The corn consumed globally today originated in Mexico nearly 10,000 years ago. From the ancient rituals of the Mayans and Aztecs to the modern tortillas, tamales, and esquites, corn remains a central element of Mexican culture, cuisine, and identity.
To safeguard this heritage, Mexico is working to phase out genetically modified (GM) U.S.-grown corn this year. This move follows a 2020 decree by Mexican President López Obrador, which has heightened tensions between the two nations. The Mexican government argues that this measure is necessary to protect the health of its citizens and preserve the country’s native corn varieties.
However, the announcement has met with strong opposition from the U.S., Mexico’s largest annual customer for GM corn. Between 2018 and 2020, Mexico purchased nearly 30 percent of all U.S. corn exports. The dispute has escalated to formal negotiations under the United States-Mexico-Canada Agreement (USMCA), with the U.S. contending that the GM ban violates the trade agreement and that Mexico has not provided sufficient scientific evidence to support its claims.
Mexico maintains that GM corn poses a threat to human health and endangers the country’s agricultural traditions and cultural identity. The sentiment is encapsulated in the Spanish idiom “sin maíz no hay país,” meaning “without corn, there is no country,” highlighting the profound significance of corn in Mexico.
Home to over 59 unique corn varieties, Mexico boasts the most genetically diverse repository of corn in the world. This diversity traces back to a wild grass called teosinte, which evolved over millennia of domestication and selective breeding to become the corn we recognize today. Native varieties are well-adapted to local environments, with some requiring less water and being more pest-resistant—traits valuable in the face of climate change.
Mexico is concerned that GM corn could lead to genetic contamination, as genes from U.S. corn have previously crossed borders and entered Mexican varieties. Pollen from GM crops can travel long distances, potentially cross-pollinating with native varieties and altering their genetic makeup.
In contrast to the U.S., where most corn is grown from seeds produced by large corporations, Mexican farmers often use seeds from seed-sharing milpas, promoting greater diversity. This genetic diversity helps corn adapt to challenging environments.
While Mexico’s importation of U.S. corn is substantial, most of it is used for animal feed or industrial purposes, not for human consumption. In 2023, Mexico banned GM corn for human consumption, although this had minimal immediate economic impact. However, U.S. corn producers and trade officials worry that the ban could lead to further restrictions.
Despite concerns, the Food and Drug Administration states there is no evidence that genetically modified foods harm human health. The U.S. has accused Mexico of violating the USMCA, arguing that Mexico lacks scientific proof that GM corn is harmful. Mexican officials claim the U.S. has been unwilling to collaborate on research into GM corn’s health implications.
Mexico also plans to ban glyphosate, an herbicide linked to health concerns. Although a 2021 study found glyphosate in children who had no direct contact with it, no major health problems were directly attributed to the chemical. Mexican officials are wary of GM farming practices that require glyphosate use.
Preserving corn’s genetic diversity is crucial. Jeffrey Ross-Ibarra, an ecologist at the University of California, Davis, believes that economic policy, rather than a GM corn ban, has a more significant impact on maize diversity. Small-scale farms, crucial for maintaining traditional varieties, are declining in Mexico.
Mauricio Bellon, a research professor at Arizona State University, emphasizes the importance of the relationship between farmers and their crops. He argues that while gene banks store seeds, they only capture a snapshot in time. The ongoing cultivation by farmers ensures the continued evolution and adaptation of corn varieties, which is essential for preserving genetic diversity.
