CAPULALPAN, Mexico -- The villagers knew that the corn stalk growing in Olga Maldonado's garden was different. It stood taller than a man, and the husks holding the ears dangled in bunches, like bananas.

"The way it grew, it was amazing," said her brother, Javier Toro Maldonado.

Many of the people who stopped to gawk had grown corn in this mountainous community for generations, swapping seeds and fine-tuning the genes so the crop would flourish on the steep slopes.

But they hadn't seen anything like this.

"People were curious," Javier Maldonado recalled. "They would say, 'Olga has such big corn, and she doesn't even take care of it.' But Olga never told anybody where she got the seed from."

The corn growing in Olga Maldonado's back yard was not some quirk of nature but a laboratory mutant -- a relative of the genetically modified crops that have been banned in Europe because of health and environmental concerns and that once caused food to be taken off American store shelves when corn approved only for animals turned up in taco shells and tortilla chips.

But its detection in the peasant fields of Mexico, where all the corn varieties in the world had their origins 5,000 years ago, has farmers fearing that the altered gene could infect native plants, creating strange but beneficial traits like the ones that caused villagers to line up along Maldonado's fence six years ago.

Over time, these traits could be preferentially selected by local farmers, slowly phasing out the corn diversity that their culture has nurtured for millennia and that the world has depended on to restock corn fields wiped out by disaster or disease.

In Mexico, some corn varieties grow in drought, another can grow on frigid slopes near mountain summits, and others can be sustained in the dry heat of valleys.

"It's a hot spot for biodiversity. For every little patch of land there, you have different conditions," said Ignacio Chapela, a University of California microbial ecologist who first discovered that Maldonado's plant was genetically modified, containing DNA from bacteria that enables the plant to produce a toxin that kills the European corn borer -- a pest that does not exist in Mexico.

Since his discovery was made public in 2001 in the journal Nature, Mexico's environmental agency has detected traces of genetically altered corn in native plants in 14 villages in the Sierra Juarez mountains, despite a 1998 ban on the planting of such corn in Mexico to protect native genes.

Mexico's agriculture department acknowledged the contamination for the first time just last week, although it said the problem was diminishing and did not pose a threat to traditional corn, public health or the country's seed banks. It said genetically modified corn will continue to be imported for food.

Local farmers fear this genetic "pollution."

"What worries us is that it is an unknown word," said Reinaldo Ruiz Vasquez, 50, a farmer from the village of La Trinidad, referring to "transgenics," another word for genetically altered food. "We worry that our seed will be polluted, and if it is, how it arrived."

Despite the agriculture department's statement, some scientists and local activists say that unless Mexico halts the importation of corn containing transgenics, it puts at risk not only the 50 or so corn varieties unique to the country -- including teosinte, the weedy ancient ancestor of corn -- but also a way of life.

Nowhere is the discovery more unsettling to corn experts and local farmers than in the southern state of Oaxaca, home of Maldonado's village. Indigenous people there have cultivated maize organically, and in isolation, for 5,000 years, creating a diversity unparalleled in any other part of the world -- evident in the seeds, which come in every color of the rainbow.

A foreign gene is viewed as a trespasser.

"At the level of the region, we are worried," said Fausto Martinez, the head of La Trinidad, a hillside village whose 180 farmers grow four separate varieties of corn -- yellow, white, red, and mixed red and white.

"We use what we farm," he said. "We never get corn from outside."

Ruiz Vasquez, who had his corn tested, added: "We like the corn here because it is organic. We don't need chemistry here. The corn is a guarantee because it lasts."

The discovery also has implications for the world outside Oaxaca.

For corn growers the world over, Mexican corn is like a genetic safe-deposit box, tapped when crops are wiped out by storms or disease. Even the country's seed stock could be contaminated by modified genes, Chapela said, because it has to be replaced every six years with seed from the fields.

"Corn is the base of this country," said Aldo Gonzalez, an activist for indigenous rights and the newly appointed leader of Guelatao, another village in the Sierra Norte, about 60 miles north of the city of Oaxaca. "Our towns are made of corn. Without it we are nothing."

Gonzalez gathered recently with about 30 other local leaders and rural farmers in the public library in Ixtlán to discuss the latest chapter in the controversy -- a report due out next month by the Commission on Environmental Cooperation, a group set up by NAFTA and comprising Mexico, Canada and the United States.

Although the meeting was supposed to start at 9 a.m., farmers from nearby villages wandered into the building until 11. Their sun-baked faces studied a screen projecting images from a laptop computer, including a diagram of corn's genetic map.

"It's not going to be easy for them to digest," said Jorge Larson, the biologist leading the meeting, one of five that was scheduled in the region before the NAFTA report is released at a five-star hotel in Oaxaca on March 11. "They are experts in maize. They may not be experts in genetics, although they know a lot about corn."

The paper, written and peer-reviewed by a group of world-class scientists, promises to be the first to recommend actions for the Mexican government, its supporters say.

"Right now, you have environmentalists saying that genetically modified crops are going to kill everyone and everything, then you have industry saying it will solve all the problems in the world," said Chantal Line, head of the environment, economy and trade program for the Commission on Environmental Cooperation in Montreal, which commissioned the report at the request of local community leaders. She compared the report to others about global environmental topics, such as climate change.

"It's the first time we will have consensus," she said.

But Gonzalez and others who got a preview in Ixtlán were not happy with what they saw.

"We are not convinced about the information in this report," said Miguel Ramirez Dominguez, head of the village of Capulalpan, where Olga Maldonado lives. The villages have banded together to form their own lab, which has thus far tested 90 corn varieties from around Mexico. So far, 25 percent have come back positive for altered genes.

"We want answers," he said.

What remains unclear is how the genetically modified corn arrived. Some, like Javier Maldonado, think that when roads were built in the 1980s and trucks started bringing in cheap corn grown in industrial-size fields in other countries, some spilled onto the streets and grew along roadsides. Others believe the genes escaped from experiments that took place in Mexico before the ban on planting genetically altered crops.

Since corn is pollinated by wind, all it takes is a gust to mix the genes of a native plant with the genes of one that is genetically altered.

The new seeds will contain some of the foreign genetic material. But unlike other grains, corn needs human assistance to reproduce. It has tough husks that prevent it from dispersing seeds.

"It's an artificial plant," said Jodie Randall, an expert in corn history at the Ethnobotanical Garden in downtown Oaxaca. "It can't reproduce itself without human help. Even if the seeds did get out, competition would make it nearly impossible for them to survive."

For Randall, the most likely explanation for how transgenic corn took root in Oaxaca is that peasants faced with the high cost of harvesting their own seeds have been purchasing the cheap seed intended only for animal feed and tortillas that sells in local stores.

Biotech companies, when asked how the genes escaped, say that corn was not supposed to be planted in the first place.

"This is a commodity intended for food and feed, not for planting, not for releasing into the environment," said Sylvia Llorens, director of regulatory and government affairs for Monsanto Latin America in Mexico City. The company produces Bt corn, the one found in Olga Maldonado's garden.

"The government is planning to inform the peasants that this is not intended to release into the environment," she said.

But some say it is impossible to keep grain and seeds separate in the hills of Oaxaca, where ecology can take a back seat to economics. While many villagers used to sell their corn, imports from the United States now are cheaper to buy and supply much of the demand for tortillas, the cornerstone of Mexicans' corn-based diet.

Most peasants grow barely enough to feed themselves and are forced to subsidize their diet with store-bought corn.

"If you keep bringing the plant in, how can it ever go away?" said Chapela, the University of California microbial ecologist, referring to the transgenic corn varieties. "It's very simple biologically. The thing is we don't need them, especially in Mexico," where the corn borer doesn't exist.

But for Javier Maldonado, who spends 130 pesos (about $11) on a 50-kilogram bag of corn that is consumed in about 90 days, the choice is difficult.

"Securing genetic diversity may be right, but you have to recognize the social problem," he said. "People need food to eat."

And in Mexico, a great majority of that food is corn. It is used for tortillas and tostadas, or toasted tortillas. A drink called tejate is made of corn, cocoa and sugar. People even eat the cheese-like corn fungus that grows on the corn husk.

And most people go where corn is the cheapest.

Alberto Jimenez Martinez works at La Asuncion, a take-out tortilla shop in Ixtlán. Here the tortillas are made, pressed and baked in one room using corn purchased from local farmers. With 1 kilogram, Martinez can make about 24 tortillas, which he sells for six pesos, or a profit of 25 cents.

But he worries about the effect of transgenic crops on his business. People in these parts like their tortillas pure, sprinkled with a little salt.

"You see the corn here, it's safe," he said. In the city, where the corn that feeds tortillerías comes from the government, "God knows."
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"none of this - nor public opinion, protecting the countryside or safeguarding future health - seems to matter to ministers so much as trying to show that like some tinpot tyrant, Mr Blair, America's poodle, is always right." - journalist Geoffrey Lean

"Why is the Government going ahead? It is not because of the science, it is because of the Bush administration applying pressure, and because of companies like Monsanto who want to make a big profit bonanza out of cornering the world food supply. It is nothing to do with feeding the world." -Michael Meacher, former UK environment minister http://www.lobbywatch.org/archive2.asp?arcid=2677