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"Outright false," says biologist Parrott. "Transgenics cannot be different from conventional varieties." Biotech crops must be "substantially equivalent" to conventional varieties before they can be marketed. In every case, biotech companies have submitted reams of information to the Food and Drug Administration (FDA) on things like nutrient profiles and feeding values before marketing genetically enhanced crops.
Conventional plant breeders don't need FDA approval to market their crops, even though they often involve far more genetic changes (through techniques like crossbreeding) than the single-gene transfers common in genetically enhanced crops. "Every single differently shaped leaf of lettuce, every different color of bell pepper, every new variety of citrus fruit, is the result of genetic mutations that produce different proteins which were noticed and then selected by conventional plant breeders," says Parrott. Yet no one worries about being poisoned by these far more massive genetic alterations in crops. Interestingly, scores of varieties of crops being grown today were produced through mutations induced by radiation and caustic chemicals in the 1940s and 1950s. No one knows what proteins these random genetic mutations produced, but people have been eating them for half a century without ill effects.
Parrott points out that plant genomes are filled with DNA fragments called retrotransposons that naturally jump randomly from one part of a plant's genome to another. These jumps occur billions of times every growing season. They often disrupt gene expression in plants and may well sometimes induce the production of novel proteins. But this is no cause for alarm, since people have been eating these crops with their jumping genomes for centuries. It is evident that such disruptions in plant genomes have an extremely low probability of producing any dangerous proteins.
Why is Commoner making claims that can be refuted simply by referring to college biology textbooks? Partly because he is still smarting from his intellectual defeat at the hands of James Watson and Francis Crick (the co-discoverers of the structure of DNA) in the 1950s and 1960s. At that time, Commoner, besides being a campaigner against aboveground nuclear testing, was one of the leading advocates of the theory that proteins carried inheritable traits. To some extent, Commoner appears to be trying to reinterpret alternative splicing as a way to rescue at least a portion of his old thesis. It turns out that Commoner may be a perfect example of Thomas Kuhn's contention in The Structure of Scientific Revolutions that old theories never die until old theorists do.