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Is DNA production normal?

  1. May 20, 2009 #1
    This is not a theory, but would like to see if anyone has been working on a model for this kind of thing. Existing Theories on this subject.

    I was wondering if DNA is a normal part of the time line of matter in our universe. In other words is DNA based life a part of the life cycle of matter in our universe. Our sun is not unique in our galaxy or others like it. So could you run a model of our universe over and over again and it always form DNA every time? You have the big bang the universe settles expands, DNA forms the universe ages life dies out as it gets to old to support it. Then the big crunch, another big bang and so on and so on.

    I would love to see your thoughts on this.
     
  2. jcsd
  3. May 20, 2009 #2

    apeiron

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    You could argue that the same "trick" has happened at least twice with genes and words. So in a universe with as much potential for complex dissipative structure as ours, this "trick" would be highly likely to appear.

    This trick is a reduction of dimensionality that creates what we can call a system memory, an ability to encode boundary constraints.

    In plainer langauge, genes are special because they are a break from the normal 4D spatiotemporal scale of metabolic processes. In a soup, there are many degrees of freedom. Stuff happens in all directions.

    Membranes are a 2D constraint on these freedoms. They confine a soup to the inside of a cell. And flat surfaces are a further constraint on metabolic dynamics. Grooves and other linear paths (like blood vessels or neural links) are a constraint down to 1D.

    We can see how these kinds of structural constraints are "information". They add restrictions to the free dynamics of the 4D soup that are productive in some fashion.

    So we have a general principle that a reduction in dimensionality leads to greater systems organisation.

    Note that it is important that these structural constraints are normally long-lived. They are memories in the sense that they persist much longer than does any patterning of the dynamic soup. 1D structures like microtubules actually have a half-life of around 10 minutes. But they get rebuild constantly (where needed) so have an existence on a different timescale to the simple metabolism of the soup.

    Anyway, there is this general "trick" that is at the heart of complex systems, dissipative structure that is "alive". A pool of dynamic processes with some characteristic free range of activities exists with a certain timescale. Then it becomes hierarchically developed as the system "steps back" in spatiotemporal scale. Spatially, dimensionality is reduced, and temporally, dimensionality is increased. Making memory that encodes boundary constraints.

    Genes are at the end of this trail. You get such a constraint of dimensionality that a 1D path is dissolved into a sequence of 0D points. Memory makes the change from analog to digital if you like. The continuous becomes the discrete. And symbolic. A sequence of bases can represent the 3D structure of a protein, and control the 4D processes of a soup. The code can endure generations, spread across many individuals, and it looks nothing like the things it produces.

    So that is the trick. And language was a repeat. Animals think. Humans evolved a physical constraint on vocal output through a vocal tract that became designed to bite air flow into a serial stream (discrete and repeatable syllabic sounds). Ideas could be broken up into words expressed in serial chains. A dimensionality was reduced until it became digital and a systems memory, information encoded, no longer needed to look anything like what it represented.

    Does any of this have any interest for cosmology? I believe it does. The reduction of dimensionality as a natural trajectory for dissipative structure could be what produces universes as a whole. As a general principle, it could be used to argue that 4D worlds evolve as a constraint on higher dimensional realms.

    So for example, we could suggest that there was some infinite and unbounded initial potential. Then a reduction of dimensionality - a symmetry-breaking dissipation - led to the self-organised and persisting 4D realm we call the universe. Brane worlds and multiverses would be possible intermediate stages of course - stepping stones in the dissipative trajectory.

    So what seems a weird question for this cosmology section - and bound to get locked/moved as a result - could in fact be directly connected to the issue of dissipative structure, information theoretic approaches to complexity, and the reduction of dimensionality as a general systems principle.

    (I could add other biological examples of the "trick". Like human tool use. The opposable thumb, the lateralisation of grip so that one side is focused on the blows, the other on the orientation of the substrate. The pre-language advance serialised, repetitive motor actions that probably laid the neural foundations for later serial vocal control.)
     
    Last edited: May 20, 2009
  4. May 20, 2009 #3
    I don't really have anything specific to add, but this concept of dimensional reduction is really interesting. Lately I've been learning about self-organizing systems and emergent phenomenon, and this seems to fit nicely into that line of reasoning.

    Is this a formalized principle, or is it more of a personal interpretation? I'd like to find out more.
     
  5. May 20, 2009 #4

    apeiron

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    I think it is new that I am expressing it in this particular way as a general principle.

    But this would not be an alien argument to those working in theoretical biology, particularly those with a background in (bio)semiosis, hierarchy theory and dissipative structure theory.

    And I can dig out more specific cites like Robert Worden on language if you are interested.

    http://www.isrl.illinois.edu/~amag/langev/author/rworden.html [Broken]

    The key insight, from a systems view, is that local degrees of freedom (dimensions) are created by global constraints.

    A self-organising system forms some prevailing state, some macrostate ambience that you can measure as a "temperature" of some kind, and this bears down at every point of the system to constrain what can occur. Then by definition, everything that is not constrained - prevented from happening - is free to happen. The suppression of multiple degrees of freedom or dimension is what creates some crisp and particular properties or freedoms or dimensions at every point in the system.

    By preventing a locale doing everything, you force it to do just something. Ironically, constraints breed freedoms.

    So as QM suggests, a naked locale could be anything. It is vague in that it represents an infiinity of degrees of freedom. But within a decohering context, most of the freedoms are suppressed, the alternative histories dissipated. The locale lines up to have some crisp classical set of properties - Newtonian inertias. The unproductive many are slimmed down to
    the productive few. "Locality" is in fact created - to a Planck-scale certainty.
     
    Last edited by a moderator: May 4, 2017
  6. May 21, 2009 #5

    Chalnoth

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    My suspicion is that there is a significant subset of the life in the universe that uses DNA. And by this I mean it has the same DNA->RNA->protein setup that life on Earth makes use of (look up the "central dogma of molecular biology" for more detailed information). My suspicion is that the DNA and RNA will look much the same, no matter where you go. Perhaps it is possible that one or two of the nucleotides will make use of different molecules, though I don't know enough about the chemistry of other possible nucleotides to be sure.

    One thing, though, that I think we can be sure about is that the RNA->protein transition will be extremely different for different abiogenesis events. The reason is simple: the transcoding of RNA to proteins is largely arbitrary: proteins are assembled with a 3-code system using small molecules with little bits of RNA attached to an amino acid. Which 3-nucleotide strand of RNA is attached to which amino acid is basically completely arbitrary. However, once a code is set up, it is nearly impossible to change, because changing such a code would change a significant fraction of all of the proteins in an organism. Such a change is very unlikely to be non-lethal.

    So my suspicion is that if we discover life elsewhere, we will find DNA, RNA, and proteins, but the relationship between RNA and proteins will use an entirely different coding schema.

    There is also the possibility, of course, of life based upon other molecules. I'm not sure anybody knows enough about the full range of possibilities out there.
     
  7. May 22, 2009 #6
    Considering that ALL life that has ever existed on this planet was and is RNA/DNA based. I would assume that life elsewhere would use the same or would we not have at least found some form of micro-organism based something else?
     
  8. May 22, 2009 #7

    Chalnoth

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    Not necessarily. Once we had life, any additional proto-life that began to form would make excellent food for existing life, and as such wouldn't survive very long. So without knowing the details from chemistry of what is or is not possible, the mere ubiquity of RNA/DNA doesn't necessarily mean that other molecules are not possible.
     
  9. May 22, 2009 #8
    True, but our own type started as proto-life as well and we are still here. Because there was nothing here to eat us. I am not saying its impossible, but unlikely that there have been any other types at the same time or before. If we find some kind of sign of new life starting now maybe that would be interesting.
     
  10. May 22, 2009 #9
    If only we could get a really close look at one of these new planets around a star like ours or even some of the smaller bodies in our own solar system. Maybe we could find fossils any kind of sign to study.
     
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