The Loss of Vitamin C: One More Proof for Evolution

Evolution never ceases to amaze me. It’s one of those scientific facts that has been proven correct over and over. I didn’t know however what to expect when one of my favorite podcasts, Irreligiosophy, tackled “5 Evidences for Evolution.” Apart from the unpronounceable name, it’s quite a good podcast. Its main focus is a critical discussion of religion (Mormonism in particular), but from time to time they also tackle skeptical topics, like this one. The episode is marked as “explicit” since they talk about anatomy and use strong language, so be forewarned if you wish to avoid such content.

I was however pleasantly surprised to hear 5 cases that contained recent research, like the following one (the 4th, just before the 35-minute mark). We humans, as almost all simian species (lemurs and prosimians excluded) are not able to synthesize our own vitamin C.

“Eat More Fruits And Vegetables High In Vitamin C.” above the lettering is a green pepper, below, one half of an orange, inside up. From the 1989 published by the National Cancer Institute (USA)

This is due to a mutation in the genes encoding for gulonolactone oxidase (GULO for short), rendering the final phase in the creation of ascorbic acid (vitamin C) inoperative.

There are a couple of important points there. First of all, we still have the gene that codes for GULO, but it is no longer activated due to the mutation, making that gene a pseudogene. Secondly, it’s a small mutation. Chuck, the co-host from Irreligiosophy speaks about only one mutation, but it seems that there are actually several mutations. Regardless, it’s probably the first mutation that nixed the ability. As soon as the gene became a pseudogene, other random mutations could happen in that region of the chromosome without any consequence.

So why does this prove evolution? Very simple: because we (humans, apes, and monkeys) still have the entire instruction set, which we share with all mammals, it shows that all mammals have a common descent (dogs and cats for instance can synthesize it pretty well), and furthermore, that all monkeys and apes (humans included) also share a common descent. Slam-dunk, if such a thing was still needed…

But then why did we lose it? As far as I can tell we don’t know, which is exactly the answer I love about science. It means there is still work to do and maybe we’ll never know. And really, there is nothing wrong with that.

From what I understand, it might have been the case that there was no pressure 63 million years ago to keep it, as the simians then probably consumed enough food containing vitamin C. Which is actually another proof of evolution—if there is no or insufficient pressure on a function, then there is a chance it will be dropped.

Some researchers have even speculated that there were additional benefits of having this gene knocked out. For instance there is less antioxidant reaction if you consume vitamin C instead of fabricating it yourself, since synthesizing it in the organism leads to the by-product hydrogen peroxide. Another researcher speculated in a 1982 paper that it might have helped to survive malaria. Another hypothesis that I like (but for no rational reason) is that it might have helped to gain weight by increasing fat storage, handy when the food supply is not stable. And that’s just skimming some references; multiple other hypotheses have been formulated.

The brown lines indicate mammals that lost the ability to synthesize Vitamin C (common names are in German- from the German Wikipedia)

All of these explanations remain speculation however. What it shows is that there was no disadvantage in losing the ability, and maybe a small advantage, otherwise our mutated simian ancestors would not have survived. The same applies for bats and guinea pigs, who have also lost the ability (but due to a different mutation).

One interesting study from 2008 tried, of course, the obvious: to reactivate this gene. They used engineered mice and human liver cells (in a petri dish) and reported success in expressing the gene. I tried to look for some more recent studies on the subject, but there hasn’t been a lot going around. One study this year reported success, but only when providing gulonola (the input to the GULO reaction). It’s not just one mutation that removed the GULO ability—it seems that several factors in the entire chain were disturbed. That shouldn’t be surprising, given that all the genes and pseudogenes involved have had 63 million years to undergo mutations.

What it shows is that we don’t have a complete answer for this phenomenon yet, and yes, more research is needed. In any case it’s too late for those ship crews suffering from scurvy, but it could have been nice to have another tool to combat obesity. But now I’m speculating too …

About Bruno Van de Casteele

Philosopher by education, IT'er by trade. Allround Armchair Skeptic, History Enthusiast, Father of Three. Twitter @brunovdc Personal website:
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30 Responses to The Loss of Vitamin C: One More Proof for Evolution

  1. freke1 says:

    the imaginary sky daddys are not gonna like this 😉

    • Rowie Truth says:

      I am not troubled at all Sir, since my Heavely Father is not imaginary. The reasoning that losing the trait to produce vitamin C is somehow proof of evolution is imaginary.

      • Bruno Van de Casteele says:

        Making a statement of one’s personal opinion is not the same as a sound scientific argumentation. Care to elaborate why it is NOT a proof for evolution?

      • Nelson says:

        Isn’t evolution a gaining of new information? This is definately a loss of information which I don’t think can be fairly called evolving.

        • Menzo says:

          This erroneous view is that evolution is always progressive, always towards more complexity or more information. A better view is that evolution is always towards better adaptation, even if that means a loss of function or information. A more interesting question to ask at this point might be what is the evolutionary advantage of the loss of vitamin C? Possibly not any. This rather silent mutation (silent in the sense that the vitamin C pathway had not been activated for many generations) simply tagged along with other more adaptive changes.

      • Pital says:

        Can you ask to your heavely father why he created humans with just the SAME wrong gen like the other primates???
        He is unable to answer, let me help Him: it doesn’t exist, it created nothing, is the evolutionary process that created species and is the common ancestry that shows why we have the same wrong gen.

  2. Pete A says:

    Thanks for the detailed explanation, Bruno. I vaguely remember reading about some animals that synthesize Vitamin C produce much high levels than humans need for good health — if I’ve remembered this correctly, any idea why this was/is beneficial rather than detrimental to the species?

    • Vitamins and other active nutrients are not a one size fits every situation. If an organism is under oxidative attack it need higher levels of antioxidants than when operations run smoothly. It is unknown what and how this function is actually handled, but there is evidence that the difference can be thousand fold. So, those animals that have the ability to produce vast amounts of e.g. C, do not necessarily produce these amounts regularly –they just have it as part of their arsenal. The question why this ability has evolved predominantly in some animals and not in others? We do not know, except we can speculate that it gives them some benefit in their specific living environment and perhaps also if their usual diet is weak in vitamins.

      • Pete A says:

        Thanks, Jon, for your reply. The part I remembered was the seemingly very high levels of synthesized vitamins, but I’d forgotten that this was a maximum level rather than an average level.

        Some human genetic defects result in increased longevity, which is fortunate for us, but they are simply defects rather than genetic adaptations (mutations) resulting from evolutionary pressure.

        • You are welcome.

          I can’t help but comment on your “genetic adaptations (mutations) resulting from evolutionary pressure” as this is an incorrect view on the theory of evolution. No mutations are derived from “pressure” or need, they are completely random. We can easily say now that the Giraffe has a long neck because it prefers to dine on the top leafs. However, going back in time there would have been no way to tell if the yellow spotted horse would later evolve to a long necked yellow spotted horse. It might, but it could equally have developed to a yellow spotted monkey climbing to the top leafs to dine.

          In the theory of evolution the mutations are absolutely random, however the natural selection of which “mutations” that will progress are not. In principal only those granting some sort of benefit in the game of survival will be passed over eons of time…

          You often hear that our pinky toe will eventually be lost in our evolution as it serves no purpose. This is nonsense, as there is no way to say what our mutational path is (because it is random) – however, I can fairly say that a foot with no pinky does not give any advantage in the game of seduction (probably on the contrary), and thus likely not to be naturally selected. In other words, our pinky aint going anywhere.

          How evolution takes a species is impossible to say. All we can say is that it will in the process optimize it for its environment or it will distinct it. So if some of us should experience a mutation granting us longevity, as you say, there is a reasonable chance this mutation will survive in our genome.

          Forgive my rant 🙂

          • Pete A says:

            I’m very glad you pointed that out, Jon. I had not spotted that I’d put “(mutations)” in the wrong place: it was supposed to refer to the “genetic defects” not the adaptations part, d’oh! But I’m glad I made the mistake because your comment is highly informative.

          • oliver says:

            all species adapt,evolve, mutate. We are all variations, mutaions, a one or a very few themes. The human species evolves as well and a lot of it has to do with adapting – to foods, weather, environments and a host of other criteria.
            The fact is, the human gene pool today is vastly varied – as opposed to how it was 300,000 years ago in east africa.
            And not all mutations are random – it was not random that the polar bear used to be all brown. It may have been random that they migrated there but evolving was just a matter of time – as they adapted to a new set of criteria.
            This is true for every species including humans.The pinky toe as well as the thumb can be done with if things allow for it over millennium – just as the number of teeth we have – your ancestors had more.

          • Jon Therkildsen says:

            @ oliver: You are incorrect in respect to the theory of evolution. This is not how it works.

            The theory of evolution essentially states that mutations happens randomly in absolute terms and so cannot be predicted.

            What can be predicted is which mutations should survive in a certain environment and under certain conditions (aka the processes of natural selection).

            So you example with Bears are only half right.

            Yes, we can predict with some certainty that white fur will benefit enough to be passed on in the genes and so we have the birth of the Polar bear. However, we could not have predicted if the Brown Bears had eventually mutated white fur or not … they surely did, and it surely gave benefits to the species in the polar regions. But that this was the evolutionary path they went on, would have been impossible to foresee back then.

            Evolutionary path can be rationalized back in time only; they cannot be rationalized forth in time. The is the essence of Darwin’s words: random mutations will eventually develop benefits for the race. What they may be is impossible to say and we just have to wait and see.

            Evolution cannot be forced.

  3. Menzo says:

    Interestingly, I received this message on the very day that I was lecturing on vitamin C in my Nutrition class and talking about how we humans lost the ability to make this nutrient. What for me is an interesting route for some research is to think about all of our vitamins (essential nutrients that we lack the ability to synthesize) and ask 2 questions. What is the evolutionary advantage to this lack? When in evolutionary time did we lose this ability for each of these vitamins? For vitamin C, we have very limited compensating mechanisms, such as extra absorptive ability, or storage capacity. Whereas for vitamin B12, we have nearly a dozen extra proteins in our physiology whose unique purposes seem to be to absorb, transport, store, and use vitamin B12. This suggests that B12 might have been a vitamin for a very very long time, especially compared to an upstart like vitamin C. An interesting thought experiment.

  4. Nelson E says:

    I would like to know how scientists have concluded we lost it 63 million years ago. Couldn’t we have just as well lost it 40 or 50 million years ago?

    • Noah Dillon says:

      It’s probably a pretty rough estimate. You might be able to track down the paper or papers that came to this conclusion. If you do, they’ll have the methodology described so that other scientists, and anyone else for that matter, can check their work. I would speculate that it’s probably derived by looking at species that diverged from us around that time that still have it, as compared to our lineage, which doesn’t. I don’t know at all, though.

      Here’s one paper: Pollock JI, Mullin RJ (May 1987). “Vitamin C biosynthesis in prosimians: evidence for the anthropoid affinity of Tarsius”. Am. J. Phys. Anthropol. 73 (1): 65–70. doi:10.1002/ajpa.1330730106. PMID 3113259.;jsessionid=6C3B8F0E4E675112EDFEF34B916FD117.f02t03

      • Bruno Van de Casteele says:

        Yes Noah, I’m on the road so I can’t access my sources but this based on a cladistic tree (see the German drawing I included). Those cladistic comparisons match, where we can compare it, quite closely to chronology.

  5. truthseeker says:

    The probability that helicase, the microscopic biochemical motor that is at the heart of DNA replication, could spin at the speed of a jet engine, which is in the vicinity of 50,000 rpm, while constructing the 3 billion genes that comprise a typical human being while correcting for discovered errors in those newly created genes with an error rate of approximately 1 in 1 billion… is zero.

    Even the simplest proteins in nature, which are the building blocks of all living things, are comprised of 200 amino acids which are arranged in a precise order and the probability that those amino acids could self-arrange in the proper order, without error… is zero.

    These calculations are based on the field of statistics, a highly respected branch of mathematics which is widely used in science.

    Evolution has always been and always will be a pseudo science which is not based on verifiable and replicable science, rather on conjecture and deception, and in fact as science progresses the evidence against the validity of evolution will continue to grow.

    Interesting how evolutionists are so determined in their efforts to pit evolution against creationism when the truth is they are both faith based.

    Lest we forget, science is not based on faith…

    • Noah Dillon says:


      Also, I don’t know what source you’re getting these “statistics” from, but OK. Even low probability events (which this might be, though the probability is not 0) have a high likelihood of occurring over billions of years, which is the time frame for life on Earth.

      The only correct thing you said is the final, unfinished sentence: “Lest we forget, science is not based on [faith.]”

    • John Tillman says:

      Ribonuclease A is a small protein, the mature enzyme only having 124 amino acid residues, with no carbohydrate attached. RNase A contains 19 of the 20 amino acids, lacking only tryptophan (Nogués et al. 1995, and Raines 1998). The three dimensional structure of RNase A is fully encoded by its amino acid sequence (White and Anfinsen 1959, and Raines 1998). All eight human RNase A-like genes are located on chromosome 14. Each encodes a secretory signal sequence and contains an invariant catalytic triad of two histidines and one lysine with a conserved motif (CKXXNTF) (Marshall et al. 2008).

      The amino acid sequences of many RNase A homologues have been identified, making RNase A a model system for vertebrate molecular evolution (Dyer and Rosenberg 2006). From the sequences and their distribution over a range of species it has been established that RNase A is a modern protein that is evolving rapidly (Doolittle 1992, and Raines 1998).

      But the first organisms didn’t need enzymes even this large, nor need they have been proteins. We now know that RNA can act both as a catalyst, ie enzyme, and as a storehouse of genetic information. These ribozymes, ie RNA enzymes, are composed of nucleotides rather than amino acids, as in proteind. Many have sequences shorter than even the smallest protein enzymes. The Hammerhead Ribozyme, for instance, consists of just 13 nucleotides attached to three helical “stems”, composed of only four or five Watson-Crick base pairs.

      While polymers of amino acids, ie polypeptide precursors to proteins, might well have played a role in the origin of life or early in its history, it increasingly appears that RNA would have sufficed for both simple metabolism and replication. A profound recent discovery was that the ribosome, the cellular molecular “machine” which synthesizes proteins, is itself a ribozyme. It consists of tranfer RNA with some proteins attached to its exterior. But the process of protein synthesis, under instructions from messenger RNA, occurs entirely along its RNA chain.

      Hence, the “RNA World” hypothesis for the origin of life.

  6. Manuel says:

    That doesn’t proof evolution, what proofs is degeneration. God created all creatures with a common instructions set (original ADN) which has been degenerating due to mutatioms since then. Consequences of that denegeration is losing our hability to produce an extremely powerful anti-oxidant which helps prevent aging and cancer. Most probably if we had kept our hability to produce ascorbic acid we wold have lived longer and healthier.

    • Noah Dillon says:

      What’s the evidence for perfect DNA? And are you saying that mutations occur, but are only “degenerate”? The theory of evolution says that mutations occur and that a small fraction are beneficial. There’s a lot of evidence for this. There is no evidence that we are in a fallen genetic state, which conflates morality with material science. You’re also speculating about a complicated mechanism of anti-oxidant/mutation/aging/cancer/degeneration that doesn’t seem to have, as far as I know, any scientific basis, despite its science-like words.

      You should check this out:

  7. Joel W says:

    I can’t help but wonder if Neanderthals were able to ‘make their own’ vitamin C. Living in Ice Age Europe would not have a lot of fruit trees.

    • Jon says:

      Since the great apes cannot I think it is safe to say that the Neanderthals could not produce own Vitamin C either. And if fruit trees were scares, green leafy vegetables were probably not, and they are usually also very rich in C Vitamin. And berries can grow in quite tough landscapes also.

  8. Jon says:

    Since the great apes cannot I think it is safe to say that the Neanderthals could not produce own Vitamin C either. And if fruit trees were scares, green leafy vegetables were probably not, and they are usually also very rich in C Vitamin. And berries can grow in quite tough landscapes also.

  9. Robert says:

    The title says it all, “The Loss of Vitamin C One More Proof for Evolution”. This demonstrates a bias in favor of evolution. Neo-Darwinian evolutionary theory mandates that random mutation + natural selection are the drivers that produce change and this change is suited to function optimally for the environment. Classical example of this: land animals ‘evolved’ into whales and lost the hind legs and forearms in favor of flippers and a tail fin… it was advantageous to the environment (I don’t believe it, but this IS what evolutionists indicate). What this article suggests is just the opposite… that evolution results in a LOSS of function (the loss of ability to produce vitamin C). I would propose that the loss of function is the result of mutation in healthy function.

    If one has a bias towards a belief (albeit even an unsupported one like macro evolution), one will make a connection regardless of whether that connection is true, or logical.

    • I’m sorry but evolution is not a belief. It is science. And within this scientific approach it is very much possible to lose functionality is there is no pressure to keep it. Humans lost our tail too…

    • Alexandria Nick says:

      Not all selection is beneficial and there are trade-offs in any system.

      Humans walk upright and we all generally complain of back problems. That’s because our spine is a cantilevered truss and performs poorly under vertical loading. But a bit of back pain in life was apparently worth it to be able to be a biped.

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