Why cats, hyenas and seals don’t love sugar

The molecular basis for taste is relatively straightforward. On your tongue, you have numerous taste buds that harbor cells with little proteins hanging out on the top. These proteins have the capacity to bind a number molecules on your tongue, and thereby transmit information regarding nutritional content.

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Mammalian taste receptor proteins and molecules that activate them.

One of these proteins is TAS1R2, which, along with the protein TAS1R3, binds sweet tasting molecules. This sweet receptor is what allows you to savor the delicious sucrose (table sugar), fructose (fruit sugar) and even artificial sweeteners such as saccharin and aspartame. If you love cake, ice cream, and cookies, be grateful that you have a functional sweet receptor!

Not all animals are fortunate enough to enjoy these treats, however, and evolution is likely to be blamed. Many species are particularly adapted to eating foods that are nearly devoid of sugars, and therefore are not expected to benefit from maintenance of the gene encoding TAS1R2. Indeed, scientists [1] have found that a number of carnivorous mammals, including cats, hyenas, seals, the banded linsang, fossa and Asian small-clawed otter have a pseudogenized (nonfunctional) version of the TAS1R2 gene.

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Examples of TAS1R2 pseudogenes in various carnivores

This helps explain why cats behaviorally seem uninterested in sugar. The scientists also confirmed that the Asian small-clawed otter also is not drawn to sweets, consistent with its TAS1R2 pseudogene. By contrast, they found that the spectacled bear, which has an intact TAS1R2 gene and is a known devourer of sweet things like fruits and honey, prefers sugary solutions over water.

spectacled-bear

These data suggest that the ancestral carnivores did eat sweets on occasion, but certain species avoided sugary foods for so long that sweet receptors were no longer necessary. Eventually mutations rendered the TAS1R2 gene nonfunctional in different carnivore lineages, rendering these species impervious to the effects of sweets.

Questions for Creationists

Why did God create some carnivores with a nonfunctional version of the sweet taste receptor gene? Would it not have made more sense for Him to create them without the gene altogether? Is it just a coincidence that He also created other animals with specialized feeding strategies, such as giant pandas and whales, to lack certain taste receptors?

References

1. Jiang, P., Josue, J., Li, X., Glaser, D., Li, W., Brand, J. G., … & Beauchamp, G. K. (2012). Major taste loss in carnivorous mammals. Proceedings of the National Academy of Sciences109(13), 4956-4961.

Photo Credit

Taste receptors, hyena, harbor seal, banded linsang,  fossa, otter, pseudogene figure, spectacled bear

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17 thoughts on “Why cats, hyenas and seals don’t love sugar

  1. In my molecular methods class two years ago we hypothesized that bowhead whale and belugas – two organisms for which I can DNA of in my freezer – would have pseudogenized copies of the sweet and umami taste receptor genes. Groups of students designed there own primers and tested them. None of the 6 groups were able to ampllfy the sweet taste receptor but several were able to amplify the umami taste receptor. We sequenced those products and found that the Bowhead has multiple stop codons and a large – more than 10bp -deletion in the gene. I haven’t looked in the Bowhead genome sequence which is now available but I expect that we weren’t successful because it is either completely missing or has so many mutations our primers wouldn’t have worked.
    Just as you say above, my students hypothesized that the whales didn’t need to taste sweet or umami and therefore didn’t need those genes but they also hypothesized that if whales had land animal ancestor that at one point their genomes would have had functional version of those genes. The results they obtained made perfect sense within the context of common ancestry.

    1. Ah, very cool class assignment! I’d love to be able to incorporate scientific discovery into a classroom someday.

      Indeed, Jiang et al. also looked at the sweet receptor in the bottlenose dolphin and confirmed what you all expected. A later study demonstrated this more broadly in whales, showing they’ve lost pretty much all of their tasting abilities!:

      https://academic.oup.com/gbe/article/6/6/1254/580618/Massive-Losses-of-Taste-Receptor-Genes-in-Toothed

  2. TFBW

    Why did God create some carnivores with a nonfunctional version of the sweet taste receptor gene?

    Why do you assume it was created nonfunctional?

  3. TFBW

    That would be a charitable interpretation of what I said, yes. Alternatively, “why do you phrase the question so that it contains the assumption that it was created non-functional,” if you’re a fan of precision over brevity.

    1. Because in my experience, creationists typically don’t think of genetic changes on this sort of scale as being possible. Therefore, the assumption is usually that the Creator designed the organism with this already in their genetic code.

  4. TFBW

    I don’t suppose you have an actual citation to back up your “typical creationist”, do you? If I accused you of attacking a straw man, would you have anything more than personal anecdotes with which to defend your position?

    1. Perhaps this is wholly unintentional, but your tone isn’t particularly friendly in some of these comments. They read as if you think I write with insidious intentions. Again, perhaps this is an unintended consequence of your writing style, but if I am correctly detecting a negative attitude, please understand that the point of this blog is not to demean creationism nor argue with people. The purpose is to simply present evidence for evolution, and discuss what it might mean for some of the common models of creationism. Many people are not aware of the data that I present, and are only familiar of things like Archaeopteryx, pepper moths and other textbook examples of evidence for evolution. These examples have been rationalized to death by leaders in the creationist community, so some creationists might go about their lives thinking that all of the alleged evidence for evolution has been explained away. Of course, it doesn’t mean I think that what I present here will convince all creationists that evolution is real, but hopefully it at least helps them become aware that there’s more evidence out there and/or gets them thinking about what they believe about the Creator.

      The questions I post at the bottom actually are not rhetorical, but are meant to either get creationists to think about the data I present and what it implies for their view of creationism, and/or for them to directly respond with how they view the data, ask questions, etc. I’m not trying to entrap anyone, set up straw men, argue people into submission, any of that. I realize that beliefs are diverse and everyone is trying to make sense of what they see in the world and reconcile that with their worldview, so I’m not as much of a fan of argumentation as I am of discussion. I’m presenting data for one particular worldview, and if someone can take in all of these data and still believe that a Creator created every organism as is 6000-10000 years ago, I’d truly be fascinated to hear their thoughts.

      Anyway, to answer your question: the first thing to keep in mind is that creationism can be diverse and contradictory, even within the same organization. There isn’t exactly a unified model of Creationism to the same extent that we have for evolutionary theory. Also, I just pulled up a few examples here rather than thoroughly mining all of the creationist literature. Maybe I’ll make time for this later, but someone who is far more up on this literature is Joel Duff and could probably answer your question more thoroughly: https://thenaturalhistorian.com

      To start, it is well known that Creationists typically accept evolution but disbelieve in macroevolution (i.e., large evolutionary changes over long periods of time), at least in part because most Creationists believe in a young earth. The problem is how to define “large changes”. In this article (https://www.icr.org/article/1156/285) the author refers to macroevolution as invertebrates turning into fish and hoofed mammals turning into whales, which are clearly consistent with this definition. So where does the loss of some taste perception, as evidenced by taste receptor pseudogenes, fall on the spectrum between micro and macroevolution? What about other pseudogenes that show evidence of loss of some aspects of vision in mammals that live underground? Or tooth pseudogenes in animals that completely lack teeth, such as anteaters, birds and turtles? (some of the examples I’ve highlighted here: https://evolutionforskeptics.wordpress.com/category/pseudogenes-2/)

      To make this distinction all the more cloudy, creationists frequently contend that mutations are never (or almost never) beneficial, which seemingly forms the basis for why macroevolution is implausible. From the above article: “Genetic mutations produce new genetic material, but do these lead to macroevolution? No truly useful mutations have ever been observed.”

      So do all beneficial mutations equate to macroevolution? Could the Creator have created these organisms with functional genes and these genes accumulated loss of function mutations and not have been “useful”? Is it not useful, if you’re a carnivore, to avoid wasting space on your tongue and metabolic energy by eliminating the capacity to taste sweets when you never encounter sweets in your diet? Is it not useful, if you’re a baleen whale that feeds using baleen plates instead of teeth, to get rid of your teeth since they crowd the mouth and aren’t helping with the way you now feed?

      I assume that this is in partly why creationists often believe that pseudogenes are not actually defunct copies of formerly functional genes, but instead suggest that they all must perform functions and were bestowed by the Creator (http://creation.com/pseudogenes-are-they-non-functional): “it is evident that these genetic elements, which are copiously spread in the genomes of different organisms, have been created with purpose”

      A final topic I’ll briefly mention is that a new type of creationism has arisen that assumes evolution is essentially true, except that it happened extremely rapidly and only within ‘kinds’ (frequently equivalent to taxonomic families). They assume that genetic diversity is due to created heterozygosity (i.e., genetic variation within the progenitor kinds): https://answersingenesis.org/natural-selection/speciation/on-the-origin-of-eukaryotic-species-genotypic-and-phenotypic-diversity/

      The above article is way way too long for casual reading, but you can see that Jeanson summarizes it in the conclusion. This idea that kinds diversified and evolved over time implies that the Creator created many organisms with pseudogenes since some genes are nonfunctional within entire taxonomic families/’kinds’ (e.g., taste pseudogenes in multiple whale families, vision pseudogenes in subterranean mammal families).

  5. TFBW

    I’m sorry if my tone comes across as harsh, but it’s common practice in evolutionists-against-creation blogger circles to mock and ridicule. Your blog doesn’t have a scoffing tone, but on the other hand it doesn’t go to any efforts to interpret the arguments of its opponents in the most charitable light. While this arguably makes it a cut above most of the alternatives, it’s still frustratingly obtuse in its treatment of creation, like the ignorant creationist who thinks he’s presented a real hum-dinger of a question when he asks an evolutionist, “if people evolved from monkeys, why are monkeys still around?”

    Your question, with its implicit assumption of creation-with-nonfunction, comes across as obtuse in this way because the following points are uncontroversial in creationist circles, and I think you ought to be aware of it.

    1. Creation was initially perfect.
    2. Sin and corruption entered the world, causing decay.

    Given these two points, why would anyone bat an eyelid at the presence of evidently broken genes? Assuming the identification is correct, it’s just more evidence of genetic decay. And why would you assume a broken gene was created that way?

    If you were aware of these common beliefs, then you had a charitable interpretation available to you, and you chose to pass it over, which is mean. If you weren’t aware of them, then you’re somewhat ill-informed about creationism, and you’re just exhibiting that ignorance with your questions (but doubling down when I suggest that it might be ill-founded). I’d prefer to argue with someone who is not operating out of ignorance or a lack of charity, and this analysis doesn’t bode well for those criteria. That’s a shame, because I thought this blog looked somewhat promising.

    You might not think of your questions as rhetorical, but they’re deterring actual engagement as far as I’m concerned. If that’s not what you’re aiming for, then take it under advisement.

    Would you like me to leave now?

    1. Hi TFBW:

      “I’m sorry if my tone comes across as harsh, but it’s common practice in evolutionists-against-creation blogger circles to mock and ridicule.”

      I have zero intention to mock or ridicule anyone, and I do not want anyone to do that in the comments either.

      “Your blog doesn’t have a scoffing tone, but on the other hand it doesn’t go to any efforts to interpret the arguments of its opponents in the most charitable light. While this arguably makes it a cut above most of the alternatives, it’s still frustratingly obtuse in its treatment of creation, like the ignorant creationist who thinks he’s presented a real hum-dinger of a question when he asks an evolutionist, “if people evolved from monkeys, why are monkeys still around?””

      It’s important to keep in mind that most creationists probably have not thought through many of these issues as much as you have. Most that I have encountered are creationist by association, i.e., their church taught them that creationism is true, evolution is demonstrably false, and to reject creationism is to reject God, Jesus and everything else that goes along with being a Christian (my impression is that a similar thing occurs in muslim circles). This blog is mostly meant to reach out to people like this, not as much to people like you. In other words, the intention is to make it more accessible to casual creationists, and therefore I believe that most of what I present here (including the questions, as simplistic as they are) is relatable to what they believe. I could of course be wrong about that, but I’m not above adapting what I present to accommodate whatever is the majority belief.

      Given that, I’m happy to discuss ideas, questions, rebuttals, etc. with anyone from any background, but your implied tone makes it difficult to want to continue talking with you.

      “Given these two points, why would anyone bat an eyelid at the presence of evidently broken genes? Assuming the identification is correct, it’s just more evidence of genetic decay.”

      Because the broken genes are nonrandom and instead appear to be associated with their particular lifestyle (=adaptations). If decay did appear randomly, genetically or otherwise, then I think that would be an interesting piece evidence for the creationist model. But decay of sweet taste receptors in species that don’t eat sweets (with an assortment of anatomical features that show they specialize on meat), the decay of tooth genes in species that do not have teeth or hardly use their teeth (relying on other anatomical traits to ingest food) or the decay of vision genes in species that are adapted to living in the deep ocean or underground is not random.

      This doesn’t mean that these species couldn’t have been created with functional genes that lost them over time, but it then raises all sorts of questions about the speed of mutations, fixation of mutation and anatomical evolution.

      “And why would you assume a broken gene was created that way?”

      You asked and I pointed you to creationist literature that suggests that pseudogenes were created. That could be one of many interpretations out there (it’s the only one I’ve seen), but Creation Ministries International is certainly a mainstream organization, and at least some of their members currently believe or have previously believed this.

  6. TFBW

    It’s important to keep in mind that most creationists probably have not thought through many of these issues as much as you have.

    True. I’m very much the exception, not the rule.

    In other words, the intention is to make it more accessible to casual creationists, and therefore I believe that most of what I present here (including the questions, as simplistic as they are) is relatable to what they believe.

    I’d have far less of a problem with this if the situation were not stacked so massively in your (the evolutionists’) favour already. It’s literally illegal to teach evidence for creation in an American public school (and in other Western countries besides). As such, “casual” creationist is pretty much all that can naturally exist, aside from freaks like me. You’re pressing an unfair advantage, which is a bully tactic even if it’s not intended that way.

    Because the broken genes are nonrandom and instead appear to be associated with their particular lifestyle (=adaptations).

    Your notion of adaptation seems curiously teleological. Surely the official doctrine is that mutations occur randomly, but persist in a manner weighted by their survival advantage. There’s nothing remarkably advantageous (or “adaptive” if you must) about a cat losing its sweet receptors in the absence of an advantage to sweetness: it’s just a feature which was lost due to random change and a lack of associated survival penalty.

    You asked and I pointed you to creationist literature that suggests that pseudogenes were created.

    The article also suggests that pseudogenes are functional. Your assertion that Creationists believe pseudogenes are non-functional elements that were created that way is not supported by the article you cite.

    1. “I’d have far less of a problem with this if the situation were not stacked so massively in your (the evolutionists’) favour already. It’s literally illegal to teach evidence for creation in an American public school (and in other Western countries besides). As such, “casual” creationist is pretty much all that can naturally exist, aside from freaks like me. You’re pressing an unfair advantage, which is a bully tactic even if it’s not intended that way.”

      For the record, I’m all for discussing the concept of creationism in schools, and do so regularly when I teach evolution classes. I think the main problem with creationism is that (1) it’s very much tied to specific religious beliefs, and (2) almost no actual science is done by creationists, so it’s hard to take it legitimately as anything but a religious doctrine. But, given its prevalence in (especially) the American public, it should definitely be discussed. Being condescending to people who believe it is not productive to finding out the truth.

      I would disagree that it’s bullying though to discuss this since such a large proportion of Americans believe it. 46% of the last Gallup poll that I saw.

      “Your notion of adaptation seems curiously teleological. Surely the official doctrine is that mutations occur randomly, but persist in a manner weighted by their survival advantage.”

      What did I say specifically that sounds teleological? That the genes that are lost are nonrandom?

      “There’s nothing remarkably advantageous (or “adaptive” if you must) about a cat losing its sweet receptors in the absence of an advantage to sweetness: it’s just a feature which was lost due to random change and a lack of associated survival penalty.”

      Yes, that’s one possibility, and it may very well be true, but (1) proteins being expressed that aren’t contributing anything to the fitness of the organism are metabolically costly, and (2) sweet receptors are specifically expressed in distinct cell populations in taste buds, so by existing they are take up valuable space that could be use by other taste channels, therefore there may be an adaptive advantage to lose them.

  7. TFBW

    For the record, I’m all for discussing the concept of creationism in schools, and do so regularly when I teach evolution classes.

    And if your blog is anything to go by, you are not presenting it in its strongest form. Have you read John Stuart Mill’s On Liberty at all? It says a thing or two about this kind of situation.

    I think the main problem with creationism is that (1) it’s very much tied to specific religious beliefs, and (2) almost no actual science is done by creationists, so it’s hard to take it legitimately as anything but a religious doctrine.

    Both of these problems are largely the fault of belligerent Darwinian hegemony, so complaining about them is a bit rich. In regard to (1), for example, attempts to produce research programmes which are not tied to specific religious beliefs (such as Intelligent Design) are identified by the hegemony as stealth creationism, and assumed to be associated with and motivated by the same religious beliefs, so damned if you do, damned if you don’t. In regard to (2), historically, the bulk of science was performed by creationists like Sir Isaac Newton. Currently, the hegemony makes it nearly impossible to hold such a non-orthodox view. Any creationists still in science are either outside the mainstream (working at privately funded institutions which specifically tolerate such deviation from orthodox Darwinism), or keeping their beliefs under wraps for fear of reprisals.

    I would disagree that it’s bullying though to discuss this since such a large proportion of Americans believe it. 46% of the last Gallup poll that I saw.

    It’s bullying to speak from a position of authority, given the above. You are not on even footing with the 46% of which you speak: you have a teaching platform.

    What did I say specifically that sounds teleological? That the genes that are lost are nonrandom?

    The entire part I quoted, but yes, the “nonrandom” part is key. In what sense are the genes lost non-randomly? You make it sound like changes happen in response to lifestyle.

    1. First: sorry, I forgot to respond to this comment:

      “The article also suggests that pseudogenes are functional. Your assertion that Creationists believe pseudogenes are non-functional elements that were created that way is not supported by the article you cite.”

      I understand, but the reality is that we know the functions of relatively few pseudogenes, and it appears likely that the vast majority are actually nonfunctional. Part of this is through analyses that suggest that they’re randomly accruing mutations, rather than showing some sort of contraint on function. Part of this is because they lack simple machinery to allow for their function (in any way that we know of). So again: did the Creator create genes without function?

      This would be a great area of pursuit for creationists: if they could demonstrate that every single pseudogene had a function (or at least analyse enough that you could project towards all), that would be very, very surprising to evolutionary biologists. I guarantee something like that would get funding. It’s something I wonder about.

      Regardless, an important point is that even these functional pseudogene elements have strong similarity to protein coding genes. As an example: (1) gene A in a human encodes a protein that performs function X, (2) gene A in a chimpanzee does not encode a protein, so it is a pseudogene, and performs function Y. But the gene structure and overall similarity of gene A in human and pseudogene A in chimpanzee suggests that the chimpanzee gene A formerly encoded a protein. In fact, if you took protein-forming gene A from a human, non-protein-forming gene A from a chimpanzee, and protein-forming gene A copies from a bunch of other species, despite their completely different functions (protein-forming vs. non-protein forming), the human and the chimpanzee are going to come out as more similar. Why then, if one species is created with a pseudogene and another with a protein-coding gene, do they come out as so similar and tell the same story as if you compared human protein-coding gene B and chimp protein-coding gene B (i.e., that humans and chimps are more genetically similar to each other than any other species is, and they are also extremely similar physically)?

      “And if your blog is anything to go by, you are not presenting it in its strongest form.”

      You seem to imply that it’s factual that your strain of creationism is the strongest form.

      First, I’d like to point out that I have an opinion on the strongest forms of creationism, and, based on your comments, you almost certainly don’t subscribe to them. To me, Intelligent Design is the most robust, as it accepts practically everything that scientists agree upon, except that it holds out that a handful of things are only attributable to a Creator. This is worth addressing to students, but it’s also important to note that it’s hypotheses aren’t exactly testable and therefore are unscientific (though this doesn’t mean it’s wrong).

      For young earth creationism, I think there is a particular conception that is stronger than others. It accepts nearly everything about evolutionary theory, but forces a 6000 year time period, Noah’s flood, invokes hyperspeed rates of evolution and speciation, etc. However, this idea seems very new and unlikely to be worth addressing because it is not popular by any means (yet).

      Second, other creationists, including ones that you disagree with based on our discussions of DNA similarity and physical similarity, might take offense that you consider their form of creationism as weaker.

      Regardless, I’m not going to address all of the different forms of creationism, but rather the form(s) that seem to be the most common. The reality is, when I teach evolution, I don’t necessarily teach the version that I think is the strongest. I teach what the general consensus is, but I have disagreements about some of the minutiae. But as science moves along, the consensus on the theory of evolution will change, and similarly, the consensus of creationism will likely change along with it. I will do my best to portray both as accurately as I can, albeit limited by time constraints.

      “Both of these problems are largely the fault of belligerent Darwinian hegemony, so complaining about them is a bit rich. In regard to (1), for example, attempts to produce research programmes which are not tied to specific religious beliefs (such as Intelligent Design) are identified by the hegemony as stealth creationism, and assumed to be associated with and motivated by the same religious beliefs, so damned if you do, damned if you don’t. In regard to (2), historically, the bulk of science was performed by creationists like Sir Isaac Newton. Currently, the hegemony makes it nearly impossible to hold such a non-orthodox view. Any creationists still in science are either outside the mainstream (working at privately funded institutions which specifically tolerate such deviation from orthodox Darwinism), or keeping their beliefs under wraps for fear of reprisals.”

      I’m not complaining about them, I’m just saying that they’re problems.

      No disagreements that biologists are extremely hostile to the idea of creationism and ID. Some of it is understandable, for example when evidence is distorted or ignorantly portrayed, etc. There is this general impression that creationists/IDists aren’t particularly scholarly about the research out there. I recall Michael Behe stating under oath that there was zero research on the ‘irreducibly complex’ system of blood clotting. He was then presented with a waterfall of research on this very subject, and then admitted that he hadn’t read any of it. It reminds me, probably in the same way to you, of how Richard Dawkins and his ilk present religion as if they completely understand it, but clearly do not.

      But again, it is definitely a problem when you consider that much of Creationism is entirely religiously motivated. The religion, or rather the specific religious interpretation of a portion of a holy text, assumes primacy and then the interpretation of the evidence flows from it. Many of the specific creationist concepts are explicitly Judeo-Christian, such as the specific date of Creation, the timing and worldwide impact of Noah’s flood, the concepts of kinds, the curse brought onto Creation, etc. Christian creationists probably wouldn’t come to the defense of a Hindu creationist or Native American creationist idea, because Creationism per se is almost never a religion-neutral idea. IDism, on the other hand, can be and often is, even though many of its adherents are religious. It doesn’t add all of the minutiae of creationism and simply posits that the complexity of the universe can’t be explained by natural processes.

      But this is not to say all, or even most, creationists and IDists are ignorant of evolutionary theory. For these people, the ones don’t have the agenda of distorting research to make a point of evangelizing, I think scientists should be engaging with them more. I think many of their criticisms of evolution provide some of the best ideas that need to be investigated in the field. And for the very reason of freedom of thought, I believe science should take ALL possibilities into account. I think it’s shameful that scientists mock or ridicule serious, scholarly Creationists and IDists.

      Could you point me to some of these IDist research programs that were unable to get funded? I’d be interested to see what kinds of questions they wanted to test.

      I think it’s fair to ask if Isaac Newton, among the many others like him, would have been a Creationist if he were born today. His predecessors also thought that the earth was the center of the universe, planetary orbits were circular, etc. As new evidence mounts, opinions change. Who knows? Maybe in a hundred years, we’ll look back on all of the evolution supporters (including yours truly) and say, “Gosh, they sure got that wrong, didn’t they?”

      “It’s bullying to speak from a position of authority, given the above. You are not on even footing with the 46% of which you speak: you have a teaching platform.”

      I might be in a position of academic authority, but I don’t tell my students “you must believe this” or “this is the truth” when it comes to evolution. We talk about how science works and how ideas are changed, and that includes the origins and diversification of life.

      But if you still think that’s bullying, don’t churches and mosques around the world “bully” their followers into believing whatever core doctrine they adhere to? This, of course, includes issues like evolution and creationism. Just like it’s not tolerated to accept creationism as a scientist, it is quite frequently not tolerated to accept evolution in certain religious circles. I’ve been to many churches where it’s preached or at least strongly implied that to believe such things is heretical. Heresy brings up questions of loyalty to the church, to the religion and ultimately brings up questions of eternal damnation and other emotionally traumatic things.

      I think the take home point is people need to be open and tolerant of diverse viewpoints and have discussions, not make this evolution and creation stuff into a war.

      “The entire part I quoted, but yes, the “nonrandom” part is key. In what sense are the genes lost non-randomly? You make it sound like changes happen in response to lifestyle.”

      Theory predicts and empirical evidence shows that gene loss can happen in response to lifestyle. For instance, right now I’m working on genes that produce enzymes that digest chitin in the exoskeletons of insects. So if you eat a lot of insects, natural selection would presumably maintain the functionality of these genes. But, say, a new food source becomes available or the insect prey are suddenly not abundant. Then, if loss of function mutations begin to creep into these chitin-digesting genes, natural selection wouldn’t necessarily weed them out. In fact, it might even favor these mutations since producing an enzyme that isn’t helping you with your diet would be wasteful. As such, the change in lifestyle (diet) can lead to a nonrandom loss in genes.

      But actually, that’s not what I meant. I meant to indicate that the types of genes are lost non-randomly, e.g., color vision genes and smell genes are lost VERY frequently, but you almost never, ever lose important developmental genes (e.g., hox genes). So across the entire genome there is a non-random pattern of gene loss: of the tens of thousands of genes found in typical genomes, only subsets are ever lost, and they almost always seem to become lost in contexts that appear to be adaptive. So if gene loss is the consequence of the curse on nature, then why does the loss appear nonrandom and only seem to occur in adaptive situations?

  8. TFBW

    I understand, but the reality is that we know the functions of relatively few pseudogenes, and it appears likely that the vast majority are actually nonfunctional.

    I won’t argue that. I will merely point out again that you have not cited a creationist source who believes that genes were created non-functional. Are you still going to insist that your question, “why did God create some carnivores with a nonfunctional version of the sweet taste receptor gene?” is in any way representative of an actual creationist position? The actual position is that the genes were created functional, as your citation shows. Why not attack the actual position instead of misrepresenting it?

    You seem to imply that it’s factual that your strain of creationism is the strongest form.

    No, I imply only what I said: that your form is a weak form, as demonstrated by your use of non-representative questions. You’d lose your job if you taught creationism in a positive light, and there’s no reason why you’d have an expert understanding of it in any case. As Mill said, these arguments are best presented by people who actually believe them; who defend them in earnest. But that would be illegal. Instead, we get the arguments of creationists presented as evolutionists state them, and accompanied by what they offer as refutations.

    Could you point me to some of these IDist research programs that were unable to get funded?

    BIO-complexity is as good a place as any to find that sort of thing.

    I think it’s fair to ask if Isaac Newton, among the many others like him, would have been a Creationist if he were born today.

    You can ask, but any answer is pure counter-factual speculation, since he wasn’t. The fact is he was a scientific and mathematical genius who was also a creationist and avid theologian. This bears some frequent repeating, given the number of New Atheists pushing the “incompatibility of science and religion” narrative.

    I might be in a position of academic authority, but I don’t tell my students “you must believe this” or “this is the truth” when it comes to evolution.

    You don’t need to be that blatant about it. You can just present a weak version of the argument you want them to reject, and let them draw their own conclusions about which argument is stronger. That’s far more effective.

    But if you still think that’s bullying, don’t churches and mosques around the world “bully” their followers into believing whatever core doctrine they adhere to?

    In the cases where the doctrine is enforced by law, rather than by the free choice of the participants, sure. And if you want to draw parallels between your own position and those of priests and imams, then far be it from me to contradict you.

    As such, the change in lifestyle (diet) can lead to a nonrandom loss in genes.

    My point is that the loss is not caused by the lifestyle: the loss is caused by random mutation. The subsequent preservation of mutation is influenced by lifestyle, but does not cause the changes so preserved. Eating a particular diet is not likely to cause mutations which support that diet, but only preserve whatever random mutations happened to support it.

    … but you almost never, ever lose important developmental genes (e.g., hox genes).

    Because that would almost certainly be fatal or severely debilitating, no? That is, if you lacked important developmental genes, you probably died early on in embryonic development, and would thus be severely under-represented in the population.

    So if gene loss is the consequence of the curse on nature, then why does the loss appear nonrandom and only seem to occur in adaptive situations?

    Because natural selection. The loss is random, but the consequent survival rate differs. Are we really disagreeing about this?

    1. ” I will merely point out again that you have not cited a creationist source who believes that genes were created non-functional. Are you still going to insist that your question, “why did God create some carnivores with a nonfunctional version of the sweet taste receptor gene?” is in any way representative of an actual creationist position? The actual position is that the genes were created functional, as your citation shows. Why not attack the actual position instead of misrepresenting it?”

      I’ll give this some thought, and see if I can come up with a better kind of question that remains relevant.

      Nonetheless, they are nonfunctional in the sense that they do not produce a mRNA that makes a protein. In fact, some of them don’t even make an mRNA for regulatory purposes (which is what the “functional” pseudogenes seem to do), i.e., they lack the basic machinery to even be turned on. Even those that do get turned on just get broken down after making an mRNA (a process known as nonsense mediated decay).

      Plus, importantly, they are highly genetically similar to functional (protein-making) versions of the genes. So, for example, SWS1 is a vision gene that allows us to see blue light. In whales, it is nonfunctional, or at least it does not produce a product that can provide instructions for making a protein. However, despite either being nonfunctional OR perhaps it functions in a regulatory role (i.e., a totally different function from making the protein), the SWS1 whale pseudogenes cluster where all the other genes do, among the various hoofed mammals. If the Creator made these non-protein producing pseudogenes and the protein-producing genes in these animals, why are they so genetically similar to one another, and why do they recapitulate the same relationships as functional genes?

      “No, I imply only what I said: that your form is a weak form, as demonstrated by your use of non-representative questions.”

      We can disagree on this, but for the record I don’t believe my questions are non-representative of the general creationist public. If through my readings and interactions I discover that they are, I will certainly adjust them accordingly.

      “You’d lose your job if you taught creationism in a positive light, and there’s no reason why you’d have an expert understanding of it in any case.”

      Well, the hope is to have an expert understanding in the not-too-distant future.

      “As Mill said, these arguments are best presented by people who actually believe them; who defend them in earnest.”

      Makes sense. More of a motivation to do so. Which of course is difficult in that it does lead to lazy caricatures. Again, that’s why it’s so important for all of us to be able to communicate openly and clearly and not simply a priori dismiss objections out of hand.

      “BIO-complexity is as good a place as any to find that sort of thing.”

      Excellent, thank you! But this is a journal. Do they give examples of grants they applied for and reviewers comments for their rejections?

      “You can ask, but any answer is pure counter-factual speculation, since he wasn’t. The fact is he was a scientific and mathematical genius who was also a creationist and avid theologian.”

      Of course it is speculation, but I don’t think the point of him having been a creationist is meaningful in any way. If there isn’t an alternative to creationism, or at least not a well-articulated alternative, then there isn’t a way for a decision to be made regarding belief. It’s like boasting about how Moses, Isaiah and Malachi were Jews and not Christians. I would bet that you, and many other Christians, would think that given the opportunity these individuals would have become Christian should they have lived in the right time, and I think that would be a very reasonable thing to say.

      “This bears some frequent repeating, given the number of New Atheists pushing the “incompatibility of science and religion” narrative.”

      Well, as I’m sure you’re aware if you’ve read my profile, I don’t believe that science and religion are incompatible per se, and it’s clearly demonstrable with the many individuals that are still religious despite practicing science.

      “You don’t need to be that blatant about it. You can just present a weak version of the argument you want them to reject, and let them draw their own conclusions about which argument is stronger. That’s far more effective.”

      I’m guessing you’re being sarcastic. Let me re-emphasize: I don’t WANT my students to reject anything. It should never be the goal of a scientist to want people to reject ideas. The ideas, if true, should be self-evident. If we always assume that our ideas are true a priori and undermine any arguments to change it, science would be no different than many of the worst (in my opinion) representations of religion.

      Obviously, in practice, a lot of scientists do the opposite of what I’m saying, which is a shame, but it’s worth pointing this out and calling them out on it.

      “In the cases where the doctrine is enforced by law, rather than by the free choice of the participants, sure.”

      Telling people to believe in evolution is not law. Teaching religious ideas for the sake of religion, not evidence, is against the law due to our constitution. So I don’t think your analogy is apt here.

      Scientists frequently pressure students what to believe about evolution. Agreed? You think so, you assume that I must do the same, and you call this bullying. I agree with you: when it happens, it is bullying. But many churches do this exact same thing. If it’s bullying by the scientists, then it’s bullying by the churches.

      This isn’t a competition about who is more righteous, scientists or clergy. If anything, it says something about the fears that humans have about having their beliefs challenged.

      “And if you want to draw parallels between your own position and those of priests and imams, then far be it from me to contradict you.”

      Yeah, there are some parallels. Why should that matter? Politicians also try to indoctrinate the masses, as do parents to their kids, and companies about the products they sell. Again, this is a very human trait to be self-serving and fear being challenged.

      “My point is that the loss is not caused by the lifestyle: the loss is caused by random mutation. The subsequent preservation of mutation is influenced by lifestyle, but does not cause the changes so preserved. Eating a particular diet is not likely to cause mutations which support that diet, but only preserve whatever random mutations happened to support it.”

      I wasn’t trying to insinuate the last point your making, so we’ll chalk this up to a misunderstanding.

      “Because natural selection. The loss is random, but the consequent survival rate differs. Are we really disagreeing about this?”

      So after I wrote this, I realized this was the case. This makes me think this should be a model that creationists really seize upon! (1) if the curse caused inactivating mutations to accumulate in genes across the genome, then (2) various animals could adapt via regressive evolution (i.e., loss of traits). This, of course, implies that they didn’t have these traits prior to the fall, which, interestingly works quite well for this particular example: assuming carnivores didn’t use to eat meat prior to the fall (a common idea I’ve seen) then they could have lost their sweet receptors as they adapted to a meat-eating lifestyle. This wouldn’t explain how carnivores got their very specialized meat-shearing dentition, and that their digestive tracts are not well-suited for eating plants, but it’s a start. One of the problems that arises, however, is that many of these genes with inactivating mutations are shared by multiple species. As we’ve talked about, getting identical mutations independently is extremely unlikely, so this complicates things for this idea. It would at least partially work for a strain of creationism that posits that organisms spectated rapidly after the Flood.

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