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Technology of mutations

Mutations are a natural part of evolution. They are caused by chemicals and natural background radiation. We rarely stop to realize that we are continuously being bombarded by cosmic rays that rip through our cells and disrupt hundreds of thousands of them on a daily basis. Some cells recover, some die, and some reform in mutated variants. This is how evolution works, and it is inevitable. Higher doses of radiation or different chemicals just speed up the possibilities, but cell destruction and restructuring processes are ongoing. Our body has developed cells and chemical processes specifically to deal with repair and removal of damaged or altered cells, but with time there is accumulation of debris, and our recovery mechanisms weaken with age. So ageing and cancers (i.e. basically cells that are damaged and out of control) are inevitable— our only input is to influence the rate at which they happen.

Laboratory-induced genetic mutations may not be intrinsically different from natural ones. However, better understanding of DNA, chromosomes, and the building blocks of our cells has often revealed specific sites that influence particular characteristics. Genetic engineering can then target such sites. Ever since the Industrial Revolution, we have been bombarded with images and mental conditioning that engineering is the way forward—it implies progress. Therefore the phrase ‘genetic engineering’ is excellent marketing, as it has very positive emotive overtones. Nevertheless, we need to understand that Victorian advances in, say, steel making were broadly successful, but steel quality is still variable and failure can occur, different steels are only useful in certain circumstances, and we still have only a partial understanding of the details of metallurgy. When we had negligible understanding, we nevertheless had useful metallurgy (e.g. the early Bronze and Iron Ages).

Genetics is far more challenging than making better iron and steel for bridges. Living cells are complex: they can vary enormously and transmute into different structures. Further, the way they encode information is poorly understood overall, despite excellent identification of some key sites. Metallurgy has taken over 4,000 years to reach our current level of partial understanding, but we have only invested less than half a century so far into genetic engineering. Therefore we are unbelievably more ignorant than we wish to admit, and are deluded by the apparent speed of advance. This means we need to apply more care and caution with genetic engineering than we currently do.

Writing as a scientist, I recognize the danger that if we are trying to achieve a particular result, and we succeed, we will relax our caution and do not continue to look for related, unwanted effects. There is a purely practical reason: the funding for the research will invariably have stopped. But in the case of genetic mutations, we need to continue to be vigilant, looking for additional changes in the cell and plant (or animal) behaviour for a very long time.

Evolution and mutations are emotive terms, but they exist naturally, and for thousands of years we have been exploiting them under the different name of selective breeding. Cattle, horses, and dogs are all familiar examples of dramatic changes from natural-source animals. Dogs, for example, seem to have a common genetic ancestry in a small group of wolves, but we have interfered; thus modern examples range from Great Danes to chihuahuas, bulldogs, and Daschunds. For rapid-breeding creatures and plants, the changes can be produced quite quickly. If we tried the same approach with humans, it would be far more difficult to control over many generations.

Nevertheless, many of the breeds we have ‘designed’ have weaknesses (no matter how attractive or useful the animal). Dog breeds have a whole range of faults, such as deafness, short life expectancy, tendency to cancers, hip dysplasia, heart conditions, problems with whelping, or poor breeding. These are familiar to the breeders, and can be informative in the sense that they often reveal genetic links between, say, deafness and patches of different coloured hair (also seen in humans), which are valuable data for geneticists. Compared with naturally evolved wolves, most dogs we have engineered are inferior specimens that could not survive without our veterinary support.

Our more extreme experiments of cross-breeding different species suggest that in those cases, one generally does not have to worry about longer-term, inherited mutations, as the progeny are often sterile. A familiar example is the mule, which has excellent characteristics for a pack animal in transport, but is a one-off, end-of-the-line species. To some extent, the same problems have existed in many cross-bred plants. Overall, it is unwise to be too specific in attempts to develop new hybrid species; my guess is that it is a topic that will develop as knowledge and skills of genetic engineering advance.

In agriculture, many crop variants that are effective and widely used are sterile. So the farmer cannot retain seed from one year to sow the subsequent crop. This example of sterility may have been added intentionally during production of the seed, as it forces the farmer into buying more seed each year. I view this manipulation of the farmer to become a pawn in the hands of the agrichemical industry as iniquitous.

Evolution also applies to the pest and diseases we are trying to battle; a chemical that is successful will never be so permanently, because the pest survivors will expand to take over from the variants that were destroyed. This ‘bounceback’ resurgence is well documented, in part because the treatments kill the natural predators, as they die of starvation. Just as with medical usage of drugs, new strains are often harder to counteract than the original ones. The battle between biochemist and bug is increasingly demanding and costly. Reliance on natural bug controls is therefore the optimal solution.

However, the difficulties are compounded because of global trade: new bugs and plants are continuously being imported into all regions. Because they rarely arrive with their natural predators, they thrive in their new homes. This is not a new problem. Even in 1962, Rachel Carson noted that in the USA, some quarter of a million non-native species had been identified. In the subsequent half-century, the number is likely to have doubled.

Positive examples have been demonstrated in which the predators of foreign species (whether bug or weed) have been imported to attack the foreign pest. In the best scenarios, the second import only thrives off the pest, so does not contaminate the rest of the native population of plants or insects. Nevertheless, this is a tricky solution to consider, because if the climates of the original and new region are different, then either pest or predator may adapt differently.

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