November 08, 2005

Abiogenesis: A Problem of Origins (part 3)

(Part 3 in a 3 part series)

Building Mansions

Assuming we have everything necessary to begin assembling proteins, what problems are then encountered? Let me use the analogy of language to illustrate the problems.

The building blocks of language are letters. These are analogous to amino acids in that there is a specific group of them — the alphabet — out of all possible symbols that are employed to make words. Likewise, amino acids come in a wide variety, but only 20 specific ones are involved in forming the proteins utilized in biological systems. The problem is that even were conditions somehow right to supply all the essential amino acids, there is still no assurance that dozens of non-essential ones wouldn't be present as well.

The next requirement for our "letters" is that they are facing in the correct direction. The equivalent in the world of amino acids are left-handed and right-handed molecules (chirality), and since they are three-dimensional structures, it is not simply a matter of flipping a single molecule in the right direction; they are two different though mirror image molecules. Proteins are assembled using only left-handed amino acids (homochiral), but again, any process that might produce amino acids is just as likely to produce right-handed as left-handed ones, as occurred in the Miller-Urey experiments. And a left-handed molecule has no greater affinity for its own kind than it does for the other.

Next we must string our letters together to begin forming words and sentences. Likewise, proteins are formed by stringing amino acids one-to-another in linear chains (polypeptide bonds). The thing is, amino acids can just as readily be connected in any number of other three-dimensional formations. Just as numerous links could attach at any given point on a chain rather than just end-to-end, so could amino acids branch and cluster in infinite patterns if unconstrained.

Just as characters ultimately form meaningful sentences and paragraphs, so are proteins the completed units of their chemical language. Proteins may be anywhere from 100 to several thousand amino acids in length. But not just any string will do; it must be a complete string which has "meaning." For a protein to be meaningful it must be arranged in some particular way that allows it to serve some utilitarian purpose. Just as a wrench is better for bolts than a lump of metal, so proteins must be "shaped" to serve their own purposes. This "shaping" involves having just the right amino acids in the right places, which allow the folding and binding of the chain into chemically active formations. The problem here is that there are vastly more arrangements that yield meaningless shapes than meaningful ones, just in the same way that random letters are vastly more likely to make gibberish than meaningful sentences.

So, in the process of assembling proteins, chance must overcome the following obstacles as it connects amino acids: Each new molecule must be another amino acid, and it must be one of the essential 20. Each must be left-handed only. And each must assume a peptide bond. Now, considering that we must repeat these conditions at least 100 times (for the simplest protein), and that what results must also be meaningful in some way, we soon reach odds that have been conservatively estimated at 1 chance in 10120 against such a thing happening without guided assistance. To satisfy these odds we would have to convert all the matter in the universe into a prebiotic soup, mix it a trillion times per second, and then wait up to one trillion, trillion years for our results (the universe is alleged to be only 13.7 billion years old).

But let's not stop the fun just yet; let's assume we can build such a protein. What good will it do? It has to survive and reproduce or it will be just a fortuitous blip on the geological time-line. And even if this lonely molecule could somehow reproduce, it is a long way off from our target of cellular life. Even if a child could build a skateboard, it would be a rather meager step toward building a Porsche.

The simplest known organism is mycoplasma gentalium with 482 proteins. But this is a parasite, meaning that a free-living organism must be more complex yet to provide its own energy and material sources (e.g., photosynthesis or chemosynthesis). The problem with the cell is that it is not just a more complex version of a self-replicating molecule; it is a whole new-order entity: an "irreducibly complex" system.

The cell solves the problem of protein production by including protein-building factories: ribosomes. But these "machines" can do nothing unless given instructions, by the RNA, on which amino acids to assemble. And the RNA knows nothing until it reads it from the DNA library. But RNA and DNA cannot come into being without the assistance of certain proteins manufactured by the ribosome. There is a 3-way dependency here without which no member could survive or function, and this does not include other essential components, like the cell membrane, which enfolds all the participants and protects them from the hostile elements.

Since there are chemical similarities between DNA and RNA, some have suggested that the precursor to the first cell may have been some form of self-replicating RNA molecule, the simplest of the two. But of all the problems encountered by amino acids and proteins, RNA and DNA molecules have these and more. This is because they are not only similarly arranged to form their unique structures (right-handed, difficult to make nucleotides in chained structures), but they are also "information" bearers. And whatever is the first complex structure to form must not only be able to produce more of itself, it must be ultimately capable of producing other distinct, complementary assemblies.

Plant physiologist (and evolutionist) Frank B. Salisbury summarizes the immense problems as follows:
Surely our ideas about the origin of life will have to change radically with the passage of time. Not only is the gene itself a problem: think of the system that would have to come into being to produce a living cell! It's nice to talk about replicating DNA molecules arising in a soupy sea, but in modern cells this replication requires the presence of suitable enzymes. Furthermore, DNA by itself accomplishes nothing. Its only reason for existence is the information that it carries and that is used in the production of a protein enzyme. At the moment, the link between DNA and the enzyme is a highly complex one, involving RNA and an enzyme for its synthesis on a DNA template; ribosomes; enzymes to activate the amino acids; and transfer-RNA molecules. Yet selection only acts upon phenotypes and not upon the genes. At this level, the phenotype is the enzyme itself. How, in the absence of the final enzyme, could selection act upon DNA and all the mechanisms for replicating it? It's as though everything must happen at once: the entire system must come into being as one unit, or it is worthless. There may well be ways out of this dilemma, but I don't see them at the moment.
In light of these and other difficulties and disappointments in the field of origins research, the theory of "panspermia," proposed by the likes of DNA discoverer Francis Crick and Oxford chemist Leslie Orgel, has become an attractive option to some (and a common movie theme). Panspermia is the idea that life was seeded on earth from outer space, either by a chance occurrence (non-directed panspermia) or by way of alien intervention (directed panspermia). It is a tacit admission of the failure of science to produce a naturalistic, earth-bound explanation, and it is a desperate hope by either path.

Chance-created life from outer space must not only overcome most of the same chemical assembly issues as on earth, it must be transported here through long, hard years of hostile conditions (e.g., cold, heat, intense radiation). And alien directed life means that we must account for the rise of such an alien race, which itself must appear by chance and take its billions of years to evolve. Besides being no ultimate answer to the origin of life from matter, it pushes the time in which it must appear into the deep recesses of a young, unruly universe. Origins of life research has been a disappointing field of study, though it continues to be pursued by an adventurous few with unfounded optimism and a vivid imagination.

Conclusion
More than thirty years of experimentation on the origin of life in the fields of chemical and molecular evolution have led to a better perception of the immensity of the problem of the origin of life on Earth rather than to its solution. At present all discussions on principle theories and experiments in the field end in stalemate or in a confession of ignorance.
Klaus Dose, "The Origin of Life: More Questions than Answers," Interdisciplinary Science Review 13 (1988), 348.
If Darwin had only been privy to the details of what he was seeking to explain then there is reason to speculate over the strength of his convictions. But once a theory is entrenched it is difficult to dislodge, even while decade-by-decade its probability is eroded away by the actual data. But having put God out of the business of creation, and banished Him from the realm of science, evolutionists are stuck with the task of making the impossible seem plausible, and portraying their skeptics, ironically, as faith-blinded fools for doubting that they will one day find their answer.

This is not to suggest a mere "God-of-the-gaps" solution, like appealing to the wrath of Zeus prior to the understanding of electro-static atmospheric discharges (lightning). There is a difference between proposing something based on ignorance and proposing it based on the detailed knowledge you do have. The problem is that we have acquired a pretty darn good understanding of how chemistry operates, and this problem of abiogenesis looks intractable in principle. If science were about reasoning to the best explanation, then intelligent design must surely be given the courtesy of consideration.

For further reading on this topic:

The Origin of Life and the Death of Materialism
Abiogenic Origin of Life: A Theory in Crisis
Loopholes in the evolutionary theory of the origin of life: Summary
The RNA World: A Critique
Life: An Evidence For Creation

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2 Comments:

At 11/09/2005 1:38 PM, Blogger Jeff said...

Those quotes are particularly compelling.

There's a peer reviewed secular scientific journal with an article from a pre-eminent scholar of this branch of science. And he's saying that he's clueless, and can't even conceive of a possible solution...

Yet we have supposedly objective scientists objecting vehemently against a statement being read to high school biology students stating simply that there are 'holes' in darwinian theories.

Think their objections are based on science? Not a chance.

 
At 11/10/2005 9:44 PM, Blogger daleliop said...

Nice pun in your last sentence, Jeff. :)

 

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