Neil deGrasse Tyson gets epigenetics completely wrong

Oy! Neil deGrasse Tyson can be as misleading as Siddhartha Mukherjee when it comes to epigenetics. Here’s a video from NOVA Science (2012) showing Tyson stating—completely erroneously—that epigenetic phenomena, like gene methylation and histone alterations, are the important factor controlling the expression of genes. As he says, they constitute “a second genome: the epigenome.”

As we’ve seen over the past three weeks, that’s not correct. What we know is that gene regulation is effected by proteins called transcription factors as well as by small RNA molecules. This is the mistake Mukherjee made when, in his New Yorker piece, he touted changes in the “epigenome” the DNA’s histone scaffold as the new Big Finding in gene regulation.

Tyson ‘s discussion of epigenetics begins at 4:30, and soon goes downhill as he asserts, “It’s the epigenome that tells our cells what sort of cells they should be.” Wrong. It’s the transcription factors and small RNAs that tell our cells what they should be. Mukherjee finally admitted that, but I don’t know whether Tyson has corrected the information in this four-year-old video.

Tyson presents a pair of identical twins that have different methylation patterns, and implies that the differences between those twins resulted from the differential methylation. There’s no any evidence for that. The twins’ different environments could have produced differential expression of genes by activating or repressing RNAs and transcription factors, and the methylation patterns could be a downstream correlate of that action without any causal effects on gene expression.

Likewise with Tyson’s misleading claim that cancer could result from epigenetic differences. That, he says, is good news because it’s much easier to change methylation patterns than gene sequences. But we have no idea if what he says about the cause of cancer is true: everything goes haywire in cancer cells, including the signaling pathways of genes that involve transcription factors.  As far as I know, cancer drugs that affect methylation patterns have not been shown to have consistent effect on cancers.

Finally, Tyson implies an epigenetic form of Lamarckian evolution (6:50), getting researcher Randy Jirtle to argue “What you [humans] eat can affect future generations”, though Tyson does note that such environmentally induced methylation patterns are effaced after a generation or two. That, of course, means that environmental changes of methylation cannot be the basis for adaptive evolution—or any evolution. But he doesn’t say that—hardly anybody says that except for petulant evolutionists like me.

Have a look for yourself:

Why is this important? First, because Tyson is an immensely popular and influential science communicator, and people will believe what he says. When he gives a misleading view of gene regulation, as did Mukherjee in his New Yorker piece, that is the view that filters down to the public, who of course doesn’t read the primary scientific literature. It then becomes the responsibility of journalists and other scientific popularizers to correct this misinformation. So far they haven’t done a very good job.

Second, the idea pushed in this video—that cancer is caused by differential patterns of methylation, and might be cured by altering methylation—is dangerous. While it might turn out to be partly correct, there’s almost no evidence for it so far; and promoting epigenetic theories of cancer might well lead people to quacks who promise to cure them by changing their epigenome. I don’t know if this is a present danger, but misinformation about medical issues can be far more dangerous to people’s well-being than misinformation about pure science.

h/t: Mark


  1. Posted May 25, 2016 at 10:20 am | Permalink

    Best to always preface comment on an area where you do not have expertise with, “Well, this isn’t my area, and I can only relate what I’ve read about in popular media; but this is what I think.”

    My son asks many questions. If I don’t know the answer (occasionally I do know), I say: “I don’t know; excellent question. What I think is … [or, let’s look it up!]”

    • darrelle
      Posted May 25, 2016 at 10:31 am | Permalink

      “I don’t know, look it up and then explain it to me” has become my favorite response to my kids when they ask questions I can’t answer. It’s like having research assistants! Well, at least if research assistants typically only do as you ask about 30% of the time.

      • Posted May 25, 2016 at 2:56 pm | Permalink

        “I don’t know.” — my favorite three words. My wife gives me a hard time over that. But it’s a bad policy to pretend to know something when you don’t.

        I am thinking of adding this to my list of Tyson errors. But I have no idea what gene methylation is.

    • Gregory Kusnick
      Posted May 25, 2016 at 3:30 pm | Permalink

      To be fair, we don’t expect TV newsreaders to preface every story with “I’m not an expert, but this is the report I’ve been given.” That goes without saying, and as far as I can see, that’s the role Tyson is playing here: host of general science show in which he reports the findings of other scientists in areas where he claims no expertise.

  2. Scott Draper
    Posted May 25, 2016 at 10:21 am | Permalink

    “people will believe what he says”

    Probably, but they won’t likely remember it. 😉

    • Posted May 25, 2016 at 10:44 am | Permalink

      Well, if they remember anything, it will be wrong. I presume you’re saying that it’s okay to purvey wrong stuff as people forget it anyway?

    • Ralph
      Posted May 25, 2016 at 11:42 am | Permalink

      Alt-med types are all over this. I’ve had a “naturopath” with almost no other scientific knowledge at all describe histones and DNA methylation to me in surprising technical detail. Lamarckian inheritance didn’t seem to be the appeal, so much as something vaguely along the lines of the trope that “it turns out scientists didn’t know everything”, and some muddled thinking about epigenetics implying that our fate isn’t predestined by our genes. As though nobody was previously aware that gene expression responds to the environment. Something like
      Holistic wheatgrass juice > epigenetic magic > genome fixed > no more pancreatic cancer.

      • Scott Draper
        Posted May 25, 2016 at 12:10 pm | Permalink

        Yeah, I was thinking that those who would remember would be those who are highly motivated to do so. i.e., those who are invested in wrongness.

        • Diane G.
          Posted May 26, 2016 at 3:44 am | Permalink

          “invested in wrongness.”


  3. GBJames
    Posted May 25, 2016 at 10:29 am | Permalink


  4. Hempenstein
    Posted May 25, 2016 at 10:39 am | Permalink

    If 4y/o, then maybe NdGT’s video was Mukherjee’s source?

  5. Damien McLeod
    Posted May 25, 2016 at 10:53 am | Permalink

    Interesting and fascinating article Dr. Coyne. I really like Dr. Tyson and most of what he says is right-on, but sometimes he gets it wrong, like all of us. Making mistakes is what we humans are best at.

    • Scott Draper
      Posted May 25, 2016 at 11:04 am | Permalink

      It’s probably not a good idea to pontificate on subjects one knows little about. Tyson didn’t just make an error of fact here, but rather demonstrated a problem of judgment. Why is he even talking about biology? Saying “we all make mistakes” tends to prevent any sort of analysis to prevent those mistakes from happening again.

      • Gregory Kusnick
        Posted May 25, 2016 at 3:24 pm | Permalink

        Presumably he’s talking about biology here because he is (or was) the series host of a popular science show, and biology is what that week’s episode was about.

        • Scott Draper
          Posted May 25, 2016 at 7:07 pm | Permalink

          I’m sure, but as I commented elsewhere, his mistake began when he agreed to come across as an expert on subjects he knew he wasn’t an expert in. Once he had made that mistake, mistakes like this were inevitable.

          • Gregory Kusnick
            Posted May 25, 2016 at 7:28 pm | Permalink

            Do you think there’d be fewer mistakes of this sort if pop-science shows were hosted by nonscientists?

            • Scott Draper
              Posted May 25, 2016 at 7:45 pm | Permalink

              Well, no, I was thinking about this more from Tyson’s sense of integrity.

      • Mark Sturtevant
        Posted May 25, 2016 at 5:08 pm | Permalink

        Problem is he has done this before, and had received push-back from it, but here he does it again. I would hope that he learned from that. But there is this Xkcd cartoon that I think is obliquely appropriate.

        • Diane G.
          Posted May 26, 2016 at 3:46 am | Permalink

          Thanks, that was especially funny!

      • Diana MacPherson
        Posted May 25, 2016 at 6:58 pm | Permalink

        Herein lies the rub. I think anyone should be able to talk about anything even if they don’t have a degree in that subject, provided they do so correctly because it’s facts, not pedigree that matters; I can think of good science journalists like Carl Zimmer or Jennifer Ouellette as examples….however, the problem arises when science celebrities screw up like this because people assume since NDT is a scientist, he must be an expert in all science so therefore he must be right.

        Of course, this would not be a problem in a world where critical thinking were more prominent and where people know how science gets done.

        • Scott Draper
          Posted May 25, 2016 at 7:05 pm | Permalink

          I don’t think critical thinking is necessarily adequate to detect when someone is getting his facts wrong.

          It’s very seldom that a layman opens his mouth about a specialist subject without making some glaring error, so I think having the relevant credentials in a subject is a good first step to being a credible source. I suspect that Zimmer solicits frequent feedback from credentialed experts.

    • Posted May 25, 2016 at 12:34 pm | Permalink

      Like saying that there are no wild penguins in the Northern hemisphere.


      • keith cook + / -
        Posted May 25, 2016 at 4:29 pm | Permalink

        You probably know this but I certainly did not until recently.
        The Nth Hemisphere had it’s equivalent, The great auk, Pinquinus impennis. The ‘original penguin’ except it was not a penguin.
        Live and learn…

        • Posted May 25, 2016 at 4:58 pm | Permalink

          I’d forgotten that “penguin” originally denote the great auk! I’m sure I must have read it before.


          • Diana MacPherson
            Posted May 25, 2016 at 6:59 pm | Permalink

            Well you auk to know it now. 😀

      • Posted May 25, 2016 at 5:32 pm | Permalink


        • keith cook + / -
          Posted May 25, 2016 at 5:54 pm | Permalink

          I did wonder about the Galapagos Is and their connection with penguins, thanks for that!

    • Shwell Thanksh
      Posted May 25, 2016 at 9:45 pm | Permalink

      I am an NdGT fan too. Unlike Mukherjee, Tyson has a history of acknowledging errors he makes and altering his views (like a Scientist Boss!) instead of denying and digging in. Let’s hope he does so in this case as well.

  6. darrelle
    Posted May 25, 2016 at 11:02 am | Permalink

    This hi-lights an issue so many, both scientists / specialists and nons, seem to have trouble understanding or believing. Brilliance alone is not enough. A certain level of experience is also necessary.

    I don’t expect NdGT to have any particular depth of knowledge about matters biological. He is nearly as dependent as any other category of non-specialist on the relevant specialists telling him what’s what in their field. Though he should have some advantage compared to non-scientists, namely experience with the processes of science in general.

    Being a scientist I hope he realizes this and can accept and acknowledge that the information he relayed here was not an accurate portrayal of the biology in question and perhaps explain what the current state of knowledge actually is. Doing so should not be viewed as an embarrassment for him. It should be viewed as a scientist doing what a scientist is supposed to do. Heck, what anyone who values evidence based reasoning should do.

    • Scott Draper
      Posted May 25, 2016 at 11:07 am | Permalink

      I think the essence of the problem started when he agreed to be a television personality, rather than a scientist. It was inevitable that there would be conflicts between the two. He’s an astrophysicist and his expertise is wasted the further afield he strays.

      • Posted May 25, 2016 at 12:36 pm | Permalink

        Yeah, you just can’t trust any kind of physicist that pontificates about other sciences. 😁


        • Diana MacPherson
          Posted May 25, 2016 at 7:00 pm | Permalink

          You just can’t trust physicists because of all that quantum.

      • Diane G.
        Posted May 26, 2016 at 3:51 am | Permalink

        Exactly what they said about Sagan, back in the day.

        • Scott Draper
          Posted May 26, 2016 at 7:53 am | Permalink

          Did Sagan stray from his field of expertise? (Never was a Sagan fan at that age.)

  7. Torbjörn Larsson
    Posted May 25, 2016 at 11:35 am | Permalink

    Added a comment and link under the youtube, for what it is worth.

  8. Daniel
    Posted May 25, 2016 at 11:38 am | Permalink

    His stance on atheism is total shit too!

    • Posted May 25, 2016 at 12:44 pm | Permalink

      Well, it is disingenuous, but I think the guy that made that video should get out more.


  9. Anon
    Posted May 25, 2016 at 11:57 am | Permalink

    I’m not a biologist, but this line sounded strange to me:
    “He feeds pregnant mothers a diet rich in methyl groups”

    What is a diet rich in methyl groups, and is there really such a direct link between methyl groups in the diet and methylation of DNA?

    • Posted May 25, 2016 at 12:23 pm | Permalink

      Methyl groups are *everywhere*.

      • Derek Freyberg
        Posted May 25, 2016 at 5:55 pm | Permalink

        To paraphrase Monty Python:
        “No-one expects a methyl group”.

    • Posted May 27, 2016 at 12:26 pm | Permalink

      The “diet rich in methyl groups” is diet fortified with the vitamin folic acid and adequately supplied with vitamin B12. These two vitamins are needed for transfer of methyl groups in the cell. It is true that methyl groups are everywhere, but most of them are not suitable for transfer.

      The “rich” diet has been around for decades. The point is not “methylation of DNA” as a method of regulating gene expression. It is about synthesis of DNA itself. To make DNA, the base uracyl (characteristic for the other nucleic acid, RNA) must methylated and so converted into the related base thymine, which is a component of DNA.

      Deficiency of folic acid and/or B12 affects the dividing hematopoietic cells in the bone marrow and so leads to anemia. (Every dividing cell needs to double its DNA, so needs a lot of thymine and hence a lot of transferable methyl groups.) In pregnant women, deficiency of folic acid increases the risk of a neural tube defect; the precise mechanism is unknown to me. Hope this helped.

  10. Posted May 25, 2016 at 12:33 pm | Permalink

    Histone configuration’s preventing expression of some genes is a very prevalent idea. I know of several books which talk about it. Is it completely false or just minor?

    • Posted May 25, 2016 at 12:33 pm | Permalink


    • Posted May 27, 2016 at 12:29 pm | Permalink

      I do not know about genes, but I read recently some papers claiming that the elusive animal centromere was based on specific histone isoforms, rather than on unique DNA sequences. If true, this is very important.

  11. Alex Gee
    Posted May 25, 2016 at 12:59 pm | Permalink

    This is the guy who thinks Dawkins is rude for telling it like it is!

  12. Kevin
    Posted May 25, 2016 at 1:00 pm | Permalink

    I used to feel superior being a physicist (ack!). Now I have watched over a decade of many physicist making claims or publicizing possibly misleading statements not only about the life science and evolution but also the climate which they are not always experts.

    Why do I never see biologists claiming to know the next superconducting-quantum-symmetric-phase-revolution-jobber is just around the corner?

    It is good to see posts like this refurbish some of the sexiness with a dose of realism.

    • Diana MacPherson
      Posted May 25, 2016 at 7:02 pm | Permalink

      Oh that climate change one is a real howler. It’s all because of that guy that I have to explain how science is done and why a physicist isn’t the professional opinion one should seek when learning about climate science.

  13. RussP
    Posted May 25, 2016 at 2:25 pm | Permalink

    My wife and I went to hear Murkherjee speak the other night about his new book (have not read it) and when asked what he might be interested in writing next he said he thought he’d give science fiction a try!

    Also when asked how he managed to devote the time needed to write such a book (600+ pages) he said he had stopped taking any new oncology patients. Perhaps he is in transition from clinical medicine to science (fiction) writing…

  14. Craw
    Posted May 25, 2016 at 3:05 pm | Permalink

    Some time ago I pointed out that Tyson’s credibility is suspect. He’s just a *terrible* spokesman for atheism.

    • darrelle
      Posted May 25, 2016 at 4:08 pm | Permalink

      I am not sure how you mean that exactly, but Tyson would be the first to tell you that he is most definitely not a spokesman for atheism. He actively avoids speaking for or about atheism because, if I understand him correctly, he wants to inform people about science and doesn’t want to scare them away by talking about atheism or identifying himself as an atheist.

      That’s why he often acts like an accommodationist. Though there are plenty of video clips available in which he has very directly criticized religious thinking.

      • Diane G.
        Posted May 26, 2016 at 3:58 am | Permalink

        + 1

      • Curt Nelson
        Posted May 26, 2016 at 8:33 am | Permalink

        I heard him interviewed on the Rationally Speaking podcast where he said that he doesn’t talk about atheism simply because it doesn’t interest him. He’s interested in science education (not in the biggest impediment to science education).

        • darrelle
          Posted May 26, 2016 at 8:57 am | Permalink

          Yes, I’ve heard him say that before, that it doesn’t interest him. I don’t think he is being completely honest about that though. I’ve seen him react as strongly and directly as, for example, Richard Dawkins in response to religious silliness on several occasions.

          I don’t mean to say I think he is lying. I think he has made a conscious choice, a marketing decision, to avoid atheism in order to better sell the science he wishes to sell. I don’t know if he is correct about that or not. He might be. He is very popular even among non-atheists. Despite his mistakes, like this one, he is, generally speaking, pretty accurate and he is good at explaining science in ways that are easy for non experts to grasp. And he is excellent at engendering some enthusiasm about science in his audience which is a big plus all by itself. All in all my opinion of Tyson is that he is a major asset to the cause of increasing public awareness, understanding and appreciation of science and rational thinking. I enjoy listening to him myself. But, he makes mistakes. Who doesn’t?

          • Curt Nelson
            Posted May 26, 2016 at 10:29 am | Permalink

            I certainly understand why he would want to avoid the topic of religion – to avoid turning religious people off – but he should just say that. It’s a good reason.

  15. gravelinspector-Aidan
    Posted May 25, 2016 at 3:23 pm | Permalink

    Hmm. How would our MacFierceOne put it? “Touch not the cat bot an glove”
    When speaking outside one’s competence, “Caveat, caveat, caveat. And let the buyer beware too! “

  16. EB
    Posted May 25, 2016 at 8:29 pm | Permalink

    Can someone help me out in this controversy? Why are the roles of DNA methylation and histone modification in terms of gene regulation considered “speculative”? Doesn’t DNA methylation repress gene expression?

    Let’s say there was a dialogue between C. David Allis and Mark Ptashne: what exactly are there differences?

    Any help appreciated of course!

    • EB
      Posted May 25, 2016 at 8:30 pm | Permalink

      Too late to edit:

      ***What exactly are their differences?
      (or “the differences”?)

  17. Posted May 25, 2016 at 10:42 pm | Permalink

    DeGrasse is an astrophysicist and doesn’t get epigenetics quite right, but he does better than this “reknowned cell biologist.”

  18. Posted May 27, 2016 at 3:58 pm | Permalink

    Does Wikipedia get Epigenetics wrong too? “Examples of mechanisms that produce such changes are DNA methylation and histone modification, each of which alters how genes are expressed without altering the underlying DNA sequence.”

    The image on the entry says Methyl group can tag DNA and activate or repress genes. It looks like it says the same thing that Tyson and Siddhartha Murkherjee have said, although in the Mechanisms section it looks like it covers the other factors.

    • Ralph
      Posted May 27, 2016 at 5:06 pm | Permalink

      If you read Jerry carefully, nobody is disputing that histone modification and DNA methylation affect gene expression.

      But these are the issues:

      (1) Are epigenetic marks just the downstream “mechanical details” of how genes are regulated? The answer, mostly, is “yes”. The primary processing of environmental inputs is mediated by transcription factors. Here, for example
      Loosely, the transcription factor network is the software & CPU; the epigenetic marks are just a downstream mechanical switch that’s controlled by the CPU.

      And note that even IF epigenetics were shown to be the “CPU”, this would have no impact whatsoever on genetic determinism. We have always known that the cell responds to the environments, it’s bizarre to suggest otherwise. It would just mean that the CPU is in a slightly different place than we first thought.

      (2) Are epigenetic marks stably inherited within an organism, i.e. in mitosis?
      Most certainly YES – epigenetic marks are critical in the process of cell differentiation.
      (But note that this still does not imply that epigenetic marks are actually doing any significant amount of information processing.)

      (3) Are epigenetic marks stably inherited with germline DNA into offspring?
      This would be REALLY important, because it would be essentially show the potential for Lamarckian evolution, and this really would have profound implications for how evolution works, for determinism, etc. etc. But this is the part that JUST DOESN’T HAPPEN. At least, there’s no evidence so far except for a few isolated cases and for no more than a few generations.

    • Ralph
      Posted May 27, 2016 at 5:14 pm | Permalink

      Also… the Wikipedia article is pretty bad. I certainly would not try to use that as a way to eluvidate the widespread horrible misunderstanding of the field.

      The Wiki first paragraph definition is completely wrong. That’s the definition of the field of “gene regulation” in general. So it’s making precisely the same mistake as Mukherjee. Transcription factors are paramount in gene regulation, not epigenetics.

  19. LisaR
    Posted May 27, 2016 at 10:51 pm | Permalink

    Apparently he doesn’t think any area is outside of his expertise.

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