Almost two years ago, I wrote an article entitled "What is life - Part 1" describing various aspects of life that dealt with the issues of "intent" and "purpose".  These are obviously heavily loaded terms, and represent a tremendous difficulty in defining life and trying to come to terms with the obvious and yet inexplicable behaviors we see.

Yet, we all recognize this type of behavior and biology even uses the term teleonomy to characterize this (1).

Now, the problem faced in biology is that we have these "purposeful" systems called organisms, and yet we must simultaneously recognize that they originated from inanimate processes.  Often the phrase "emergent properties" is used to describe this, but this ultimately explains nothing.  Similarly concepts like "self-organization" may describe what we observe but it offers no explanation as to why we see the behaviors we do.

In considering the transition from basic chemical processes to life, we are faced with the difficulty of having to explain the origin of life.  However, we can gain some insights and avoid the tangled problem of origins, if we can utilize an existing organic molecule [RNA enzyme] and establishing whether it might be subject to Darwinian selection and evolution.  The answers this would provide can handily sidestep the questions around the origin of life and leave that as a separate concern, while simultaneously establishing that chemical processes may actually be subject to the same kind of selection pressures [or something quite similar] we observe in organisms that are alive.

One of the essential points here is that RNA is not alive.  So whatever "behaviors" one observes are simply a property of the chemistry involved and cannot be construed as anything more.  Similarly, by using an RNA enzyme, we don't have to address the question of how such a molecule formed, or deal with the historical process that might have produced such a molecule.  We simply take it as given, and attempt to see if its behavior is comparable to biological systems.  Finding such a link would strengthen the argument about an RNA world, or some such organic molecules achieving higher degrees of complexity, ultimately producing "life".

In fact, precisely such experiments were performed, with some very interesting results.

An autocatalytic RNA ribozyme was used as a replicator, but was only able to double, twice, over a period of 17 hours.  However, when two RNA ribozymes were employed using a cross-catalytic network, replication occurred within an hour and could be sustained indefinitely.  In effect, these cross-catalytic ribozymes demonstrated the equivalence of chemical "cooperation"
The above results, though still limited in scope, suggests that cooperative behavior can emerge and manifest itself at the molecular level, that the drive toward more complex replicating systems appears to underlie chemical, and not just biological, replicators.
However, despite these results, it is important to recognize that one cannot arbitrarily extend the Darwinian theory into the realm of chemistry.  Darwin's theory is a biological theory and must be extended and refined if it is to include biological precursors in chemistry.
The observation of Darwinian-like behavior at the chemical level is highly significant, not because it suggests that molecules behave in a biological fashion, but because it opens up the possibility of explaining biological behavior in chemical terms.
An additional biological concept that has a chemical corollary is the "competitive exclusion principle" where two absolute competitors cannot coexist in the same niche.  One will be driven to extinction.  In the chemical version, we find that two replicators that are dependent on the same resources will result in one of the replicators also being driven to "extinction".  
Thus chemical natural selection appeared, the first step in the transition from inanimate to animate matter. It initiated the first animate property, fitness, i.e., the capacity to adapt to the environment and to survive. can therefore say that biological natural selection emulates chemical kinetic selection, i.e., biology reduces to chemistry for this most fundamental of biological phenomena
Perhaps one of the most striking results occurs when two RNA ribozymes competed for five substrates.  When they competed for the same resources, extinction was assured for the least efficient of the enzymes.  However, the availability of multiple substrates, comparable to multiple niches, resulted in mutations accumulating and each enzyme "evolving" to utilize available substrates without direct competition, thereby assuring the survival of both, by "adapting" to their own respective niches.  
The competitive exclusion principle states that 2 species that compete for the exact same resource within the same environment cannot stably coexist.

However, when the 2 enzymes were presented with 5 potential substrates, each enzyme adapted to use a different substrate, demonstrating what is termed ‘‘ecological character displacement’’. Once differentiated in this way, the 2 enzymes were capable of sustained coevolution, which in principle could be continued indefinitely.

In the present study, those interactions were entirely competitive, but other types of interactions, such as commensalism or predation, might have emerged.
The upshot of all this is that these experiments strengthen the ideas that biology can be ultimately reduced to chemistry.  Given the constraints mentioned previously in not merely jumping to biological conclusions when there are chemical similarities, but rather to consider that when chemical systems can "behave" in comparable ways to the principles governing biology, then there is a reason to be optimistic in presuming that this scientific gap can be bridged.  


(1) For more discussion regarding the teleonomic nature of biological systems [and possibly making sense of it].