The Daily Beast distorts epigenetics with bogus claims that children can “inherit memories of the Holocaust”

I’ve written extensively on this site about recent claims that environmental modifications of DNA, through either methylation (sticking a -CH3 group onto DNA bases or by changing the histone scaffolding that supports the DNA, can constitute a basis for evolutionary change. This claim is simply wrong. To date, while we can show that environmental “shocks” given to animals or plants can sometimes be passed onto their descendants, the inheritance lasts at most three or four generations, then disappears. This cannot in principle support evolutionary change, which requires DNA changes that are permanent, so that they can spread through a population and effect a long-term genetic transformation.

Further, the changes shown are almost never “adaptive”—that is, they usually don’t produce anything that would enhance reproduction even under the environmental conditions in the lab that produce them.

Finally, extensive genetic mapping of real adaptations in nature, ranging from insecticide resistance in mosquitoes to lactose intolerance in humans and to armoring in marine stickleback fish, show that the changes invariably reside in the sequence of DNA bases themselves, not in add-on methylation or histone changes produced by the environment. I don’t know a single adaptation in nature that, when we isolate down its genetic basis, resides in some environmentally modified, epigentic change in DNA that can be transmitted for generations.

(Let me add here that epigenetic changes have promoted adaptive evolution when those changes reside in the DNA itself: that is, there are stretches of DNA that, in effect, tell the organism things like: “put a methyl group in the DNA on nucleotide X”. But these changes are themselves the product of conventional natural selection, and the epigenetic changes are produced by the DNA itself and not by the of the environment.)

Nevertheless, because the idea of evolution caused by environmental modification of our genomes is both appealing and “nonDarwinian”—violating how scientists think evolution works—it appeals to a subset of people who think that the theory of evolution is woefully incomplete. These are the “Kuhnabees” like Steve Gould, who think a brand new evolutionary paradigm is in order. (The Templeton Foundation gives out millions of bucks for people trying to reach this conclusion.)  I’ve been critical of this type of revisionist excitement, not because I want to defend the modern evolutionary synthesis at all costs, but for the reasons stated above: there’s no evidence for lasting environmentally-caused, adaptive modification of DNA, and genetic mapping experiments of real evolved adaptations invariably show that the evolutionary changes residing in the DNA’s sequence of nucleotide bases: the order of Gs, Cs, Ts, and As.

But the juggernaut rolls on, promoted by articles like this one in The Daily Beast by Elizabeth Rosner, “Can we inherit memories of the holocaust and other horrors?” (Subtitle: “In the trailblazing field of epigenetics, researchers are finding evidence that the descendants of victims of atrocities are inheriting those experiences in their DNA.”)

It’s the standard boilerplate article, showing some environmental modification of DNA that can be inherited for a few generations, but then bears a title and subtitle that are wholly misleading, and are echoed in the article’s text.

Rosner cites three experiments, only one of which I’ve been able to read. That one is a study of mice given an electric shock when exposed to a particular odor (reference and free access below). After a while, the mice froze in the presence of the odor (cherry blossoms), even in the absence of a shock. This is a pretty normal result. But then the authors bred subsequent generations of mice and showed that they, too, froze in the presence of that specific odor but not others. This behavior was associated with hypomethylation in sperm (reduced methylation) affecting a particular gene associated with olfaction. This genetic change was, in turn, associated with changes in brain structure. This is a correlation, not a causation, but it’s certainly intriguing.

But the inheritance of this behavior lasted only two generations: last seen in the grandchildren of the exposed mice. While author Rosner says the inheritance lasted “three subsequent generations” beyond the offspring of the tested mice—that is, a total of four generations of inheritance—I can see only two generations of inheritance. Unless I’m misreading, Rosner has misrepresented the results, and of course there is no testing a hundred generations later, which would be necessary if this freezing behavior (which is simply a neural response to shock, and not necessarily adaptive), were to be the basis of a real adaptation.

Now reacting to an odor behaviorally is not the same thing as remembering the Holocaust. Rosner gets that conclusion from a study of 32 Holocaust survivors (a small sample, with Rosner citing only a book and not the original papers). Apparently that study showed that PTSD in the offspring of PTSD-afflicted Holocaust survivors than in the population as a whole (again, I haven’t seen the data, and don’t know what the control group was, which should properly be the kids of non-PTSD Holocaust survivors). And I’m dubious when the study’s author, Rachel Yehuda, says she’s found this correlation “‘inexplicable’ by any other means than intergenerational transmission.”

Well, cultural transmission is also intergenerational (traumatized parents could treat their children in a way that these kids would themselves be traumatized), but let’s assume that the author of that study managed to show that the inheritance was truly genetic rather than cultural. (This kind of separation isn’t easy, and often uses adoption studies.)

And if the changes were genetic, were they due to methylation or to changes in histones? Nothing is said in the article. What Rosner and other summaries say is that Holocaust survivors have lower levels of cortisol, a hormone that helps people recover from trauma (clearly not an adaptive response), but also lower levels of an enzyme that breaks down cortisol, helping store metabolic energy—something that might be adaptive under starvation. Most important, the children of these survivors also had lower levels of cortisol—but (unlike their parents) also higher levels of the enzyme that breaks it down, an environmental modification of biochemistry that was inherited across one generation. Both of these modifications are palpably nonadaptive in the offspring, as reduced cortisol makes you recover more slowly from trauma, and so the offspring of Holocaust survivors would be more susceptible to trauma.

While you can make up a story why being more likely to get PTSD if your parents were traumatized might be adaptive, you have to do some tortuous argument here. I could, with a minute’s thought, make up an adaptive story were the results to be in the opposite direction. Further, you can easily argue that this is simply a biochemically induced change, heritable for just one generation, that doesn’t modify offspring in an adaptive way. Too, there’s no evidence to date that this change in behavior persists for more than one generation. I’d also like to see adoption or other studies showing that the correlation between parents and offspring is due to genetic rather than cultural inheritance. Finally, note that what we have here is “heritable” changes in mental illness, not heritable “memories of the Holocaust”, as the article’s title implies.

Finally, Rosner mentions a book that produces what I see as very slim evidence for heritable PTSD:

Psychiatrist Nirit Gradwohl Pisano published a book titled Granddaughters of the Holocaust: Never Forgetting What They Didn’t Experience. She focused on ten subjects who are survivors’ grandchildren and, following current theories in epigenetics, found evidence of what she refers to as the “hard-wired” PTSD passed down to the descendants of survivors.

“[These] ten women provided startling evidence for the embodiment of Holocaust residue in the ways they approached daily tasks of living and being … Frequently unspoken, unspeakable events are inevitably transmitted to, and imprinted upon, succeeding generations. Granddaughters continue to confront and heal the pain of a trauma they never experienced.”

Ten subjects! Yes, it’s two generations of inheritance, but did Pisano rule out, in her book, cultural transmission of propensity to PTSD? How did she know it was “hard-wired” (i.e., in the DNA)? Note, too, the bogus “unspoken, unspeakable events inevitably transmitted to. . . succeeding generations.” That is a gross distortion, and one that Rosner doesn’t even bother to examine critically. These grandchildren didn’t inherit memories of the Holocaust—at best they inherited a propensity to get PTSD. The only reason they’d even KNOW about the Holocaust is by cultural transmission from their ancestors or through reading. The events are not remembered at all, at least genetically!

So, in answer to Rossner’s title question, “Can we inherit memories of the Holocaust and other horrors?”, the answer is “we have no evidence for that”. And the subtitle’s claim that we “inherit experiences in our DNA” is just wrong. Rossner and The Daily Beast, unfortunately, have been hit by the epigenetics juggernaut, and in a way that makes them pass on completely misleading implications about inheritance. This is science reporting at pretty much its worst: a sundae of misconceptions topped with a clickbait cherry of a title.

h/t: Saul

________________

Dias B. G., and K. J. Ressler. 2014. Parental olfactory experience influences behavior and neural structure in subsequent generationsNature Neuroscience. 17(1):89-96. doi:10.1038/nn.3594.

 

 

26 Comments

  1. Posted September 24, 2017 at 9:22 am | Permalink

    Reblogged this on The Logical Place.

  2. Posted September 24, 2017 at 9:32 am | Permalink

    Hear, hear! I wonder how many people have the patience to read your rebuttal? It seems that we live in an era of click bait and sound bites and one person’s analysis is as good as another’s.

    The War on Evolution is generally religion fueled and is rarely based upon reason as the conclusion has already been made and any scrap of evidence that might could support the conclusion is grasped and touted, much as the creationists have done ad nauseum.

    Also, the posing of scientists as wedded to this or that theory or being “unable to change” or immune to contrary evidence is psychological warfare employed to affect peoples attitudes toward science, not scientists themselves. It seems to be working.

    • Posted September 24, 2017 at 12:13 pm | Permalink

      Judging by the number of comments likely to accrue here, the answer to your first query is “not very many,” which makes me sad.

      • Cate Plys
        Posted September 24, 2017 at 10:44 pm | Permalink

        Me too, I can’t provide a comment worth anyone’s time so although I read most posts, I would almost never comment on a scientific one. In newspapers, you assume there are a huge proportion of positive opinions that you’ll never hear, because the vast majority of people who will be motivated to write the paper (even email) are the ones who are pissed off. So l hope Prof CCE remembers we’re out here! A sort of silent majority.

        • Richard
          Posted September 25, 2017 at 7:40 am | Permalink

          Same here.

          Please don’t give up on the science posts, Jerry. I find them very educational, and to a layman such as myself they clearly show the difference between real science and “creation science”.

      • Richard Bond
        Posted September 25, 2017 at 6:05 am | Permalink

        Well, I read it right through, but I do not have the technical expertise to submit a non-trivial comment.

        • Richard Bond
          Posted September 25, 2017 at 6:16 am | Permalink

          I should add that, in general, I would comment more than I do. (I like the sound of my own voice!) However, although retired, I have retained my habit of going to bed early in order to go to work early, and by the next morning, which is when I first see most posts, other commenters have usually made any points that I might have done. I wonder if any others in the UK have the same problem.

    • Steve Pollard
      Posted September 24, 2017 at 1:05 pm | Permalink

      Well then, it’s just worth adding that some of us (well, me, anyway) read all PCC(E)’s cogent and well-written posts, and appreciate and are grateful for them, without necessarily having a coherent observation to make. Please don’t take silence for indifference!

      • nicky
        Posted September 24, 2017 at 9:17 pm | Permalink

        I’ll second that.

  3. Hempenstein
    Posted September 24, 2017 at 9:38 am | Permalink

    The trouble with the Internet is it allows anyone to spread any amount of bullshit to the widest number imaginable without the least amount of work.

    To wit: National Buffoon.

  4. Posted September 24, 2017 at 10:06 am | Permalink

    We are far from done with hearing about the magical and unfounded properties of epigenetics. It is like the olde days when electricity was touted to have medicinal properties, peddled by snake oil salesmen.

  5. Randy schenck
    Posted September 24, 2017 at 10:15 am | Permalink

    It must be true that in a country that will bring us Donald Trump, anything is believable. This person should be ashamed of such an article but then, we are in the no-science zone. Along the same lines, I know a guy who’s father was a prisoner of war in Germany during WWII and this son is now about 72 years old. He still attends American Legion meetings and takes part in the military funeral events, dresses up in the gear for these thing. Does everything to give the appearance that he is a veteran when, in fact, he is not. Is this epigenetics or just a wannabe?

  6. frednotfaith2
    Posted September 24, 2017 at 10:31 am | Permalink

    The very idea that anyone can genetically inherit memories of even the most horrific strikes me as absurd. I can buy people experiencing PTSD simply from reading or listening to stories about or seeing graphic pictures of events such as the Holocaust, but as PCC points out that is cultural transmission and I’d be very suspicious of any claims that none of the supposed test subjects had never heard anything about the Holocaust from their ancestors who survived it. And even if so, if they were Jewish (either culturally or religious) would they really have been entirely oblivious to having had ancestors, of at most perhaps 5 generations ago for a 20 year old in 2017, who lived in the regions that came under Nazi occupation between 1933 and 1945 and very likely was rounded up and sent to a concentration or death camp? Such knowledge might be traumatic for some people, as was watching the events of 9/11/01. And shouldn’t these supposed genetic memories also apply to the descendants of slaves and American Indians and, heck, of anyone who suffered under the brutal dictatorships of Hitler, Stalin, Mao, etc.? I’m certainly no expert but I don’t believe genetics or memories work like that.

    • Carey Haug
      Posted September 24, 2017 at 8:01 pm | Permalink

      I agree with you completely. I do enjoy works of fiction where the protagonist has inherited memories from ancestors. It is an appealing plot device for a novel. Maybe some people just want to believe fanciful nonsense.

      • Posted September 25, 2017 at 11:45 am | Permalink

        IIRC, Dune shows how that this can give one (psychological) certainty but not correctness.

    • Posted September 25, 2017 at 11:45 am | Permalink

      Exactly: re other victims. At the very least they make an intermediate control group.

  7. jcook@napanet.net
    Posted September 24, 2017 at 10:33 am | Permalink

    I wonder if Dr. Rosner thought about populations that experienced sustained ecstatic states i.e. meditation or some such, and passed that on genetically?

  8. Posted September 24, 2017 at 10:38 am | Permalink

    Hi Jerry, nice article. Possible typo:

    “Holocaust survivors have lower levels of cortisol, a hormone that helps people recover from trauma (clearly not an adaptive response), but also higher levels of an enzyme that breaks down cortisol […] Most important, the children of these survivors also had lower levels of cortisol—but (unlike their parents) also higher levels of the enzyme that breaks it down, …”

    Should one of the two “higher levels” of the enzyme be “lower levels”?

    • Posted September 24, 2017 at 12:12 pm | Permalink

      Yes, thanks for catching that. The survivors had lower levels of the cortisol-destroying enzyme, while their offspring had higher levels.

  9. Saul Sorrell-Till
    Posted September 24, 2017 at 11:28 am | Permalink

    I’d just like to state for the record that I like the Daily Beast.

    Its science journalism really can be bloody awful, but apart from that(and the inevitable presence of a handful of identity politicking grievance-mongers) it’s a good site with a diverse set of political views. It has a nice cross-section of conservatives, lefties, liberals, centrists, and there’s not so much of the completely insane, reflexive tribalism that you find at other websites on either side of the political divide. I suppose they’re pretty anti-Trump, but then I don’t have much time for the idea that every news site should have a perfectly Trump-neutral editorial policy.

  10. Chris Swart
    Posted September 24, 2017 at 11:34 am | Permalink

    How many people will read Rosner, and pass the false conclusions on in casual conversation for years? Like many such rumors, it will probable be exaggerated as well, beyond her assertions.

    • John Conoboy
      Posted September 24, 2017 at 1:33 pm | Permalink

      I have not looked at Facebook yet today, but I would bet that someone will post the Daily Beast article–I even have a good idea who that will be. Nice to have a solid rebuttal that I can then post.

  11. Heather Hastie
    Posted September 24, 2017 at 1:56 pm | Permalink

    Another possibility – these people might have naturally lower levels of cortisol and the Holocaust is irrelevant. To find out you’d need to test ancestors that weren’t caught up in the Holocaust and had low-stress lives.

  12. infiniteimprobabilit
    Posted September 24, 2017 at 8:22 pm | Permalink

    Memories? Inherited? Garbage.

    Even IF the studies showed that there was some physiological effect passed down – which I think PCC has pretty well discredited in his post – that’s not memories.

    The idea of inheriting ancestor’s memories is pure woo, whether they were Holocaust victims or Marie Antoinette.

    cr

  13. Posted September 24, 2017 at 9:05 pm | Permalink

    Thank you for trying to clarify the significance of epigenetics. It is frustrating to see exaggeration and misunderstanding popularized.

    What is actually being discovered is so much more interesting than the hype.

  14. Posted September 26, 2017 at 7:31 am | Permalink

    Thanks for this post, PCC. I’m reading Robert Sapolsky’s book “Behave” right now and just got through a section on epigenetics. It’s a complicated subject for a non-scientist and this post adds to my slow grasp of the topic.


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