Epigenetics – what revolution?

By Razib Khan | October 7, 2010 1:06 am

A reader who goes by the handle “biologist,” and happens to be a molecular geneticist by training, states more clearly what is probably close to my own position (though he is far more well informed) in the comments below. I think it’s worth promoting:

As far as I can tell, the existence of epigenetic mechanisms doesn’t change anything that we *should* have already known about the social implications of genetics (i.e. what people care about).

Quantitative genetic methods that estimate a substantial contribution of genetic variation to phenotypic variation do not now and has never told us anything about actual or counterfactual causal mechanisms involved. They have also never told us much about development other than what we already knew must be true — there will be genes involved in some way.

Nothing we’ve learned in the last 30 years about molecular biology makes any difference at a general level to those conclusions. What it mostly does is make clearer that the causal mechanisms behind phenotypic variation in complex traits are probably themselves really really complex.

As soon as you realize that complex traits have non-Mendelian inheritance patterns — something that’s been abundantly clear for many many decades — everything else follows and epigenetics only adds new dimensions to the causal mechanisms that might be involved.

Whether a trait is amenable to manipulation (and at what stages of development) is an interesting and very challenging question, but there’s no revolution in our understanding of biology involved in asking it. The only way to see a revolution is to ignore all of the incremental changes in understanding that have happened between decades.

Just to be clear, this is not a very mature sounding 12 year old. The commenter above is a biologist with whom I am personally familiar and whose opinion on this topic I value because not only do they grasp molecular biology in its fine-grained details, but they are very familiar with quantitative and behavior genetics (a rare combination). I can probably transfer some of the same general cautions about epigenetics that I brought up with Jim Manzi in relation to epistasis several years back.

The great thing about science is that this likely won’t be a debate 10-20 years from now. If you have an equation of the form:

A[genetics] + B[epigenetics] + C[environment] → Outcome

The scalars A, B, and C will be known with more precision as science progresses. Or more accurately, their values will be known for the range of outcomes which we find of interest. Our current surfeit of commentary is a function of mystery and uncertainty.

CATEGORIZED UNDER: Genetics, Genomics
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  • http://www.wired.com/wiredscience/neuronculture David Dobbs

    This hits the mark. I would add, however, that attention to epigenetics does have the capacity to change perception of how, as this commenter puts it, genetics + epigenetics + environment > outcome. How? B/c some of the work is showing the conversation between genes and environment to be far more fluid and quick than previously recognized: just fast and fluid enough, maybe, to get people to see that the two do not stand apart, but shape each other constantly, producing the thing that is us and life. And that therefore “nature v nurture,” as Stephen Suomi put it to me one day in technical terms, “is bullshit.”

    As the commenter notes, new findings don’t change anything we *should* have already known about the social implications of genetics. But they could — and that means something.

    To put it another way: It’s probably a good time to warn about the dangers of overreaching with epigenetic explanations. Yet that doesn’t mean they won’t let us grasp *some* things more securely.

  • http://math-frolic.blogspot.com “Shecky R”

    except it will never be that simple… by the time your 3 scalars are comprehended with any precision a 4th and maybe 5th, 6th, 7th scalar (today unknown) will have raised their complex heads; such is science. People continually way underestimate the complexity of genetics.

  • http://lyingeyes.blogspot.com ziel

    “the conversation between genes and environment to be far more fluid and quick than previously recognized: just fast and fluid enough, maybe, to get people to see that the two do not stand apart, but shape each other constantly…”

    When a statement like that hits popular media, the implication is quickly drawn based on the sociological definition of “environment.” So that it will be understood that if, say, you are raised in a deprived home, bereft of books or proper role models, epigenetics will conspire with that environment to alter your (and your progeny’s) genes that influence intelligence in such a way that confirms prior sociological expectations. I had an actual conversation with a couple who had watched a PBS show on the topic, and that was their clear takeaway.

  • onur

    I am asking the same question: what revolution? Epigenetics doesn’t change the DNA, it only changes the gene expression to some extent and, more importanly, epigenetics has no effect on the offspring except some very rare cases that last for some limited number of generations. Genetics, and not epigenetics, still rules biological inheritance (=heredity) and will always rule it as long as organic life exists.

  • ChristianK

    It’s certainly not
    A+B+C ->O

    There’s no reason to assume that those factors add linearally to each other.

    It’s rather something like:
    A + B + C + xAB + yAC + zBC + vABC -> O

  • http://www.kinshipstudies.org German Dziebel

    Biologist’s statement “The only way to see a revolution is to ignore all of the incremental changes in understanding that have happened between decades” is reversible to the effect that “the only way to see incremental changes is to ignore all of the revolutions in understanding that have happened between decades.” It’s the matter of a glass being half empty or half full. For the purposes of, say, integrating biology and anthropology into a synthesis more sophisticated than sociobiology, every little epigenetic change in the Mendelian approach to inheritance may be revolutionary. Unless biologists can anticipate the potential significance of those incremental changes for adjacent disciplines, their revolutionary value may remain hidden from those who are not privy to genetic or epigenetic research. The problem is that epigenetic (non-Mendelian) findings are overblown in general media and are broadcast at audiences who wouldn’t know what to do with them, but they are not targeted at other members of the scientific community outside of biology who could put them to good use. There’s currently a sharp break between scientists and science popularizers, with very few or nobody in-between who could translate scientific findings not to general public but to other scientists, especially social scientists.

    “Nothing we’ve learned in the last 30 years about molecular biology makes any difference at a general level to those conclusions. ”

    Again, I don’t know if this is objectively true or it stems from the lack of training on the part of biologists in anything else but biology and from the existence of institutional silos between biology and, say, anthropology.

  • miko

    Yes, the commenter hits the mark. These discussions tend to get circular…as Razib pointed out a few days ago, the concept of “gene” was simply a conceptual placeholder for “that which is inherited and produces traits.” So when we found a chemical substrate for inheritance, we stuck it in that box. So to say genes “rule” inheritance is to say that lunch is the best midday meal. Now we think of genes as one of the several molecular definitions, but are strict that they are made of DNA. My point is that “gene” doesn’t have the same ontological status as, say, “muon.” It is an operational category we made up to help us think, not a particle in the universe. We could say gene only means protein coding sequence, or it includes cis regulatory elements, or it’s anything transcribed, or anything except rRNA–it doesn’t matter, as long as we kind of agree.

    To call all inheritance not based on your nuclear genotype “epigenetic” is meaningless (or at least makes it a less useful category). Maternal effect mutants were studied for decades and no one called it epigenetics as far as I know. I’m not sure, but I think people still argue over whether PSI+ inheritance and related phenomena should be considered “epigenetics”–the methylation people have really co-opted the term. I don’t really care–again, it’s just a word–but I think my preference for its use is to restrict it to inherited modifications of chromatin. It is a tighter category and contains an operational and structural component. Despite what onur says, the relevance of most inherited methylation patterns is not known, but there is no reason to think it’s particularly rare. One incredibly interesting place where this will be played out is in imprinting and parental conflict: differing methylation patterns from maternal and paternal alleles. This has non-trivial implications for evolutionary dynamics in sexually reproducing organisms.

    I agree there is no “revolution” for anyone who has been paying attention. But it is foolish to dismiss all the added mechanistic complexity which has been added to our understanding as mere nuance or details. But if all you know is Punnet squares and DNA->RNA->protein (i.e. science journalists), you’re in for some surprises that will trip up facile reasoning about inheritance. I think this is what triggers cries of “revolution.”

    ziel, I would point out that in mice and rats, “enriched environments” (which you might call “sociological”) have major effects on offspring development and behavior that correspond to what I think you probably mean by “sociological expectations.” Since you don’t say, I’m not sure. The mechanisms are likely highly varied, but absolutely include chromatin modification. I’ll leave you to exercise your Pubmed skills if you’re interested.

  • omar

    “revolution” is a subjective term. I generally agree with Razib’s take on this one. Of course, that does not mean that there is no excitement in the field or no new information. The ability to map the epigenome is still in its infancy. And we are (as always) looking more where the light is better. But new technologies are appearing at a very impressive rate. And are now being applied to existing databases that we have already scanned for sequence changes (we are starting one such effort). Within the next few years, we should see a tremendous increase in the available hard data. For example (just looking at it from the perspective of a clinician who has wandered into science, not the POV of a biologist who has spent a lifetime looking at the molecular mechanisms of heredity) what is the epigenome like in the early embryo? at birth? in early childhood? in adult life? what drives those changes? How much of that variation is itself determined by underlying sequence variation? The gene-envt interactions that alter your purely DNA-sequence based risk of disease will become less of a black box…all this is important stuff. But revolution may not be the right word.
    btw, while my own field is obesity and metabolic syndrome in children, not psychiatry/behavior, it is my (mostly uninformed) impression that the big excitement in psychiatry (early experiences alter the epigenome, change gene-expression, lead to this or that psychiatric disorder) and its new-agish extension into notions of how you can THINK new changes into your epigenome is going to be the first bubble to burst…
    http://articles.latimes.com/2010/may/03/health/la-he-epigenetics-side-20100503
    http://www.sciencemag.org/cgi/content/full/329/5987/24

  • biologist

    To be clear: a lack of “revolutions” doesn’t mean enormous progress isn’t being made incrementally. In net the last 30 years have been a revolution, but only of the “lots of things have been done for the first time” kind, less of the Kuhnian paradigm shift kind.

    Maybe epigenetics — which at the moment seems to mostly refer to DNA methylation, histone methylations, and histone acetylations, (but not say small RNAs) — will have huge impacts on other fields we can’t anticipate as molecular biologists, but I don’t see hope that it will revolutionize questions about say determinism and free will, which seems to be the hope pinned on it.

  • Katharine

    What you want to bet that in 20 years there’s going to be a whole new level of subspecialization in science and science education is going to change to reflect the increased complexity of our knowledge?

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    It’s certainly not

    A+B+C ->O

    There’s no reason to assume that those factors add linearally to each other.
    It’s rather something like:

    A + B + C + xAB + yAC + zBC + vABC -> O

    two possible points

    1) diminishing returns as you add variables

    2) what is non-linear on a lower level/scale (e.g., mechanistic) may be linear on a higher leve/scale (e.g., statistical)

  • http://www.kinshipstudies.org German Dziebel

    Biologist: “I don’t see hope that it will revolutionize questions about say determinism and free will, which seems to be the hope pinned on it.”

    Anthropologist: There’s an iceberg of philosophical and politeconomical interpretations and applications underneath those two words. You use them in a simplified mass market sense because when it comes to philosophy and political economy you very well may be a mass consumer. There needs to be a pathway for biological discoveries to code for something meaningful in other scientific circles/schools/subcultures and to get filtered through their categorical systems before it gets broadcast through mass media and then picked up by the very same biologists who suddenly choose to put on a philosopher’s gown to lambast what is ultimately an unfinished scientific product. It takes some social scientific or metascientific “expertise” and a “contextualizing procedure” to assess whether something in biology is incremental or revolutionary (in the Kuhnian sense, if you will) because determined by the nature of reality or because geneticists are modern human beings and as such are endowed with free will to apriori decide what is primary and what is secondary in their discipline and hence invest more resources in the advances in the former and not in the latter. If it’s the free-will situation then your statements “nothing we’ve learned in the last 30 years about molecular biology makes any difference at a general level to those conclusions” and “causal mechanisms behind phenotypic variation in complex traits are probably themselves really really complex” are just a self-fulfilling prophecy and a tautology, respectively.

  • miko

    “modern human beings and as such are endowed with free will ”

    that’s exciting news.

  • biologist

    @ German Dziebel

    You’re promising a lot there. I won’t say it’s impossible, but it seems at least implausible.

    At least to me, post-translational modifications of histones (to pick one example) don’t seem the basis for predicting a revolution in social thought about the human condition. Most popular writing about epigenetics reads more like science fiction than science.

    Also, you’re correct that I’m deliberately talking about social implications in the language that an educated NY Times reader would understand them.

  • miko

    I missed something here… why would epigenetics change anyone’s opinion about determinism or free will more than any other collection of observation in molecular biology? I can think of nothing more deterministic than the causal chains that would result in an acetyltransferase tagging a histone.

    I realize there is some dualist fantasizing about “mind” influencing methylation or something, but I’m hoping the discourse on GNXP hasn’t degenerated that far. Why not rainbows driving topoisomerase activity?

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    I realize there is some dualist fantasizing about “mind” influencing methylation or something, but I’m hoping the discourse on GNXP hasn’t degenerated that far. Why not rainbows driving topoisomerase activity?

    to my shock i noticed someone actually bought that weird book i linked to (can see amazon purchases). hope it was a gag gift….

  • biologist

    @miko

    I think at the popular level, your dualist description is pretty much on point.

    I am vaguely familiar with an aspirational movement in anthropology towards a unify doctrine of social and biological evolution. A mechanism by which cultural evolution could loop back around and affect biological evolution without invoking selection would probably thrill them to no end, so that might be part of what stimulates interest in heritable epigenetic modifications.

  • miko

    Shit, people buy that book? I’m going to write one…. maybe I’ll claim that daydreaming about how awesome you are (while sipping my proprietary blend of organic methyltransferase agonists in a green rooibos acai tea, available at a Whole Foods near you) will reprogram your child’s chromatin such that they will get into the Ivy of their choice, be free of allergies, and spare them your strange WASP facial features. Maybe I can swing it with my credentials and institutional affiliation… the shocking discovery that will skip your child two evolutionary grades ahead.

    Benchwork just isn’t paying the mortgage.

  • http://www.kinshipstudies.org German Dziebel

    Biologist: “I am vaguely familiar with an aspirational movement in anthropology towards a unify doctrine of social and biological evolution.”

    Anthropologist: Would you care to read Cultural Transmission and Evolution by Cavalli and Feldman, who are molecular biologists? They refer to cultural transmission as an example of non-Mendelian inheritance.

    Biologist: “A mechanism by which cultural evolution could loop back around and affect biological evolution without invoking selection would probably thrill them to no end, so that might be part of what stimulates interest in heritable epigenetic modifications.”

    Anthropologist: If cultural evolution is essentially non-Mendelian, and molecular biologists seem to concur, then it’s possible that anthropological interest in heritable epigenetic modifications is more than just a vague conspiracy against Darwin and selection. People are just trying to understand if there a Mendelian slant to culture (e.g., could certain units of language be conceived of as relational “traits” that are different from discrete and continuous traits but are still traits) and a non-Mendelian aspect to biological transmission. It would help a lot when we are trying to unravel such problems as the origin of language and cognition.

    BTW, “selection” is one of those unfiltered words that Darwin picked up from the European tradition of breeding birds, plants and animals, which had nothing “natural” about it in the first place. And it continues to create confusion. It is the mind influencing methylation.

    Biologist: “At least to me, post-translational modifications of histones (to pick one example) don’t seem the basis for predicting a revolution in social thought about the human condition.”

    Anthropologist: Biologists expend too much useful energy on articulating what seems “implausible” to them. You could just report the results of your researches and do so in a language that would be promising to social scientists and philosophers of science. They could take it from there and figure out how it fits with free will and stuff. This should be doable within the capabilities of a university in which biologists sit catty-corner from anthropologists, don’t you think?

  • biologist

    Hi German Dziebel, I’m familiar with their work, having attended a number of their talks. Their theories don’t thrill me. Maybe that’s just a way of saying rationalism boo, empiricism yeah.

    At the level of the NY Times reader, I don’t see much more to get excited about, but maybe you can offer some substantive examples of epigenetics that should make us reconsider the human condition.

  • miko

    It is the mind influencing methylation.
    Example, please. And what do you mean by mind? If you mean something that is separate from the brain, I think we’re done here.

    anthropological interest in heritable epigenetic modifications
    It is unclear to me why anyone thinks that the existence of such a mechanism is somehow outside the bounds of standard concepts of natural selection or evolution as we currently understand it. I can’t even tell if you think so… if you do, why?

    a non-Mendelian aspect to biological transmission
    There are loads of non-Mendelian phenomena in biology. Do you mean non-genetic? It’s hard to get your point when you are fuzzy with terminology.

  • Josh

    Been a while since I’ve commented, but this epigenetics stuff gets on my nerves sometimes. Montgomery Slatkin wrote a paper once arguing that epigentics cannot explain, e.g., the missing heritability problem. I don’t think that it’s going to be the magic bullet that a lot of people think. Moreoever, as P-Zed has pointed out, epigenetic inheritance is one of the most trivially obvious things that comes out of developmental biology: every cell has the same genes, so somehow, some of them must get turned off!

    In my own area, evolution, I have a suspicion (though I lack the mathematical skills to prove this) that as long as epigenetic modifications happen “relatively fast” compared to the rate of environmental change, they won’t have that much of an effect on gene trajectories… which is something that I think people like Jablonka et al. feel like is one of the primary effects of epigenetics.

  • miko

    I’m not sure “fast” means no long-term consequences. Considering a case like imprinting as a mechanism for mediating parental conflict–these are “fast” modifications, but change the dynamics in a fundamental way.

  • http://www.kinshipstudies.org German Dziebel

    “Their theories don’t thrill me. Maybe that’s just a way of saying rationalism boo, empiricism yeah.”

    Interesting. It’s funny how scholars trying to work across two disciplines often end up booed by both. People love pure-breeds.

    “maybe you can offer some substantive examples of epigenetics that should make us reconsider the human condition.”

    You set the bar very high and I’m forced to bring it down. Epigenetics is not my field. It requires more in-depth knowledge of the primary subject. But in other fields in which I feel more competent I do just that. But my main point remains: unless there’s an operationalized procedure for biologists and the social scientists to share and cross-check their results before they hit the masses, or cross-disciplinary training is consistently fostered across universities, there’s no way to say whether epigenetics is a new Kuhnian revolution underestimated and underfunded within the biological community or just icing on the Mendelian cake overhyped by the media.

    @miko

    “And what do you mean by mind? If you mean something that is separate from the brain, I think we’re done here.”

    What I meant is that some of the language, the terminology and the category biology uses, including the very term “selection,” is unfiltered through social scientific analysis and if often confusing and simplistic. No surprise public debates rage about it. Nature doesn’t select, humans do, just like those British pigeon-breeders whom Darwin admired as forerunners of his theory. This may seem like a minor point but it’s just an example of how biologists shouldn’t be surprised their empirical theories get often misinterpreted by the public.

  • miko

    Nature doesn’t select, humans do

    Natural selection occurs despite the fact that there is no “selector” and does not require humans. It is a substrate-neutral process that has been occurring since before there were humans, before there were mammals, before there were multicellular organisms, and probably before there were cells. There is no agency involved.

    The fact that biologists use the term “selection” in a way that does not exactly correspond to common usage is not much of a criticism–all academic fields use terminology borrowed from everyday vocabulary that acquires specialized and context-specific meanings. I don’t criticize English majors who claim they are deconstructing a novel for not dissolving the glue and taking the pages out. Subatomic particles have spin, but this is not the same thing as rotating rapidly. Something being statistically significant does not lend it any other kind of significance.

    No one needs the permission of social scientists to use language in a useful, field-specific way.

    For anyone who has taking a more than 30 minute interest in understanding evolution, there should not be any confusion between human breeding and natural selection. It is an analogy, and a very useful one. This is why Darwin prefaced “selection” with the word “natural” and wrote a very long and clear book explaining it.

    I would suggest before you do any further wading into discussions of evolution, you learn some of the basics terms and concepts.

  • http://www.kinshipstudies.org German Dziebel

    @miko

    All of the below is meant as a conversation about term usage and the conceptual analogies and metaphors science has been using to describe its observations and communicate it to outsiders. It’s not about the nature of those observations. Plus it’s a historical excursion and not an attempt to simplify or diminish biology’s achievements.

    “I would suggest before you do any further wading into discussions of evolution, you learn some of the basics terms and concepts.”

    I love how people parade their knowledge of basics and expose their absolute ignorance of anything slightly more sophisticated. I’m sure you’ll graduate from high school with merit.

    “It is an analogy, and a very useful one. This is why Darwin prefaced “selection” with the word “natural” and wrote a very long and clear book explaining it.”

    Artificial or natural, it’s still “selection” and “natural” was extended from “artificial” as a metaphor thereof. More importantly, this analogy wasn’t a necessary one. You would benefit from contextualizing your knowledge of biology from the point of view of the history and anthropology of science. Science is a behavior subject to the same empirical analysis as it’s own primary objects of study. Darwin’s view of nature was shaped by the European tradition of animal domestication. Contrast Darwin with his contemporary Lewis H Morgan – the founder of anthropology and a forerunner of comparative psychology – who in 1868 arrived at a different view of evolution on the basis of his observation of wild [sic!] animals in North America. Check out his “American Beaver and His Works.” It didn’t occur to him to use the word “selection” because he dealt not with pigeons in urban British clubs or with sheep in the vast expanses of Shropshire, but with wild beavers. Different social context – different theory. I’m not saying, forget Darwin, celebrate Morgan, but it’s just a fascinating example how polymorphic science is at all the nodes of its development. Look up my book “The Genius of Kinship” and read the first part of it. It has further literature on the topic.

    “No one needs the permission of social scientists to use language in a useful, field-specific way.”

    It’s not about permission. It’s about the proper choice of words and a basic knowledge of history, anthropology, linguistics, etc. to make sure important biological discoveries are meaningful and interesting to other professionals.

  • miko

    German, I’m very aware of the history of terminology and concepts in the history of science. Evelyn Keller, a physicist by training (!) has written the best works on this subject regarding genetics and developmental biology, without the help of anthropologists. I also know that science is a human, social practice, and that the metaphors we use can shape the way we think. None of this is relevant to your bizarre ramblings about mind and epigenetics, which is what I was originally trying to understand. But you do seem to lack knowledge (or “sophistication”) in understanding evolutionary mechanisms or what is meant by basic terminology. Coming from someone whining that biologists make poor word choices, this is trying. If you want to discuss what biologists mean when they say things like “selection” then find out what they do mean, rather than assuming you know.

    Darwin used animal husbandry as an analogy to help engage the intuition of his audience in describing his theory of evolution. It was a useful analogy–I do not know of any analogies that are “necessary.” Is your point merely that you wish Darwin had chosen a different word? The analogy of selective animal breeding is not central or necessary to evolutionary theory. You seem hung up on it in some fundamental way, which I don’t get. I don’t think understanding of evolution, particularly after the modern synthesis, would be different if he had chosen a different analogy, or none. Maybe the terms would be more aesthetically pleasing to you, but so what?

    I don’t know much about Morgan so I won’t make any sweeping claims about his work. However, my cursory and shallow understanding was that he was interested in theories of social evolution. Since 99.999999% of evolution on this planet has occurred among non-social organisms you might see why this is of limited interest to biologists as a unifying model. Biologists are–for the most part–trying to explain life, not people. Evolution does not require mind, agency, wild animals, or social systems. I don’t doubt that one’s cultural context shapes scientific thought, but I am reasonably certain that the differences between Darwin and Morgan have more to do with the fact that they were attempting to explain different phenomena than their slightly different shades of white European-ness.

    “proper choice of words”
    Pardon me, but fuck you very much. Go tell a particle physicist that quarks don’t really spin, I’m sure they’ll thank you for enlightening them. You’re just being effete.

    I think interdisciplinarity is great, but I have the feeling that what you’re on about (besides policing language) is something that interests some anthropologists a great deal and biologists not at all. I am embarrassed on behalf of biologists when one of us makes sweeping biological claims about human culture or society, with scant respect or understanding of the fields that have made those phenomena their object of study. Your uses of the term selection, Mendelian, epigenetic, etc, indicate that you do not have much understanding of what they mean or their mechanisms. Somewhere, maybe an anthropologist is embarrassed for you.

  • Chris T

    Whether or not you believe the use of ‘selection’ was historically necessary or accurate is rather irrelevant since it is the understood and accepted terminology today when discussing biological evolution. I fail to see why accepting another field’s terms and definitions is so difficult when discussing something within that field.

  • http://www.kinshipstudies.org German Dziebel

    @ miko

    “I’m very aware of the history of terminology and concepts in the history of science.”

    No, you don’t. You are just defending your own misreading of my words.

    “Evelyn Keller, a physicist by training (!) has written the best works on this subject regarding genetics and developmental biology, without the help of anthropologists.”

    She is a philosopher of science, who originally wanted to become a physicist. Physicists don’t have time to observe biologists. I mentioned philosophy of science earlier. Whether it’s anthropology of science or philosophy of science, without these filters biology or physics may be an incomplete product.

    “your bizarre ramblings about mind and epigenetics.”

    I didn’t “ramble” about any of that. I just wasn’t convinced that epigenetics is “not revolutionary.” I think it very well may be if this research trend is better funded and if it’s socialized better within the social scientific community.

    “in understanding evolutionary mechanisms or what is meant by basic terminology.”

    I didn’t discuss them either, so how do you know?

    “You seem hung up on it in some fundamental way, which I don’t get.”

    You may be right here. I prefaced my note on “selection” with a caveat that may be a minor historical thing. (same to Chris T)

    “I do not know of any analogies that are “necessary.”

    It just means that there are different analogies and not just one. Just like the metaphor of a ball spinning down a concave vessel toward its center is different from the metaphor of one ball attracted to another (the former describes relativity theory, the latter Newtonian physics, also to your quarks example). This is what is interesting about Darwin’s selection. I never said that Darwin was useless, but it’s interesting that biologists praise Darwin, are familiar with Wallace but don’t know L H Morgan.

    “However, my cursory and shallow understanding was that he was interested in theories of social evolution.”

    Yes, but it was part of his broader agenda of understanding evolution as such. Think of him as a forerunner of niche construction theory. In fact, on another thought, I think Morgan would say that evolution is achieved not just in an agency-free “field of selection” but through creative, selective, constructive activity of the organism itself. He limited himself to higher-order animals like genus Castor and then switched to humans. Read him and compare his focus with Darwin’s focus. It’s possible that Darwin, who knew Morgan personally and mentioned him in his Origins, wrote his “The formation of vegetable mould, through the action of worms, with observations on their habits” (1881) under the influence of Morgan’s “American Beaver and his works,” which, btw, was one of the very first monographs devoted to a single species.

    “I have the feeling that what you’re on about (besides policing language) is something that interests some anthropologists a great deal and biologists not at all.”

    I don’t police language – I already said that. I understand you are trying to assume the pose of a victim. Also, I gave an example earlier when it’s molecular biologists who are interested in cultural transmission as an example of non-Mendelian inheritance. Direct your complaints to Cavalli and Feldman that they are interested in what other biologists are not interested in.

    “I am embarrassed on behalf of biologists when one of us makes sweeping biological claims about human culture or society, with scant respect or understanding of the fields that have made those phenomena their object of study. Your uses of the term selection, Mendelian, epigenetic, etc, indicate that you do not have much understanding of what they mean or their mechanisms. Somewhere, maybe an anthropologist is embarrassed for you.”

    You are just the type of commenter who takes advantage of internet anonymity to rant about the one thing you love and to abuse other people.

  • onur

    What does Darwinian terminology to do with epigenetics!?

  • http://www.kinshipstudies.org German Dziebel

    “What does Darwinian terminology to do with epigenetics!?”

    Nothing really. I used “selection” as an example of biology’s conceptual language that’s confusing to outsiders, creates rifts within academia (comp. Biologist’s snide remark “A mechanism by which cultural evolution could loop back around and affect biological evolution without invoking selection would probably thrill them to no end”) and often gets misinterpreted. I also noted that there was a certain social context underlying its invention and this context was different, albeit easily comparable, for biology (Darwin) vs. anthropology (Morgan). Darwin portrayed evolution as “acting upon” organisms (just like human breeders act on domesticated birds, animals and plants), while Morgan portrayed “evolution,” using the example of wild, higher-order animals such as beavers, as being acted out by organisms.

    It was a footnote, but miko, then, decided to use all his ignorance to fight over it.

  • onur

    Instead of drifting into off-topics, we should focus on what is true, what is hype and what is blatant lie about epigenetics.

  • genomicist

    The remarkable aspect of epigenetics is not that it affects a trait. There are innumerable non-genetic factors which affect a quantitative traits. What is revolutionary about epigenetics, as pointed out by Eva Jablonka over a decade ago, is that traits can be inherited by non-genetic mechanisms. To lump environmental factors affecting a trait with epigenetic factors affecting a trait is a false comparison, as the environment is not strictly heritable, while the epigenetics are!

    The appropriate simplification of this is:

    Heritable information + environmental interaction = quantitative trait

    Where heritable information includes both genetic and epigenetic factors. There is ample evidence that epigenetic factors are both heritable as well as significant sources of heritable variation (and thus information; see research on agouti mice).

    The truly revolutionary aspect of epigenetics is the instability in which it is inherited. Epigenetics and tandem repeats (another unstable carrier of information) hold the key to understanding heritable sources of phenotypic (trait) variation. An excellent review on the subject was published in Cell by Rando and Verstrepen in 2007.

    The big unknown at this time is how much heritable variation is actually caused by epigenetics. While it is certain that epigentic inheritance is important, its level of significance is not yet fully known. If we can keep an open mind about it, and continue funding research in epigenetics, we might one day find out.

  • http://www.kinshipstudies.org German Dziebel

    Completely agree, Genomicist. BTW, for those who are interested, the Rando and Verstrepen paper can be downloaded from http://www.biw.kuleuven.be/dtp/cmpg/G%26G1/publications.html

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Gene Expression

This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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