Breaking the "Central Dogma"

By Razib Khan | June 20, 2011 11:32 am

Epigenetics is making it “big time,” Slate has a review up of the new book Epigenetics: The Ultimate Mystery of Inheritance. In case you don’t know epigenetics in terms of “what it means/why it matters” holds out the promise to break out of the genes → trait conveyor belt. Instead positing genes → trait → experience → genes, and so forth. Or perhaps more accurately  genes → trait × experience → genes. Epigenetics has obviously long been overlooked as a biological phenomenon. But, I think the same could be said for the ubiquity of asexual reproduction and unicellularity! Life science exhibits anthropocentrism. That’s why there’s human genetics, and biological anthropology. My own concern is that epigenetics will give some a license to posit that the old models have been overthrown, when in fact in many cases they have been modified on the margin. Especially at the level of organisms which we’re concerned about; human-scaled eukaryotes. Humans most of all.

The last paragraph in the review highlights the hope, promise, and perils of epigenetics in regards to social relevance:

It’s almost enough to make one nostalgic for the simplicity of old-style genetic determinism, which at least offered the sense that the genetic hand you were dealt at birth was the same one you would play your whole life—except that epigeneticists hold out the promise that the blessings of a single life, too, can be passed on. Disease researchers, Francis reports, have hopes that the effects of abnormal epigenesis may be reversed. For example, it’s possible that the damage caused by many cancers is epigenetic. If those epigenetic attachments can be altered, then it’s possible the cancer can be stopped. Still, even if we are discovering that an extraordinary range of conditions may be epigenetic, not all of them are. There are still specific diseases that follow a deterministic path. If you are unlucky enough to draw the Huntington’s mutation in the genetic shuffle, you will develop the disease. Francis rightly emphasizes the wonder of epigenetics and the molecular rigor it brings to the idea that life is a creative process not preordained by our genome any more than it is preordained by God. Yet even as epigenetic research invites dreams of mastery—self-creation through environmental manipulation—it also underscores our malleability. There is no easy metaphor for this combination. But if we must have one, we should at least start with the cell, not the gene. The genome is no blueprint, but maybe the cell is a construction site, dynamic, changeable, and complicated. Genes are building materials that are shaped by the cell, and they in turn create materials used in the cell. Because the action at the site is ongoing, a small aberration can have a small effect, or it can cascade through the system, which may get stuck. Recall that your body is a moving collection of these building sites, piled in a relatively orderly way on top of another. Malleability? It’s an ongoing dance with chaos, but, incredibly, it works.

If people have a hard enough time with the concept of heritability, I have no idea how they’ll deal with heritability of epigenetic modifications! In science itself epigenetics has really come to the fore over the last 10 years. Here’s a plot which shows the change over time in the scientific literature:

And here’s the Google Trends results:

Either the media only discovered epigenetics in 2008, or Google’s index wasn’t very good. I suspect the former, as I started being asked about the term by intellectual non-science types circa 2008. For Google Correlate “epigenetic” and “subjective” have a correlation of 0.91, and “epigenetics” and “we create” have a correlation of 0.89. These are a little disturbing, and I hope epigenetics doesn’t go the way of quantum theory and general relativity and become abused in other disciplines. For example, “epigenetics means that genetic inheritance is a subjective fiction!”

CATEGORIZED UNDER: Behavior Genetics, Genetics, Genomics
  • I_Affe

    On your last sentence, I’ve a few liberal friends who know a little about genetics (at least the central dogma plus a little more) and are somewhat excited about epigenetics, in that they believe that it strikes a blow about genetic determinism. I usually send them this book review from Nature. It’s a decent summarizing review, though, I’ve never actually read the book reviewed in the article.

  • I_Affe

    Of course I also had a rather conservative classmate during my undergrad years who refused to use the term epigenetics, instead preferring something like gene expression modification or some variation thereof.

  • http://www.epigenie.com PeteJ

    Nice post Razib. Thanks for calling attention to the most exciting field in science. I’ll offer a few explanations on your graphs. Basically, scientists have been studying epigenetics for a long time, but haven’t really referred to it by the more adopted term used today. Government initiatives combined with an increasing use of the term, which typically comes with an increasing number of peer review publications, have thrown “epigenetics” into the mainstream vocab.

    Epigenetics research has been hindered by a technology gap that started being addressed back in 2002 with microarrays, but more so today with next generation sequencing. This is shown in your Google Scholar plot of publications. These are the tools that were necessary to boost epigenetics’ relevance into almost every lab and the momentum continues fortunately.

    Keep the coverage coming!

  • Kiwiguy

    ***only discovered epigenetics in 2008, or Google’s index wasn’t very good. I suspect the former, as I started being asked about the term by intellectual non-science types circa 2008. ***

    I came across it in 2007 in a book called ‘Survival of the Sickest’. I read the book after seeing the author, Sharon Moalem, on the Daily Show with Jon Stewart.

  • omar

    I have not read the book (yet) but it does seem that epigenetics is being hyped beyond its actual potential. First of all, the idea that biologists had no notion of “epi” genetic levels of control a few decades ago is obviously false. We did not know HOW its done, but everyone knew that all the genes are not switched on all the time and in every cell line…some kind of “epigenetics” was taken for granted. While it is true that the notion of intergenerational inheritance of acquired characteristics was vigorously denied, it is not like we are suddenly back to Lamarckism. Only if we find that epigenetic inheritance eventually changes the genetic code itself will we be in the Lamarckian domain and that has not happened yet.

    More importantly, we are talking about RELATIVELY subtle effects here. After all, Holland did not lapse into barbarism one generation after the Dutch hunger winter. Some increase in metabolic syndrome and schizophrenia among survivors should not obscure the fact that MOST hunger winter survivors did just fine and are in fact the tallest and close to the healthiest people on this planet. The idea of crude genetic determinism may have been held by some biologists, but is mostly a straw man used to burnish a particular “nurture” bias in influential sections of the intelligentsia.
    The human organism is not built up from scratch using a factory blueprint. We are extensions of our parents and connect to an unbroken line of life that is 3.5 billion years old. And every cell is more complex than the largest factory or corporation and every body is made up of trillions of cells and lives with trillions of other living things and a complex non-living environment. Epigenetics is a fascinating field and adds another layer of subtle and wonderful knowledge to our existing understanding of biology, but it is important to keep it in perspective. we cannot “nurture” our way to superman or cro-magnon man in one generation no matter what the environment does to the genome. In fact, we are remarkably stable organisms, given all the chaos in our world..and the DNA code is still the most important and basic arbiter of inheritance. Epigenetics adds to our understanding of biology, but it does not overturn it.

  • Stephanie

    I just learned about epigenetics a month ago, and I for one am VERY excited. It is a HUGE break in my mind. It has provided an answer to questions I’ve had since childhood (a long time ago), some bridge to all the holes in mainstream theories that I’ve been privy to over the decades (I’m not a scientist, just an observor). Of course it’s not the final answer–that’s the beauty of it. Once again we are reminded there is no final answer–by the answer that’s not the final one. I love it.

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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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