Genetic modification is like mayonnaise; almost everyone has strong feelings about it, whether negative or positive. A solid opinion is justified, as the genetic modification of crops is an important characteristic of our food system. According to the USDA, over half the land used for crops in the U.S., or 169 million acres, was planted with genetically engineered crops in 2013. Common arguments in favor of genetically modified organisms (GMOs) are that they enable farmers to use fewer pesticides and that heartier varieties (drought/frost resistant) have an important role to play in feeding an ever-growing global population. Arguments against GMOs point to health concerns and a watering down of the gene pool. Rather than speaking universally of GMOs as “good” or “bad,” I suggest digging a little deeper into the science of genetic manipulation.
The terminology we use to describe genetic modification is important. First, we must distinguish between genetic modification, which can be achieved through breeding, and genetic engineering, which involves the mechanical manipulation of gene sequences. For instance, bio-fortified crops can be enhanced either through genetic engineering or through conventional breeding methods quite unlike the much-cited example of a vegetable that has been endowed with a gene from an animal, which will not be found on the market. Conventional breeding entails selecting for mutations that are advantageous to a plant in some way, and breeding so that characteristic may proliferate expeditiously. The orange flesh sweet potato (OFSP) is one example of such a crop, and its benefits are irrefutable. In sub-Saharan Africa, this nutritionally superior staple crop is playing an important role in alleviating vitamin A deficiency, a leading cause of child mortality.
“Golden rice”, another important combatant of vitamin A deficiency, is principally employed in Asia, where persistent malnutrition and growing population has resulted in a significant emphasis on enhancing both the quality and quantity of rice production. Golden rice, unlike OFSP, is transgenic in that it has received two genes in order to turn on an existing pathway to formulate and accumulate beta-carotene; see goldenrice.org for more information on the engineering process. The goal of the crop, however, is the same: an aggressive response to a very preventable condition that affects 190 million children and 19 million pregnant women worldwide (World Health Organization).
Another term we frequently hear is hybrid, or the result of breeding across species or varieties to create something entirely new. Once again, DNA has not been mechanically altered, but the outcome is a plant (or animal) that did not formerly exist in nature. I recently attended a webinar concerning the development of drought tolerant rice cultivars (through hybridization and inbreeding) in India, under the Cereal Systems Initiative of South Asia (CSISA). The presenters shared compelling evidence of farmer willingness-to-pay for hybrid varieties which reduce variability in yield, and also those that outperform traditional varieties under normal conditions as well as drought conditions. Similarly, farmers in Mozambique have demonstrated a preference for OFSP varieties that have a comparable eating quality to the traditional white varieties.
Many farmers worldwide are enthusiastic supporters of bio-fortified, hybridized and genetically engineered crops. One key challenge, however, is finding appropriate export markets; many countries have a ban on GMOs, limiting their utility in Africa and Asia to regional consumption. This is not necessarily negative, but may inspire hesitance in farmers seeking to grow their market share.
While there is a lack of non-biased evidence from empirical research showing any negative health consequences of GMOs, it is important to know that not all genetic manipulation is the same. Mutagenesis, or the random deletion or rearranging of genes through a process that mimics the sun’s radiation, is more likely to cause unintended changes than genetic engineering that focuses on specific genes. While it sounds quite futuristic, this process is not new; breeders have relied on mutagenesis for decades to create thousands of new varieties of crops that have not been proven harmful to human health in any way.
The moral of the story: all genetic modification is not created equal, and many scientists suggest a case-by-case evaluation of new varieties as they are released for human consumption rather than an unequivocal acceptance or rejection. In order to speak intelligently on the topic, we should all make sure we have a firm grasp on the terminology as well as the scientific research that supports our position.