By Ashleigh Marshall
Genetically Modified Organisms (GMOs) are controversial. At worst, they are the subject of vitriolic derision by anti-GMO activists, at best they are upheld by advocates as a silver bullet to all of the world’s problems. For many, they are a source of misunderstanding and unease. So…what actually are they? And, in the face of a rapidly changing planet and methodological advancements making GMO creation easier than ever, what does the future hold for this divisive technology?
What are GMOs?
GM, aka “genetically engineered”, organisms have had their DNA altered in a manner that doesn’t occur naturally, typically via transfer of individual genes between organisms or species using laboratory techniques.
The History of Modified Organisms
A precursor to modern genetic modification techniques was artificial selection (“selective breeding”), where only individuals possessing desirable traits are used to breed the next generation. Humans have been performing artificial selection in the form of domestication for more than 10,000 years, but it’s safe to assume that the earliest practitioners were unaware that by choosing plants and animals with the ‘best’ traits they were altering their genetic profile. Some famous examples include corn, wild mustard, and bananas, and the creation of dogs from wolves thousands of years ago. However, few people would argue that they are uncomfortable with the existence of dogs because they are unnatural, modified versions of wolves, so why is public opinion of GMOs often so low1, especially given their many potential benefits?
Benefits and Uses
GM crops are grown and consumed worldwide, particularly in the US, where 10 crops are licensed for commercial sale. Only two GM crops have been approved for commercial growth in the EU, and none are grown in the UK, but GM crops grown abroad can enter Europe as food, animal feed, or biofuels. These crops have typically been engineered to express traits that improve their appearance, make them tolerant to herbicides that can be used to kill off their competition, and confer resistance to insect pests or disease. However, GM crops also have the potential to bestow substantial health benefits. A key example of this is “Golden Rice”, a rice plant genetically modified to produce and accumulate provitamin A (β-carotene) in an effort to combat the millions of childhood deaths each year resulting from vitamin A deficiency.
GM plants are even being used to mitigate climate change. In 2013, GM crops contributed to reducing CO2 emissions associated with applying fertilisers, fuel-use, and ploughing by 28 billion kg – equivalent to taking 12.4 million cars off the road for one year2. There are even plans to turn plants into biological carbon scrubbers by genetically modifying them to grow bigger, hardier root systems which produce more of a carbon-rich substance called suberin, enabling them to absorb larger amounts of atmospheric carbon.
Compared to crops, the use of GM animals in agriculture/aquaculture is in the early stages. The first GM animal marketed as food – a fast-growing salmon – only went on sale in August 2017. Future engineering of farm animals would likely aim to create animals which are more productive, of higher quality, or immune to particular diseases. For example, pigs with immunity to Porcine Reproductive and Respiratory Syndrome, a disease that currently costs the European pig industry ~£1.5billion/year. Alternatively, animals – domestic or wild – may be engineered to prevent them spreading diseases, such as chickens which don’t transmit avian influenza, or modifying mosquitoes to prevent the spread of diseases such as Zika, malaria, and dengue virus.
The most widespread current application of GM animals is in laboratory research, with proponents arguing that modifying animals to create models of human disease is the best method to identify disease pathways and evaluate new therapies and treatments.
Along with their many benefits, there are also numerous problems associated with GMOs. GM animals (and potentially humans) present a range of moral and ethical issues, while the use of GMOs in food raise health concerns. In particular, the potential transfer of antibiotic resistance genes (used as markers during the GM process) to cells of the body or gut bacteria could potentially aggravate the already worrying problem of widespread antibiotic resistance in pathogens. A more general concern is ‘outcrossing’, which is the potential migration of genes from GMOs into other species in the environment. For example, if a crop with improved herbicide resistance was to transfer this gene to an undesired species in the environment this could lead to problems with weed control. While such issues with GMOs are context-dependent, these concerns have added to public fear over GM technology itself. Due to public concerns, and the very real potential dangers GMOs pose, each genetic modification is carefully reviewed and tested for safety before licensing, and, so far, no examples of harmful effects or escaped genes have been conclusively demonstrated.
While concerns remain, the demand for genetically modified crops and livestock is growing as governments and scientists desperately search for solutions to global poverty and malnourishment.
Presently, 815 million people (~11% of the world’s population) suffer from chronic undernourishment. This situation is likely to worsen with an increasing global population, and with climate change predicted to have adverse impacts on crop yields causing global food shortages3. At the same time, the occurrence of zoonotic diseases is rising, partly due to increased transport of people and animals around the globe4. Modifying plants and animals to have greater productivity, improved tolerance to hostile conditions, and resistance to disease and pests could not only help humanity survive, but, if used correctly, could help to mitigate climate change itself.
Ultimately, there are valid arguments and strong voices on both sides of the debate, and there is unlikely to be a universally agreed answer in the near future. However, with the extensive research being undertaken and the stringent protocols already being employed to protect biosecurity, health, and biodiversity in the event of widespread GMO usage, at least we are going into this with our eyes open to what we are doing. Contrast this to the ignorance with which we undertook the widespread artificial selection of the past and perhaps we can see the wisdom of using this potentially life-saving technology to keep the (GM) wolf from the door.
- Blancke S, Van Breusegem F, De Jaeger G, Braeckman J, Van Montagu M. (2015) Fatal attraction: The intuitive appeal of GMA opposition. Trends Plant Sci. 20(7):414-418. doi: 10.1016/j.tplants.2015.03.011
- James C. (2014) Global Status of Commercialized Biotech/GM Crops: 2014. ISAAA Brief no. 49. URL: http://www.isaaa.org/resources/publications/briefs/49/executivesummary/default.asp
- Wheeler T, von Braun J. (2013) Climate change impacts on global food security. Science. 341(6145):508-513. doi: 10.1126/science.1239402
- Jones KE, Patel NG, Levy MA, et al. (2008) Global trends in emerging infectious diseases. Nature. 451:990-994. doi: 10.1038/nature06536