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Thread: Evolution

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    Supporting Member spot's Avatar
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    Evolution

    A bacterium which uses no oxygen or carbon dioxide in its metabolism is described at http://news.bbc.co.uk/1/hi/in_depth/7663927.stm

    The most telling detail in there for me is "It was identified in DNA". This bacterium, like every other life form ever detected, uses DNA to encode its genetic heritage and to express itself as an individual.

    I would venture to guess that a significant fraction of the DNA in that bacterium is also found in you or me.

    I assume that the evolutionary steps to go from an inorganic environment to a DNA-based lifeform are far more complex than the steps to go from the common ancestor of that bacterium and people to the modern world. I have absolutely no idea what those early steps involve. The ones after the common ancestor arrives are trivially easy to follow by comparison, it's like following a thousand footsteps across a field, each representing a type of event, and analysing only the very last of them.

    What stable states of life are there before DNA takes the reins?

    Why has nobody yet found one? That's the big puzzle, to me - that there's not even small outposts of these intermediates alive today. There are undoubtedly places where competition wouldn't have driven such intermediaries from their niches. Is it that nobody's looked yet? Or is it that the possible niches are so small by comparison to the world in which they developed that they've just not clung on for those billions of years?
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  2. #2
    Scrat
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    Re: Evolution

    What stable states of life are there before DNA takes the reins
    I guess you have to ask the question, what is life? I cannot help but think that our current definition of life is as limited as knowledge of our universe.

    I read a very interesting article about the future of humanity and evolution. It seems we are actually getting to the point of being able to control our own evolution and even acquiring the ability to defy death, nothing less than immortality.
    If humans are ever so advanced as to be able to record the memories, personalities of a person in such a way as to maintain the awareness and individuality of said person, is that person still living?

    From my knowledge of the processes that created DNA there appears to be no stable states of life (as we know it) before the creation of it. Some first molecule aquired the abilty to replicate itself in some way thus came about DNA, there was not a living process before that. I think there is a force behind the engine of creation though. Given time order comes from chaos. I believe this is a universal constant, could this creation of order be the key?

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    Supporting Member spot's Avatar
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    Re: Evolution

    You're suggesting that it was a single-step process, from a purely inorganic substrate there was a key moment at which all the bits came together in one place and organized themselves into a DNA replication machine.

    That's a God-event. I'd much rather, as with all the subsequent evolution steps which don't demand a God-event, we looked for a succession of processes which each gave rise to the conditions necessary for the next and which were each stable enough to successfully await the next event.

    Just because it's hard to fathom doesn't mean it's impossible, it just means we've not experimented sufficiently.
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    When the flowers want to oxygen and nutrition, or you’re a wedding or party planner, I will help you too much.
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    Senior Member SlipStream's Avatar
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    Re: Evolution

    sorry if this sounds negative but the way things are going mankind'll die out b4 they've a chance to expaned

  5. #5
    Ian
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    Re: Evolution

    This is interesting..

    "You know, if we ever discover life on other planets, it may very well be that they live without oxygen and instead potentially use chemicals like sulphate to get their energy."

    The picture reminds me of the so called microfossil found in the Mars meteorite.
    http://www.lpi.usra.edu/lpi/meteorit...meteorite.html




    http://newsfeedresearcher.com/data/a....16.40.02.html

    http://neurophilosophy.wordpress.com...cro-organisms/

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    Senior Member Galbally's Avatar
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    Re: Evolution

    Its a series of interesting questions, I suppose what one must always keep in mind from the human perspective is the enourmous amount of time that all this self-organization has occurred over. I try to think about it, but its usually overwhelming. We do know that the basic building blocks amino acids are very readily made given the right conditions, and that stability seems to be promoted by the organization of these amino acids into the RNA and DNA structures, which of course have become self-replicating and now dominate every niche in the planet.

    My own guess about the absense of any other form of code other than the DNA which every living thing is based upon, is that at the level of self-replicating amino acids and proteins, the rewards of being the most sucessful replicator was the complete overwhelming of any other form of biochemical replicator, and once that foothold was established by DNA-based forms, it was impossible for any other replicator to compete, hence the 100 percent dominance of DNA now, and the question of whether there could have even been another type of replicator.

    I suppose the really big underlying question is why all this organization on such a complex level, which is very difficult to answer other than in vauge philosophical or religious terms, in that the universe seems to be based on laws that promote inherent organization for some reason and life seems to be one of the functions of this organization, unfortunately from a human perspective we ourselves are a part of this process of evolving pattens of complexity, so its hard for us to have any sort of perspective upon it.
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    Supporting Member spot's Avatar
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    Re: Evolution

    I agree entirely with what you say Galbally. By all means make the first step employ amino acids which are, as you say, readily available from non-life processes. By all means have them self-organize into DNA, large though that step may be - I have no problem with that as a single step. What leaves me totally lost is the extent of code which has to be put in place before self-replication can happen and functionality exist. What steps are needed to go from any number of random assemblies on a DNA construct and the emergence of functionality? That's the step too far, regardless of the length of time available. You're agreed that you need a chance event to bring those amino acids into conjunction in the first place. That's one, and it didn't randomly generate functional code. Then it happens again, on a different occasion, and again and again, all separate fortuitous events. Bear in mind that these are themselves remote and unlikely conjunctions. What's the simplest functional code that'll self-replicate? I think it's an immensely complex program, that simplest possible code set.

    It's the sort of thing ideally suited to computer simulation. That's the way I'd see it being cracked but it's rather a larger problem than this distributed protein folding FG's been engaged in. It's not just a developmental jump to go to what I'm talking about, it's a different scale altogether.

    Assume that such a sequence of steps can be simulated and that the minimum possible DNA sequence can be demonstrated which is self-replicating, granted the optimum environment. The single step you're faced with is assembling that sequence randomly because there's no earlier stage which fulfils my requirement of being a stable step which can exist indefinitely waiting for the next step to occur. That's the jump from non-life to life. It's the jump which leaves me puzzled. It seems a huge one to assume to be possible in the single universe we see around us.
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    The watch of your vision has become reasonable today.

    It’s normal. You must provoke. You must insult the belief of all monotheists. You must make fun of the belief of all monotheists.
    From the upper tier of the Leppings Lane End of the Hillsborough Stadium, I watched the events of that day unfold with horror.
    When the flowers want to oxygen and nutrition, or you’re a wedding or party planner, I will help you too much.
    Write that word in the blood

  8. #8
    Scrat
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    Re: Evolution

    You're suggesting that it was a single-step process, from a purely inorganic substrate there was a key moment at which all the bits came together in one place and organized themselves into a DNA replication machine.
    I think inorganic is the wrong word. At some point in time some organic molecules got together and somehow became capable of replicating themselves. There was a first set of DNA as we know it. Before that I think you get back to the question of life and what it is.
    Is a virus a living organism? Not by our standards, it cannot reproduce on its own having to use hosts, it does not not have a cell wall.
    Organic compouds are known to be abundant all around us in a chaotic form, they if given enough time will become something more organized. Life will arise from them, I have no clue just how that can happen in progressive steps nor does anyone else, other than random chance. To imply anything else other than random chance is to imply tampering by a conscious entity.

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    Supporting Member spot's Avatar
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    Re: Evolution

    You're just playing with the word "organic" - I was brought up to understand it to mean carbon-chained. These amino acid bases are commonplace in nature from chemical processes which don't involve life.

    Are there any viruses which aren't DNA/RNA coded? Whether you start off with something that eventually becomes a virus or something that eventually becomes a bacterium doesn't affect my core puzzle - how you get that minimum coded information set to come together when nothing less informationally-dense can build toward that starting point. All the information has to be brought into being in one moment in time in one place out of components which aren't alive.
    Nullius in verba|||||||||||
    Who has a spare two minutes to play in this month's FG Trivia game!

    The watch of your vision has become reasonable today.

    It’s normal. You must provoke. You must insult the belief of all monotheists. You must make fun of the belief of all monotheists.
    From the upper tier of the Leppings Lane End of the Hillsborough Stadium, I watched the events of that day unfold with horror.
    When the flowers want to oxygen and nutrition, or you’re a wedding or party planner, I will help you too much.
    Write that word in the blood

  10. #10
    Scrat
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    Re: Evolution

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    Are there any viruses which aren't DNA/RNA coded?
    None that I know of personally, although I have no doubt there are somewhere. If you're referring to another medium of encoding information for such uses as replication and reproduction, other than carbon based building blocks I see no reason why it couldn't happen. Why not another element instead of carbon?

    Why not silicate based life? It would be fundamentally different outwardly to us but I am sure it would use the same techniques to reproduce itself as nature does here. It's got to follow the same rules as carbon based organisms.
    The information carried would be done in the same way, the medium used to carry it can be different as would the process after a point of complexity.
    The only way to possibly get around this is evolving into another state which frees the process of life from the constraints of the physical laws that govern this universe.

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