DNA is DNA: The anti-GMO movement ignores basic genetics

Genetic engineering (GE) is one of the most misunderstood technological marvels we have invented. The internet is full of articles and videos denouncing the supposed evils of genetically modified organisms (GMOs) with one of the most common arguments claiming that GMOs are inherently dangerous because they alter organisms’ genetic codes. It certainly is true the GE works by altering genomes, but what this argument ignores is the undeniable fact that all of our breeding methods work by altering organisms’ genomes. We’ve been genetically modifying organisms for thousands of years, GE simply lets us do it faster and more precisely.

At this point, I can already hear people screaming at their screens, “SELECTIVE BREEDING AND GENETIC ENGINEERING AREN’T THE SAME THING!!!!!!” This is the response I get every time, often accompanied by statements about the horrors of moving genes from one organism to another. If you are tempted to have this response, then all I ask is that you actually hear me out, because this response ignores very basic concepts in genetics, and I want to talk about those concepts. If you lay aside your biases for a second and walk through this with me, I will show you how the genetics actually works and why GMOs are not fundamentally different from other crops.

I’m going to focus here on transgenic GMOs (i.e., ones that move DNA from one species to another) because they are the ones most people freak out over, but please realize that they are not the only type of GMOs (others simply alter existing genes) and everything that I’m going to say applies to the other types of GMOs as well.

Note for clarity: Obviously GE and selective breeding are not the same thing. No one thinks they are. Rather, the point is that the products they produce are not fundamentally different from each other. They both are the result of modifying genomes.

 Note: I am in no way shape or form affiliated with or paid by any GE companies. In fact, I pay to maintain this blog out of my own pocket.

 DNA is DNA is DNA

The first major problem with this anti-GMO argument is that it inherently assumes that the DNA of different organisms is somehow fundamentally different. It isn’t. DNA is just a code. It’s a blueprint for constructing and operating organisms, with different genes coding for different proteins, and in all organisms, it is made of the same four bases A, T, C, and G. How you arrange those bases determines which proteins an organism will make and how those proteins will be arranged. That’s it. That is all that it is.

There is no such thing as a “tangerine gene” or a “lizard gene.” There are just genes. We may use taxonomic names to describe where a gene evolved, but there is nothing inherently lizard-like about a gene in a lizard. It is just the sequence that happened to arise and be selected in lizards.

To put that another way, given enough generations, any organism can, in concept, evolve to have any DNA sequence. In other words, a lizard could independently evolve the exact same sequence of DNA that is present in a tangerine. Would that make the lizard some sort of bizarre, mutant tangerine/lizard hybrid? Of course not, because DNA is DNA regardless of what organism it is in.

Think about DNA like an alphabet. In this analogy, the alphabet is the DNA bases and the words are amino acids (strings of bases) that join together to form sentences (proteins). Different books, blogs, etc. have different strings of words, but those strings are not intrinsically tied to a given work. They are just the arrangement that a given author chose. The sentences on my blog, for example, are not somehow special just because they are on my blog. They are strings of letters, just like every other sentence, and you can shuffle those strings around to make new strings or just copy them and directly paste them into another work (that would be plagiarism, of course, but the point is that you could do it). It’s the same with DNA. Just as all English books are operating off the same alphabet, all organisms are operating off the same four bases, which can be arranged in an infinite number of ways, even allowing different organisms to converge on similar strings of bases.

Mutations and selective breeding

Now that I have hopefully cleared up some misconceptions about DNA, let’s talk about genetic variation and breeding. First, we need to understand some basics of mutations. I talked about this in detail here, but to be brief, every time and organism reproduces, it copies its genetic code and passes that on to its offspring. However, those copies are rarely perfect, and chance mutations (modifications) arise. There are many different types of mutations such as insertions (where a new base is inserted into the DNA), deletions (where a base is removed), duplications (where a section of DNA is duplicated), inversions (where a section of DNA is flipped around so it is “backwards”), etc. These random mutations are extremely important because they give organisms variability, and both natural and artificial selection require variability.

This illustrates a hypothetical example of how mutations can change a genome, by taking our starting crop and mutating it to have the sequence we want (highlighted in green)

So how does this fit into breeding? To explain that, I want to use the illustration to the right. Imagine that we have a crop, we’ll say it’s tangerines, and we want to breed them to be larger. We’ve already been selecting the biggest crops for a few generations, but now we are running out of variation and things are slowing down. Are we screwed? Well, not necessarily. Let’s imagine for sake of example, that currently our crops have the sequence GCGCTA, but the sequence GCGGTCGTACTA would produce larger crops, with the GTCGTA being the critical section (I’ve highlighted this green in the illustration). Can we get there without using genetic engineering? Well, if we are lucky enough to get the right mutations, and each step of that mutation process has a benefit (like slightly larger crops), then yes, we can get there.

I’ve illustrated one way this could work. During one replication, a duplication could occur and give us another GCG. Then, if we are lucky enough to get a T inserted between the GC, all we need is a deletion of an extra C and we have our GTCGTA. We have, by careful breeding and fortunate random mutations, managed to produce the sequence we want, with some caveats. There’s actually a lot that I need to elaborate on and clarify here, so bear with me.

First, you’ll notice that in my example, there are unintended consequences. We got an extra A in the second base position, and we lost the CTA on the end. This very often happens with selective breeding. Genomes are getting shuffled around each generation, so while you are selecting for one trait, another part of the genome will likely change, and that change may not be advantageous. Indeed, as I’ve written about before, this process once resulted in toxic Lenape potato that produced potentially dangerous levels of solanine. The point being that artificial selection can have lots of unintended consequences.

The second point I want to make is that farmers are not usually aware of what is happening at the genetic level. For the tens of thousands of years that it took us to make our modern crops, farmers weren’t going out each year and collecting DNA samples. They were simply selecting the best plants each year and breeding those. Nevertheless, each generation, this was happening. New mutations were arising, and genomes were getting shuffled around. Every generation, the genome was being modified. Indeed, if you look at our modern crops and compare them to their wild varieties, the difference is staggering. We have used this slow, gradual process to make countless changes; we just didn’t know exactly what changes were happening from one generation to the next (note: pay attention to both the scale of these changes and our lack of knowledge about them, because that will be important later).

The final point here is that this process is inherently very slow. It takes many, many generations, but what if we wanted to speed it up? Can we get new mutations more quickly? Well that is where mutation breeding (aka mutagenesis) comes in. For this form of breeding, we take crops and expose them to radiation or various chemicals to increase their mutation rate. Thus, we can make this process happen much more rapidly, by quickly making many mutations.

The catch here is obviously that it is extremely imprecise. In fact, it is random. We make countless random mutations to a plant’s genome and hope that a good variety gets produced, but somehow, that doesn’t seem to bother anyone. I very rarely meet an anti-GMO activist who also rails against these haphazard genetic mutations (odd, it’s almost like the anti-GMO movement is based on emotions rather than facts).

Crosses, hybrids, and GMOs

 So far, I have been talking about modifying the genomes of highly related organisms (i.e., a single crop variety), but it is often faster and easier to simply supply a crop with genes from elsewhere, rather than waiting and hopping that they randomly arise (indeed, crosses have been prevalent throughout agricultural history). So, let’s take a look at those.

This hypothetical example shows that crossbreeding varieties, hybridizing species, and using genetic engineering can all produce a product with the desired target sequence (highlighted green), but methods other than GE often involve unintended changes. Note: these are fictitious sequences that I made for the sake of example.

I’m going to use the same example as before. We have a tangerine crop with the sequence GCGCTA, and we want the sequence GCGGTCGTACTA, with the GTCGTA in the middle being the most important (again, highlighted green in the illustration).

Now, if we are lucky, there will be another crop of the same species that already has the GTCGTA sequence. If that is the case, we can simply crossbreed the two varieties. This results in the gene we want from the other variety being inserted into our variety, and, with a few generations of breeding for the trait it produces, we get the crop we are after.

However, just as before, there will likely be unintended consequences. You see, when we crossed those crops, we didn’t just move the gene we were after. Rather, we recombined the entire genome, which means that multiple traits which were not originally in our crop are now there. We have made thousands of changes to the genome. Some of those may be benign, some may be helpful, but some could be harmful.

Note: Again, to be clear, farmers usually aren’t aware of the specific gene sequence they want. Rather, throughout history, we have selected based on visible traits (what is known as the phenotype), but by selecting phenotypic traits like crop size, we were actually modifying the genomes (genotype).

Now, let’s suppose that no other tangerine varieties have what we want, but grapefruits do. As it turns out, tangerines and grapefruits can actually hybridize, despite being different species. Once again, this moves DNA from one variety to another (in this case actually jumping species), and, as before, the entire genome gets screwed with, not just the gene we are after. Further, in this case, the changes are likely to be fairly dramatic since we are swapping thousands of genes between species.

Finally, we get to genetic engineering, and for the sake of this example, let’s say that grapefruits don’t have the gene we want, but lizards do. Thanks to GE, we can take that gene and put it into our tangerine. This accomplishes exactly the same thing as every other method I have talked about, except, unlike all of the other methods, GE very precisely moves just the gene we are after without moving anything else! In other words, we can make one very precise change to the genome rather than making hundreds or even thousands of unintended changes.

This is what boggles my mind about the anti-GMO movement. If the gene was in a grapefruit (as in the second example) no one would have any problems with me swapping entire genomes around via hybridization to get that gene into my tangerine. Even though I would have just moved thousands of genes around with countless unintended consequences, no one would care, but if I very carefully and precisely take just that one gene and move it via GE, suddenly there are riots in the street.

Similarly, if I couldn’t get that gene from a grapefruit, I could repeatedly blast my tangerines with radiation, randomly mutating hundreds of genes until I eventually got the sequence I was after, then I could grow that crop on an organic farm, and almost no one would throw up a fuss about it. No one would be accusing me of “playing God” or making some unnatural “frankenfood.” Yet if I use GE to make the exact same thing, just with far fewer unintended genetic changes, suddenly everyone loses their minds!

Let me put this one final way. Imagine that we are using GE to move the gene, but we are moving it from the grapefruit into the tangerine. Would you have any problems with that? If you would, then why would you be fine with hybridizing those crops? Conversely, if you’d be fine with moving that gene from a grapefruit to a tangerine, then why would you have issues if the gene was coming from a lizard?

The cognitive dissonance here is just unfathomable to me. Again, look at the difference between our crops and the wild varieties they started out as. Countless genes have been changed, and no one cares. Why should carefully and precisely modifying one more make such a big difference?

The reality is, of course, that this is no rational justification for these logical inconsistencies, because the anti-GMO position is not based on facts or logic. It is based on appeal to nature fallacies and appeal to emotion fallacies. Eating something that was designed in a lab feels wrong to many people, whereas eating something that was bred in a field feels natural and normal, even if the lab crop involved only one very precise change, while the field crop involved thousands of imprecise changes as entire genomes were mixed from separate species.

Also, to be clear, the relatedness of two species is quite irrelevant when we are talking about moving single genes. Remember, there is nothing inherently lizard-like about lizard DNA. A gene that evolved in a lizard is just as foreign to a tangerine as is a gene that evolved in a grapefruit. They are both genes that are not found naturally in the tangerine. So, again, if it is ok to randomly move thousands of genes between tangerines and grapefruits via hybridization, why is it wrong to precisely move one gene?

Note: Throughout this post, I have very carefully avoided using the fish gene in a tomato example because I often hear people use that as an example of how bad GMOs are when, in reality, no such tomato is on the market. Therefore, I refuse to perpetuate that misconception.

Note: In all my examples, I have been using a simplistic short sequence of DNA for illustrative purposes. In reality, a gene is typically made of much longer strands, but everything that I have said fully applies to those longer strands.

Natural selection won’t help you

At this point, I often find that people try to wriggle out of the inherent logical blunders of their position by invoking natural selection and claiming that there are checks and balances in nature that just don’t exist in a lab. That argument is, however, utter nonsense. I’ve previously devoted an entire post to this argument, so I’ll be brief here.

First, nature doesn’t care about you. Natural selection does not have checks and balances for your protection. It simply selects whatever traits allow a given organism to pass on the most genes. In other words, it helps the organism in question, regardless of whether or not that is beneficial for you. So, the entire premise of this argument is wrong.

Second, our crops came from artificial selection, not natural selection, and as I explained previously, artificial selection often has unintended (even dangerous) consequences.

Third, GMOs are far more stringently tested than other crops. So not only are they more precise, but they are more rigorously tested.

Finally, this argument hinges on GMOs being novel crops, but, again, all of the methods described produce novel crops. When someone makes a new crop by bombarding it with radiation, that is a novel crop when farmers first start using it. When someone hybridizes two plant species that have never been hybridized before, that is a novel crop when farmers first start using it, etc. Why should GMOs be held to a different standard than any other type of crop? Please explain to me exactly what checks and balances are in place for new hybrids and mutants that aren’t in place for the GMOs?

Different methods, same result

joker meme, GMO mutation breedingThe point that I am trying to get you to grasp is that all of our agricultural methods modify genetic codes and produce genomes that aren’t found in nature. All of them can achieve the same result. However, only genetic engineering achieves the result precisely. DNA is DNA. It doesn’t matter where it came from or how it was moved. Really think about this. If you are going to insist that GMOs are somehow fundamentally different from the products of other methods, then I want you to justify that. Explain to me why it would be ok to introduce the sequence GTCGTA by randomly mutating a crop, but not ok to introduce it by GE? Similarly, why is it ok to introduce that sequence by hybridizing two species, but not ok to do so via GE? Why is the former totally acceptable while the latter is considered mad science? Swapping thousands of genes around by hybridizing species is far more likely to have unintended consequences than precisely moving a single gene, regardless of the source of that gene.

The simple reality is that we have been modifying organisms’ genetic codes for millennia. Almost none of our food is “natural.” It didn’t evolve naturally in balance with its ecosystem. Rather, we cleared forests and grasslands to make agriculture fields and carefully bred the crops with the deliberate intention of making them unnatural. We didn’t want the small crops nature had to offer, so we modified them. We improved them by altering their genomes to suit our needs. Genetic engineering is simply the most recent development in a process that has been playing out for thousands of years, and it only differs from its predecessors in that it is far faster and more precise.

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6 Responses to DNA is DNA: The anti-GMO movement ignores basic genetics

  1. Owen says:

    There is, if course, no basis for concerns about safety. Less recognized is the environmental impact when the modification is for pesticide or herbicide resistance, which can make farm fields sterile of important species. Fencerow to fencerow of clean crops are a problem with or without the GMO assistance.


    • Fallacy Man says:

      Here’s the thing though, GMOs have actually resulted in a net decrease in overall pesticide use. This is particularly thanks to Bt GMOs which have dramatically reduced insecticide use, have fewer consequences for non-target species, and have higher biodiversity in their fields than comparable non-GMO crops.

      Further, although some particular pesticides have increased (e.g. glyphosate) they are less toxic than many of the pesticides they replaced.

      Finally, anytime we are talking about biodiversity effects, we have to consider total land usage, not just what is happening on the farm fields themselves. Farm fields always have majorly reduced biodiversity compared to forests, grasslands, etc. As a result, even in the cases where GMO fields do have lower biodiversity than the fields of other crops, the GMOs are still beneficial because they grow more crops per unit area, thus reducing total land use. To put that another way, 9 acres of GMO crops and 1 acre of forest is far, far better than 10 acres of non-GMO crop and 0 acres of forest, even if the biodiversity in the 10 non-GMO acres is slightly better than the biodiversity in the 9 GMO acres.

      More details and sources here https://thelogicofscience.com/2018/03/20/bt-gmos-reduce-pesticides-increase-yields-and-benefit-farmers-including-organic-farmers/


      • Jason says:

        While I will be reading the entire article, I don’t have time until later tonight. I would however like to know the credentials of the author. I checked at the top and bottom of the article and don’t see the name or background


        • Fallacy Man says:

          I write this blog under a pseudonym to avoid the constant attacks that get levied against scientists who maintain blogs like mine, but I have a BSc and MSc in biology, and will be handing in my PhD thesis on September 10. I have published over 20 papers on conservation biology, including studies on genetics.


    • Fallacy Man says:

      It is also worth pointing out that scientists have taken potential environmental impacts seriously and the literature on this topic is extensive. To sum it up, GMOs are no worse than other crops and in many cases (like Bt GMOs) they are better. https://www.researchgate.net/publication/256664216_An_overview_of_the_last_10_years_of_genetically_engineered_crop_safety_research


  2. mvschulze says:

    Thanks you for this well presented and descriptive piece about GMO’s, and your related and further reading post links. The sheer advancement of science deniers in the current political environment is frightening, almost akin to retarding the nature of human intelligence, for the sake of political agendacizing. M 😦


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