Two theories of life's origins

Two distinct theoretical approaches have emerged in the quest for explanations concerning the origins of life. One school of thought subscribes to the idea that metabolism predated genetics. The main proponent of this theory is Dr. Günter Wächtershäuser, a chemist by training, and now a patent lawyer in Munich.

Dr. Wächtershäuser thinks that life on Earth had hydrothermal origins, - i.e., probably near deep hydrothermal vents on the ocean floor. Metabolism by this reckoning involves the evolution of progressively complex chemical reactions ultimately yielding life out of primitive energy exchange mechanisms in a cyclic process. This process of evolutionary development has come to be known as the iron-sulfur world theory.

The iron-sulfur recipe described by Wächtershäuser can be summed up by the following: bring water to a boil and stir in iron sulfide and nickel sulfide. Mix in carbon monoxide and hydrogen sulfide gas, and then wait for the amino acids to convert into peptides.

In 1997, Wächtershäuser and Claudia Huber actually performed the experiments and successfully produced peptides by mixing carbon monoxide, hydrogen sulfide, nickel sulfide, and iron sulfide particles at 100°C. In 2006 the two collaborators produced glycine, alanine and serine from a similar mixture. These are simple amino acids found in proteins. Potassium cyanide was their source of nitrogen.

A clear description of a proto-ecological system exists, from the establishment of the catalytic environment consisting of micro scale caverns coated by thin membranous metal sulfide walls up to the synthesis of the lipid membrane which finalizes the creation of a true living cellular organism capable of escaping the confines of the alkaline hydrothermal vent environment. The condition of the “life form” up to the evolution of the lipid cell walls represents the “Last Universal Common Ancestor” (LUCA).

RNA world hypothesis is the title given to the other explanation for how life began. In this scenario, RNA predates the emergence of DNA-based life – i.e., genetics before metabolism. The logic in this theory lies in the fact that RNA can act as both a storage mechanism and a catalyst. The thinking is that ribosomal RNA, which catalyzes protein production, is the evolutionary remnant of the RNA world.

Some adherents to the theory suggest that pre-RNA nucleic acids, which manifest in the pre-biotic environment, were the first types of nucleic acids to emerge as a self-reproducing molecule. Among the candidates are peptide nucleic acid (PNA), threose nucleic acid (TNA), and glycerol nucleic acid (GNA), all of which are similar to RNA but for their backbones, which are not composed of the ribose sugars that comprise RNA. For example, TNA is composed of repeating threose units linked by phosphodiester bonds. These molecules do not occur in the natural conditions of today's Earth.

What encourages RNA world hypotheses is the fact that short RNA molecules with self-replicating properties have been synthesized in the lab. What discourages the theory is that stable pre-biotic conditions would have to exist which encourage the proliferation of self-reproducing RNA-like analogs. This includes the ability of these molecules to have been capable of independent life in an environment dense with sugar-phosphate molecules.

The iron-sulfur world theory is very compelling. It is likely that both processes occurred in the earliest stages of the emergence of living organisms, with the RNA world only a phase predated by the iron-sulfur world.

That is not to say that other conditions cannot bring about the beginnings of primitive life forms. In an earlier post, I noted Carl Sagan's description of a prebiotic Earth, and that they were very much the same as those which currently exist on the moon Titan, around the planet Saturn. It wouldn't surprise me in the least if some type of methanogen were periodically struggling to emerge there.

Whichever of the two theories of life's origins holds sway, the fact remains that they are both integral to a theory of origins based on anthropic reasoning, which yet remains uncomfortably lodged in the realm of philosophy more so than in true science. However, one can't deny that life is determined to emerge, however it comes about.

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Proving the beginning

M. Bendio of Orem, Utah asked the experts at Scientific American Magazine the following question:

"According to the big bang theory, all the matter in the universe erupted from a singularity. Why didn't all this matter--cheek by jowl as it was--immediately collapse into a black hole?"

Surprisingly, he is answered by a pool of experts who each state their version of the explanation. They are Scientific American astronomy editor George Musser; Robert J. Nemiroff, assistant professor of physics at Michigan Technological University; Christ Ftaclas, associate professor of physics, also at Michigan Tech; and Edward L. Wright, vice chair for astronomy at the University of California at Los Angeles who closes his response by saying...

"..the advanced reader could look at the technical solution to the question. Solving the field equations will show that the space metric in a Friedmann-Robertson-Walker universe expands from infinite density without forming a black hole."

The four respondents more or less agreed as to why the Universe did not immediately collapse into a black hole. In short, black holes are relative singularities in that they can only occur in non-homogeneous environments. In the beginning, every region in the expanding Universe in creation had equally probable outcomes. No relative non-homogeneity existed until after the process of formation of stars and galaxies.

Wright's response is a fascinating confirmation of my own simple model in which there was a beginning before which nothing existed and at which space/time and matter evolved. I interpret nothing as having an infinite density with therefore an infinite potential so I am able to accept that we are living in a Friedmann-Robertson-Walker universe without doing the math, and I am relieved about that since I admit to a different species of advanced readership than that required to extrapolate that monster.

I doubt that mathematics will ever deliver the explanation for what started everything to begin with, so we will have to settle for speculative idealizations until such time as we can reproduce the process to prove them, itself an impossible feat for obvious reasons. We can as an exercise, however, draw some conculsions from the evidence that we exist at all in a Universe which for our purposes will be around for some time yet.

Let's not take consciousness and life for granted. Let's assume that they represent the true nature of the Universe, ie. -- that it is anthropocentric in nature. In other words, the Universe would not exist without the presence of life. Now, that's not like saying, if a tree falls in a forest and there is nobody there to hear it would it make a noise? Of course it would. The point that I am making is that the initial moment of creation was produced by a stimulus precipitated by the precognition of the conscious, cognizant sentience which exists as the necessary predisposition which brought that quantum fluctuation about. Causal precognition is not dependent on a directional temporal framework. In this case it actually creates time after the fact of its impact. It is after that initial impetus that the infinite potential of nothing is realized and becomes manifest as the difference between nothing and existence thereby laying the groundwork for the establishment of the polarized physical concepts which contain the laws to which reality conforms. The paradoxes that abound throughout creation are the glue which maintains it.

The Universe can only be observed from within. I think that creation continues at the periphery. What this Universe represents is a very heavy idea, that anything existing at all is so staggeringly awesome and profound that it alone provides the fuel for that precognition: the premonition. We are present to make existence rational. It only makes sense, at least to me, when seen in this light.

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