Naturalistic theories concerning
life’s origin began to take shape in 1953. Watson and Crick unraveled the structure
of DNA, and Stanley Miller performed an experiment showing that amino acids can be
produced in a spark chamber. Most scientists of the day assumed that the mystery of
life’s origin would be solved in a few years.
The early pioneers in this field realized that a complete living organism,
like the bacteria in figure 9.1, could not spontaneously appear in a spark chamber or in
any other environment governed by purely naturalistic laws. The pioneers needed the first
form of life to be simpler than anything that is present on earth today.
Figure 9.1: Information Transfer in a Bacteria Cell
Initial theories hypothesized that the first living thing was a protein. This
assumption seemed reasonable at the time because many of the building blocks of proteins,
amino acids, are easily synthesized under plausible prebiotic conditions. Because proteins
regulate and control almost all of the activities necessary for life, the living protein
theory quickly gained widespread acceptance, but soon scientists realized that there was a
major flaw with the protein theory.
Proteins cannot self replicate, so the first living protein would not be able
to reproduce itself, and without replication there can be no natural selection; therefore,
the first living protein would have no way to evolve.
This issue led to the demise of the protein theory. In its place, emerged the
RNA theory. This theory gained substantial momentum when it was found that just like
proteins some RNA molecules can catalyze chemical reactions. Recently this theory has also
fallen out of favor because it has its own set of problems which will be discussed later.
Today the most popular theory involves a self replicating pre-RNA molecule.
Self replicating molecules are probably not the best theory to pursue,
because such molecules cannot reproduce for any length of time without running into
serious problems with the second law. Nevertheless, many researchers in the origins field
are absolutely sure that the first living thing was a self replicating chemical, and their
point of view is understandable. There is simply no chance that a complete bacterium
spontaneously formed from the chemicals in a puddle four billion years ago. In many ways,
a self replicating molecule that violates the second law is a better choice.
Nevertheless, the second law should not be casually dismissed because its
existence explains why investigators have not been able to create a self replicating
molecule in the lab. Unless a self replicator has the knowledge and ability to harness the
power of sunlight (or some other abundant energy source) and use this energy to drive its
own replication, then its lifetime will be short lived and its existence forbidden by the
laws of physics.
The origin of self replication requires a solution to three problems:
• Chemical evolution must create a protein, an RNA molecule or an
RNA like molecule.
• This molecule must possess the molecular knowledge that enables
self replication. It must also be able to implement this knowledge.
• The molecule must possess the molecular knowledge needed to
harness an energy source to do useful work, and it must also be able to implement this
knowledge in such a way that the energy source drives replication.
Experiments investigating the origin of life have for the most part ignored
the last issue. This is understandable because until a molecule that can at least
replicate itself for a little while can be found, there is no need to try to find one that
can replicate itself indefinitely. This chapter will investigate the prebiotic synthesis
of RNA and proteins. The next chapter will investigate self replication.
The pioneers in chemical evolution expected to show that the primordial ocean
was full of biological molecules. These researchers suggested that the early atmosphere
contained no free oxygen, and that under these conditions, the required biological
precursors should be plentiful. The remainder of this chapter will evaluate the validity
of this hypothesis.
It is difficult to synthesize the relevant molecules, and today this
difficulty has led most to conclude that the primitive ocean contained a very limited
supply of biological precursors. This finding does not mean that the primordial soup did
not exist. It does mean that the primitive ocean was not the primordial soup because any
relevant molecules in it would be too dilute.4,11,18
It is possible to imagine environments that will concentrate biological
precursors, but this leads to further problems. It limits the soup in such a way that the
conditions necessary for its existence rarely exist and leads to the perhaps alarming
conclusion that even given 5 billion years the soup may not have existed.
Origin of life theories often speculate that hydrothermal vents like
the ones shown in the pictures that I took in Dominica are responsible for the origin of
life. Since these vents exist today, plenty of oxygen in the atmosphere would prevent the
formation of useful prebiotic precursors that might give rise to life. The first
picture is in the valley of desolation on the trip to the boiling lake and the
second is in about 30 feet of water at a dive site called Champagne. The bubles are
created by hydrothermal vents.
 
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