Skip to content

Biomedical Odyssey

Life at the Johns Hopkins School of Medicine

Biomedical Odyssey Home Perspectives in Research Genetic Modification, Then and Now

Genetic Modification, Then and Now

A cornfield at sunset.

Genetically modified organisms (GMOs) as they exist today are the latest advance in a long history of human-imposed changes to the DNA of the crops we eat. While public skepticism of GMOs is widespread, a look at our history shows that some of this skepticism may be misguided.

What does ‘genetically modified’ really mean?

DNA acts as a blueprint that cells can read to build a living thing such as a person or a plant. Those blueprints are passed down from biological parents to their children, the study of which is referred to as genetics. The word “genetics” comes from the word “gene,” which is a small section of the instructions encoded in the DNA blueprint. Genetic modification refers to the purposeful altering of the DNA blueprint, and can be carried out in many different ways. Although the idea of genetic modification may be scary to some, humans have been creating GMOs for longer than you think.

Agricultural practices have altered the blueprints of the food we eat for thousands of years.

Thousands of years ago, when hunter-gatherers first made the transition to farming, they introduced changes to the environments in which they grew their plants. In doing so, they changed the DNA blueprints of those plants. Cereal crops like wheat provide an excellent example. In nature, the DNA of cereal crops includes instructions for seed shattering: The seed shatters so its contents can be widely dispersed. This provided an advantage in the wild, which turned into a disadvantage in agricultural fields. When farmers came through to harvest and collect seeds for the next year, the only seeds that remained in the field were the ones that did not have this genetically encoded tendency to shatter. These non-shattered seeds gave rise to the next year’s crops, so seed shattering was even less common in the next year’s harvest. In this way, after a few generations of this early farming system, crops lost the gene for seed shattering.

Seed shattering is just one example of how, from the very early days of farming, humans’ agricultural practices altered the DNA blueprints of the plants we ate. As agriculture advanced, farmers began selecting for foods that tasted better, smelled better and were easier to farm. Considering that the plants resulting from this process look and behave nothing like the ones that truly arise in the wild, these are very “unnatural” changes, but since agriculture has been around since the beginning of human civilization, we’ve had 10,000 years to get comfortable with eating these farmed foods.1, 2

Genetically modified food as we know it today began with the Flavr Savr tomato.

In the past few decades, rapid advances in molecular biology have given rise to new methods for altering DNA, collectively referred to as genetic engineering. With these new methods, it’s possible to introduce changes that previously would have been very difficult to bring about. In 1994, the California company Calgene developed the first genetically engineered crop to hit the market: a tomato with enhanced flavor. They did this by changing the DNA of the tomato that told it to soften as it ripened. Without genetic engineering, the ripening and softening of tomatoes go hand in hand. Challenges in transporting soft produce make it easier to pick unripe tomatoes for distribution and artificially induce ripening before sale. While this produces tomatoes that look ripe, the shortened natural ripening process prevents the full development of flavor. By inhibiting softening, Flavr Savr tomatoes were able to buy themselves more time on the vine, extending natural ripening and allowing the flavor to more fully develop. The Flavr Savr tomato was a hit with consumers, and Calgene took a route of thorough transparency, voluntarily seeking FDA approval and even publicizing an 800 number that customers could call if they had questions about this new kind of product.3

So what’s the big deal?

If we have been genetically modifying plants for thousands of years, why are concerns about genetically modified foods so common today? The obvious answer would seem to be that new methods for genetic engineering are less safe than more established agricultural practices. But in reality, the reason may be more subtle. When Calgene first brought modern-day GMOs to market, they got off to a promising start. But the leaders of Calgene were experts in biotechnology, not agriculture. Logistical challenges prevented efficient distribution of their popular product, leading to their gradual buyout by the large seed company Monsanto. This merging of genetic engineering and large agricultural companies contributed to the widespread skepticism we see today, driven in part by a transition away from consumer-motivated engineering as well as a lack of transparency.

While Calgene engineered the Flavr Savr tomato to meet consumers’ needs, Monsanto decided to focus more on benefiting farmers. The most common GMO products today have been engineered for resistance to herbicides and/or pesticides, allowing farmers to spray chemicals such as Roundup to prevent crop loss to insects and weeds.3 Evidence has shown that consumption of/exposure to these chemicals above a certain level can be dangerous. Regulatory organizations such as the EPA and WHO collect and examine scientific evidence to specify a safe tolerance level for chemical products used in farming. These organizations release reports at least once a year to keep up to date with changes in common practice as well as new scientific evidence.

Monsanto and other large companies have additionally been accused of a lack of transparency and of being resistant to label their GMO products. GMO corn, for example, is used in a wide variety of processed foods, so it can be difficult to know which products contain ingredients that have been genetically engineered. Additionally, intellectual property questions have led to disputes between Monsanto and small farmers. Genetically engineered crops are the property of the company that holds the patent, and replanting seeds that come from these crops is illegal. This has led to conflicts with small farmers whose land is near fields of genetically engineered crops as they fear that inadvertent contamination could lead to a lawsuit. Monsanto has won several legal cases surrounding this issue, but they claim that they will not pursue patent infringement in the case of slight contamination (less than 1%).4

What is the landscape of GMOs today?

So, where are we now? Plants that have been genetically modified through traditional agricultural practices like selective breeding are everywhere, but modern-day GMOs (foods created using genetic engineering) are a bit more complicated. If I stand in the produce aisle at my local grocery store will I be surrounded by genetically engineered foods? Not really. The USDA keeps a list of “[bioengineered] crops or foods that are currently in legal production somewhere in the world,” and as of October 2020, it contains 13 items. Each item on this list has been approved by the FDA and found to meet the same standards for safety as non-bioengineered foods5. This means that for many of the fruits and vegetables you can buy (including but not at all limited to tomatoes, berries, bananas, cucumbers, carrots and oranges), you can be confident that they have not been genetically engineered. That said, to claim that modern-day GMOs are not common would also be extremely misleading. Two members of the list, corn and soybeans, represent the top two crops grown in the U.S. by acreage, covering more than 175 million acres of land in 20206. That’s enough to fill the entire state of Maryland 22 times, with enough left over to fill up the city of Baltimore almost 20 more times; it’s almost a tenth of the area of the continental United States7. With a majority of these crops going into animal feed as well as processed food and food products around the country, it is safe to say that genetic engineering has come to play a very prominent role in the food industry.

Practice informed skepticism.

The objective of this article is not to silence skepticism toward modern-day GMOs. We should absolutely be mindful of what we eat and purchase, whether it’s been engineered or not. However, we should direct that skepticism where it is most warranted. Pesticide and herbicide use is not limited to modern-day GMOs — in fact, none of the three produce items found to contain the highest levels of pesticides fall into the category of bioengineered foods8. Similarly, opposition to the legal practices of large companies relating to their use of GMOs certainly warrants skepticism of those companies and their products, but should be considered separately from the safety of the technology behind the product itself. While scientific advancements have made it more efficient, the truth is genetic modification of food is a tradition as old as civilization itself.



Related content

Want to read more from the Johns Hopkins School of Medicine? Subscribe to the Biomedical Odyssey blog and receive new posts directly in your inbox.