Letter: Engineered crops

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Sir: The current debate about the pros and cons of genetic engineering and agriculture has made repeated reference to how long it has been going on. It may be worth summarising what we know about past genetic intervention.

It is clear that naturally occurring but rare plant and animal mutants have been picked out and bulked up for at least 10,000 years in South- west Asia, and possibly China. These are now familiar as crops and livestock species. It is probable that particular genes, for example for baking quality in wheat, have been targeted for selection for at least 5,000 years. From ancient illustrations of mules and hinnies, it is also probable that the genes of separate species have been artificially brought together for at least 3,000 years. None of the actual genetic mechanisms involved is without parallels widespread in nature. There is no evidence in previous times for any forerunners to the direct manipulation of chromosomes we now refer to as genetic engineering.

These 10,000 years of intervention have not been completely benign. The narrowing of genetic range in foodstuffs has repeatedly been linked with environmental destabilisation, and the precondition for devastating episodes of famine and disease. However, it has also been the precondition for a modern world in which famine and disease can be combatted scientifically. Of course it is neither realistic or desirable to return to a world free of genetic intervention. It is reasonable nonetheless to assume that beneficial advances in genetic agriculture will carry a downside about which we shall need to be vigilant. In this way genetic engineering today is very similar to many other changes in agricultural practice in the recent and distant past.