Manipulating Biology: Costs, Benefits and Controversies

Content Objectives

Student Prior Knowledge

At this point in my course, students have studied the following topics: The Living World, Human Population, and Agricultural Land Use. The Living World covers everything from energy and matter flow through ecosystems to the diversity of life on earth and major climate regions and biomes of the world. The Human Population unit covers population growth, demographics, and the stresses a growing population places on the earth. The Agricultural Land Use unit covers agriculture as a major land use, traditional practices vs the modern farming that came out of the Agricultural Revolution, and a cursory overview of the threats to agricultural output.

A Growing Population

In this portion of the course, students learned that the human population has grown essentially exponentially since the advent of the Industrial Revolution, with most of the growth occurring in Europe and Asia. They learned about how advances in medical and agricultural technology paved the way for massive population growth, and about the environmental pressures that this growth placed (and continues to place) on the planet. They also learned about demographics and how and why populations change over time (deemed the demographic transition). Students learned that the current population is 7.4 billion people, and that by 2050 it is predicted to increase to nearly 10 billion, before leveling off in 2100 between 11 and 13 billion people. Most of this growth will occur in Sub-Saharan Africa (SSA) and Southeast Asia (SEA), areas that are already food stressed and have the highest incidences of under and malnutrition worldwide.⁵ This information is critical as a set up to the problem of feeding a growing population, and I make several hints to this in my instruction during this unit.

Modern Agriculture

When I ask my students to imagine a farm, their descriptions often go something like this: a small farm with a few acres of several crops, some livestock (perhaps chickens, pigs, and dairy cows), a red barn and green tractor, and other idyllic images of a bucolic scene. The family sells most of their harvest and keeps some for themselves, making enough money to live a comfortable and manageable life. However, this is an extremely outdated and naïve view of what modern agriculture has become in the wake of the Industrial Revolution. Considering that in order to feed the growing population referenced above, worldwide food production must be increased anywhere from twenty-five to seventy percent by 2050,⁶ the fantasy farm I just described would spell doom for humanity if it were reality. Instead, farming is, and has been for quite some time, a commercial/industrial operation. The mechanization of all aspects of agriculture has significantly increased yields worldwide, while the actual number of farms has plummeted. The emergence of the biotechnology industry has coincided with the consolidation of smaller farms into supermassive factory farms. The reality is that the majority of our crops are grown in monocultures (when farmers plant acres and acres of just one genotype) by a decreasing number of farmers and harvested by massive machinery. Enormous quantities of fertilizer are used to increase yields, while heavy doses of pesticides and herbicides are used to ward off crop losses, and irrigation is used extensively to make previously non-arable land highly productive. These factory farms can be considered both high input and high output. They are highly dependent on the use of fossil fuels for the development of those fertilizers, pesticides, and herbicides, as well as for running the machinery needed on the farm.⁷ However, all of these inputs lead to incredible crop yields. For example, between 1866 and 2014, US yields of corn increased from 1.63 tons per hectare to 10.73 tons per hectare. This represents a more than 500% increase in yield. These statistics are repeated worldwide, as every major agricultural region has experienced dramatic yield increases through advances in technology.⁸

This reality of modern farming often comes with a negative connotation, but there are several environmentally friendly farming techniques being implemented as a way of increasing crop yields in the long term without all of the harmful side effects familiar to modern agriculture. These include many practices used by early farmers, including crop rotation, polyculture, and integrated pest management (IPM).^9,10 Crop rotation is a process where crops are rotated through fields according to their nutrient demands and ability to restore fertility. Some crops require high amounts of nitrogen, while others can help put back nitrogen into the soil¹¹ (this occurs through a symbiotic relationship with nitrogen-fixing bacteria and is beyond the scope of this unit). By moving crops from field to field, natural processes can restore soil fertility and reduce the need for high inputs while maintaining yields. Polyculture is a technique that mimics the biodiversity of natural ecosystems whereby several crops are grown in concert with one another. Coffee plantations are well-known for growing several fruits alongside their coffee plants in order to maximize agricultural output without having to increase acreage. Essentially this works due to varying heights of plants, sunlight/water/nutrient requirements, and differences in planting/harvesting times. IPM is an approach to dealing with pests that employs several methods in concert or succession and requires an understanding of the ecology of the pests. The goal of IPM is not necessarily to eradicate the pest but to manage its population at acceptable levels. One outcome of IPM is that the amount of chemical pesticides is reduced. No two IPM plans are exactly the same because plans must be targeted to specific situations, but in general, IPM involves using such strategies as polyculture, intercropping, planting pest repellent crops, natural pest predators, crop rotation, routine monitoring and data collection, mechanical controls, and as a last resort, targeted applications of chemical pesticides.

Climate Change and Arable Land

Although climate change is its own unit in my APES course, there are several aspects of it that creep into other portions of the course. The impact of climate change on agriculture and arable land is one of those portions. The Intergovernmental Panel on Climate Change (IPCC) reports that some portions of the planet will become more suitable for agriculture while others will become less suitable. The areas of the planet that are predicted to become more arable are mostly limited to the high latitude boreal regions. Much more of the planet is predicted to become less arable, including areas in SSA and SEA.¹² As previously stated, this is problematic because these regions already face the problems of food security and under and malnutrition. The IPCC also reports that warming above 3^oC will result in significant yield declines across major crops that cannot adapt (whether through natural or artificial means) even when gains in yield due to additional rainfall and CO₂ are accounted for.¹³

The mechanisms for the shift in arability aren’t terribly important for student success at this point in the course, but it is important that they have at least a superficial understanding of the processes at work. In areas that experience an increase in arability, it is mostly due to prolonged growing seasons caused by an increase in surface temperatures as a result of the enhanced greenhouse effect brought about by increased concentrations of atmospheric CO₂. The reasons for decreased arability are more numerous and slightly more complex: in some regions, increased surface temperatures lead to decreased crop yields as the plants are no longer suitable for that environment. In others, increased temperatures lead to decreased soil moisture making it difficult to grow crops without frequent irrigation. In others, pests may become more prevalent or may expand into new areas. In still other areas, precipitation patterns shift so that rains are less frequent/more frequent/more irregular, leading to decreases in crop yields.^14,15 These impacts offer an opportunity for the use of GMOs in order to sustain or increase food production in threatened areas such as SSA and SEA.

Key Unit Content

Conventional Breeding Techniques

Selective breeding, which is also known as artificial selection, is the original process by which domestication of plants and animals occurred.¹⁶ In this process, traits that are deemed desirable by humans are “selected” for, meaning that individuals that possess those traits are bred to advance that trait in the next generation.¹⁷ The expression of those traits are observed as the organism’s phenotype. The timeline of selective breeding is painstakingly slow, as favorable traits can only be passed down as fast as organisms can reproduce (or as fast as researchers can create breeding pairs). This process occurs incrementally and takes many generations to obtain the desired outcomes. And just like evolution by natural selection, there must exist variation in the population to begin with for artificial selection to occur. If there isn’t variability in the trait of interest, then selective breeding may not be possible.

Cross breeding is another version of artificial selection that is depicted in Figure 1 below.¹⁸ In this technique, two compatible species are bred to create a variety of the species that has the most desirable traits of the parents.

Figure 1: various crop modification techniques used to select for desirable traits in organisms.

Selective and cross breeding are methods responsible for the development and refinement of nearly every familiar agricultural species. For example, the domestication of corn in Mesoamerica was achieved by cross breeding of wild teosinte and maize plants. Through enough generations, cross and selective breeding produced the multi-eared, single stalk corn plants so ubiquitous in the Americas.¹⁹ These simpler breeding techniques are still used throughout the world. But like selective breeding, cross breeding can take several generations to produce the desired outcome and is still blindly working off of the species’ phenotype. The remainder of the techniques presented in Figure 1 are all forms of GM, some of which are discussed in the next section.

Genetic Modification

GMOs are living organisms whose genetic material has been artificially manipulated in a laboratory through genetic engineering. GMOs are often the product of combinations of DNA from plants, animals, bacteria, and viruses, and do not occur naturally or through traditional selective breeding methods.²⁰ At its basis, GM is simply a more precise version of the selective breeding that farmers have been doing for millennia. However, the mechanisms for GM are more complex than that and warrant some discussion so that students have a solid understanding of how traits like drought tolerance, increased protein content, or resistance to pests arise in the target organisms.

Instead of waiting for desirable phenotypes to emerge and then breeding those organisms in hope that the offspring also express that phenotype (or express it greater), scientists can use a form of GM to more precisely influence the desired phenotype. Of particular importance in the recent waves of GM are transgenesis and genome editing (Figure 1). In transgenesis, a desirable gene from one organism is inserted into another. As depicted in the figure, resistance to a virus found in the genome of a bacterium can be inserted into a popular fruit. There are several examples of GMOs of this type. For example, Bt corn, RoundUp Ready crops, and Golden Rice are all GMOs that arose from transgenesis.

“Golden Rice” is a variety of rice that produces higher amounts of beta-carotene than traditional rice. Beta-carotene is a precursor to Vitamin A, so Golden Rice is an incredibly important non-medical solution to Vitamin A deficiencies that currently cause 670,000 children to die prematurely²¹ and an additional 500,000 cases of permanent blindness each year.²² The genes for this over-production of beta-carotene are psy (which first came from a daffodil species but was later sourced from a maize plant), and crtl (which comes from a soil bacterium). The genes are engineered to only be expressed in the endosperm of the plant, which is the part that eventually gets harvested for human consumption.²³ Bt corn is a variety of corn that is resistant to certain species of moth, caterpillar, and nematode pests thanks to insertion of a resistance gene found in the soil bacterium Bacillus thuringiensis. The use of Bt corn was introduced as a way of reducing the use of pesticides needed to kill those moths, caterpillars, and nematodes that plagued farmers and reduced crop yields.²⁴ Glyphosate resistance was pioneered by Monsanto when scientists discovered that bacteria residing in the wastewater of a glyphosate production facility had evolved resistance. The gene responsible for this resistance was isolated from the bacterium and then inserted into corn using transgenesis. This allowed farmers to spray glyphosate on their fields, killing any weeds and leaving the crop unharmed.²⁵

Genome editing of crops is a relatively new method of genetic technology that shows promise for creating the next generation of GMO crops. In this process, the existing DNA of an organism is directly modified using restriction enzymes²⁶ or Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR).²⁷ This allows scientists to insert specific sequences of DNA into a targeted part of the organism’s genome instead of having to transfer genes from one organism to another.²⁸ One potential organism that could be modified this way is the tomato: the gene sequence that codes for the production of locules in tomatoes could be altered to produce more locules (causing the plant to produce more tomato fruits). Or the fruit size could be increased, or ripening could be made to occur faster, or height could be fixed to allow for mechanization of harvest.²⁹ A more detailed explanation of this method is beyond the scope of this unit, but the hallmark is that those altered gene(s) can be engineered to be preferentially inherited through the germ-line, significantly reducing the cost of seed development and tinkering from year to year. Other crops that have been successfully modified using this technology include barley, corn, soy, sorghum, and rice.³⁰ The struggle to develop successful genome-edited crops has to do with the exact heritability that makes this technology so exciting. However, much research is needed before these GMOs hit the market and become readily available.

Prevalence of GMOs

Students should understand that many of the crops which they are familiar with are genetically modified in some way. According to industry statistics, the use of GMO crops increased from 1.7 million hectares in 1996 to 185.1 million hectares by 2016, representing a 110-fold increase. Much of this growth occurred in developing countries, who grew 54% of all GMO crops, compared to 46% for developed countries. Soybean, corn, cotton, and canola were the most widely used GMO crops.³¹ GMO crops represent 75% of all crops grown worldwide.³² Students should also realize that even non-GMO crops have been genetically altered using selective and cross-breeding practices dating back millennia to the domestication of plants and animals in the Neolithic period.

Advantages of GMOs

The benefits of using GMOs can be characterized in two ways. The first is that they have direct positive outcomes for people. For example, using GMOs can improve food security in regions like SSA and SEA where millions of people are either chronically under or malnourished, as in the case of Golden Rice. This is true for other varieties of GMOs as well, since GMOs have been proven to increase agricultural yields time and again. Their use can also increase, or at least maintain crop yields in the wake of changes to arable land as a result of climate change.³³ As previously discussed, this becomes incredibly important as weather patterns shift, pest ranges increase, and intensely farmed lands face desertification. The second characterization is that they have positive outcomes for the planet, and thus humanity in general. Using pest/disease-resistant crops can reduce the use of harmful pesticides and insecticides that threaten species biodiversity in agroecosystems, while using drought-tolerant crops can reduce the need for irrigation in water-stressed regions, lessening the need for non-direct water consumption.  The potential reduction in inputs can lead to more sustainable crops overall.³⁴ Additionally, a reduction in inputs can lead to lower costs for consumers, so long as the agricultural industry passes along these savings.

For many years these benefits were touted by industry and stakeholders, but recently the United States Department of Agriculture (USDA) has reported that the use of GMOs does indeed represent cost savings both for consumers and farmers and has several key benefits for the environment. The report found that GMOs hold a yield advantage over conventional varieties, and that this advantage has become larger as refinements in modification technology have improved the specificity and efficacy of targeted modifications. They also report a decrease in insecticide use due to widespread adoption of Bt varieties of several crops, as well as a shift away from more toxic and persistent forms of herbicide in favor of glyphosate and glyphosate-tolerant varieties. Finally, the report demonstrates significant realized economic gains by farmers using GMO crops.³⁵  Table 1 summarizes the potential benefits of a widespread GMO program.

In summary, the use of GMOs has been shown to increase yield, improve the economic standing of farmers, and reduce the use of the most environmentally harmful active ingredients in herbicides and insecticides.³⁶ These benefits are not trivial, especially considering the scales of both the agricultural productivity and climate change issues. Consumers seeking to make a sustainable choice must give credence to such benefits when weighing GMOs as part of their diet. These benefits must also be considered by governments seeking to fight hunger and the effects of climate change simultaneously.

Disadvantages of GMOs

As discussed above, the primary arguments for GMOs consist of a body of scientific evidence that demonstrates increased yields compared to non-GMO varieties as well as early experimental evidence that GMO varieties of crops can better withstand potential harmful effects of climate change. The primary arguments against GMOs are less scientific, as the preponderance of scientific evidence shows no adverse human effects or ecological influence.³⁷ There are two valid concerns surrounding GMOs. The first is the business practices employed by large biotechnology companies who stand to make a large profit by selling their product. This was brought to the forefront in 1998 when Monsanto sued a Canadian farmer for unauthorized use of their GMO canola seed. The farmer claimed to have never purchased seeds from Monsanto and argued that the glyphosate resistant gene found in his crop must have transferred indirectly from a nearby farm planted with Monsanto’s variety. While this argument seems plausible, Monsanto argued that the level at which the gene was present in the farmer’s plants could not have been elevated to such high levels by accident. Their argument was that the farmer accidently harvested some of the neighbor’s seeds and planted them in his own fields next year.³⁸ This story resurfaced in 2014 when the US Supreme Court ruled in favor of Monsanto’s patent rights and ability to sue for infringement.³⁹ Although no legal wrongdoing was ever proven, the fear of such a major company using its mighty resources to squash such accidental use is very much alive and, in my opinion, valid. Another criticism of such companies’ business practices is that small farms end up on a never-ending treadmill of purchasing seeds and herbicides or insecticides from the company. This is worrisome because of the limited number of vendor options, especially for those in developing countries.

The second argument against GMOs concerns how their use might influence resistance in weeds and pests. The long term evolutionary impacts of using GMOs is certainly concerning, but the speed by which resistance arises in agroecosystems is most troublesome. For example, from 1996 to 2002, the use of Bt corn increased from 1.1 million hectares to over 10 million hectares. Within that time, and likely a consequence of the increase in use, a Bt-resistant pest evolved. By 2011, there were at least 5 confirmed species that evolved Bt-resistance.⁴⁰ A similar story arose after the introduction of Roundup Ready crop varieties. Within ten years, twenty-four species of glyphosate-resistant weeds had independently evolved. The issue with altering the genes of crops is that it imposes an intense selection pressure on the very pests and weeds they are designed to overcome.⁴¹

Summary of GMO Controversy

Regardless of their opinions on GMOs, people can generally be categorized into theorists or rationalists.⁴² Those who support GMOs may idealize the use of GMOs as a silver bullet in the fight against hunger, while other supporters may point to the previously discussed concrete evidence of their increased yields and economic benefits to farmers. Some of those who question the use of GMOs may point to those unproven claims of the health dangers of consuming GMOs while others may point to the previously mentioned Bt-resistance in pests and glyphosate-resistance in weeds. In my experience, the people who fall into the theorist camp tend to be the most fervent and vocal supporters and opponents of GMOs, while those who can be considered rationalists are milder in their support or opposition. These rationalists also seem to be more open to changing their mind in light of new evidence.

Table 1: summary of potential pros and cons of using GMOs

Table 1, a summary of the potential pros and cons of GMOs adapted from a popular APES review book⁴³ is emblematic of the struggle to present arguments based on concrete evidence. The author is careful to qualify certain statements with “may” or “unknown,” playing right into the controversy between rationalists and theorists. It is my hope that this unit will help my students fall into the rationalist group.

In general, this controversy is difficult to settle because GMOs are simultaneously a scientific, political, economic, agricultural, commercial, ethical, and personal issue.⁴⁴ For example, FDA approval of a GM salmon that matures faster than natural salmon sparked outrage by prominent US politicians, including Alaskan senator Lisa Murkowski. Senator Murkowski, along with Congressman Don Young, criticized the FDA for approving something more akin to a science experiment than food. What the senator and congressman failed to realize though is that the company behind the salmon began seeking the approval process in the 1990s and only received initial approval in 2010. The FDA spent the next five years reviewing the scientific literature and considering objections before finally granting the final approval. In this case, Senator Murkowski and Congressman Young engaged in a misinformation campaign that muddied the otherwise crystal-clear water in part because the salmon fishing industry is worth tens of thousands of jobs and billions of dollars in revenue.⁴⁵

Politicians on both sides of the ideological aisle routinely engage in such campaigns in order to protect the interests of their constituents (and subsequently their place in government). Part of the reason that politicians and other people in positions of power can be so successful is due to declining scientific literacy in the population. This, combined with the unbelievable amount of information available at our fingertips through the internet, makes it all too easy to stir up controversy on an issue that is relatively controversy-free among the scientists who actually study it.⁴⁶ This is exactly what has happened with GMOs; despite countless studies that demonstrate no harmful effects on human health or on the environment,⁴⁷ there still exists an anti-GMO fervor. I should note that this sentiment is much stronger in the European Union, where only twenty-three percent of people trust GMOs, while in the US people are either more accepting of their prevalence or simply ignorant to their widespread use.⁴⁸ Part of my job as a teacher is to help students wade through this controversy and identify what is simply rhetoric and what is backed up by evidence. In tackling the perceived controversy over GMOs, I have the ability to influence students to think rationally, seek evidence, and revise and update their understanding of an issue in light of new information. 

Using GMOs as Part of a Broader Agricultural Strategy

The debate over GMOs would make it seem it’s either all or nothing: those in favor of GMOs envision a world where GMOs rule and less insecticide is used, there is less tillage, agricultural inputs are potentially lowered, and maybe advanced seed technology potentially lessens agriculture’s dependence on petroleum. In a world without GMOs, farmers spray large quantities of broad spectrum insecticides damaging surrounding food webs, farmers till more, which kills soil biota, and inputs of fertilizer and water are high, enhancing agriculture’s contribution to climate change. But the people who are most vested in this debate, the farmers, don’t see it that way.⁴⁹ If farmers don’t need GMOs (economically or otherwise), then they won’t use them. If they need to use pest-resistant crops because of an infestation, or drought tolerant crops in the wake of changing precipitation patterns, then they will.

Given their potential limitations, GMOs are not likely to be a one-size-fits-all solution to increasing crop yields amidst threats to productivity by climate change. Instead, they can be used alongside other farming techniques that show promise. As discussed earlier, IPM, crop rotation, and polycultures are just a few other useful strategies that can be employed alongside GMOs as modern agriculture adapts to the needs of the global population. Under this paradigm, GMOs can be used to move farmers away from the chemical-dependent practices of their predecessors without sacrificing their yields– something conventional environmentalists should be cheering, not opposing.⁵⁰