Are GM foods Frankenfoods?
Many people are concerned and asking whether genetically modified food products are dangerous. My question in reply is, as many times in this book: dangerous compared with what?
Genetically modified cultivated plants have been consumed for at least ten thousand years, most probably for the first time in southern Turkey. Wild species which had hybridized spontaneously have been consumed for even longer. In the so called Fertile Crescent in the Middle East, a hybrid of two grasses of the wheat family was born due to species crossing and mutations – and this new species could propagate. The genes in the 14 chromosomes of wild Triticum wheat merged with those in the 14 chromosomes of a related Aegilops grass species. Emmer wheat (Triticum dicoccoides) with 28 chromosomes was born! Emmer wheat crossed further with another wild Aegilops grass to create spelt (Triticum spelta), which has as many as 42 chromosomes, or three times the “natural” number (therefore called hexaploid). Both Emmer wheat and spelt are much more productive “chromosome cultivars” than natural varieties. For the benefit of humans but for the disadvantage to the plant, the seed capsule of spelt and those of the wheat varieties cultivated today (Triticum aestivum) will not break easily – in fact it is so tight and heavy that the seeds cannot be dispersed into the wind, they need human help.
When man started breeding plants and animals, in other words modifying them to be as useful for himself as possible, the first method was simple selection. Grape seeds coming from the best grapevines were sown and the foals of the best and most docile horses were bred. Sometimes mutations occurred that produced weird individuals. If they pleased the owners for whatever reason, they were bred further and thus were born many “unnatural” dog breeds. Natural mutations and selection as a basis of breeding plants and animals suffer from two problems. Since useful mutations are rare, the process is rather slow, and it is haphazard, really trial and error.
Use of radiation
As soon as a basic understanding of genetics developed, it was found possible to deliberately increase the number of mutations e.g. by irradiating plants or treating them with cell poisons. The number of mutations can, indeed, be increased, but unfortunately most of them are unwanted and detrimental. The unwanted properties then have to be weeded out in what is a tedious and long-lasting breeding process.
Transfer of genes
Next, scientists learned to transfer genetic material, in the form of chunks of DNA-molecules, from one cell to another. Initially, an ancient property of many bacteria was utilised. They can squeeze themselves into plant cells, add some of their own genetic material to the DNA of the plant, and in that way they can trick the plant into manufacturing proteins determined by bacterial genes. Now scientists fool these bacteria, instead of a bacterial gene, they now transfer a desired gene from one potato strain into another potato cultivar. For example, a gene to increase resistance against potato late blight was transferred from a wild naturally resistant potato species to a more productive but sensitive potato variety. Subsequently, an arsenal of other laboratory methods for gene transfer have been developed. Thus it was possible to transfer a gene producing beta-carotene in the seeds into rice which normally have no such gene. The result is a vitamin producing rice cultivar. Alternatively the gene producing the protein which is responsible for soy allergies can be extinguished in the soy plant. Viruses can be used in animal breeding for the same purpose as bacteria in plants – they are called vectors.
What is a “clone”?
A clone is simply a copy of a plant (or in research laboratories also an animal) that has been produced from a vegetative or somatic cell, not from the germ line cell (seed). All of the potatoes that we eat are clones, individuals with identical genes originating from potato tubers, not seeds. Grapevines, apple trees and most other fruit trees are grafted by using short twigs of a “noble” individual and a rootstock of a robust, sometimes wild, plant. Thus they are unnatural products by a sharp knife. In a way, this is the closest we get to “Frankenfoods.”
Compare the risks
So, what is causing the risks? Genetic manipulation by Mother Nature that produced wheat? “Normal” breeding of cultivated plants or domestic animals by trial and error? Accelerated improvement by using radiation or cell poisons to speed up the formation of mutations? Sophisticated and accurate improvement by adding or removing only one gene at a time? Nothing in this world is perfect, and probably all of these can cause risks under certain conditions.
A “natural” mutation can take place any day in tomato or potato causing the plant to produce the same toxins in the edible parts that already exist in leaves and stem. Conventional breeding may well produce unwanted changes in addition to those we are seeking e.g. mixing thousands of unknown genes when crossing cultivated plants with their primitive forms may have very unpredictable results. Even genetic transfer is not necessarily as selective and fool-proof as the scientists hope. But to me it is quite obvious that the risk of unwanted consequences was greatest during the conventional trial and error period and breeding by inducing random mutations by radiation and cell poisons. Those are very haphazard methods as compared with accurate gene transfer.
Past experiences are reassuring
However, the history of breeding has not revealed terrible risks. On the contrary, it has been possible to decrease the concentrations of poisonous glycoalkaloids in potatoes and of harmful erucic acid in rapeseed oil. Now there are concerns of some supercultivar emerging and conquering the whole world. But during the whole history of active breeding, the breeds or cultivars that have been useful for human beings have been inferior, not superior, when compared with wild varieties with respect to their spreading capabilities.
A property useful for humans is usually a handicap in nature, decreasing the competitiveness of the cultivar. Emmer wheat cannot spread as effectively as wild wheat. It is not easy to produce a competitor that would be more competitive than the wild varieties developed over millions of years, struggling continuously for their very existence. It is not likely that domestic cow with its huge udders could survive, if left on its own, or threaten the existence of the wild ox or elk, or that a poodle would threaten a wolf. If something threatens these wild species it is the human being himself.
New health hazards?
Concerns have been voiced that genetically modified food might cause allergies. A new cultivar is, however, simply a new cultivar irrespective of the method by which it was created, and of course the possibility of allergies exists. Why would it be more likely in a genetically modified cultivar than in a conventionally bred variety? In the GM cultivar, one beneficial gene was specifically transferred to the nucleus, in the conventionally bred cultivar probably thousands of random genes and gene combinations have been moved to new individuals.
“Does gene modification cause risks?” seems to be the wrong question. The correct question is whether it causes more risks than other kinds of plant or animal breeding. The answer to this question seems to be no.
Notes and references
- Normal chromosomes are diploid, one copy of DNA coming from mother, the other from father
One level up: Here a risk, there a risk, everywhere risks, risks!
Previous chapter: The precautionary principle – better safe than sorry?