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Thread: A question regarding self-replicating molecules.

  1. #1 A question regarding self-replicating molecules. 
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    I have been reading various articles on the web about self-replicating molecules created artificially. Apparently under controlled conditions these molecules can exist and replicate for a time. The hypothesis is that they were precursors to life.

    It is also my understanding that there is an inverse relationship between complexity and probability; i.e., the more complex a system is, the less probable its existence and vice versa.

    My question: Are self-replicating molecules commonly found in nature, or do they only exist under controlled laboratory conditions? I would guess they are very common given the fact they are less complex than life.


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    Can you give us the ref so we can start from the same data set?


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  4. #3  
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    Quote Originally Posted by Jorge1907
    Can you give us the ref so we can start from the same data set?
    Sorry, I have no data set. Just various articles on the web. If I had such data I could probably answer my own question, so I defer to those who might have such data.
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    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Clays are self-replicating and even show a form of heredity, in that their patterns are passed on to the layers that form above them.
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    Quote Originally Posted by i_feel_tiredsleepy
    Clays are self-replicating and even show a form of heredity, in that their patterns are passed on to the layers that form above them.
    I think I read about that, but are any of these clays organic? My understanding is they are not. Thanks for the response. I will look further into this.
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    Didn't mean your data - the ref's (I hope) are based on data. Can you give us some of the ref's?
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  8. #7  
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    Crystals are self-organising molecules and are very common in nature. Come to think of it, many patterns are self-replicating in a sense, for a start on examples try here : http://www.cs.bgu.ac.il/~sipper/selfrep/

    Some commonly seen, and bioogically useful, forms are predicted given the laws of the universe, such as spheres. Further, the composition of life (% H-C-O-etc)closely mirrors the chemical makeup of the universe (or the galaxy at any rate) arguing again for mundane explanations underlying the formation of life.
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  9. #8 Re: A question regarding self-replicating molecules. 
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    Quote Originally Posted by williampinn
    I have been reading various articles on the web about self-replicating molecules created artificially. Apparently under controlled conditions these molecules can exist and replicate for a time. The hypothesis is that they were precursors to life.
    I take it this is a reference to the work of Lincoln and Joyce using self-replicating RNA ribozymes? It's likely that the first replicating molecules were similar in concept, though there are some fundamental differences.

    Quote Originally Posted by williampinn
    It is also my understanding that there is an inverse relationship between complexity and probability; i.e., the more complex a system is, the less probable its existence and vice versa.
    Not really. Although the argument is often raised by creationists, it displays a misunderstanding both of evolution and of what probability means.

    The nature of self-replicating systems is that they undergo variation and increases in complexity incrementally. So, whilst the probability of an amoeba genome popping into existence out of a soup of nucleotides in a single step is negligible, that probability would not at all reflect the likelihood that the genome could arise incrementally over extended time. There's also the matter of specificity. In probability, the likelihood of finding any specified sequence is always higher than finding any non-specified sequence of identical size and complexity. So the probability of the exact amoeba genome emerging incrementally over time is lower than the probability of some fit sequence of comparable complexity emerging over the same time. This last calculation is the more appropriate, as evolution is non-teleological, in other words it is not moving towards any specified configuration.

    So the only meaningful question when looking at complexity in self-replicating systems is to ask "what the is probability that any similarly fit and similarly complex system could arise through incremental changes over time via natural selection and the various relevant chemical and physical laws?"

    Quote Originally Posted by williampinn
    My question: Are self-replicating molecules commonly found in nature, or do they only exist under controlled laboratory conditions? I would guess they are very common given the fact they are less complex than life.
    They're not found in nature for a couple of reasons. Firstly, they are likely to be extinct as cellular life would "prey" upon (more like just absorb and re-configure) and out-compete such life, leaving new abiogenesis as the only means for such life to appear. Second, current cellular life now consumes the organics required for any new abiogenesis. They're pretty much constantly tied up in some biological process as life is already in pretty much every place that abiogenesis could occur.
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  10. #9 Re: A question regarding self-replicating molecules. 
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    Quote Originally Posted by TheBiologista



    So the only meaningful question when looking at complexity in self-replicating systems is to ask "what the is probability that any similarly fit and similarly complex system could arise through incremental changes over time via natural selection and the various relevant chemical and physical laws?"
    Thanks for the detailed information. I think the probability is the same no matter what the result, even if life never happened. Since we are living, we tend to be biased in favor of life. For example, there is a very slim chance you will ever be struck by lighting, but whereever lighting strikes, that spot is just as improbable as any other. All it takes is a probability greater than zero to make something happen.
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