Public resistance to GM crops is rooted in a perception that genetic modification is unnatural and, by association, unhealthy. In fact, there’s yet to be a single scientifically documented case of ‘GM poisoning’ anywhere in the world.

However, this doesn’t mean that GM is safe. The real dangers of the technology are more subtle than the ‘frankenfood’ headlines would suggest, but potentially more significant.

In a disquieting article for Wired, Brandon Keim looks at the example of ‘Bt corn’ – one of the most successful GM crop varieties produced so far:

“Until Bt corn was genetically altered to be poisonous to the pests, rootworms used to cause billions of dollars in damage to U.S. crops. Named for the pesticidal toxin-producing Bacillus thuringiensis gene it contains, Bt corn now accounts for three-quarters of the U.S. corn crop…”

Given its benefits, the popularity of Bt corn (in those countries that allow it) is not surprising:

“First planted in 1996, Bt corn quickly became hugely popular among U.S. farmers. Within a few years, populations of rootworms and corn borers, another common corn pest, had plummeted across the midwest. Yields rose and farmers reduced their use of conventional insecticides that cause more ecological damage than the Bt toxin.”

But then things went wrong:

“After years of predicting it would happen — and after years of having their suggestions largely ignored by companies, farmers and regulators — scientists have documented the rapid evolution of corn rootworms that are resistant to Bt corn.”

This shouldn’t have happened. The idea was that ‘refuges’ of non-GM corn would be planted alongside the GM fields, thus preserving a largely non-resistant rootworm population. However, this advice went unheeded:

“…an advisory panel convened in 2002 by the EPA [Environmental Protection Agency] suggested that a full 50 percent of each corn farmer’s fields be devoted to these non-Bt refuges — were resisted by seed companies and eventually the EPA itself, which set voluntary refuge guidelines at between 5 and 20 percent. Many farmers didn’t even follow those recommendations.”

There were also supposed to be crop rotations – thereby disrupting the evolution of resistance temporally as well as spatially. However, Bt corn proved too attractive (helped along by agricultural subsidies) – and so it was grown continuously, year-to-year and field-to-field – thus providing the ideal environment for the spread of resistant genes.

The real problem with GM crops is not that they are unnatural, but that they cause us to forget just how dangerous the natural world is. Not to put too fine a point on it, Mother Nature is a complete bitch – constantly evolving new, diverse and unexpected stratagems to do us down. The only sustainable defence is to beat her at her own game by carefully conserving the complexity, variety and flexibility of our agricultural methods.

The GM industry promotes spectacular but simplistic solutions to what nature throws at us – and in the process centralises agricultural know-how to itself. Instead, of mounting a multi-layered defence against pests, diseases and other environmental threats, farmers come to rely on a much narrower range of options. These may well produce impressive results in the short-term, but in the longer-term, nature tend to finds a way around our tricks – leaving one-trick agricultural systems badly exposed.

GM advocates like to point to the proven or potential advantages of the latest GM breakthroughs. Look at the upside, they say, surely it must outweigh the downside. But the weakness in this argument is that the bigger the benefits of a new variety, the more widely it will be deployed and so the further it will go in reducing the depth of our defences.

In the ever-evolving biological battleground that is agriculture, the consequences could be devastating.