13 thoughts on “Epigenetics

  1. I’m not one of the experts.

    My understanding is that there is some epigenetic inheritance, but that it is small, and not permanent (lasts for only a few generations).

    As to why it is discussed — this is partly because creationists latch onto anything that they think they might be able to use to disparage evolution.

    (Your link was broken — I fixed it).

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  2. Not an expert, but it’s certainly covering a lot of the basics. Still, what’s this about inheriting your grandparents’ experiences? Their experiences might affect your own genetic expression, but that’s nothing like inheriting their “experience.”

    As to creationists, often it’s kind of mysterious whatever they’re yammering about, but it seems usually to come down to, science doesn’t know everything (proved by scientists making finds–what did creationists expect would happen? But, after all, they don’t make discoveries), therefore there’s plenty of reason to doubt it. And, since science, “materialism,” “Darwinism,” or whatever the name of the day that they have for the enemy, is a religion (because they say so!), it shouldn’t change, yet it does (ID doesn’t–well, it does, but they won’t admit it), so it’s a false religion.

    Works for the ignorant.

    Glen Davidson

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  3. Neil Rickert: (Your link was broken — I fixed it).

    Thanks. As is now likely obvious, I have the record (and trophy) for Posts Requiring Most Fixes in my sight, and I’m not giving up until they’re safely in my grasp.

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  4. As a YEC creationist I guess i’m like a expert!!! Just kidding.
    The answer is NO. you can not inherit experiences/on the dna from your relatives.
    First we are souls and can’t have material world impression on our souls.
    If the body was changed by some relatives then it was changed. So it would travel to the kids. Yet prove their was a change.
    The mice claim misses a point. Its not fear that would be inherited but a memory that would be at best. its possible the memory being so sensitive the parents would have it stamped and so it carry to the kids. In fact possibly the origin for instincts. Just guessing here.
    i don’t like the idea of thoughts being inherited. One needs a pracxtival machine operation here. Memory rules creatures however and is so sensitive its an option.

    By the way evolutionists. I note the article said some researchers think this way and others say its wishful thinking.
    How is this science? How is this to be trusted by the public? Science is meant to be a methodology to eliminate wishful thinking!
    Evolution is wishful thinking and been inherited!!

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  5. The article was hedged a lot, as is appropriate. It was somewhat confusing — it cited evidence for inheritance of epigenetic changes across generations, followed by citing researchers who said that there were no well-established cases of this.

    The one massively misleading phrase was that parents’ experiences influenced their offspring. That applies to evidence of famine experienced by one generation affecting rates of diseases in grandchidren. However, it gives the impression that subjective experiences of grandparents show up as similar subjective experiences in their grandchildren. As far as I know, there is no evidence for this, as much as people might like to believe it.

    There is also no evidence I know of that the changes in your grandchildren are adaptive, leading you to have higher fitness. Like genetic mutations, they are not preferentially in an adaptive direction.

    Those like the folks at Uncommon Descent who think that epigenetics creates the need to totally redo evolutionary biology, and who think that evolutionary biologists are wilfully ignoring epigenetics, are in for a disappointment. They have not understood that epigenetic marks revert after a few generations. Epigenetics does not explain why (say) a chimpanzee differs from a human — unless there are also ordinary genetic changes that stabilize the epigenetic change.

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  6. Joe Felsenstein:
    The article was hedged a lot, as is appropriate.It was somewhat confusing — it cited evidence for inheritance of epigenetic changes across generations, followed by citing researchers who said that there were no well-established cases of this.

    The one massively misleading phrase was that parents’ experiences influenced their offspring.That applies to evidence of famine experienced by one generation affecting rates of diseases in grandchidren.However, it gives the impression that subjective experiences of grandparents show up as similar subjective experiences in their grandchildren.As far as I know, there is no evidence for this, as much as people might like to believe it.

    There is also no evidence I know of that the changes in your grandchildren are adaptive, leading you to have higher fitness.Like genetic mutations, they are notpreferentially in an adaptive direction.

    Those like the folks at Uncommon Descent who think that epigenetics creates the need to totally redo evolutionary biology, and who think that evolutionary biologists are wilfully ignoring epigenetics, are in for a disappointment.They have not understood that epigenetic marks revert after a few generations.Epigenetics does not explain why (say) a chimpanzee differs from a human — unless there are also ordinary genetic changes that stabilize the epigenetic change.

    I agree that one does not genetically affect ones offspring(s). I’m sure your offspring don’t wear straw hats! Just a joke.

    UD folks would not say epi ruins evolution but only is a body blow.
    You seem to admit its true by saying it reverts back a few generations later.
    I don’t think its true and need actual scientific biological evidence.
    As I said its possible the memory absords a new conclusion and this transports to off spring. Thus a possible origin for instincts.
    However even this needs evidence.
    I question this stuff is any more well done then anything in evolutionism. Its just this is more doubted. Yet the same mechanism of poor investigation.
    This is not a inherited impression but my own.!

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  7. This reminds me of a Pandas Thumb article by Andrea Bottaro some years ago where he proposed an epigenetic memory system that might be based on prion folding. I remember thinking it seemed a bit far-fetched as prion folding is irreversible. I said so in the comments and I can’t recall any further developments on the idea.

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  8. Alan Fox:
    This reminds me of a Pandas Thumb article by Andrea Bottaro some years ago where he proposed an epigenetic memory system that might be based on prion folding. I remember thinking it seemed a bit far-fetched as prion folding is irreversible. I said so in the comments and I can’t recall any further developments on the idea.

    Alan Fox:
    This reminds me of a Pandas Thumb article by Andrea Bottaro some years ago where he proposed an epigenetic memory system that might be based on prion folding. I remember thinking it seemed a bit far-fetched as prion folding is irreversible. I said so in the comments and I can’t recall any further developments on the idea.

    Alan Fox:
    This reminds me of a Pandas Thumb article by Andrea Bottaro some years ago where he proposed an epigenetic memory system that might be based on prion folding. I remember thinking it seemed a bit far-fetched as prion folding is irreversible. I said so in the comments and I can’t recall any further developments on the idea.

    Read the post. The only way I see a new thought trait being translated to kids would be, if so, by the memory being so sensitive as to having a permanent new print.
    I don’t know about the machinery or slugs. however the paradigm shift , I think, should be too turning mans brain into merely a memory machine. The thinking coming from our immaterial soul but using the memory.
    So the memory being material could be affected by ones parents. not likely but a option. Instincts has never been explained and possibly its from this possible mechanism.

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  9. I’m on the extremely sceptical side. It goes against some pretty fundamental principles – which may just mean I’m a dinosaur, but it does raise the eyebrow a few notches. Each individual has the input of 2 parents, 4 grandparents, 8 great grandparents… Even in one generation, what’s the proposed means by which one individual’s experience ‘trumps’ that of its partner? Epigenetic inheritance is real. It is the mechanism of imprinting in mammals for example, whereby a paternal or maternal copy is preferentially expressed. There are 2 genes, and an asymmetric fitness regime for certain genes – there are legitimate circumstances whereby a gene may further its interests by preferential expression, and not be opposed. But this is down to a general selective effect over many lives, not an individual experience.

    For pan-generational effects, however, we have a problem. There are only two means of transmission: the genome and the cytoplasm. The cytoplasmic contribution of all individuals dilutes every generation. The genomic contribution concentrates (for one allele) and dilutes (for all the others). The ultimate fate of any given gene copy is either to be eliminated or to become the ancestor of every population member at the locus (barring certain selective effects). It’s hard to see how one individual’s experiences can transmit at all, let alone trump all the others.

    One of the main epigenetic mechanisms is methylation. This is restricted, because it has chemical consequences. The main target is a Cytosine neighbouring a Guanine – a CpG dinucleotide. Methylation of such a dinucleotide within a gene is mildly mutagenic – methylated C deaminates to T, a normal DNA base. Unmethylated C deaminates to U, which is an RNA base and readily repaired in DNA. CpG dinucleotides tend to cluster in ‘islands’ where any individual deamination is unimportant; the whole affects gene expression without being involved in translation. DNA replication is not prevented by methylation, but how do you preserve it through cell divisions or new generations? Well, copy a CG dinucleotide and you get two CG dinucleotides going in opposite directions, because C and G are complementary. But you have to actively methylate the copy – DNA polymerase doesn’t add methylcytosine when it looks for a companion to a G, just because that G’s neighbour was methylated. The other strand is miles away, it has no idea. There are active methylation mechanisms of course which restore methylation state. But we are looking for one that is responsive to an individual’s nutritional or experiential regime, and targets a relevant gene, rather surgically. Methylation is not allowed to run riot.

    So, for this particular mechanism to prosper, we need some means by which an experience or nutritional regime has a direct effect on a CpG island’s methylation state within the germ line. It really isn’t clear how this could be effected. And this individual’s experience’ has to trump the multiple experiences of its generational companions in or rivals for the offspring’s genome – and those of the offspring itself. If your dad lived through poverty, and you don’t, your somatic cells are influenced by his experience, while your germ cells carry yours? Well, maybe, but to me it has the flavour of the infamous “memoire de l’eau”.

    [I had to type that whole bastard piece in again because WordPress hung when I tried to be a smartarse and use the French double-brace quotes!]

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  10. Miller: “But we are looking for one that is responsive to an individual’s nutritional or experiential regime, and targets a relevant gene, rather surgically. Methylation is not allowed to run riot.”

    This is why I’m really skeptical on the epigenetic starvation claims. Folate and methionine, for example, are required for the 1-carbon pool that is used for DNA methylation.

    So are we seeing a (mal)adaptive program in action, or getting excited about a metabolic consequence of starvation?

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  11. RobC:
    Miller: “But we are looking for one that is responsive to an individual’s nutritional or experiential regime, and targets a relevant gene, rather surgically. Methylation is not allowed to run riot.”

    This is why I’m really skeptical on the epigenetic starvation claims. Folate and methionine, for example, are required for the 1-carbon pool that is used for DNA methylation.

    So are we seeing a (mal)adaptive program in action, or getting excited about a metabolic consequence of starvation?

    Since there is no information about whether the descendants of people who experienced starvation had more methylation or less methylation, it is quite possible that it was inability to methylate normally-methylated DNA that caused the effects.

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