Biology Darwinism Evolution Self-Org. Theory

Putting the Cart Before the Horse

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When it comes to discussing open systems aren’t we getting a little ahead of ourselves here? There are still some very basic problems to solve before getting into hand-waving over the evolution of computers and human minds.

http://www.pnas.org/cgi/content/abstract/0605863103v1

Solutions with as little as 1% enantiomeric excess (ee) of D- or L-phenylalanine are amplified to 90% ee (a 95/5 ratio) by two successive evaporations to precipitate the racemate [mixture]. Such a process on the prebiotic earth could lead to a mechanism by which meteoritic chiral {alpha}-alkyl amino acids could form solutions with high ee values that were needed for the beginning of biology.

1. A homochiral protein is of no use without a homochiral sugar to match with in the genetic code. Breslow and Levine refer to other researchers who have found possible ways this might have happened, though so far with only 10% success at best, and not under plausible prebiotic conditions.
2. It only worked with the alpha-alkyl amino acids (so far, although they said they are testing other kinds).
3. All the amino acid types would have to be left or right-handed. Consider that there are 20 different amino acids in living organisms (and please don’t start arguing over the definition of “living” 😛 ).
4. Unlike the protected and sterile environment of a lab, in realistic prebiotic conditions nothing is going to prevent the next natural disaster or even a medium-sized wave from messing it all up.
5. The need for repeated evaporations severely limits the physical space where all required ingredients could form and process their walk through configuration space. Now whether this walk is completely blind or random depends on whether certain chemical laws facilitate such processes.
6. This scenario rules out the deep-sea vent and open-ocean scenarios. Going by previous conferences that focus on abiogenesis, proponents of those views are undoubtedly going to search for any holes in this new scenario.
7. Evaporative environments expose the amino acids to destructive ultraviolet radiation.
8. There is still the problem of getting amino acids to link up into polypeptides which then need to form a functional sequence.
9. One mis-handed amino acid in a growing chain will still render it useless for biology. The chance for this happening, even if amino acids did link up somehow, grows with the length of the chain.
10. Even if a pure polypeptide formed, there still needs to be a genetic code that is also homochiral and capable of replicating.

13 Replies to “Putting the Cart Before the Horse

  1. 1
    Jehu says:

    Claiming that natural processes can create amino acid and therefore life is like claiming that natural process can create steal and therefore automobiles. Except that life, even the simplest

  2. 2
    Mats says:

    [OFF TOPIC]
    hey, what do you think of this?

    http://www.faultline.org/place.....03063.html

  3. 3
    mike1962 says:

    Mats,

    If books on ID belong in the religion and social sciences section, so does much of NDE. Maybe someone should write a letter. 🙂

  4. 4
    jwrennie says:

    Patrick I think you are being entirely unreasonable here. I mean seriously, didn’t you know that all of these steps can be accomplished by magic, umm … er .. I mean … Natural Selection.

    Your appeal to all these obstacles and problems is just because you are an ultra religious fundie who wants to send science back to the dark ages and establish a theocracy centered around not having any fun.

    Seriously, where is your imagination. If you can imagine it then it must have happened that way.

    😛

    Jason

  5. 5
    Mats says:

    Mike1962,
    What is irrational is the uncontroled panic that Darwinists show everytime their religious myth is under scrutiny.

  6. 6
    idnet.com.au says:

    At best, getting the left handed amino acids that are used in life if like getting the english alphabet.

    The alphabet has nothing to do with the meaning of the words that it is used to communicate. This point was made very well years ago by AE Wilder-Smith. Media vs message. Voie http://www.idnet.com.au/files/.....atural.pdf makes a similar point well.

    Amino acids are essential to make functioning proteins, as letters are essential to make english words. Letters do not lead directly to words, and even words themselves have no independent meaning.

    The simplest life form needs at least 400 very long (50-500 letters long) protein words that work together in unique and meaningful way to make the novel of life.

    Even one specific small 50 letter protein word would be virtually impossible to get by chance. What will that one impossible word do while it waited for the other 399 impossible words to form and find it geographically by chance? It is silly even to speculate such a senario.

    To type just one specific 11 letter english word by chance typing one letter every second would take the entire history of the universe.

    Does anyone really believe that the origin of life can ever be explained without intelligence?

  7. 7
    David vun Kannon says:

    idnet.com.au,

    Hop over to that other thread and check out the Orgel paper that DaveScot so helpfuly referenced. In the RNA World hypothesis discussed there, self catalyzing RNAs rub up against each other and get the evolutioary ball rolling before we have to worry about proteins.

    But the main point is that smaller networks of mutually catalyzing RNAs need to be shown to stable, accumulative, and able to merge into larger networks before we get to 400 internetworked oligonucleotides.

    Getting from here to there is not worthy of being dismissed, it is worthy of being researched.

  8. 8
    David vun Kannon says:

    Patrick,

    For some people, the back of the envelope kind of calculation Sewell attempted is a useful sanity check. That isn’t putting the cart before the horse. Sure, all the points you bring up will require active research, but without a high level sketch of things, we wouldn’t be sure it was worth investigating at all.

    Now in this instance Sewell’s high level sketch is flawed, but the idea of doing such a sketch is fine.

  9. 9
    idnet.com.au says:

    David

    “self catalyzing RNAs rub up against each other and get the evolutioary ball rolling before we have to worry about proteins.”

    Sounds all very nice but this is evidence free science. Take a look at this stinging review of RNA hypothesis at http://www.sexandphilosophy.co.....biosis.htm

  10. 10
    DaveScot says:

    DvK

    self catalyzing RNAs rub up against each other and get the evolutioary ball rolling before we have to worry about proteins

    Imaginary RNA. You forgot to mention that the RNA World is an imaginary world.

  11. 11
    David vun Kannon says:

    idnet,

    Its hardly evidence free. Some catalytic activity by RNA was noticed by scientists and followed up, researched and refined, to get to the current hypothesis. This involved hard evidence gathering science.

    The article you reference makes a claim about the RNA World hypothesis that I have not seen elsewhere, that it depends on one special RNA molecule. I don’t think you’ll find any such notion in the Orgel 2004 review paper that DS provided reference to.

    (and as an aside, his opinion of ID wasn’t too high, either! ;-p)

    He does make an intersting observation about oscillations, and we will have to see if that is taken up by others.

  12. 12
    David vun Kannon says:

    DS:
    Imaginary RNA.

    Hypothetical would be more accurate.

  13. 13
    idnet.com.au says:

    David,

    The web page I referred you to was not supportive of ID, gut it did consider ID a scientific hypothesis.

    The article in pnas referenced above requires a subscription. I have not been able to see it.

    I think that it is of very little interest for prebiosis because it requires initial pure racemic mixture of a single amino acid. This could never happen in any conceivable prebiotic senario. At best we may get a mixture of racemic isomers of many useless and the occasional useful amino acid or sugar (less likely)

    What it does do is to openly acknowlege the severe problem of monochirality in prebiosis, which is a huge issue.

    Going on with my words to proteine (or RNA sequences for that matter). It is hard enough to make a specific word by chance. It is even harder if half the letters are mirror images of the others, even if x’s and o’s would work either way.

    I can confidently predict that what prebiotic experiments will find is that they have grossly underestimated first how difficult it is to get any single useful polypeptide or polysugar, secondly that even if we fudge it and intelligently design the poly whatever molecules, that to get an “evolving system” up and running will not happen without a whole lot more intelligent design.

    Those who are shrewd in the Evolutionary debate will stay well away from pre biosis. Even Dawkins calls life a lucky accident. That is the mest spin you will ever be able to put on it and that is tantamount to miracle.

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