1.The Natural Why-Quirer (story map)

2.GM corn squabble

3.Nature pulls a U-turn

4.New news on old experiments

5.Madness in the method?

In a CIMMYT test plot, various strains of corn are tested for yield and disease-resistance. © David Tenenbaum

The report described finding "promoter genes" -- genes often used in genetic engineering -- in traditional races of corn in Mexico.

Like Hollywood talent agents who find jobs for their stars, promoter genes put other genes to work. It's a two-step process. Promoter genes cause what we could call the "working genes" to do what the genetic engineers want -- like resist a herbicide.

Without promoter genes, working genes might lie as dormant as a kid in a calculus lecture. Chapela and Quist made two separate claims:

Conclusion #1: Promoter genes from GM crops were present in traditional corn varieties grown in two remote locations in Oaxaca, Mexico.

Conclusion #2: The promoter genes were scattered through the corn genome.

The first finding incited environmentalists and food activists alike. Greenpeace called for an expansion of the current ban on planting GM corn in Mexico to include importing the stuff. It also demanded an emergency program to eradicate the genetically cursed corn, all in pursuit, it said, of preserving the future of a vital grain. (Indeed, corn's the world's largest crop. Global production amounts to 100 kilograms per capita per year; slightly above wheat's 95 kilos.)

To opponents of genetic engineering, such contamination is a disaster. Once the genes are loose, it's hard to conceive how they could be recalled. However, the real degree of hazard is difficult to know, since little research has been done on the issue of contamination of land races by GM corn. And on the other side, advocates call genetic engineering one of the best hopes of feeding the world.

Jerry Kermicle, a professor emeritus of genetics at University of Wisconsin-Madison, has studied mechanisms limiting flow of genes between corn and its ancestor, teosinte. He says conclusion #1 is not disturbing. "Biologically, I don't see it as such a challenge to the land races, they've been exposed to outside sources of germplasm before, and this is just one more source of genes. Psychologically, it's quite a challenge especially for the ecologists, who think of these land races as being genetically fixed."

To many scientists, however, conclusion #2 was more interesting -- and questionable. If promoter genes were scattered through the genome, that could have unpredictable effects for native corn. For that reason, and because this phenomenon had never been seen before, the finding came under intense scrutiny.

No-till planting of corn in Iowa. Gene Alexander, USDA.

Your job now!
On April 8, the critics won. Nature's editor beat a hasty retreat, and publicly ate crow. "Nature has concluded that the evidence available is not sufficient to justify the publication of the original paper. As the authors nevertheless wish to stand by the available evidence for their conclusions, we feel it best simply to make these circumstances clear, to publish the criticisms, the authors' response and new data, and to allow our readers to judge the science for themselves."

The rare and oh-so-public disowning made it sound as if the entire paper was unfounded. But in fact, the attack focused on conclusion #2 -- the dispersal of GM genes, not their simple presence.

Michael Freeling, a geneticist at the University of California at Berkeley, signed one of those critical letters about conclusion #2 (see "Biodiversity (Communications Arising): Maize Transgene..." in the bibliography). Conclusion #2 explains why Nature published the original paper, he says. "The reason the Quist and Chapela paper was originally published in Nature, in my opinion, involved the unexpected conclusion that [the inserted genes] 'went wild.'" The idea that promoter genes had spread throughout the genome, he adds, was based on "completely artifactual data [resulting from experimental error]... This conclusion was not obvious, is not valid, and this conclusion has not been retracted."

The switcheroo?
Oddly, the finding that so alarmed environmentalists -- conclusion #1, the fact of contamination -- seems uncontroversial among scientists, although not all of them are convinced by the way Chapela and Quist proved it.

Science magazine talked to Timothy Reeves, director-general of CIMMYT, the international corn and wheat research center. He said it is "very likely" that some transgenic maize will eventually end up growing in Mexico (see "Has GM Corn...?" in the bibliography). CIMMYT is unsure whether contamination has occurred, but says tests of its massive corn seed bank have detected no GM genes.

Freeling, who continues to scoff at conclusion #2, wrote us to say, "I would be shocked if transgenic genes were not found in local corn."

According to some estimates, about 40 percent of corn imported into Mexico is transgenic, and much of it is apparently planted as seed. Freeling thinks pollen from GM corn has probably moved downwind to fertilize other strains.

Got that right!
In their rejoinder to the critics, Chapela and Quist did acknowledge some errors. But they stood by conclusion #1, and said it would be backed a forthcoming Mexican government study.

Indeed, last week the Mexican government confirmed the discovery of promoter genes in corn in Oaxaca and neighboring Puebla state. A British newspaper reported that 95 percent of farm locations had at least one plant with GM promoters. "Mr. [Jorge] Soberon, secretary of the environment ministry's national commission on biodiversity, said: 'This is the world's worst case of contamination by genetically modified material because it happened in the place of origin of a major crop. It is confirmed. There is no doubt about it.'" (See "'Worst Ever' ..." in the bibliography). (We quote a European newspaper because the story apparently didn't run in a major U.S. paper.)

If one of two conclusions was right, did Nature go too far in disowning the original article? Yes, says Glenn Stone, associate professor of anthropology and environmental studies at Washington University in St. Louis. "One wonders why the editor issued a statement impeaching the whole study. Consider that the aspect of it that the press picked up on was the ... transgenes ...that had invaded Mexican maize land races. This has been confirmed by other sources... But the scientific row leading to the retraction is a different issue.... The retraction may have thrown out the baby with the bathwater. Industry will now claim the study was invalidated, which isn't true as far as the most important part goes."

This corn may be exported from the United States to Mexico. Is it genetically engineered? Dunno. Will its genes contaminate Mexican corn? Maybe. Agricultural Research Service, USDA.

The stakes
It's hardly necessary to say that the flap over GM corn exists in a big-time economic and political context. Corporations are promoting GM seed as a profitable way to feed the world's growing population.

But people are nervous about eating the stuff, not to mention releasing it into the environment. Environmentalists and food activists have branded GMs as "frankenfoods," and used them as a potent rallying point.

Adding to the public unease, Monsanto, one of the largest sellers of transgenic seeds, just admitted that oil from transgenic canola had probably entered U.S. food markets, where it not approved for sale (see "Monsanto Says..." in the bibliography).

While millions of acres of transgenic corn, soybeans and potatoes grow in the United States, the European Union has not decided whether to extend its ban on GM crops.

Unquestionably, this context of money, passion and globalization feeds the controversy on both sides. "GM technology is ... also central to the spread of corporate high-external-input agriculture to the Third World," says Stone. "This exterminated the small farmer in the US (although well before GMOs) -- where would India's 700 million farmers go?"

Good question. We will note that Mexico's small corn farmers are facing increasing competition from U.S. corn imports.

Having said that, we're going to duck the question and return to our scientific-process track.

By what standards do scientific publications judge accuracy? How does something get to be called "scientifically valid?" What roles do politics, economics and social trends play in science?

Is there a madness with the scientific method?

There are 1 2 3 4 5 pages in this feature.
Bibliography | Credits | Feedback | Search

©2002, University of Wisconsin, Board of Regents.