific slopes of modern Mexican states. Obviously, human ingenuity, curiosity, and immediate necessity for food grains might have induced this event. Domestication, then selection for better traits were perhaps most crucial during initial stages of the development of a maize cropping zone around Mexican dwellings. Let us now delineate various historical facts authenticated using archeological samples, archaebotanical analysis, potteries, and physical effects found around pre-historic Mexican human settlements. Modern techniques like carbon dating of grain samples, inscriptions, and ancient literature have also contributed to better understanding of this topic. Firstly, maize is a native crop of Mesoamerica. Archeological evidences and genetic analysis suggest that maize was probably domesticated in Southern and Central Mexico some 8,000 years ago. The wild type or ancestor of domesticated maize called “Teosinte” (Euchlaena) is found abundantly in Central America. Primitive types of cultivated maize were derived from teosinte through repeated selection. Mexico and adjoining areas in Central America is considered the primary center of genetic diversity for maize. Carbon dating of archaeological remains such as maize cobs and grains found in Guila Naquitz caves and Oaxaca valley suggest that it was grown in Mexico some 6,250 years ago (Piperno and Flannery, 2001). Similarly, carbon isotope analyses of grains from Tehuacan in Peubla indicate that maize was cultivated during 2750 B.C. It seems by 1700 B.C. inhabitants of Tehuacan valley were regularly growing maize along with gourds and amaranth. Maize cultivation spread rapidly into several areas within Mesoamerica around 1500 B.C. It is believed that Guatemala served as conduit for adoption many of these strains of maize that entered Andean regions, Peru, Bolivia, and other parts of South America (Argentina, Chile). The initial appearance of maize in Peru has been dated to 6070 B.C. In South America, regular cultivation of maize was in vogue by 2500 B.C. Peruvians and other people in Andean highlands grew maize, potatoes, and gourds regularly during 2nd and 3rd millennium B.C. There is no doubt that maize agroecosystem that existed in its rudiments during pre-historic period was really confined to areas surrounding human settlements. Spread of maize cultivation into different locations within South America occurred gradually during Neolithic age. This is actually much after its initial domestication in Mesoamerica. Sculpted figures, folklore, and religious scripts of Mayan culture from 3rd to 9th century clearly prove the importance of maize to local population in Latin America (Jenkins, 2002). Next, the spread of maize cultivation into vast stretches of Northern Great Plain is said
to have caused perceptible changes in food habits, as well as soil and environmental parameters. It is said that during 1st millennium A.D. maize cultivation diffused into most of Southwestern USA and right up to Southern Canada. It did transform the landscape perceptibly. It mostly replaced forested zones with maize. Obviously, it must have generated a sort of upheavals in biomass and nutrient turnover in the landscape. Human migratory trends had a major impact on extent of spread of maize cropping zone into North American locations. Maize cultivation spread into farther regions in north, including Canada during 1st to 5th century A.D.
