The Demise of the Genetic Blueprint Metaphor

News Type: Other — Seeded on Fri Jan 9, 2009 2:35 PM EST

Article Source: rationallyspeaking.blogspot.com

science, evolution, biology, dna, genetics, intelligent-design, genes, genomics, massimo-pigliucci, pigliucci, chouard, genetic-blueprint, tanguy-chouard

Seeded by iarnuocon

[E]ven serious biologists (i.e., unlike Behe) have been guilty of enthusiastically pushing what is clearly a flawed metaphor: the idea that the DNA sequence of an organism's genome is analogous to a computer "program," and that it provides the "blueprint" for building said organism. Hence the wild (and, as it turns out, completely unfounded) claim a few years ago that sequencing the human genome will tell us everything there is to know about "making" a human being. The human genome has been sequenced, and what we have found is that genes, though playing a crucial causal role in development, are just one piece of a vast and as yet largely unresolved puzzle.

Ironically, the harbinger of the demise of the genetic program-blueprint metaphor is the serious study of genomics itself. A recent article by Tanguy Chouard in Nature (20 November 2008) explains why. Researchers are finding out that what matters is not so much individual genes, but the way networks of genes function together.

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{"commentId":4736823,"authorDomain":"iarnuocon"}

iarnuocon

Massimo Pigliucci is a professor of Ecology and Evolution at the State University of New York at Stony Brook. He received his doctorate in genetics at the University of Ferrara, Italy, a Ph.D. in botany from the University of Connecticut, and a Ph.D. in philosophy at the University of Tennessee. He's a regular contributor to the Skeptical Inquirer and Philosophy Now, as well has having authored several books, among them the commonly known Denying Evolution: Creationism, Scientism, and the Nature of Science, which is an excellent popular overview of the topic.

{"commentId":4736823,"threadId":"465691","contentId":"2293335","authorDomain":"iarnuocon"}

1 vote

#1 - Fri Jan 9, 2009 2:38 PM EST

{"commentId":4740948,"authorDomain":"AnthonyTyler"}

Anthony T

I believe that what Pigliucci is speaking of is the idea of epigenetics? If memory serves me correctly, then I believe that's one of "his babies".

I'm not really certain that this idea is "mainstream" right now, but he may be rather on the "fringe" of thinking (which is good). I read somewhere that Massimo Pigliucci will be on a committee that will revamp/rewrite the modern evolutionary synthesis taking into account a variety of new observations (such as epigenetics).

Actually I just found a resource that says the same idea, Pigliucci in "Expanding Evolution" in Nature, June 2, 2005 refers to the "neo-darwinian synthesis" to be "incomplete" and "due for a major revision".

As with any scientific theory, revision is something expected and something that you can relatively count on. How this changes the creation/evolution debate remains to be seen. I'm curious as to the basis of his arguments more than just a need to revise the current evolutionary synthesis.

He desribed 4 methods of inheritance: genetic (dna/rna), epigenetic inheritance systems, behavioral inheritance systems, and social learning.

He argues that "some hereditary variations are non-random in origin" [one must ask what mechanisms put this non-random hereditary variations in place]

He says that

the suggestion is that some heritable, adaptive changes come not from natural selection, but from the action of evolved internal system that generate non-random "guesses" in response to environmental challenges. Examples are not hard to find, contrary to the assumed wisdom of neo-darwinism. Consider the existence of 'hotspots' that make mutations in certain regions of the genome much more likely than in others. Or the impressive ability of some bacteria to increase the mutation rate of a specific gene involved in the metabolism of a given amino acid when that amino acid becomes scarce in the environment.

We'll see what happens with this idea...

Pigliucci advocates that this idea of epigenetics makes the evolution of "novel" structures more likely due to this somewhat "intelligent" mechanism. One has to wonder where such a mechanism came from, and how this mechanism knows which genes to mutate in response to what types of environment, etc.

I believe a metaphor (which I know he specifally argues against) that genes are like the keys on a piano, and this epigenetic mechanism is the score that says when to activate and use which genes.

Interesting theory, though would you agree that he is currently on the fringes a bit, or would you say that there are more and more people going that route?

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#2 - Fri Jan 9, 2009 6:22 PM EST

{"commentId":4755401,"authorDomain":"iarnuocon"}

iarnuocon

I don't think that epigenetics, specifically, is what Pigliucci is talking about, although it might play a part in his argument. I think more generally he's speaking to the fact that the genome isn't a map of the organism in the sense of genetic determinism. He specifically refers to "genetic causalism" as opposed to "genetic determinism."

I can't tell you how "mainstream" Pigliucci is in terms of evolutionary theory, since I haven't read much of his work other than his occasional article in Skeptical Inquirer and his popular book Denying Evolution. But the latter makes me think he's more mainstream than not. He certainly accepts at face value the core set of ideas underpinning the modern evolutionary synthesis. I would say that his posts on his blog regarding the Altenberg 16 (what you refer to, I think, as "a committee that will revamp/rewrite the modern evolutionary synthesis") suggest a belief that evolutionary theory is incomplete-- but that's hardly a radical or fringe idea.

But he seems pretty responsive to inquiry-- you should drop him an email to get his take on his position.

Regarding whether there is a mechanism which "knows" which genes to mutate, I'd guess there's something more along the lines of fractal self-organization in the genome-- some genes or strings of DNA may simply be more amenable to changes which result in "novel" structures, for instance. And I doubt there are many (or any) mainstream evolutionary biologists who would deny that there is a feedback loop between genetic material and the environment, especially given the existence of pseudogenes, cis-regulatory and trans-regulatory material which exists outside the genes themselves, but that can play very important roles in the development of significant morphological features in an organism. For me to speculate either Pigliucci's position or the general state of current evolutionary science on phenotypic plasticity, developmental plasticity, epigenetics, multi-level selection, et cetera, would be pure guesswork, since I'm not up to speed on those specific subjects.

But here's the thing, I don't think anyone thinks the modern evolutionary synthesis is complete, and we certainly don't know everything there is to know about the ways in which (as Pigliucci calls them) networks of genes "cooperate" with each other during development. If we did, the sequencing the genome really would mean that we'd know how to put together a human being. But we obviously don't.

Which is simply a wordy way of saying that evolutionary science still isn't sterile, played out, or boring. Future states of the evolutionary synthesis no doubt will contain some (perhaps many) features of all of these various more tightly focused theories.

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1 vote

#2.1 - Sat Jan 10, 2009 6:44 PM EST

{"commentId":4747160,"authorDomain":"snvcogar"}

SamC

a flawed metaphor: the idea that the DNA sequence of an organism’s genome is analogous to a computer “program,” and that it provides the “blueprint” for building said organism. ............... Researchers are finding out that what matters is not so much individual genes, but the way networks of genes function together

HUUUMMM, me thinks someone has "tunnel vision" or "near sightedness" ..... because I have always looked at the resident CP and/or OS of a computer and the hundreds of "software routines" and the thousands of Application Programs associated with them to be like a "network that functions all together".

Said "software routines" are absolutely worthless unless called upon by the CP, OS or an Application Program to perform a function.

{"commentId":4747160,"threadId":"465691","contentId":"2293335","authorDomain":"snvcogar"}

#3 - Sat Jan 10, 2009 8:11 AM EST

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The Demise of the Genetic Blueprint Metaphor

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