George A. Dyer Leal: Maize in Mexico
George A. Dyer Leal and son.
Photo of George A. Dyer Leal and son in the Galapagos Islands.

By combining the disciplines of biology and economics, former UC MEXUS-CONACYT Postdoctoral Fellow George A. Dyer Leal has been able to highlight the key role that small farmers play in the evolution of crop seeds such as maize. Dyer has described the evolution of maize in socio-economic terms and uncovered the poorly understood effect of formal and informal maize seed exchange in Mexico. This year, the UC Davis visiting scholar concluded two landmark studies that show that the evolution of maize seeds results from the actions and reactions of small farmers to seed availability, quality, and external economic pressures.

The evolution of maize in Mexico, the birthplace of this staple food product and home to hundreds of varieties that have adapted to a wide range of climatic conditions, has long been a focus of evolutionary biologists. In recent years, however, maize has become particularly lucrative as major seed producers such as Monsanto have promoted its use as a major food crop worldwide. Moreover, the genetic modification of maize seed, at a time when the United States is exporting large quantities of grain to Mexico, has engendered fears that the artificially modified seed might escape into the local crop populations and threaten the invaluable diversity of Mexico's landraces.

Research on maize has tended to focus on the genetics of the intermingling of genetically modified seed and uncultivated varieties such as teosinte (a kind of "weed" maize). Evolutionary theorists have paid less attention to the social aspects of crop evolution, according to Edward J. Taylor, Dyer's UC Davis host and former dissertation adviser. In so doing, they have largely ignored the effect of centuries'-old customs of seed exchange, experimentation, and seed modification at the hands of small farmers. According to Taylor, Dyer's work potentially could spark new debate on that aspect of traditional genetic modification by contributing to "a more rigorous scientific exploration of these complex interactions between social factors and crop population genetics."

Dyer's multidisciplinary approach began to take shape during his early undergraduate days in Mexico, when he combined a bachelor's degree in biology from UNAM with a master's in economics from El Colegio de México. Accepted in the doctoral program at the UC Davis Department of Agricultural and Resource Economics in 1998, his dissertation (supported by a 1999 UC MEXUS grant) studied the effects of markets and of farmers' informal seed exchanges on the preservation of traditional seed varieties. His work with the farmers of the indigenous community of Zoatecpán, in the rugged Sierra Norte region of Puebla, broke new ground by focusing not only on individual farms but also on the farmers' interactions with each other and with the ecosystems of which they were part. Dyer's paper, "Subsistence Response to Market Shocks," published in the American Journal of Agricultural Economics, won an Outstanding Journal Article honorable mention from the American Agricultural Economics Association in 2007.

After graduating in 2004, Dyer returned to Mexico to work with Taylor's long-time research partner Antonio Yúnez-Naude, director of El Centro de Estudios Económicos, Programa de Estudios del Cambio Económico y la Sustenabilidad del Agro Mexicano (PRECESAM) in El Colegio de México. Two consecutive UC MEXUS-CONACYT Postdoctoral Research Fellowships in 2003 and 2004 enabled Dyer to pursue his focus on the social effects on maize propagation in a study of maize seed systems and the management of biodiversity in rural economies. In his two postdoctoral research projects, Maize in Mexico: Grain markets and seed networks and Maize in Mexico: Environmental concerns and social repercussions, Dyer conducted a wide-ranging examination of the effect of NAFTA on small farmers and their prospects by the end of NAFTA-instigated policy-liberalization in 2008. In addition, he explored the structure of regional maize markets and seed networks nationwide and was also able to analyze the social repercussions and environmental concerns associated with Mexican maize production. His work produced more than a dozen publications and presentations, including invitations to Korea and Colombia, countries interested in learning from the Mexican example.

By examining the dual roles of economics and population genetics in combination with social forces to promote biological diversity or loss of diversity, he was able to break new ground, Taylor says. Maize seed dynamics and evolution are part of a complex social process driven by farmers, who have historically been overlooked in the ecological literature inspired by wild species models. Dyer suggests that the dispersal of transgenes across rural Mexico occurs across formal and informal seed systems. His work, "A Population Perspective on Maize Seed Systems in Mexico," was published in the January 15, 2008, issue of Proceedings of the National Academy of Sciences (PNAS) and in an article under submission, "Escape and Dispersal of Transgenes through Maize Seed Systems." This work built on a 2003 UC MEXUS-CONACYT Collaborative Grant to Taylor and Yúñez-Naude to conduct a comprehensive Mexico National Rural Household Survey, Encuesta Nacional a Hogares Rurales de México, (ENHRUM). As one of the coordinators of the National Survey, Dyer trained Mexican university students and their professors on sampling and surveying methods. He also shared his unique bio-economic perspectives by teaching a course on the valuation of natural resources to Mexican biological science students in 2003 and 2004.

Taylors says that Dyer's work stands at the forefront of efforts to bring social and biological scientists together to seek strategies to make economic development more compatible with the preservation of nature and the environment. The use of Dyer's demographic modeling on the evolution of other crops may well produce equally interesting results, Taylor says. "One could well imagine that this might lead to a change in the way crop evolution is understood by many researchers."

George Dyer can be contacted at