An out-of-date review of epigenetic transgenerational inheritance

This December 3, 2019, French review title was “Transgenerational Inheritance of Environmentally Induced Epigenetic Alterations during Mammalian Development”:

“We attempt to summarize our current knowledge about the transgenerational inheritance of environmentally induced epigenetic changes. While the idea that information can be inherited between generations independently of the DNA’s nucleotide sequence is not new, the outcome of recent studies provides a mechanistic foundation for the concept.

The systematic resetting of epigenetic marks between generations represents the largest hurdle to conceptualizing epigenetic inheritance. Our understanding of the rates and causes of epimutations remains rudimentary.

Environmental exposure to toxicants could promote changes in germline cells at any developmental stage, with more dramatic effects being observed during embryonic germ cell reprogramming. Epigenetic factors and their heritability should be considered during disease risk assessment.”


The review showed an inexplicable lack of thorough research. 2017 was its latest citation of epigenetic transgenerational inheritance studies from the Washington State University labs of Dr. Michael Skinner. I’ve curated six of the labs’ 2019 studies!

  1. Transgenerational diseases caused by great-grandmother DDT exposure;
  2. Another important transgenerational epigenetic inheritance study;
  3. The transgenerational impact of Roundup exposure;
  4. Epigenetic transgenerational inheritance mechanisms that lead to prostate disease;
  5. A transgenerational view of the rise in obesity; and
  6. Epigenetic transgenerational inheritance extends to the great-great-grand offspring.

This lack led to – among other items – equivocal statements where current definitive evidence could have been cited. The review was submitted to the publisher on October 31, 2019, and the above studies were available.


The publisher provided insight into the peer review process via https://www.mdpi.com/2073-4409/8/12/1559/review_report:

  • Peer reviewer 1: “Taking into account that this is not my main area of expertise..Do the authors really believe in that?”
  • Peer reviewer 2 provided a one-paragraph non-review.
  • Peer reviewer 3: “The authors are missing a large sector of what types of environmental factors can influence methylation and do not acknowledge that other sources exist.”

The authors responded with changes or otherwise addressed peer reviewer comments.

https://www.mdpi.com/2073-4409/8/12/1559/htm “Transgenerational Inheritance of Environmentally Induced Epigenetic Alterations during Mammalian Development”

A GWAS meta-analysis of two epigenetic clocks

This 2019 UK human study conducted a meta-analysis of genome-wide association studies of two epigenetic clocks using 13,493 European-ancestry individuals aged between ten and 98 years:

“Horvath-EAA, described in previous publications as ‘intrinsic’ epigenetic age acceleration (IEAA), can be interpreted as a measure of cell-intrinsic ageing that exhibits preservation across multiple tissues, appears unrelated to lifestyle factors, and probably indicates a fundamental cell ageing process that is largely conserved across cell types.

In contrast, Hannum-EAA, referred to in previous studies as ‘extrinsic’ epigenetic age acceleration (EEAA), can be considered a biomarker of immune system ageing, explicitly incorporating aspects of immune system decline such as age-related changes in blood cell counts, correlating with lifestyle and health-span related characteristics, and thus yielding a stronger predictor of all-cause mortality.

The meta-analysis of Horvath-EAA identified ten independent associated SNPs [single nucleotide polymorphisms], doubling the number reported to date, and highlighted 21 genes involved in Horvath-based epigenetic ageing. Four of the ten Horvath-EAA-associated SNPs are mQTL [methylation quantitative trait loci] for CpGs used in the Horvath/Hannum epigenetic clocks. A possible interpretation of this is that the functional mechanism by which these SNPs influence the rate of biological ageing is via altering methylation levels.

Father’s age at death, a rough proxy for lifespan, was nominally significantly correlated with both EAA measures, and parents’ age at death was additionally correlated with Hannum-EAA. Aside from these, genetic correlations with age-related traits were surprisingly few: it is possible that this could reflect an overly conservative correction for the multiple tests carried out, or low statistical power, rather than a genuine lack of correlations.

Genetic correlation analysis should be restricted to GWAS with a heritability Z-score of 4 or more, on the grounds of interpretability and power, so the Horvath-based results particularly should be interpreted with caution.”


A non-apologetic way to explain the above graphic is that NONE of these 218 “health and behavioral traits” were any more associated with the studied genetic measurements than would be expected by chance!

Fervent believers in the GWAS methodology’s capability to exactly predict individual phenotypes eventually become victims of the scientific method. These GWAS researchers griped about “overly conservative correction, or low statistical power” and other predictable shortfalls, and ended a long limitations statement with:

“While we have identified a number of SNPs and genes significantly associated with EAA, including genes already known to be related to ageing, the analyses presented here fall short of providing a mechanistic explanation for how these variants and genes act to influence biological age.”

Outside of beliefs, it’s hard to understand why research money keeps pouring into the GWAS dead end. If these researchers and their employing institution and sponsors want to make a difference in human lives, they need to get busy in other areas.

These researchers were employed by the same institution that couldn’t be bothered to scrape together six more weeks of funds to study the transgenerational damaging effects of acetaminophen – an analgesic available to billions of people – in Epigenetics research that was designed to fall one step short of wonderful.

https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1008104 “A meta-analysis of genome-wide association studies of epigenetic age acceleration”

PNAS politics in the name of science

This 2019 Germany/Canada human fetal cell study was a Proceedings of the National Academy of Sciences of the United States of America direct submission:

“In a human hippocampal progenitor cell line, we assessed the short- and long-term effects of GC [glucocorticoid] exposure during neurogenesis on messenger RNA expression and DNA methylation profiles. Our data suggest that early exposure to GCs can change the set point of future transcriptional responses to stress by inducing lasting DNAm changes.”


The study’s basic finding was that cells had initial responses to stressors that primed them for subsequent stressors. Since this finding wasn’t new, the researchers tried to make it exciting by applying it to novel contexts that were yet circumscribed by official paradigms.

Hypothesis-seeking associations of human fetal hippocampal cell behaviors with human behaviors were flimsy stretches, as were correlations to placental measurements. These appeared to have been efforts to find headline-making effects.

There wasn’t even a hint of the principle described in Epigenetic variations in metabolism:

“Because of the extreme interconnectivity of cell regulatory networks, even at the cellular level, predicting the impact of a sequence variant is difficult as the resultant variation acts:

  • In the context of all other variants and
  • Their potential additive, synergistic and antagonistic interactions.

This phenomenon is known as epistasis.”

It would have condemned pet models of reality to admit that a cell exists in multiple contexts of other cells with potential additive, synergistic, and antagonistic interactions.

A research proposal to trace a specific cell type’s behaviors – while isolated from their extremely interconnected networks – to trillion-celled human behaviors would be rejected in less-politicized organizations.

Sanctioned speculations manifested in this paper with phrases such as “although not significant..” and “although not directly tested..” The study’s title was probably a disappointment in that it conformed to the study’s evidence.

Involvements of psychiatry departments at the pictured Kings College, Harvard, etc., as part of PNAS entrenched politics, retard advancements of science past approved paradigms.

This is my final curation of PNAS papers.

https://www.pnas.org/content/pnas/early/2019/08/08/1820842116.full.pdf “Glucocorticoid exposure during hippocampal neurogenesis primes future stress response by inducing changes in DNA methylation”

Would you return a lost wallet?

The researchers in this 2019 Swiss/US study intentionally “lost” > 17,000 wallets under experimental conditions:

“We conducted field experiments in 40 countries to examine whether people act more dishonestly when they have a greater economic incentive to do so, and we found the opposite to be true. Citizens were more likely to return wallets that contained relatively larger amounts of money. Neither nonexperts nor professional economists were able to predict this result.

When people stand to heavily profit from engaging in dishonest behavior, the desire to cheat increases but so do the psychological costs of viewing oneself as a thief.”


The study did well in some aspects, including publicity. However:

1. The researchers admitted in the final paragraph:

“Using average reporting rates across countries, we find substantial variation in rates of civic honesty, ranging from 14 to 76%. This variation largely persists even when controlling for a country’s gross domestic product, suggesting that other factors besides a country’s wealth are also at play.”

Yet the paper’s first page contained the above graphic, which used each country’s GDP as a dependent variable! Wasn’t a behavioral economics study of honesty required to present their data honestly, and use factors that were experimentally significant?

2. “Other factors..at play” were relegated to the supplementary materials. The paper was only three-and-a-half pages long, so there was room for further explanations.

Here’s one comment on cultural differences from a Chinese PhD student:

“Biased design. In China (and Asian countries), people seldom use email, and our merit is to leave things untouched (“路不拾遗“:no one picks up lost articles in the street (idiom)).”

3. The study design had nothing to do with avoiding taxes, but three of the four sentences in the paper’s first paragraph did. This impressed as pointless.

https://science.sciencemag.org/content/365/6448/70 “Civic honesty around the globe” (not freely available)

Caloric restriction’s epigenetic effects

This 2019 US review subject was caloric restriction (CR) without malnutrition:

“Cellular adaptation that occurs in response to dietary patterns can be explained by alterations in epigenetic mechanisms such as DNA methylation, histone modifications, and microRNA. Epigenetic reprogramming of the underlying chronic low-grade inflammation by CR can lead to immuno-metabolic adaptations that enhance quality of life, extend lifespan, and delay chronic disease onset.

Short- and long-term CRs produce significant changes in different tissues and across species, in some animal models even with sex-specific effects. Early CR onset may cause a different and even an opposite effect on physiological outcomes in animal models such as body weight.”

 


1. Charts usually don’t have two different values plotted on the same axis. There wasn’t evidence that equated survival with methylation drift per the above graphic. Methylation drift should point in the opposite direction of survival, if anything.

2. No mention was made of the epigenetic clock method of measuring age acceleration, although it’s been available since 2013 and recent diet studies have used it. The sole citation of an age acceleration study was from 2001, which was unacceptable for a review published in 2019.

3. The review provided many cellular-level details about the subject. However, organism-level areas weren’t sufficiently evidenced:

A. Arguments for an effect usually include explanations for no effect as well as opposite effects. The reviewers didn’t provide direct evidence for why, if caloric restriction extended lifespan, caloric overabundance produced shorter lifespans.

B. Caloric restriction evidence was presented as if only it was responsible for organism-level effects. Other mechanisms may have been involved.

An example of such a mechanism was demonstrated in a 2007 rodent study Reduced Oxidant Stress and Extended Lifespan in Mice Exposed to a Low Glycotoxin Diet which compared two 40%-calorie-restricted diets.

The calories and composition of both diets were identical. However, advanced glycation end product (AGE) levels were doubled in standard chow because heating temperatures were “sufficiently high to inadvertently cause standard mouse chow to be rich in oxidant AGEs.”

The study found that a diet with lower chow heating temperatures increased lifespan and health span irrespective of caloric restriction!

  • The low-AGE calorie-restricted diet group lived an average of 15% longer (>20 human equivalent years) than the CR group.
  • 40% of the low-AGE calorie-restricted diet group were still alive when the last CR group member died.
  • The CR group also had significantly more: 1) oxidative stress damage; 2) glucose and insulin metabolism problems; and 3) kidney, spleen, and liver injuries.

https://academic.oup.com/advances/article-abstract/10/3/520/5420411 “Epigenetic Regulation of Metabolism and Inflammation by Calorie Restriction” (not freely available)

Do delusions have therapeutic value?

This 2019 UK review discussed delusions, aka false beliefs about reality:

“Delusions are characterized by their behavioral manifestations and defined as irrational beliefs that compromise good functioning. In this overview paper, we ask whether delusions can be adaptive notwithstanding their negative features.

We consider different types of delusions and different ways in which they can be considered as adaptive: psychologically (e.g., by increasing wellbeing, purpose in life, intrapsychic coherence, or good functioning) and biologically (e.g., by enhancing genetic fitness).”


1) Although the review section 4 heading was Biological Adaptiveness of Delusions, the reviewers never got around to discussing the evolved roles of brain areas. One mention of evolutionary biology was:

“Delusions are biologically adaptive if, as a response to a crisis of some sort (anomalous perception or overwhelming distress), they enhance a person’s chances of reproductive success and survival by conferring systematic biological benefits.”

2) Although section 5’s heading was Psychological Adaptiveness of Delusions, the reviewers didn’t connect feelings and survival sensations as origins of beliefs (delusions) and behaviors. They had a few examples of feelings:

“Delusions of reference and delusions of grandeur can make the person feel important and worthy of admiration.”

and occasionally sniffed a clue:

“Some delusions (especially so‐called motivated delusions) play a defensive function, representing the world as the person would like it to be.”

where “motivated delusions” were later deemed in the Conclusion section to be a:

“Response to negative emotions that could otherwise become overwhelming.”

3) Feelings weren’t extensively discussed until section 6 Delusions in OCD and MDD, which gave readers the impression that feelings were best associated with those diseases.

4) In the Introduction, sections 4, 5, and 7 How Do We Establish and Measure Adaptiveness, the reviewers discussed feeling meaning in life, but without understanding:

  1. Feelings = meaning in life, as I quoted Dr. Arthur Janov in The pain societies instill into children:

    “Without feeling, life becomes empty and sterile. It, above all, loses its meaning.

  2. Beliefs (delusions) defend against feelings.
  3. Consequentially, the stronger and more numerous beliefs (delusions) a person has, the less they feel meaning in life.

5) Where, when, why, and how do beliefs (delusions) arise? Where, when, why, and how does a person sense and feel, and what are the connections with beliefs (delusions)?

The word “sense” was used 29 times in contexts such as “make sense” and “sense of [anxiety, coherence, control, meaning, purpose, rational agency, reality, self, uncertainty]” but no framework connected biological sensing to delusions. Papers from other fields have detailed cause-and-effect explanations and precursor-successor diagrams for every step of a process.


Regarding the therapeutic value of someone else’s opinion of a patient’s delusions – I’ll reuse this quotation from the Scientific evidence page of Dr. Janov’s 2011 book “Life Before Birth: The Hidden Script that Rules Our Lives” p.166:

“Primal Therapy differs from other forms of treatment in that the patient is himself a therapist of sorts. Equipped with the insights of his history, he learns how to access himself and how to feel.

The therapist does not heal him; the therapist is only the catalyst allowing the healing forces to take place. The patient has the power to heal himself.

Another way Dr. Janov wrote this was on p.58 of his 2016 book Beyond Belief as quoted in Beyond Belief: The impact of merciless beatings on beliefs:

No one has the answer to life’s questions but you. How you should lead your life depends on you, not outside counsel.

We do not direct patients, nor dispense wisdom upon them. We have only to put them in touch with themselves; the rest is up to them.

Everything the patient has to learn already resides inside. The patient can make herself conscious. No one else can.”

https://onlinelibrary.wiley.com/doi/full/10.1002/wcs.1502 “Are clinical delusions adaptive?”

Non-emotional memories

This 2019 US review covered memory mechanisms:

“With memory encoding reliant on persistent changes in the properties of synapses, a key question is how can memories be maintained from days to months or a lifetime given molecular turnover? It is likely that positive feedback loops are necessary to persistently maintain the strength of synapses that participate in encoding.

These levels are not isolated, but linked by shared components of feedback loops.”


Despite the review’s exhaustive discussion, the reviewers never came to the point. The word cloud I made of the review’s most frequent thirty words had little to do with why memory occurs:

  • Why do some stimuli evoke a memory in response?
  • Why are almost all of the stimuli an organism receives not remembered?

Much of the discussion was baseless because it excluded emotion. Many of the citations’ memory findings relied on emotion, though.

For example, in the subsection Roles of persistent epigenetic modifications for maintaining LTF [long-term facilitation], LTP [long-term potentiation], and LTM [long-term memory]:

  • Histone acetylation is increased after fear conditioning in the hippocampus and amygdala.
  • Correspondingly, inhibition of histone deacetylase enhances fear conditioning and LTP.
  • Following fear conditioning, histone phosphorylation is also increased.
  • DNA methylation is also up-regulated in the hippocampus and amygdala after fear conditioning, and inhibition of DNA methylation blocks fear LTM.”

http://learnmem.cshlp.org/content/26/5/133.full “How can memories last for days, years, or a lifetime? Proposed mechanisms for maintaining synaptic potentiation and memory”