Maize origin and diversity

Maize is the cereal of the peoples and cultures in the American continent. The most ancient civilizations in America –from the Olmecs and Teotihuacans in Mesoamerica to the Incas and Quechuans in the Andean region of South America- flourished accompanied with this plant. This link between culture and agriculture had motivated the humanists and scientists to ask: which is the origin of this cereal? How was the evolution of maize once the different human groups adopted and cultivated it for their own profit? These questions had led them to explore the past, and nowadays -thanks to the technological and scientific development- led them to unravel several enigmas which surround the domestication of this crop. Although not all the details that allow us to explain its origin and domestication had been found, the scientists reached a consensus: the direct ancestor of maize is the teosinte. Nevertheless, during more than 70 years and before reaching such conclusion, there was a deep debate which contributed to the advancement of knowledge in several areas of the scientific endeavor. So is it that some of the greatest scientists of the 20th century studied maize, its origins and diversification. For example, in 1983 the American researcher Barbara McClintock was awarded the Nobel Prize in Physiology due to her discovery of the mobile genetic elements1 in the chromosomes of maize. Maize is the cereal which has had more importance in the economy sector worldwide during all the 20th century and the beginning of the 21st. In the industrialized countries, maize is mainly used as forage, raw material for the production of processed foods and, recently, for ethanol production. On the other hand, in some Latin American countries and increasingly more in Africa, a great percentage of maize produced or imported is used for human consumption. In this sense, maize had been and still is a key factor for the survival of farmers and indigenous people who live in most of the countries of the American continent. It is paradoxical that, even with each time less and less economic resources allocated for the inhabitants of the poorest communities, they are the stewards of maize diversity. Such situation is putting at risk valuable seeds: the researches and studies conducted throughout several years from the point of view of scientific and humanistic disciplines, have proved that the role of the farmer is of uttermost importance for the preservation and diversification of maize. However, the research and development programs for in situ conservation of maize are very restricted and had not been generalized to important regions with great concentration of ethnic and farming groups. Nowadays, keeping maize germplasm banks, or ex situ conservation, is the dominant strategy because it is linked to the technological path of the developed countries and also because the in situ conservation in several less developed countries is not supported due to financial restrictions. It is foreseen that within a few years, the lack of care and attention to these rural communities where the mayor percentage of native germplasm is, will have a negative impact on maize diversity. It is also foreseen that the public policies that promote the intensive capital technologies which move the jobs towards urban areas or towards foreign countries, will determine the rate of extinction of genetic resources of maize. The risk of loosing genetic diversity of maize is very high. The economic conditions of poverty and marginalization faced by the farmers, as is already evident in several regions of America, will lead to a generalized extinction of maize diversity. One way to alleviate this situation is to re-value the crop through the knowledge of its origin and diversification in the American Continent. This document aims to recover the history of the scientific research and socio-cultural aspects related to the origin and diversity of native maize, in order to allow the peoples of America rescue the plant which is a symbol of the American continent and its culture.