4 ms·

Well here's a Google talk from last month https://m.youtube.com/watch?v=SJSJx5slLEM https://m.youtube.com/watch?v=SJSJx5slLEM

klmr 8y ago
Elizabeth Rosner isn’t a biologist, and (unintentionally, I’m sure) misrepresents the research. The majority view in the field of epigenetics is that trans-generational epigenetic inheritance of things like trauma currently lacks compelling evidence and, just as importantly, a plausible mechanism. The studies from Emory University and Mount Sinai, for instance, were widely panned (see article) for lack of controls, lack of mechanistic insight, and weak statistical analysis. What little evidence there exists shows a very narrow range of effect in model animals. I’ve co-authored one such study that specifically shows the heritability of stress in mice. I can confidently say that this only works in very specific, artificially constrained instances, the evidence is tenuous, and mechanisms are elusive. To clarify, this isn’t to say that trans-generational epigenetic inheritance doesn’t exist. Rather, we know that it does in specific circumstances (in particular in invertebrate models). But the claims by Rosner and in some of the more sensational (and flawed) papers require a big leap of faith that most scientists in the field aren’t willing to take, lacking evidence and a mechanistic explanation. What’s more, none of the scenarios described by Rosner requires trans-generational epigenetic inheritance. It’s much easier explained by social/cultural transmission. Invoking epigenetics in this context is pseudoscience.
- zgramana 8y ago
  Regarding mechanisms, I was under the impression that DNA methylation was widely accepted as a primary mechanism for epigenetic inheritance. Not so much, or is that one of those artificial scenarios you referenced?
  - klmr 8y ago
    That’s correct but you’re (understandably) confusing “epigenetic inheritance” with “trans-generational epigenetic inheritance”. The first (i.e. epigenetic inheritance, particularly via DNA methylation) is a ubiquitous biological process by which a state is encoded in the cell and can be passed down to daughter cells upon cell division. Hence the daughter cells inherit the mother cell’s state. At its simplest, it just acts like a “bookmark” in the genome which informs the cell what parts to read, and what parts to skip over. But things are different when talking about multi-cellular organisms that pass heritable information through the germ line. This is what trans-generational refers to. For the longest time it was assumed that no epigenetic information could be transmitted through the germ line due to a concept known as the “Weismann barrier” (think of it as the librarian: upon return, she removes all the bookmarks from the books). We now know that, under specific circumstances, this barrier can be “violated”, and “leaks”. However, unlike normal (genetic) inheritance, this leak does not allow a structured transmission of information according to our current understanding (that is, a bit of information encoding a phenotype “A” wouldn’t necessarily cause the same phenotype in the offspring; it would simply lead a perturbation). There are more specific exceptions to this rule which, for instance in nematode worms, allow a more structured information transmission (though it’s an open question whether DNA methylation is causally implicated).
    - zgramana 8y ago
      Thanks for that clarification. I wish the popular literature on the topic took similar pains to point this out. I can’t help but wonder if this is the root of much of the misguided interest in epigenetics.
      - klmr 8y ago
        > I can’t help but wonder if this is the root of much of the misguided interest in epigenetics. In a word: yes. Even within the field this causes confusion (researchers of course know the distinction in principle, but the term “inheritance” is suggestive, and has led more than one person down the garden path). To make matters worse, “epigenetics” also can refer to several different things.

klmr 8y ago

Elizabeth Rosner isn’t a biologist, and (unintentionally, I’m sure) misrepresents the research. The majority view in the field of epigenetics is that trans-generational epigenetic inheritance of things like trauma currently lacks compelling evidence and, just as importantly, a plausible mechanism. The studies from Emory University and Mount Sinai, for instance, were widely panned (see article) for lack of controls, lack of mechanistic insight, and weak statistical analysis. What little evidence there exists shows a very narrow range of effect in model animals. I’ve co-authored one such study that specifically shows the heritability of stress in mice. I can confidently say that this only works in very specific, artificially constrained instances, the evidence is tenuous, and mechanisms are elusive. To clarify, this isn’t to say that trans-generational epigenetic inheritance doesn’t exist. Rather, we know that it does in specific circumstances (in particular in invertebrate models). But the claims by Rosner and in some of the more sensational (and flawed) papers require a big leap of faith that most scientists in the field aren’t willing to take, lacking evidence and a mechanistic explanation. What’s more, none of the scenarios described by Rosner requires trans-generational epigenetic inheritance. It’s much easier explained by social/cultural transmission. Invoking epigenetics in this context is pseudoscience.

zgramana 8y ago
Regarding mechanisms, I was under the impression that DNA methylation was widely accepted as a primary mechanism for epigenetic inheritance. Not so much, or is that one of those artificial scenarios you referenced?
- klmr 8y ago
  That’s correct but you’re (understandably) confusing “epigenetic inheritance” with “trans-generational epigenetic inheritance”. The first (i.e. epigenetic inheritance, particularly via DNA methylation) is a ubiquitous biological process by which a state is encoded in the cell and can be passed down to daughter cells upon cell division. Hence the daughter cells inherit the mother cell’s state. At its simplest, it just acts like a “bookmark” in the genome which informs the cell what parts to read, and what parts to skip over. But things are different when talking about multi-cellular organisms that pass heritable information through the germ line. This is what trans-generational refers to. For the longest time it was assumed that no epigenetic information could be transmitted through the germ line due to a concept known as the “Weismann barrier” (think of it as the librarian: upon return, she removes all the bookmarks from the books). We now know that, under specific circumstances, this barrier can be “violated”, and “leaks”. However, unlike normal (genetic) inheritance, this leak does not allow a structured transmission of information according to our current understanding (that is, a bit of information encoding a phenotype “A” wouldn’t necessarily cause the same phenotype in the offspring; it would simply lead a perturbation). There are more specific exceptions to this rule which, for instance in nematode worms, allow a more structured information transmission (though it’s an open question whether DNA methylation is causally implicated).
  - zgramana 8y ago
    Thanks for that clarification. I wish the popular literature on the topic took similar pains to point this out. I can’t help but wonder if this is the root of much of the misguided interest in epigenetics.
    - klmr 8y ago
      > I can’t help but wonder if this is the root of much of the misguided interest in epigenetics. In a word: yes. Even within the field this causes confusion (researchers of course know the distinction in principle, but the term “inheritance” is suggestive, and has led more than one person down the garden path). To make matters worse, “epigenetics” also can refer to several different things.