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Modifying An Opinion

The Resistance to Evidence About GMOs
February 10, 2019 | Comments

Mark Lynas once gleefully destroyed fields of genetically modified crops. He was an outspoken critic of genetic engineering of the food we eat, insisting that what we commonly refer to as GMOs are dangerous to our health and to the environment. He felt as passionately about this as he did about another cause he embraced, human-induced climate change.

        And then he reviewed the evidence.

        He found that unlike the case for climate change, there was no scientific evidence that GMOs are harmful to human health and almost none that it has negative impacts on the environment.  “Was it really possible,” he writes in his book Seeds of Science, “that…pretty much the entire environmental movement, and indeed polite progressive liberal society in general, had got the GMO issue flat-out wrong?”[1]

        Lynas details in the book how he relied on scientific evidence and consensus to support his certainty that humans are responsible for climate change. When he tried to find the same sort of strong scientific evidence for his belief that GMOs are dangerous, he came up empty-handed. And that set him off on the journey, detailed in Seeds of Science, to publicly acknowledge his reversal of opinion. Doing so meant alienating many people in his social network, people with whom he had chopped down GMO crops and raided the offices of the Monsanto corporation, now a division of the Bayer company and a major manufacturer of genetically-modified seeds.

Tribe Over Facts

        Lynas’ story is, of course atypical; radically changing one’s mind and position in response to acquiring new information is exceptional. In fact, studies show that for people with tightly held ideas about a scientific issue, providing accurate information that conflicts with their points of view does not work to change their minds. In fact, it usually has the opposite effect.  “Simply put,” explains Yale Law School Professor Dan Kahan, “as ordinary members of the public acquire more scientific knowledge and become more adept at scientific reasoning, they don’t converge on the best evidence relating to controversial policy-relevant facts. Instead they become even more culturally polarized”.

        Kahan and others speculate that the reason for this paradox by which more information leads to less intellectual flexibility stems from the fact that individuals can do very little by themselves to change many pressing policy and political issues, but they can do a lot to alienate members of their social group. For example, if one person does or does not consume food grown from genetically modified seeds, it will have no impact by itself on either whether the public accepts GMOs or on world hunger. But if a person who is a member of a social group that fervently believes GMOs are bad changes her mind about them and decides they are, in fact, not harmful, that will be sufficient to get her tossed from the group. Hence, there is little to gain and a lot to lose for an individual to change her mind.

Most Passionate, Most Inaccurate

        For most people, then, new information is threatening, and we use all the powers of confirmation bias to either twist it into some form that seems to agree with our existing point of view or to find fatal flaws in the new information that allows us to reject it. Unfortunately, a new study shows that the information provided by the most fervent anti-GMO advocates is likely to be highly inaccurate.

        Researchers from the University of Pennsylvania and the University of Colorado surveyed more than 2000 people about both their attitudes toward and knowledge about genetically modified foods. They also administered the study subjects a test of their knowledge about science and genetics. They found that “the more strongly people stated their opposition to such foods, the more they thought they knew about the topic but the lower they scored on the test”. Thus, the more fiercely opposed a person was to GMOs, the more he thought he knew about them, but the less he actually did know. People who pass themselves off as experts about GMOs, therefore, may be the least knowledgeable about the subject.

Breakthroughs in Agricultural Science

        This is unfortunate to say the least because the scientific community is increasingly calling for wider use of genetically modified crops in order to battle the planet’s ever-increasing hunger problem. A meta-analysis published last year showed that genetically engineered corn has increased crop yields and contains reduced amounts of a toxic substance called mycotoxin compared to non-GMO corn. The winners of this year’s Nobel Prize for chemistry recently stated that genetically modified crops are in fact safe and actually enhance the environmental sustainability of the world’s food production.

        More such progress is likely to happen now that the wheat genome has finally been sequenced. The common wheat plant from which we make bread turns out to have a more complicated genetic structure than humans do. Because of both natural and farmer-conducted cross-breeding that has taken place for centuries, the wheat plant now has over 100,000 genes, with six copies of most individual genes. By contrast, humans have about 20,000 genes and two copies of each gene (except in special cases). When people say they are sensitive to gluten, it could be that they are actually sensitive to one of the almost innumerable proteins for which all of those wheat genes code. Because of this complexity, scientists had an incredibly hard time figuring out the genetic sequence of the common wheat plant, but now that this has been accomplished, opportunities abound to make wheat plants that are more robust against drought, heat, and insects and less likely to contain allergens.

Confronting Our Fears

The safety of genetically modified foods for human consumption is now well-established and there are multiple benefits besides increased crop yields. As Lynas notes, GMO crops reduce the need for pesticides and reduce carbon dioxide admission.[2] For scientists, there is little question that the benefits of genetically modification of agricultural products outweighs any risks. So how can we break through the public’s fears about them?

        First, we must convince people that the misdeeds of large corporations do not automatically mean their products are dangerous. Many people have legitimate complaints about the manufacturers of genetically modified seeds, especially Monsanto. But that does not mean that the technology behind genetically engineered food is dangerous. Large pharmaceutical companies are often correctly accused of ethical lapses, but we continue to value many of their products, including antibiotics and insulin. Solid independent research that is not industry-funded substantiates the claim that GMOs do not pose a risk to human health.

        Second, we have to listen to those who are nervous about GMO technology. While we may not ever convince the hardcore opponents of any type of scientific advance, most people who question the safety of GMOs are probably not iconoclastic but rather worried. As science writer Anita Makri notes “To respect the public’s understanding of a technological risk is not to say that the public is right or more correct than the experts. Rather, it is to acknowledge that the public has legitimate concerns that expert assessments might miss”.

        Third, we need to continue to work on the “science of science communication” and figure out how best to overcome the refusal to accept scientific evidence. For example, curiosity has been shown to be a fascinating trait that increases an individual’s ability to accept information that contradicts a firmly held belief. In his very compelling Scientific American article “Why Smart People Are Vulnerable to Putting Tribe Before Truth,” Dan Kahan considers the possibility that enhancing curiosity about science might help overcome science denialism.

“But if the science of science communication is not yet in a position to tell science communicators exactly what to do to harness the unifying effects of curiosity,” he writes, “it unmistakably does tell them how to figure that out: by use of the empirical methods of science itself”.

One piece of empirical research that may be helpful suggests that having people listen to Mark Lynas tell his own story can change minds. In research done at the Annenberg Public Policy Center of the University of Pennsylvania, people were randomized to either listen to a video tape of Lynas simply relating facts about GMOs or to video tapes in which Lynas explained his personal conversion story. The latter were more effective in inducing people to change their minds and become more favorable towards GMOs.  Thus telling a story–in this case a personal conversion story–was more influential than simply reviewing the scientific details.

        We need to understand why people listen to purveyors of misinformation and how to steer them toward the evidence. The technology involved in genetically engineering crops is complex and difficult to convey clearly to people who lack a deep understanding of genetics. And whenever a topic is complex, it creates openings for people to intrude with simplistic and incorrect explanations. Right now, it seems clear that GMOs are the subject of a tremendous lack of understanding. As climate change and population increases continue to challenge our ability to provide the world with enough food, especially affecting the world’s most vulnerable populations,, there is clear urgency to figure out how we can better communicate the safety of genetically modified foods. It is time to put away our fears and get on with the critical task of growing more food.


[1] Mark Lynas: Seeds of Science: Why we got it so wrong on GMOs. London, Bloomsbury, 2018, p. 42.

[2] Ibid., p 257.


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