More evidence against pervasive “epigenetic” heritable and environmentally induced changes in DNA

July 23, 2018 • 1:30 pm

I’ve discussed at great length the lack of evidence that the environment can change the DNA in a way that is both inherited through successive generations and can also be adaptive: the view that there is a new “epigenetic” form of Lamarckian inheritance of acquired characteristics. Go here to see a panoply of my pieces on this topic. The pervasive and loud claims that there is a new and non-Darwinian form of evolution afoot stand in stark contrast to the lack of evidence supporting those claims.

And it’s even worse than I thought. At the post below at the Wiring the Brain site, Kevin Mitchell, a neuroscience researcher in Dublin, takes a hard look at the claims in humans and other species—and finds them severely wanting.

Just go to the links on his post to see his earlier writings taking apart the very weak evidence for transgenerational inheritance of acquired epigenetic DNA changes, but I’ll provide some links in an excerpt:

I recently wrote a blogpost examining the supposed evidence for transgenerational epigenetic inheritance (TGEI) in humans. This focused specifically on a set of studies commonly cited as convincingly demonstrating the phenomenon whereby the experiences of one generation can have effects that are transmitted, through non-genetic means, to their offspring, and, more importantly, even to their grandchildren. Having examined what I considered to be the most prominent papers making these claims, I concluded that they do not in fact provide any evidence supporting that idea, as they are riddled with fatal methodological flaws.

While the scope of that piece was limited to studies in humans, I have also previously considered animal studies making similar claims, which suffer from similar methodological flaws (here and here). My overall conclusion is that there is effectively no evidence for TGEI in humans (contrary to widespread belief) and very little in mammals more generally (with one very specific exception).

Jill Escher (@JillEscher), who is an autism advocate and funder of autism research, recently posted a riposte, arguing that I was far too sweeping in my dismissal of TGEI in mammals, and listing 49 studies that, in her opinion, collectively represent very strong evidence for this phenomenon.

So, have I been unfair in my assessment of the field? Could it possibly be justified to dismiss such a large number of studies? What is the right level of skepticism to bring to bear here? For that matter, what level of skepticism of novel ideas should scientists have generally?

It turns out that Mitchell hasn’t been unfair in his assessment. The 49 studies cited by Escher are riddled with flaws, including un-kosher statistical analysis (p-hacking, failure to correct probability values for multiple comparisons, incorrect analyses). Further, epigenetics research has stalled at the point where mechanism is neglected: researchers using flawed methodology just report the phenomenon over and over again, with little progress being made. He also claims that there are no plausible mechanisms for this form of environmental stimulus to produce heritable behavior that persists several generations down the line, and that the possibility of epigenetic behavior being transmitted to future generations doesn’t solve any long-standing puzzles. The buzz about epigenetics is, I think, just one of those “Darwin was wrong” ideas that persists because of its revolutionary character, despite the lack of any supporting evidence.

Mitchell’s conclusion?

Ultimately, there is nothing where we can say: “We know that X happens, but we don’t know how. Maybe TGEI is a mechanism that can mediate X.” Instead, the introduction to these papers usually reads like this: “We know that TGEI [trans-generational epigenetic inheritance] can happen in X. [Narrator: we don’t know that]. Maybe it also happens in Y”.

So, until someone can show me a scenario where TGEI solves a known problem, has at least a conceivable, biologically plausible mechanism, is robust enough to provide an experimental system to work out the actual mechanism, and has convincing enough evidence of existing as a phenomenon in the first place, I will keep my skepticometer dialled to 11.

Until we have strong and repeated evidence for TGEI and, for evolutionists, evidence that it’s led to any adaptive evolution in nature, the proper attitude is firm skepticism. Caveat lector.

h/t: Matthew

26 thoughts on “More evidence against pervasive “epigenetic” heritable and environmentally induced changes in DNA

  1. Asking as a non-biologist, a question on the status of the “Extended Evolutionary Synthesis” nowadays.

    Is it: (1) a real research program producing significant non-Darwinian results; (2) A not-needed label for interesting complications of how evolution proceeds, that are worth studying but are not really anything out of keeping with the standard package; Or (3) a buzzword kept alive only by “Darwin was wrong” Templeton funding?

    1. The $8,542,047 grant runs until May next year, so Laland & Co will have to get their skates on if they want a Templeton dollars mid-air refuel. There is a table of EES Predictions at the bottom of THIS PAGE. You can click on each prediction to see what studies/experiments are being conducted in the name of EES with the dollars provided.

      As a layman some of these predictions look particularly non-Earth shatteringly different from the MS.

    2. IRRC, “Extended Evolutionary Synthesis” was coined by philosopher of science and SJW, Massimo Pigliucci, to describe a ragtag assemblage of unconnected hypotheses ranging from half-baked to crackpot to disproven.

      There will always be a certain academic job security for the purveyor of fringe ideas, whatever their merit or lack thereof.

  2. Is it odd that I find this sort of news relieving? Grandma’s smoking habit didn’t screw me over for life!

    1. I am pretty sure Arnold Schwartzenegger would say that PP-hacking is the wet noodle version.

  3. The buzz about epigenetics is, I think, just one of those “Darwin was wrong” ideas that persists because of its revolutionary character, despite the lack of any supporting evidence.

    The broad popularity of epigenetics among SJWs can be ascribed to their ideological Weltanschauung, which posits that humanity is a blank slate that can be molded by social engineering into a utopia.

  4. Biology seems to have a long-standing tradition of an excess amount of scientists who simply refuse to accept Darwinian Natural Selection as the main thrust of adaptive evolution, and instead wish to be revolutionaries overthrowing the orthodoxy, while only suggesting weak alternatives or alternatives that are merely rephrasings of regular old wrinkles of Natural Selection discussed ages ago.

    (Thinking of Niche Construction for example, which seems like something I always took for granted as something already a part of the orthodox, in arms races for example. Another classic is how muddled Group Selection is, where it can easily become a distorted rephrasing of regular Natural Selection when examined more closely.)

    I suspect many biologists still suffer from the same universal human fallacies we see in more extreme versions in creationists, where it still stretches the imagination, and our imagination still fails to grasp how powerful Natural Selection can be.
    The argument from ignorance (or incredulity) is one of the most pervasive bugs in human reasoning, and usually the style of arguing that goes against Natural Selection or Gene Selection, takes the same tactic of trying to poke holes at the orthodox while assuming their pet theory will win by default as a result.

    Of course it doesn’t help that there are the moral intuitions that also come in to make people go crazy about Natural Selection and Gene Selection.

  5. Good to read. I’ve figured epigenetics doesn’t amount to much, but I’m no expert in the field and when people bring up studies I don’t know about, I haven’t been able to say much. (Now I have some ammunition.)

  6. I asked a fan of epigenetics to help me understand the distinction between that concept and plain old differential gene expression (I.e., developmental gene regulation). I suggested that epigenetics concerns the subset of regulatory mechanisms that involve covalent modifications (e.g., methylation). She did not buy it and I am still puzzled.

  7. I’m always surprised at how many people (usually of a spiritual bent) who think it would be great if the sins of the fathers really are transferred to subsequent generations. They’re usually the same folks who, a generation ago, were complaining about behaviorists studying lab rats and projecting their characteristics wholesale onto humans.

  8. Posting on day after.

    IN my work as a math tutor, I’ve learned that far more statistics is being taught at a high school level than was the case in my day, but it doesn’t stress much the subtleties surrounding the flaws in this study. But it’s a step forward.

  9. A couple of weeks ago I heard a lecture by Larry Moran on junk DNA. It seems to me that the “extreme epigenetics” hypothesis may also be used to salvage some sort of adaptations that should have been ruled out by the seeming truism (that Dawkins, for example, denies) that most DNA is junk.

    (I think, however, there’s an interesting question about adaptations at the organ and system level and that sort of thing vs. at the level of genes and protein expression.)

    1. When he wrote The Selfish Gene, Richard Dawkins believed in junk DNA. Hence this: “The simplest way to explain the surplus DNA is to suppose that it is a parasite, or at best a harmless but useless passenger, hitching a ride in the survival machines created by the other DNA.”

Leave a Reply