Kaleo the Dinosaur, Dalton the Turtle, Adam the Pumpkin, Alexander the Lion. Image by Nathan LeClair via Flickr.
One major “ick factor” of genetic engineering is taking genes from one species and adding them to another species. While it sounds strange, we are all wearing the same genes. It’s not something to be afraid of – in fact, as we learn more it becomes more and more amazing.
Look at the genome of any organism on the planet and you’ll find at least some genes in common with other organisms. The root of this idea is evolution itself. People, dinosaurs, turtles, pumpkins, and lions – we’re all related!
Phylogenetic trees
Since we all have a common ancestor, we have genes in common. One way to look at this is in a phylogenetic tree. Like a tree, phylogeny starts with one trunk that then branches out into smaller and smaller branches. Organisms that are closer together on the tree will have more genes in common.
Phylogenetic tree on the Understanding Evolution website.
While the similarities between organisms were originally determined by examining physical characteristics from bones to biochemistry, the advent of genome characterization and later sequencing has allowed us to better understand the similarities.
The Understanding Evolution website (created by the University of California Museum of Paleontology and the National Center for Science Education) has a great tutorial on how to read and create phylogenetic trees.
Whole genome comparison
Another way to look at similarities is to compare whole genomes. According to the Genome News Network, “the genomes of more than 180 organisms have been sequenced since 1995.” This includes humans, mosquitoes, various bacteria, and many more (and they’re even missing a few, such as corn!). The genomic sequences can be aligned based on the similarities of their sequences so we can see how similar the genomes are as wholes.
Close-Ups of the Genome, Species by Species, from the NY Times. Click for a larger version.
Chunks of genome may be rearranged, mutated, duplicated, and changed in other ways, but we can still find their similar areas. A comparison between human, chimpanzee, Rhesus monkey, mouse, and chicken are shown in this image (click for a larger version). Many parts of the human genome parts are very similar to parts of the other genomes.
Individual gene comparison
While we can see similarities at the whole genome level, looking at individual genes is useful, too. There are many genes in common across wildly different organisms. Some of them are conserved with amazingly few changes while others have mutated over millennia so we can just barely tell the genes had a common ancestor.
A recent example is that popped up in traditional and social media is farnesene synthase – an enzyme that catalyses the synthesis of farnesene, which is a chemical compound that causes odor. Various forms of farnesene (and the enzyme that makes it) are found in many different organisms, including aphids and apples. In apples, farnesene makes a nice apple smell. In aphids, a slightly different farnesene is an alarm pheromone that tells the aphids to run away because a predator is near.
Rothamsted Research in England took a farnesene synthase gene and inserted it into the wheat genome with the goal of scaring aphids away. They also used a farnesyl pyrophosphate synthase gene, with the goal of increasing expression of farnesene (because farnesyl pyrophosphate is a precursor of farnesene). As one of the researchers, Gia Aradottir, described in an interview with Biofortified, both genes were actually synthesized in a lab. The farnesene synthase gene was most similar to the peppermint version of the gene while the farnesyl pyrophosphate synthase gene was most similar to the gene found in mammals, with one tiny sequence particularly similar to the cow version of the gene.
What all this means is that these genes appear in many different types of organisms with minor differences. These homologous genes have a common ancestor, just as the organisms that the genes appear in have a common ancestor. It’s not scary once you understand what’s happening, and it’s clear that the wheat hasn’t been turned into mint or into a cow due to the addition of these genes.
Gene movement between species
Red aphids stand out from their green cousins. Image by Charles Hedgcock via Not Exactly Rocket Science.
Not only do we all have a lot of genes in common, there’s also natural movement between species. My favorite example is fungus genes that produce carotenoids that were borrowed by aphids. The colorful pigment contributed by the fungal genes helps the aphids be less interesting to some of their potential predators. Another example is moss that has picked up genes from fungi, bacteria, and viruses! Want to learn more? David Tribe collects “Natural GMOs” at his blog – he’s up to 149 examples as of October 2012.
Surely, as more and more genomes are sequenced, we will find more gene swapping. Still, while horizontal gene transfer does happen, it is rare, and there are restrictions. For example, genes very rarely move from eukaryotes (multi-celled organisms) to bacteria even though genes can move more easily from bacteria to eukaryotes.
What does this mean for GMOs?
Nothing, really. Humans moving genes between organisms, especially more related ones, isn’t any special cause for concern. Instead, we have to look at what the gene does.
Open bible by Gerry Brague via Flickr.
One way to think about it is sentences in books. If we have a cookbook and a bible and we move a sentence from the cookbook to the bible – does it make the bible a cookbook?
There are already some sentences in the bible that are similar to those in the cookbook, and they have many words in common. Consider: “And you, take wheat and barley, beans and lentils, millet and emmer, and put them into a single vessel and make your bread from them.” This verse is Ezekiel 4:9, the recipe behind Ezekiel Bread.
Adding a sentence doesn’t change any of the other sentences. It just adds more information. It definitely does not transform the bible into a cookbook – just as adding a gene to wheat that is similar to a gene from cows does not turn that wheat into a cow.
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I’ll close this post with one of my favorite songs: “My brother the ape” by They Might Be Giants 
Biofortified 
Ha ha ha! That’s great. I’m glad you did this one. If I had done it, there wouldn’t have been either children or bibles. But I think they help the case very much 🙂
Such a good point. If you put lion ears or a pumpkin shell on your kid you do not change her species.
Frankenkids? Nope. Frankenfood? Nope.
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Lion ears on a kid does add something but doesn’t turn her into a lion, at least not beyond the fact that she may stalk and pounce and growl!
That was exactly the conclusion I was going for – though I didn’t want to just come out and say it so the reader could figure it out. Here’s hoping that means my writing is getting a little better. 🙂
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How much of a role do endogenous retroviruses (ERVs) play in the similarity between species?
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Good question! We should ask ERV to come over and school us 🙂
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Loved this until the final paragraph;
1) “Adding a sentence doesn’t change any of the other sentences. It just adds more information.”
Not sure about this concept. If I am writing an essay on architecture, and in a paragraph describing the Bauhaus movement I suddenly throw in a sentence on the use of external facades (from a paragraph elsewhere in essay on Baroque), then I will most certainly not be “just adding(sic) more information”, I will be confusing the purpose of the paragraph (and confusing the reader) and therefore the intended outcome (communication of concept) will be impacted. Not sure where you were going with that analogy, but I’m not following.
2) “Humans moving genes between organisms, especially more related ones, isn’t any special cause for concern.” In most cases, yes, but not without considering intent and ethics. Transferring bonobo genes into humans, or vice-versa is a bit disconcerting (hey, we’re all hominids!), no matter that “nature” did it via an evolutionary process.
I know you were likely referring to current commercial or experimental applications of gene transfer (which don’t bring the same ethical concerns as the example I gave), but think it’s worth mentioning that given the right tools – we will be tempted to tinker in more troubling directions.
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1) Thanks for the feedback, Rita. No analogy is perfect, but the goal of this one is just to say that adding a sentence doesn’t change the content of all of the other sentences. In the specific example here, the bible does not turn into a cookbook. Yet, the bible already has some parts that are similar to parts of a cook book (recipe lists, etc) even though it isn’t a cook book.
Where the analogy breaks down is that genes don’t have context in the same way that sentences have context in paragraphs. Genes that are physically close together may have higher or lower expression rates as a group, but it doesn’t matter which genes are next to each other – so there’s no confusion for the “reader” (RNA polymerase).
2) There are ethical considerations that I did not address here, but I want to stress that there is no scientific reason why we should not transfer a Bonobo gene into a human. In fact, there may be ethical reasons why we should do it.
A thought experiment – what if it was determined that some people have a mutant copy of a particular gene that causes a terrible disease. Bonobos happen to have a slightly different copy of the gene that rectifies the problem better than the non-mutant human version does. Gene therapy with the Bonobo gene could certainly be a scientifically appropriate and ethically appropriate solution, in my opinion. One of the main points of this post is that humans and Bonobos (and chickens, and corn, etc) have many genes in common anyway.
Of course, gene therapy is very different from genetically engineering human embryos to have new traits that would be inherited into the next generation. A whole different discussion for another place – if you’re interested in talking about this more, may I suggest starting a new topic in the Forum?
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“but think it’s worth mentioning that given the right tools – we will be tempted to tinker in more troubling directions.”
This does not necessarily follow, although it is a common perception. I watched through Steven Pinker’s LongNow talk last night and he made a very good, evidence backed case that even though we have become more and more efficient in our ability to destroy one another (eg the right tools), the rates of death and violence have actually dramatically and steadily declined through history. I think a similar pattern applies here. Just because we have the capability does not automatically imply we will do bad things. GE is a good example. Before anyone really started doing such things, or even had the ability, people got together to lay out guidelines and to direct the outcomes. Same thing for human cloning. That said, your concern is well placed, if only because it is exactly that kind of thinking that prevents the bad things from happenng.
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Brilliant, excellent point. Anastasia’s analogy is in fact accurate, and “adding” something to the Bible does indeed change it, distorts it and dilutes it. This is exactly the danger that is not being addressed here. The fact is these scientists do not fully understand the implications of what they are doing…and yet, the drive for profit and “progress”, and the lack of careful oversight creates a fertile ground for potentially harmful experimentation, the consequences which may not be understood until the damage is done.
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Good points – and yes Anastasia, I was thinking of inheritable traits not gene therapies.
As for the human temptation to tinker in troubling directions, I agree with Pinker’s assessment that we are committing violence at a lower rate, but that is not the point – the point is that we try almost any weapon we create…even if then we put it back in the gun cabinet (or silo). I think there will be those who push for cloning for many of the reasons that sci-fi writers conceived of as plausible (harvesting organs).
But…I think Anastasia suggestion for that as a forum conversation is a good one. Let me see if I can find time to make a more cogent case for concern.
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But what about my right to not eat GM food if I do not feel comfortable putting it into my body? If there is no labeling how can I be sure I am avoiding it? I don’t get a right to choose?
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Sherry, there are many companies that offer non-GM food, and clearly label it as such. Check out the Non-GMO Project, for instance, which tests and labels non-genetically engineered foods as such. That way, you would know precisely what you are eating, and that it doesn’t contain more than 0.9% GE ingredients.
In contrast, do you think that prop 37 would make you confident about what you are eating? “May be partially produced with genetic engineering” – does that tell you that it does or does not in fact have GM ingredients? At the same time, if prop 37 passes, and you saw a product containing corn that does not identify it as being GM (or non-GM) would you be confident that it is not GM? With about 2/3 of food exempted by the proposition, I daresay you might not feel any more secure that you are avoiding these foods than you are now.
This issue is similar for vegans and vegetarians, practicing Jews who eat kosher, and Muslims who eat halal – they look for and support products that monitor their ingredients for the specific desires of their customers.
You already have the power to choose these products!
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Hi Sherry, thanks for your question. I do feel sympathetic for your situation. Let me explain – I’m vegetarian, because I do not feel comfortable putting animal flesh into my body, even though I know other people don’t have a problem with it, and I know there aren’t any health concerns with a balanced diet containing animal products.
There are no mandatory labels for products containing meat, bone, gelatin, etc (things that often hide in “natural flavorings”). I have to choose products that have voluntarily labeled or ones that I have checked out online or by calling the company. Sometimes I think it would be convenient if there was a mandatory label for animal based ingredients so I wouldn’t have to look for the information.
But once I think about it a bit more, I realize that such a mandate would likely result in labels that say “may contain animal based ingredients” or something like that (not to mention any foods that might be exempt from the mandate). Only products that definitely contain animal products would be labeled as such – and I can already figure those out pretty easily. Since the default state of food right now is that it might contain these ingredients, adding the label doesn’t help at all.
It seems to me that GMOs are actually very similar to animal products here. Some people want to avoid it on a mostly philosophical basis. There are voluntary labels, and many companies who don’t have a label on the box do list that information on their website. It’s relatively easy to avoid for a majority of products that contain them (pretty much any processed food containing soy, corn, or canola). Lastly, for some products, there may be GMOs hiding in “natural flavorings” or other minor ingredients – but in those cases a “may contain GMO” label wouldn’t be useful because the default state is already that they might have GMOs in there, so someone who really wanted to eat that product would still have to call the company.
So, I don’t really see the benefit in mandatory labeling for either animal products or GMOs. Instead, I very much support truthful, voluntary labeling that provides valuable information to people who might want it!
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Here’s a blog post by the “Botanist in the kitchen” that is very relevant to this post!
Phylogenetic tree view shows how plant foods are related to each other using phylogenetic trees. I didn’t know that avocado is more closely related to cinnamon than to paw paw 🙂 Lots of very interesting information there for the reading!
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Anastasia,
The point is that the default becomes that there is no warning for GMOs coming into our foods, voluntarily labelling does NOT address this issue. The only ones who would label are those companies that see a benefit from specifically noting that there are NOT GMOs in the product…this is not fair to consumers.
What I find disturbing is that well-meaning scientists like yourselves fail to respect the natural integrity of a species of plant or animal. Injecting genes DOES have an impact and it can be a detrimental one….which is not to say that all GE is bad…the problem is that there is hardly any incentive to thoroughly understand in advance the consequences of injecting a new GM hybrid into the environment, and yes there are numerous examples of where this has caused an imbalance in nature…super weeds being just one of them.
The other thing that REALLY frustrates me is the stated equivalence of GE, which modifies genetic material more directly, with the kind of cross-breeding that farmers have been doing for hundreds, probably thousands of years….but using mechanisms provided by nature herself…can you not see the difference? And what is truly heinous is that with the GM of seeds, companies like Monsanto take advantage of that natural cross-breeding to SUE neighbouring farms, forbidding them from saving their seeds…this has been documented and widespread, and has been literally destroying the ancient legacy of farmers to intelligently cross-pollinate and save their seeds for the next year….this is monstrous, if you know anything about subsistence farming….
but its ok because science is so much better? Really, this is hubris….GM engineers do NOT understand life itself, but they understand enough about it to muck with it….really, a lot more research and responsibility is required for this, but there is no market or governmental incentive to do this, and the consequences of irresponsibility are at least partially irreversible. I pray that you can see this.
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There is equally no warning when a new variety of Soy, Wheat, Corn, Potato, Sugarcane… or any other crop is introduced into our food. There’s no warning when a new improved machine or a changed cooking time is introduced to say, dorito manufacturing.
Hey, if nature ain’t gonna respect your arbitrarily defined barrier which only holds true for a fleeting temporal moment in evolutionary time anyway… why on earth should I?
Demonstrate that it has been in something relevant to the conversation. Scientists know that insertion of material into the genome can be deleterious (reverse genetics rather depends on it) but are equally aware that this isn’t always (or even the majority of the time) the case.
Imbalance in nature? Where the imbalance? All a “superweed” is, is a regular weed that is resistant to a given herbicide. This is evolution in action. Nature doing what nature does. We don’t live in a marvel comic book, imprecise bizarre terms like “imbalance in nature” are essentially meaningless. But hey, you got to use the word superweed, so hurrah, that sounded scary right?
This frustrates me too actually, while it is illustrative to show that in terms of risk assessment there are parallels between breeding and GM which make criticism of GM on this front frankly silly, simply saying they are directly equivalent is odd and unhelpful – we know there are differences, we know that when someone is talking about genetic modification they have a meaning in mind that is specific to transgenic approaches and not the rather pedantic “but all modifications to the genome are genetic modifications, whether traditionally bred, mutagenized, or transgenically altered”.
Although that said… current GM practices rely utterly on mechanisms provided by nature.. (restriction enzymes, agrobacterium etc)
This would be pretty heinous if it reflected reality. It doesn’t however. Thus your whole rant is meaningless. I do note that you state it has been documented and widespread however, you’ll easily be able to provide references I suppose?
So is your arguement that we must absolutely understand everything before we do anything? Good luck getting out of bed in the morning then. (or does this only apply to a single branch of science but for some reason not to everything else that anyone ever does?)
Indeed they are. You irresponsibly, for instance, block the release of golden rice for decades by forcing a ridiculously convoluted regulatory system onto a production method and the deaths and blindness that could have been prevented are most certainly irreversible. You prevent the release of a trait that’d reduce toxic pesticide use and prevent kids from some of the poorest regions of the world being exposed and harmed by these pesticides… again, yes, irreversible. This works both ways, and given that there are very real, very obvious and very impactful consequences of not adopting the technology on many fronts it absolutely infuriates me that people like you demand we hide from the boogeyman under the goddamn bed because of scary consequences which to date have not raised there head whatsoever and have not been seen at all in many studies looking precisely for effects.
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(So irate I was that their somehow because there…)
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and indeed became became because…
I wonder some days that I manage to communicate at all.
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Thumbs-Up! You are an inspiration.
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Stephen,
You make a pretty big error in your third paragraph, you say “The other thing that REALLY frustrates me is the stated equivalence of GE, which modifies genetic material more directly, with the kind of cross-breeding that farmers have been doing for hundreds, probably thousands of years….but using mechanisms provided by nature herself…can you not see the difference?”
The error here is that you assume that the “natural” crossbreeding methods are based in some sort of inherent benefit to humans on the part of the plants being crossed. Plants don’t develop traits for our benefit, they are only concerned with replicating. Us eating plants is not in the best interest of the plants. When we cross breed, we are taking a gamble that the traits we want will be in the new plant, and there will be no new ones that are harmful to us. But in traditional cross-breeding, there is a chance that we will get undesired traits, it’s a gamble. In GE, we know exactly what traits we want, and we know (with relative certainty) which genes we have to add to get these traits. We are also able to reduce the variables that could create harmful changes, because we are being so specific. You are correct that there is a difference here, but you choose the side of the more risky method.
You also bring up the FALSE notion that Monsanto sues farmers for accidental contamination, they have not, and have said numerous times that they will not. They do sue some farmers, but only for obvious and undeniable patent infringement. The most famous is the case of Percy Schmeiser, whose fields had a concentration of 90%+ GM Canoloa, which he didn’t pay for. Hard to call that accidental.
I’m also hoping that you know about the fact that farmers stopped saving seeds when hybrids started to become popular. Saving seeds from hybrid plants gives crappy results , so farmers prefer to pay in order to have a predictable yield. This has been going on since decades before GM.
You seem rational, so I would hope you are willing to look at the available literature on this site to better educate yourself in the wonderful world of Biotechnology. It’s a great benefit to mankind, and the world in general.
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Nicolai,
I would add that UNCONTROLLED crossbreeding by NATURE can be very dangerous indeed. I am particularly interested in Phaseolus lunatus, and in its native area, there are periodic poisonings, apparently sometimes due to introgression by wild types. http://www.cabdirect.org/abstracts/19402701670.html;jsessionid=61C8A231B79631EAABBC00E81F1B9A5D
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