Small Farms in Mexico Are Saving Corn’s Genetic Diversity

Small Farms in Mexico are driving the evolution of corn in North America and possibly saving humanity from unimaginable crop losses.

Family farms in Mexico frequently select the seeds stored from the previous growing cycle, plant them and care for the seedlings. This process carried out generation after generation yields billions of genetically different corn plants. It Domesticates corn across a wide range of temperatures, altitudes and slopes, allowing rare mutations to establish genetic diversity that would otherwise disappear.

Genetic diversity provides resilience and massive monocultures do not have it. In 1970, 91 percent of the corn sowed in the US contained the same genetic trait, the TMS or Texas male sterile trait. This hybrid variety was bred to be resistant to corns most common diseases, but all the corn shared the same genetic susceptibility to one pathogen, southern corn leaf blight. When the fungus encountered the new corn variety, a quarter of the US corn crop was wiped out.

Researchers reported in Proceedings of the Royal Society B. that in 2010 alone, family farmers in Mexico grew approximately 138 billion genetically different corn plants. This real world evolutionary experiment has been ongoing for thousands of years. The efforts of small-scale farmers generate the bulk of corn’s genetic diversity in North America and are also generating the bulk of North American corn’s genetic resilience. The small Farms are generating an evolutionary service essential for them, for their country and given the global importance of corn, for the world.

Scientists say this type of farming, fueled by traditional practices such as saving or sharing seeds from one season to the next, rather than purchasing sterilized homogeneous seeds has resulted in Mexico’s 59 native maize varieties. Diversity is rarely seen in the US, the largest producer of corn. The average farm in Iowa has three million genetically identical plants- Identically vulnerable, identically susceptible. 



Photo: “Still Life with Corn Cobs – Museum of Mexican Art – Pilsen – Chicago – Illinois – USA” by Adam Jones is licensed under CC BY-SA 2.0