There is a good story in the NY Times about the use of genetically modified crops, that reflects some of the politics, and much of the genuine complexity of the life sciences and their application to human problems. The headline, Study Says Overuse Threatens Gains from Modified Crops.
Pesticide or insecticide resistant crops have been engineered so that crops either have natural insect resistance (the produce a toxic substance called BT), or they are resistant to an herbicide called Roundup. These crops yield about the same amount as formerly, but require less tillage to turn over weeds, or less insecticide spraying. By not requiring tillage every year, they help retain ground water and reduce soil erosion. This seems all to the good.
Any evolutionary biologist would predict that sooner or later the target species of insects or weeds would evolve resistance to the GM crops' engineered distance. The Times story refers to growing Roundup resistant weeds, and we can expect insects to 'learn' to eat these BT plants.
The social side of this has to do with agribusiness--forcing farmers to pay for GM seed because the plants can't be fertilized and proliferated by the farmers, raising the cost of the crop because of the seed costs, domination of the market by monocropping of the same type of plant, which can encourage a more rapid evolution of resistance, and the escape of the engineered plants to contaminate wild strains hence reducing biodiversity and future, different breeding stocks.
And of course there are those who either don't trust the safety of the genetically different plants for human consumption, or who don't like the corporate monopoly and greed, or who think the engineered plants will spread too widely, or will kill off necessary insects (like pollinators). And those who just don't like big business and yearn for small family farms and their communities.
In fact, all of these sides to the story have some merit, and what the long-term impact on society--if any--will be is of course unknowable. The issue involves not just the science, but the social sides, because protagonists seize on any fact that supports their side.
So far, it does not seem that most of the worries about food safety are valid. It seems that soil erosion and reduced spraying are good, and can help stall some of the erosion and other problems with mass-scale monocropping. Yes, small farmers are being replaced by capitalists in Omaha and New York, but different jobs are being created as well. How you rate the good and the bad will depend as much on your politics as the science.
The bigger questions are whether genetic engineering technology can stay one step ahead of evolutionary ecology. Or whether all this exotica will become moot or even life-way threatening, if society goes into a serious slump, such as an oil crisis depriving supplies of fertilizer or pesticides, or the human population grows too large or paves over too much land.
So if someone asks whether GM crops are good or bad, perhaps the best answer is 'yes'. Or simply the evolutionary response: 'wait and see.'
On the other hand, tomorrow we'll post about a program that is trying to balance all of the above objectives--and it's not pie in the sky, either.