Proponents of biotech crops would have us believe that genetically engineering crops is a fairly simple matter. Nothing could be further from the truth according to the zoologist, Colin Tudge, author of So Shall We Reap. Tudge writes that “genetic engineering, even at its very simplest, implies the ad hoc introduction of exotic genes into the genomes of established organisms, and this, in principle, immediately suggests a hierarchy of possible problems. Most obviously, the newly introduced gene could disrupt the host genome in undesirable and quite unpredictable ways”.
One of the best analogies for understanding the changes involved is the nature of language. “If we compare genes to language as in the title of Steve Jone’s 1993 book; The Language of Genes, individual genes are then compared to words. But the meaning of individual words is not to be captured in the stripped-down, dictionary, definitions. …”. The meaning of words depends very much on their context in which they are used. Behind the dictionary definitions of individual words lies the syntax of the language and actual current usage.
Tudge points out that genes work in a similar way. Genomes evolve “trailing their history behind them.” He continues with the language analogy, “if genes can be compared to words, then the genome of any particular creature as a whole should be compared to literature.” This means for him that, “genetic engineering is not engineering at all”. In fact, it is much closer to gardening, where you plant, then stand back and watch what is happening. He returns immediately to the language metaphor. Genetic manipulation “is more like editing. Every writer knows that the injudicious alteration of a single word can change the import of a text absolutely.”
Tudge reminds us how little we still know about biology and genetics despite a “100 years of formal Mendelian genetics. He acknowledges that “we have some small insight into the function of a few genes in a few genomes (including a few human genes)”. He would consider that this knowledge only constitutes the beginning of a dictionary. “But the genome of an organism – any organism – might be compared in literature terms, to some sacred poetic text written in a language of which we have virtually no inkling; medieval Tibetan or Linear B”. Then he poses the crucial question: “Would you, or anyone who was halfway sane, undertake to edit such a text if all they had to guide them was a bad dictionary?.”
We drop novel genes into genomes, and exotic organisms into ecosystems, at our peril – ours and the world’s. There is simply no way of knowing, a priori, what will happen. 
Tudge dismisses the claim that GM crops will feed the world. “The startling truth is (at least I think it’s startling, in view of the hype) that genetic engineering has contributed nothing of significance to world food security – that is, to issues that really matter – and is not likely to do so in the foreseeable future. As far as human survival goes its contribution is precisely zilch. In reality it is locked into and is designed to promote an economic strategy that is already proving pernicious, and in the longer term could well prove disastrous. The net contribution of genetic engineering to human well-being is negative.” .
Colin Tudge is not against genetic engineering in principle. His approach can best be judge from his comments on sorghum, the staple crop of many people in the Sahel region of Africa. Tudge points out that sorghum is resistant to drought and heat but not resistant enough. Scientists have searched international gene banks for varieties of sorghum that could be crossed with sorghum to provide the requisite gene(s) for super-toughness, but thus far they have found none. They are now screening ground-nuts to see whether it has the required gene. Since this could not be introduced by conventional breeding, genetic engineering would be necessary. “Here (if it can be made to work) is a prime example of the highest technologies deployed to help the world’s poorest people. For people in some of the harshest environments, such science could, in principle, be a godsend”. Tudge ends this reflection by adding a word of caution about the limits of our current knowledge. 
 Colin Tudge 2002, So Shall We Reap, Penguin, London, page 225.
 Ibid, page 261.
 Ibid, page 268
 Ibid, page 254.