Posted by: Leander | January 15, 2010

GM Crops: Good or Bad or Somewhere in the Middle?

Corn Specimens in the Manchester Museum Collection


I must admit that when I was growing up and first heard the term ‘genetic engineering’ I had visions akin to H. G. Well’s Island of Doctor Moreau where elephants would have wings and giraffes would swim in the sea with dolphin-like tails, poking their long necks out of the water to see what was going on whilst singing lullabies to schools of attentive bespectacled jellyfish.  The reality of genetic engineering has, so far, been a lot duller than my teenage imaginings with most of the effort being focussed on such things as crops that are resistant to herbicide sprays or resistant to insect attack.  Nonetheless, as undramatic as these genetically engineered organisms seem to be, their appearance has stirred up a huge amount of controversy and I’ve been attempting to find out what the key issues are.

 The Irish author Jonathan Swift once said in the book Gullivar’s Travels (1726), 

“Whoever makes two ears of corn, or two blades of grass to grow where only one grew before, deserves better of mankind, and does more essential service to his country than the whole race of politicians put together”

 I have often seen this quote pinned to the notice boards in the offices of plant breeders and geneticists as inspiration and justification for the work they are doing.  In theory, at least, the production of genetically modified crops surely offers the people of the world enormous benefits.  Genetically modified crops offer the potential to have higher yields, better disease resistance and to endure tough and fluctuating environmental conditions.  They can be altered to improve their nutritional quality (e.g. by adding vitamins as has been done in Golden Rice) and be altered to stay fresher for longer in shops.

Plant breeding has been ongoing since the dawn of agriculture some 10,000 years ago with farmers selecting the progeny with the most desirable traits for sowing the following season.  Following the discovery of the mechanism of evolution by natural selection by Charles Darwin  and the underpinning genetic mechanism by Gregor Mendel  in the 19th century, plant breeding received an enormous science-backed impetus in the 20th century.  The consequences in terms of increased yields across the globe have been enormous.  This is exemplified by the so-called ‘Green Revolution’ the father of which has been deemed to be Norman Borlaug.  He led the introduction of high-yielding, short-strawed varieties of wheat and modern plant breeding techniques to Mexico, Pakistan and India.  As a result Mexico, which previously imported half its wheat in 1956, became self-sufficient in wheat and, by 1964, exported half a million tonnes of wheat.

Food output in the last four decades of the 20th century increased considerably as a result of plant breeding and the introduction of intensive farming techniques as can be seen from this graph produced by the UN Food and Agriculture Organisation


For most of the 20th century plant breeding techniques were still based on essentially traditional methods with the selection of beneficial traits and hybridisation within a particular species or at least between closely related species.  The dawn of genetic engineering technologies from the 1970s onwards introduced a new and more precise technique for modifying crops that targeted specific genes of interest.  These genes (transgenes)can be sourced from any organism in theory not just closely related species.  This has caused a good deal of controversy.  So, what are the issues?  Why is it so controversial when it appears to be such a good thing?

The reasons against planting and using GM crops generally fall into three categories.  These are Human hazards, Environmental Hazards and Economic concerns

Human Hazards:

There has been concern that some GM crops could cause allergic reactions in people.  There has been one case where a gene from Brazil nuts was inserted into soybean to improve their nutritional quality   Some participants under laboratory conditions showed an allergic reaction to the transgenic soybeans in skin prick tests and, as a result, this particular transgenic soybean variety has not been made commercially available.  However, a problem such as this could be overcome by good labelling on produce similar to the ‘nut allergy’ labelling that currently exists on packaging.

There has also been concern over the transfer of transgenes from ingested GM plants to bacteria and other microorganisms that naturally occur in the human gut.  Studies on such horizontal gene transfer   have indicated that parts of transgenes were transferred but no entire transgenes. The researchers concluded that this does not represent a significant risk to human health.  The Food Standards Agency (FSA) are conducting ongoing research into this area.  However, the Soil Association have objected strongly to the conclusions drawn from this and other studies.

Environmental Hazards:

There is concern about cross pollination of GM crops with closely related wild species or other non-GM crops (sometimes called non-target species) and the consequent spread of transgenes resulting in weeds that are resistant to herbicides etc.  A good review of the environmental considerations of GM crops is given here .

There is concern that pollen containing an insecticide producing transgenes could be consumed by non-pest insects.  A study showed that such pollen in GM corn was toxic to Monarch Butterfly caterpillars in a laboratory test.  This generated a lot of publicity and controversy .  However, other studies have shown that it is unlikely that the concentrations of pollen required to poison monarch butterfly caterpillars would occur in the wild. 

Other studies have been equally controversial.  A recent study on the effect of GM corn, containing an insecticide transgene, growing close to streams and its impact on Caddisfly larvae has also caused controversy within the scientific community.

Economic Concerns:

The development of a GM crop takes a long time and resources and is a very expensive undertaking. Agri-biotech companies want to ensure a profitable return on their investment.  As a result many new GM plants and the transgenes they contain have been patented.  There is concern that these patents will raise the price of seed so high that small farmers and third world countries will not be able to afford seeds for GM crops.

Both Biotech companies and anti-GM campaigners recognise the global problems of increasing population and increasing demands on the resources of the planet for food, clothing and fuel and both see themselves as offering the solution to these global problems.

Whereas Biotech companies look to industrial scale farming as the solution, anti-GM campaigners such as Greenpeace  look to locally focussed, sustainable farming methods to confront the same global problems.  Several interesting articles on approaches to farming have been written by Colin Tudge which are well worth a read.



  1. though, with an indian perspective, the following link might help

  2. i heard, corn we have nowdays, were undergo genetic alter. The original corn was actually look like as in the picture. Which is means that, all corn we have today are genetically altered. Is it true?

  3. I couldn’t resist replying, not least because I found your article by doing an Internet search for a graphic, using the words “dinosaurs gm “!

    I was particularly pleased, because I came across the graph (very helpful, thank you) by doing the search. What that demonstrates quite clearly is that we’ve reached some sort of a plateau in terms of yield potential from conventional breeding. I was a farmer representative on the HGCA R&D committee for seven years at the end of the 1990s. I once brought up that is you with the man leading cereals varietal trials that for many years they had been suggesting that each year’s new varieties were increasing yields by 3%. On this basis we would have been growing much bigger crops and we actually were. Your grass has a plateau level, during that period of alleged 3% per annum growth. All the technology we were using, all the chemical and artificial inputs, and the yield wasn’t going anywhere.

    However, GM techniques have yet to produce anything better. Therefore it could be that we’re going to have to look at how we consume as much as how we produce. Shocking levels of waste, both before and after the plate, and by the person sitting at the plate eating more than he/she should be all need attention.

    With regard to GM crops, I thought you might be interested in this analysis. I’m well aware that there are many in the conventional and scientific world who would dispute it, and have their own agendas to push. I have no agenda to push of a commercial or other nature, other than of personal interest as a farmer. I was once politically involved, through representative roles with the NFU, but I’m not now. My main interest these days is in soil biology, and totally sustainable production. That has to be in harmony with totally sustainable consumption, including sustainable processing. Those should be our goals.

    You may find this article interesting.

    It comes in the light of the announcement today by the US Sec of agriculture to give the green light to GM alfalfa. This strikes me as a horrendous development, and Representative mostly of his background within biotech companies before he was appointed to his current role.

    With best wishes, Oliver Dowding

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