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Genetic Pollution of Corn in Mexico

The New York Times December 9, 2001, Genetic Pollution
By Michael Pollan
The way we think about and deal with pollution has always been
governed by the straightforward rules of chemistry. You clean the
stuff up or let it fade with time. But what do you do about a form of
pollution that behaves instead according to the rules of biology? Such
a pollutant would have the ability to copy itself over and over again,
so that its impact on the environment would increase with time rather
than diminish. Now you're talking about a problem with, quite
literally, a life of its own.

This year, the idea of genetic pollution -- the idea, that is, that
the genes of genetically modified organisms might end up in places we
didn't want them to go -- became a reality. In September the Mexican
government announced that genes engineered into corn had somehow found
their way into ancient maize varieties grown there -- this despite the
fact that genetically modified corn seed has not been approved for
sale in Mexico. The country where corn was probably first
domesticated, Mexico is today the source of the crop's greatest
genetic diversity. Now that diversity could well be threatened.

Companies like Monsanto have long acknowledged that their engineered
genes ("transgenes") might on rare occasions "flow" by means of
cross-pollination from one of their crops into neighboring plants. But
because sex in nature takes place only between closely related
species, and because most crop plants don't have close relatives in
North America, the risk that new genetic traits would contaminate the
genome of the world's important crops was, the companies claimed,
remote. As long as genetically modified corn seed wasn't sold to
Mexican farmers, or potato seed to Peruvians, these crucial "centers
of diversity" could be protected.

So how did transgenes ever find their way into traditional Mexican
corn varieties? It's a mystery, but the leading theory is that some
campesinos in remote mountainous fields outside Oaxaca bought some
genetically modified corn as food -- then planted the kernels as seed.
No matter how it happened, Monsanto's genes have spread widely in the
region.

Why does this matter? The presence of transgenes in what some experts
call "the cradle of corn" represents a threat to the crop's
biodiversity. Should the traits introduced into Mexican fields confer
an evolutionary advantage (for insect resistance, say) on certain
plants, their offspring could crowd out older varieties, leading to
the extinction of genes we may someday need. For whenever a food crop
suffers a catastrophic failure -- as when blights destroyed the potato
crop in Ireland in the 1840's -- breeders return to that crop's center
of diversity to find genes for resistance. Next time around, those
genes may be nowhere to be found, a casualty of genetic pollution.

Greenpeace has called on the Mexican government to halt imports of
genetically modified corn, but the genie is already out of the bottle.
Genes released into the environment can replicate themselves ad
infinitum. Indeed, some studies suggest that transgenes are
particularly "sticky" -- better at getting themselves around in nature
than ordinary genes, possibly because of the viral and bacterial
vectors used to engineer them. So far that's just a hypothesis; we
don't really know how transgenes will behave once they've found their
way into a crop's center of diversity. What we do know, now, is that
we're about to find out. Michael Pollan
http://www.nytimes.com