GMOs: An Introduction

By Marc Brazeau | illustrations by Leah Zins | LZ Graphic Design |

The debate around GMOs has heated up and people are looking for answers. For those new to the issue, that can be very difficult to do with confidence. As someone who has waded through every aspect of the discussion, I’d like to share with you what I’ve learned, some important things to keep in mind, and some tools for assessing the information and misinformation that flies fast and furious around in documentaries and on the internet.

What people refer to as Genetically Modified Organisms, or GMOs, are crops bred with the most sophisticated breeding technology. In this context, genetic modification happens when breeders take the specific trait that they want from one plant or organism and transfer it to another plant. Or it can be as simple as slightly changing how a single protein in a given plant expresses itself, as in the case of the Arctic Apple which is an apple that has been bred to resist browning after it’s been cut.

Without a little a basic botany, genetics, and history, it can be an intimidating technology. In their proper context, it’s clear that GMOs represent an important advancement in agriculture. Let’s start at the beginning.


Humans began changing the genetics of plants 10–12,000 years ago in the Fertile Crescent with the beginnings of agriculture. By choosing the most palatable plants, and then the most robust of those, we began making intentional decisions about the genetic makeup of our food before we even knew what genes were. The fruits, grains and vegetables we eat now bear little resemblance to the crops we started cultivating ten millennia ago. Take corn for example. Corn started as a small grass called teosinte in Central Balsas River Valley of southern Mexico. Teosinte has about a dozen small seeds in a rock hard shell. Evidence was found in Xihuatoxtla by archeologists that by 8,700 years ago that primitive corn was already under cultivation in that region.

A familiar vegetable like broccoli does not appear on the scene until 8000 years later in the 6th century BC. Broccoli was the result of careful breeding from the wild mustard plant in the Northern Mediterranean of leafy cole crops. It was Alexander the Great who brought back a wild dwarf apple from Kazakhstan to Europe. There it was bred from something close to a crab apple to the big, sweet, juicy fruit that we know today.

Wild strawberries first enter the historical record in 234 BC and were growing in the New World when Europeans arrived in Virginia in 1588. Although Europeans had been growing wild strawberries in their gardens for some time, the big juicy strawberry that we recognize today wasn’t bred for cultivation until the 1750s in France, a cross between that wild strawberry from Virginia and one from Chile.

Consider the kiwi fruit, previously known as the Chinese Gooseberry. It was grown and used for medicinal purposes in China and India for centuries before it was brought to the United States in 1904 where it was used for decorative purposes in arbors. In 1906, it made it’s way to New Zealand where it finally became recognized, and cultivated as food.

Perhaps the most striking example of the radical impact of human intervention on wild plants is the brassica family. Starting in the wild as mustard, it has been bred into cabbages, brussels sprouts, mustard greens, cauliflower, rapeseed (canola), turnips, rutabaga, collard greens, bok choy, watercress, radish, wasabi and of course, broccoli. It’s amazing to think what we coaxed out of a little mustard seed when we put our minds to it.

That process sped up and intensified when Gregor Mendel, an Austrian monk and student of natural history, began systematically breeding pea pods in 1854. His discovery of dominant and recessive traits in plants set the stage for the highly targeted selective breeding that revolutionized modern agriculture. That insight was among those ideas that turned the 20th Century into an unparalleled engine of innovation and human progress. Mendel observed that cross breeding different varieties of compatible plants resulted in predictable outcomes. That allowed for isolating desired traits. Those traits could then be further selected in new and improved hybrids.

It took a few decades for Mendel’s ideas to take hold. When they did, the career of the modern breeder came on the scene. As breeders set to work improving crops with greater intention and efficiency, they needed to protect their inventions. They needed to secure a means of being rewarded for their labor. In 1930, the United States passed the Plant Patent Act. Testifying on behalf of plant breeders, Tom Edison remarked, “This [bill] will, I feel sure, give us many Burbanks.” referring to Luther Burbank an American botanist who developed over 800 strains and varieties of plants.

It’s hard to look at the increase in something like corn yields since the passage of that law and not be in awe of what contemporary plant breeders have accomplished. Extending breeders those same protections as other inventors was a wise move.

In the last 100 years, breeders have bred crops to improve the flavor and texture of crops and to raise yields. They have also bred crops to tolerate drought, high temperatures, resist viruses, fungi and bacteria. They have bred crops to resist insects and other pests. They have bred crops to resist weed killers. Without these traits, the kind of agriculture necessary to feed 7 billion people would be impossible. They have done this through selecting the traits they want and cross breeding crops with plants that have those traits.

Let’s consider one strategy from nature that will surprise most people. Resistance to insects and other pests. Did you know that many plants produce their own pesticides? In a paper from 2000, environmental pioneer Bruce Ames wrote:

About 99.9 percent of the chemicals humans ingest are natural. The amounts of synthetic pesticide residues in plant food are insignificant compared to the amount of natural pesticides produced by plants themselves.Of all dietary pesticides that humans eat, 99.99 percent are natural: they are chemicals produced by plants to defend themselves against fungi, insects, and other animal predators. We have estimated that on average Americans ingest roughly 5,000 to 10,000 different natural pesticides and their breakdown products. Americans eat about 1,500 mg of natural pesticides per person per day, which is about 10,000 times more than the 0.09 mg they consume of synthetic pesticide residues.

Fig, parsley and celery produces psoralen which is toxic to insects and fish. Potatoes, tomatoes, apples and okra produce the solanine which protects against fungi and blight. Cassava produces cynanide which protects the root from being eaten by insects and animals. Borrowing from nature’s playbook, breeders have sometimes tried to increase the amounts of pesticide produced naturally in order to make the plant hardier. Resilient plants mean the farmer can bring more to harvest. Sometimes, they try to decrease the amount of toxins to make the plant safer for human consumption.

In the 1920′s Lewis Stadler of the University of Missouri first used X-rays on barley seeds. He found he was able to induce novel mutations in the genes of the plants. Through the next few decades, breeders experimented with mutagenic breeding. This method really took off after World War II with an effort to find peacetime uses for atomic age technology. By exposing seeds to X-rays, gamma rays or chemicals, plant scientists could create varieties faster, choosing the most useful results to create many of the foods that we enjoy today. Calrose rice, released in 1948, jump started the California rice industry. The Star Ruby grapefruit was released in 1970 followed by the Rio Star in 1984. There are hundreds of crops like these that we’ve been enjoying for decades.

Mutagenic breeding has the advantage of generating novel, useful traits, but it requires huge amounts of trial and error. Another drawback is that it is less predictable in its outcomes than traditional selective breeding.

Spontaneous mutations are the motor of evolution,” Dr. Lagoda said. “We are mimicking nature in this. We’re concentrating time and space for the breeder so he can do the job in his lifetime. We concentrate how often mutants appear — going through 10,000 to one million — to select just the right one.

Selective breeding, meanwhile, has become increasingly sophisticated over the years:

… a sophisticated approach known as marker-assisted breeding that marries traditional plant breeding with rapidly improving tools for isolating and examining alleles and other sequences of DNA that serve as “markers” for specific traits. Although these tools are not brand-new, they are becoming faster, cheaper and more useful all the time. “The impact of genomics on plant breeding is almost beyond my comprehension,” says Shelley Jansky, a potato breeder who works for both the U.S. Department of Agriculture (USDA) and the University of Wisconsin–Madison. “To give an example: I had a grad student here five years ago who spent three years trying to identify DNA sequences associated with disease resistance. After hundreds of hours in the lab he ended up with 18 genetic markers. Now I have grad students who can get 8,000 markers for each of 200 individual plants within a matter of weeks. Progress has been exponential in last five years.” . . . Mills can look for these markers in cantaloupe seeds before deciding which ones to plant thanks to a group of cooperative and largely autonomous robots, some of which are housed in Monsanto’s molecular breeding lab at its vegetable research and development headquarters in Woodland, Calif. First, a machine known as a seed chipper shaves off a small piece of a seed for DNA analysis, leaving the rest of the kernel unharmed and suitable for sowing in a greenhouse or field. Another robot extracts the DNA from that tiny bit of seed and adds the necessary molecules and enzymes to chemically glue fluorescent tags to the relevant genetic sequences, if they are there. Yet another machine amplifies the number of these glowing tags in order to measure the light they emit and determine whether a gene is present. Monsanto’s seed chippers can run 24 hours a day and the whole system can deliver results to breeders within two weeks.

Breeder’s have always known which traits they want their plants to exhibit. Today they know which genes are responsible for those traits. Technology is allowing them to get the desired genes, to produce the desired traits, into the plants with fewer and fewer steps, and greater and greater precision.


In traditional cross breeding, two related plants are identified with different desirable traits. Imagine a popular fruit threatened by a bacterial sickness. The sickness can’t be treated successfully with pesticides. There is a related fruit that is immune to the bacterium, but it doesn’t taste as good. To create a new variety of fruit that will survive the bacterium but still remain flavorful, the two plants are crossbred in the hope of producing a new plant with the best traits of each. This will result in the transfer of tens of thousand of genes between the two plants. Unfortunately, while the bacterial resistance may reside in just one, or a few genes, something complex like flavor will be the result of many, many genes. Inevitably something will be lost in the mix. In our example, flavor would be lost, but with the interaction of multiple genes, something unexpected could be added, and it may not always be helpful.

In genetic engineering, plant scientists select precisely the gene with the trait they want and insert it into the plant that needs it. That way, only the desired trait is added, without affecting the rest of the plant’s character. In our example, the plant scientist can bring over the gene for bacterial resistance and add it to the tasty fruit without sacrificing flavor. The technique gives the plant scientist greater control.

It also provides a greater range of options.

Imagine now that there is no related plant with bacterial resistance that we can transfer to our flavorful fruit. What if there is another plant with bacterial resistance that could be useful, but it is an unrelated plant? With traditional breeding we would be out of luck. The bacteria will eventually wipe out our crop. With genetic engineering, we can move that resistance from one plant to another even if they aren’t sexually compatible.

In fact, this is exactly what is going on in an effort to save the world’s citrus supply from devastation. Citrus greening is a bacterial disease that affects citrus fruit. It destroys the vigor of the trees and turns the fruit bitter and salty. If you have noticed the rising cost of limes lately, this disease is one of the reasons. Farmers have tried to hold the disease at bay by attacking the small bugs that carry the disease with more and more pesticides. As the bugs become resistant to the pesticide and more trees around the world become infected, a solution is desperately needed if we are going to continue to have oranges, lemons, limes, and grapefruit. The fate of Mexico’s lime farmers and Florida’s $1.5-billion citrus industry hang in the balance.

Fortunately, spinach contains a gene that makes it immune to this disease. After searching among many different solutions, plant scientists have successfully transferred the spinach protein into orange trees. Except for surviving citrus greening, you would never know the oranges have a gene from a spinach plant in them. Not surprising since different species share lots of DNA. Humans share a quarter of their DNA with a wine grape, half their DNA with a banana and three quarters with a zebrafish. Hopefully, the new bacteria resistant oranges will be cleared by the government regulators in the next year.

You can see the advantages that genetic engineering brings to breeders and plant scientists. Consider the potato breeder profiled by PBS Nova:

Selective breeders like De Jong work hard to develop resistant crops, but farmers still have to turn to chemical pesticides, some of which are toxic to human health and the environment. De Jong enjoys dabbing pollen from plant-to-plant the old-fashioned way, but he knows that selective breeding can only do so much.
So while De Jong still devotes most of his time to honing his craft, he has recently begun to experiment in an entirely different way, with genetic engineering. To him, genetic engineering represents a far more exact way to produce new varieties, rather than simply scrambling the potato genome’s 39,000 genes the way traditional breeding does. By inserting a specific fungus-defeating gene into a tasty potato, for example, De Jong knows he could offer farmers a product that requires fewer pesticides.

It’s important to keep in mind that we are talking about a single, or a few at most, well understood genes being transferred and that the traits they bring with them are very well understood. That’s why it’s so misleading when anti-GMO activists portray cartoon images of a tomato crossed with a fish. Inserting one or two genes from another organism is not crossbreeding. There was a tomato bred in the early 90’s that never made it to market, that utilized a single gene from a winter flounder to make a tomato withstand frost better. One gene out of 31,700 tomato genes does not result in a half fish, half tomato hybrid. It simply would have been a tomato that withstands frost better. You share half your DNA with a banana. To a geneticist those genes are the same, whether they come from you or the banana.


We’ve looked at the efforts to address citrus greening, let’s look at the GMO foods that are on the grocery shelves and on our kitchen tables.

Rainbow Papaya: In 1992 papaya ringspot virus hit Hawaii’s papaya groves, decimating the livelihoods of farmers and damaging the island’s economy. By 1998, most trees were infected and production cut by half. Then Dennis Gonsalves, a plant pathologist developed a papaya that was inoculated against the virus by inserting a bit of the virus into the DNA of the plant. Since humans are immune to the virus and had already been eating mildly infected fruit for years, there were no real health concerns. The Hawaiian papaya industry has largely bounced back. In fact, the transgenic papayas help organic papaya producers by creating buffer zones to isolate the organic papayas from the virus.

Bt Corn and Bt Cotton: The concept behind Bt traited crops takes a page out of nature’s playbook and one from the organic farmer’s playbook. Bt stands for Bacillus thuringiensis, a soil bacteria. Bt produces crystal proteins or ‘Cry proteins’. In the gut of certain pests, notably the European corn borer which eats both corn and cotton plants, the Cry proteins bond to a receptor in the bug’s gut and acts as a poison. Organic farmers have been safely using Bt as a pesticide for decades. Humans don’t have the receptors for the Cry proteins to bind to and while the protein survives in the bugs alkaline guts, the proteins are destroyed in the acidic environment of our guts. Breeding corn and cotton plants to produce their own pesticides borrows from the idea we spoke of above. Adoption of Bt traited crops has resulted in a reduction in the use of soil applied insecticides, primarily organophosphates and carbamates, two classes of problematic insecticides.

In India, where there was the greatest room for improvement, Bt cotton has been a boon to growers. They have seen yields and income increase while incidents of poisoning from pesticides have greatly diminished.

One study assessing the economic and environmental impact of Bt cotton in India showed that farmers were able to produce 24% more per acre through reduced pest damage and see a 50% gain in profits. They found that consumer spending by Bt cotton farmers in India increased 18% during the period after Bt cotton was adopted.

Meanwhile, impacts to the environment are lower than those of traditional insecticides.

RoundUp Ready Soy, Corn, Canola, Beets and Alfalfa: RoundUp Ready crops have been bred to tolerate glyphosate (the active ingredient in RoundUp), a weedkiller of very low toxicity and environmental impact. Glyphosate works by interfering with the plant enzyme EPSPS. RoundUp Ready crops produce a slightly different version of that enzyme that is not vulnerable to glyphosate. Because the way glyphosate works is so specific to certain plants, it is virtually non-toxic to mammals. On a standard scale of toxicity, glyphosate rates lower than table salt and much lower than aspirin or ibuprofen.

This has allowed farmers to move away from herbicides like atrazine, trifluralin, and metazachlor which are more problematic than glyphosate. Another major impact of the use of RoundUp Ready crops has been reduced tillage. This means instead of tilling the soil to interrupt the weeds’ growth, the farmers kill the weeds with RoundUp without upsetting their soil. Leaving the soil alone means less carbon emissions, less need for fertilizer, less need for irrigation and less erosion. This has improved the environmental impact of farming quite a bit.

Virus Resistant Summer Squash and Zucchini: A small amount of the squashes grown have been bred to resist different mosaic viruses.


Arctic Apple: This apple has been developed by a small company and has been bred not to brown when cut. Instead of inserting a new gene, the breeders simply switched off the one responsible for the enzyme that cause apples to oxidize when peeled and cut. It is hoped that this apple will be a gift to mothers with picky kids, who won’t eat apples unless they are peeled and won’t tolerate any browning either. This could mean more kids eating more apples and less apples in the garbage pail. Good for kids’ nutrition and less food waste, good for the environment.

Golden Rice: Vitamin A deficiency affects 190 million preschool children and 19 million pregnant women in 122 countries. Each year, it is responsible for up to 2 million deaths and 500,000 cases of irreversible blindness. In many of these countries, the poor cannot afford a balanced diet, but they can afford rice and that is a crop that local farmers are skilled at growing. The International Rice Research Institute has been working to add the vitamin A source beta carotene to rice. A small bowl of this rice could deliver as much 60% of the Recommended Daily Allowance to needy kids who currently are at the mercy of being able to get supplements twice a year from the UN.

When it’s finally approved, seeds will be distributed for free to farmers in developing countries. In those countries, it will be released under a special humanitarian license, allowing farmers to save seeds and local breeders to adapt it to local conditions and continue to improve it.

BioCassava Plus: This is a cassava being developed for Africa by the Gates Foundation. Cassava is a staple crop in Africa. This cassava has been bred to resist two damaging viruses and to deliver increased amounts of iron, protein, beta-carotene and zinc. It will be a boon to both farmers and villagers in the most underdeveloped parts of Africa.


That all sounds great, right? So there must be a catch. What’s driving the controversy?

When I asked Kevin Folta, chairman of the Horticultural Sciences Department at the University of Florida, he had this to say, “It is hard to think of a scientifically-based downside to the technology. The central one is resistance to Bt and specific herbicides. It is particularly a problem because Bt is one of a few pesticides allowed in organic cultivation, and resistance takes away an option. Acquired resistance is not a GMO-specific problem.”

Resistance refers to when an insect or weed evolves to withstand the farmer’s strategy for dealing with them. In the case of RoundUp Ready crops, weeds have evolved to withstand larger and larger doses of RoundUp. Herbicide resistant weeds are sometimes referred to as ‘superweeds’. In the case of Bt crops, rootworms and borers, and cotton bollworms have developed immunity to the Bt trait in some parts of country. This means that farmers are forced to return to using some of the insecticides that they had been able to abandon. In the best cases, farmers address the problem by adding new crops to their rotations, thereby breaking up the pests’ food supply from year to year.

The key thing to remember is that resistance will develop in response to any pest management system that isn’t varied often enough. The better a system works the more likely farmers will lean on it until resistance becomes an issue. Resistance is not a GMO issue, but a pest management issue and the only ‘super’ power these weeds have is the ability to withstand whichever herbicide they’ve been subjected to. Change the weed management strategy, and the ‘super’ power becomes moot.

In the 1990s ryegrass farmers in western Australia developed the worst weed problem anyone had ever seen. This was before GM crops had been adopted. It’s simply what happens when you rely on a single strategy for dealing with pests.

The real issue here is that farmers who don’t use these tools with great care end up creating problems for their neighbors who do. When herbicide resistant weeds develop on a farm where they haven’t followed the guidelines for use, or changed up their rotations, those resistant weeds can become a problem for their neighbors.

The issue with Bt and organic farmers that Professor Folta raised is particularly sensitive. Bt is one of the few insecticides available to organic farmers. If conventional farmers overuse Bt traited crops and insects evolve resistance, it is organic farmers who will really pay the price as one of the main tools in their toolbox becomes useless.

A related issue is so called ‘monoculture’. It is a fact that many GM crops are grown on large farms with non-diverse crop rotations. While this form of agriculture is very efficient, it is harder on the environment than using more diverse rotations. However, when critics raise this, they are getting cause and effect backwards. GM traits were developed for corn and soy that are grown this way because those are the most widely cultivated crops. GM seeds are very expensive to develop and the seed producers have been very conservative in choosing where to make their investments. Farmers grow so much corn and soy because consumers demand products derived from corn and soy. Our farms can only be as good as our diets.

Which leads to the third issue of concern in regards to GMOs. GMO corn, soy, sugar beets, canola and alfalfa all too often wind up as livestock feed, sugary beverages and junk food, the foods that are fueling a diabesity epidemic. Meanwhile, the ecological footprint of meat production leaves a lot to be desired. While it is possible to produce meat responsibly, as a people, we should be eating less meat. Very few would disagree that Americans should be eating far less sugar and junk food. Here’s where it gets complicated. Yes we should be eating less meat and a lot less sugar and junk food. But we are better off producing the meat, sugar and junk food that we do eat with GM crops. That doesn’t fit on a bumper sticker very well, but it does mean less pesticides, less toxic herbicides and less land under tillage. It’s a complicated world and the devil is in the details.


Step one: Understand how vast the legitimate scientific literature is on this topic. Just last year a team of Italian researchers published a literature review of the scientific papers from the previous ten years. They looked at 1783 different papers and came to this conclusion:

The scientific research conducted so far has not detected any significant hazards directly connected with the use of GE crops.

The EU has spent over €300 million on GMO research over two decades. Their last report in 2010 on the previous decade of research was summarized this way [pdf]:

It follows up previous publications on EU-funded research on GMO safety. Over the last 25 years, more than 500 independent research groups have been involved in such research. According to the projects’ results, there is, as of today, no scientific evidence associating GMOs with higher risks for the environment or for food and feed safety than conventional plants and organisms.

I could go on. You get the idea.

Step two: Beware of single study syndrome. There are a handful of small studies, often discredited or retracted that critics of GMOs cling to as evidence of harm or potential harm. These studies have results that don’t square with what other researchers have found and are often characterized by serious methodological flaws. Often they are published in junk pay for play journals that will publish nearly anything if the authors pay a fee.

Step three: Recognize the Rogue’s Gallery of irresponsible GMO scientists. The following names come up over and over in reporting on GMOs. These folks are not reliable sources of information on the subject.

Gilles-Éric Séralini: Author of the infamous ‘rat corn study’. The paper was retracted for poor study design and unreliable conclusions. He is the author of other papers that have been heavily criticized for poor methods and statistical work. He also has had conflicts of interest that he failed to disclose.

Charles Benbrook: Benbrook is an agricultural economist at Washington State University in a position funded by the organic industry. He published an often cited paper purporting to show an increase in pesticide use in relation to GM crops. The problem is that, while he admits that insecticide use has greatly decreased, herbicide use has increased in terms of pounds used. This does not take into account that the switch to glyphosate from more problematic herbicides has reduced environmental impact.

Judy Carman: Carman was responsible for a study of pigs fed GM corn. The main problems with this study were the lack of a ‘dose dependent response’ and ‘data mining’. When a higher dose does not result in a higher response, a cause and effect relationship is doubtful. Data mining is when you start an experiment without deciding what you are trying to test and then look at so many variables that you are nearly assured to come up with at least one false positive.

Stephanie Seneff and Anthony Samsel: This duo uses artificial intelligence computers to analyze a body of literature looking for correlations between glyphosate and various health problems ranging from celiac to cancer to autism. They publish in one of those obscure pay-for-play journals mentioned above. More damning is that when someone is blaming multiple, biologically unrelated health problems on a single cause, then you are probably dealing with pseudoscience.

Vandana Shiva: Shiva is an activist with a PhD in the philosophy of science who passes herself off as a physicist (she’s not). She is best known for fear mongering about so-called ‘Terminator Seeds’. This was a technology that was proposed for pharmaceutical crops so that they could not cross pollinate with other crops. This technology never got out of the planning stages. This didn’t stop Shiva from spending a decade warning audiences that the Terminator Seeds could cause ecological catastrophe. This wasn’t only false, but ecologically illiterate, since sterile seeds couldn’t have passed on their genes. It’s like worrying about seedless grapes taking over the world and ruining the grape crop.

David Suzuki: Suzuki was a geneticist in the 70’s and has been a prominent Canadian environmentalist. He has regained some notoriety lately by warning against the potential environmental risks GMO crops. His mantra is that we don’t know enough yet to anticipate the risks that GMOs pose. The problem with this analysis is that it is equally true of all new crops. “We just don’t know” sounds deep, but it applies to nearly everything we do.

Don Huber: Huber was a respected agricultural researcher at Purdue University for many years. However in his retirement, he seems to have lost his way. In early 2011, he sent a secret letter to Secretary of Agriculture Tom Vlisack warning that he had discovered a new pathogen that was associated with RoundUp Ready soybeans. He claimed the pathogen was neither a virus or a bacterium but a wholly novel category of organism. He has turned down offers to analyze this pathogen for three years and has not produced any work to submit for peer review. This is very odd behavior for a scientist with a major breakthrough on his hands that he claims puts the environment in grave danger. Instead of using the last three years to publish the results of his research on this pathogen, he has been on the paid lecture circuit.

Theirry Vrain: Vrain was a mid-level former soil biologist and genetic scientist for the Agriculture department in Canada. He currently tours the paid lecture circuit making poorly sourced claims about the dangers of GMOs.

As a final note, I’d like to tackle the one question that critics of GMOs bring up over and over. They often complain that there have been no long term human testing of GMOs. Understanding why long term human feeding testing is unnecessary should bring together the concepts that we’ve covered here in a way that gives people some confidence in the role GMOs play in the food system.


There are no long-term human feeding studies because there is no hypothesis to test.

There is no hypothesis to test for a couple of reasons.

1.) There is no hypothesized mechanism for harm in any of the current GMO crops. Neither from their bred traits or owing to the breeding techniques. (If the issue was the process of genetic engineering, it would have turned up in the clinical trials for recombinant insulin or the many other biotech medicines. Instead we’ve seen three decades of safe use of insulin derived from recombinant DNA.)

As we talked about earlier, we know enough about Bt and the Cry proteins to know that there is no mechanism for harm. Nor do we have reason to believe that EPSP in RoundUp Ready crops is a problem.

2.) We’ve done animal studies to look for potential unforseen problems. None have been discovered.

In science, you start with manageable studies of rats and mice to see if that generates evidence of something that justifies bigger, more expensive studies. But if there is no proof of concept, there is no interest and no funding for further testing.

Consider the findings of a literature review on long-term animal feeding studies:

The aim of this systematic review was to collect data concerning the effects of diets containing GM maize, potato, soybean, rice, or triticale on animal health. We examined 12 long-term studies (of more than 90 days, up to 2 years in duration) and 12 multigenerational studies (from 2 to 5 generations). We referenced the 90-day studies on GM feed for which long-term or multigenerational study data were available. …. The studies reviewed present evidence to show that GM plants are nutritionally equivalent to their non-GM counterparts and can be safely used in food and feed.

We’ve had long-term and/or multi-generational testing on mice, rats, quail and cows. None of that has generated a hypothesis of harm to test. Why would a researcher choose to dedicate years of their life to testing a hypothesis that they don’t believe in just to allay fears that cannot be allayed?

This may not be a terribly satisfying answer to the anxious lay person. But you have to ask, after all the testing that has been done, why is this the one thing you choose to worry about? So far we haven’t seen any problems in GMO crops that require extensive testing, but we have seen problems with celery, potatoes and beets bred the old fashioned way without testing. We still eat celery, potatoes and beets without thinking twice about it.

Maybe we can move on to the problems in our lives where there is evidence that supports our concerns.

Originally published at on September 3, 2014.