Epigenetics and the "Piano" Metaphor - Evolution News & Views

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Epigenetics and the "Piano" Metaphor

Writing here at ENV back in November 2010, I remember trying to come up with a metaphor, a way to explain -- not least to myself -- how the genetic information conveyed by DNA is put to use in producing the three-dimensional creature for whose characteristics it is conventionally said to "code."

I was seeking to convey some of the main points of Steve Talbott's illuminating essay in The New Atlantis, "Getting Over the Code Delusion." Talbott did a brilliant job of dispelling the misconception that DNA can accurately be said, by itself, to map out the lineaments of any creature.

Instead, I wrote, the situation was like that of a gifted, sensitive pianist playing his instrument and thereby giving life to a piece of music. To get from the music on the sheet to the music in the air you need the intermediating purposeful agency of the performing musician. It's nice to be able to report that, since then, this same metaphor has suggested itself to other people, not all of whom seem to have seriously considered its implications.

The piano and the notes on the page don't together account for a successful musical permanence. There must also be an artist at the keyboard who plays the piano. In biological terms the pianist corresponds to the epigenetic processes that "play" the otherwise static linear information represented in DNA:

It is as if a piano were being played by a skilled and sensitive musician -- say, an improvisational jazz pianist -- with the instrument itself responding to his touch not as the expression of an algorithm but of its own life force. There is a very minimal musical score, in the form of DNA, inadequate to describe the music being performed, and then there is the pianist himself engaged in an improvisation on a swiftly shifting suite of themes.

And this is only the construction of proteins we're talking about. It leaves out of the picture entirely the higher-level components -- tissues, organs, the whole body plan that draws all the lower-level stuff together into a coherent, functioning form. What we should really be talking about is not a lone piano but a vast orchestra under the directing guidance of an unknown conductor fulfilling an artistic vision, organizing and transcending the music of the assembly of individual players.

What do you know, the cover article in the current National Geographic, on identical twins, makes use of the same comparison:
If you think of our DNA as an immense piano keyboard and our genes as keys -- each key symbolizing a segment of DNA responsible for a particular note, or trait, and all the keys combining to make us who we are -- then epigenetic processes determine when and how each key can be struck, changing the tune being played.

One way the study of epigenetics is revolutionizing our understanding of biology is by revealing a mechanism by which the environment directly impacts genes. Studies of animals, for example, have shown that when a rat experiences stress during pregnancy, it can cause epigenetic changes in a fetus that lead to behavioral problems as the rodent grows up. Other epigeĀ­netic changes appear to occur randomly -- throwing a monkey wrench into the engine of nature versus nurture. Still other epigenetic processes are normal, such as those that guide embryonic cells as they become heart, brain, or liver cells, for example.

That piano metaphor has really been getting around. Recently the University of Texas Health Science Center at San Antonio announced a study by its researchers, published in Science, on gene expression with possible implications for cancer therapies:
Like keys on a piano, DNA is the static blueprint for all the proteins that cells produce. Epigenetic information provides additional dynamic or flexible instructions as to how, where and when the blueprint will be used. "It corresponds to a pianist playing a piece of music," said Kohzoh Mitsuya, Ph.D., postdoctoral fellow in the School of Medicine.
What's the problem for Darwinism? ENV's Jonathan M. has put it in terms of an "information debt" ("Newly Discovered Mode of RNA Replication Uncovers Previously Hidden Layers of Complexity," August 16, 2010).

Neo-Darwinism explains how natural selection, spinning out life's wonders, operates by selecting new configurations in the genome, randomly generated by mutation. But epigenetic information doesn't arise by genetic mutation. In the economy of Darwinian theory, the pianist is missing.

As new research is produced in the field of epigenetics, as well as developmental biology and genome biology, the nature of the information debt now confronting Darwinism grows, resulting in a respective decline in the likelihood of such systems having been constructed by non-intelligent means. A large question mark, then, resides over the causal sufficiency of the dual forces of random mutation and natural selection (and other unguided mechanisms).

It now stands without question that, to borrow a phrase from Michael Behe, life "reeks" of design. Since Darwinism is an attempt to explain away this appearance of design (albeit so far unsuccessfully), the proposition of intelligent design must be considered a feasible alternative, and one which is increasingly supported by molecular and biochemical research.

Exactly.