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W.R. STOEGER S.J.
73
1 (2008) 64-77
Unforeseen events and occurrences from outside the immediate environment can intrude
– very violently. A large meteoroid can collide with the planet, a nearby star can
become a supernova bathing everything in lethal radiation, the whole system can collide
with another system suddenly altering all the conditions. But these, too, can eventually
lead to new and promising evolutionary tracks.
Thus, there is a range of directionalities coded into physical reality as it is constituted
by the systems and entities, by the conditions, and by the processes, regularities and
relationships which obtain at any given time. There is more to this than merely a pattern
of regularities that we observe. That pattern must have some sufficient cause in the
structure of nature itself. With Paul Davies 1 I locate this cause in the laws of nature
themselves. The directedness and propensities we discover in nature and in the evolutionary
process is due to the laws of nature, the inherent regularities and inter-relationships
within reality.
At his point we need to consider the appearance of those molecules capable of reproducing
themselves which are the immediate precursors of life on Earth. We are, of
course, interested in the fabrication of amino acids and nuclei acids, the basic constituents
of proteins and DNA/RNA, respectively. How did the rich variety of proteins
and the replicating DNA sequences coding for them arise? Could this have happened
just as a result of the chemical and physical regularities and relationships operating
under certain constraints and conditions?
The answer to this question is, “Yes!” Though we cannot say for sure how in fact it
did happen, we now know that it could have happened, for instance, by the operation of
autocatalytic hypercycles consisting of mutating DNA or RNA sequences coevolving with
the proteins for which they code. The diversifying DNA/RNA sequences lead to new
proteins, and the proteins in turn enable the maintenance and faithful replication and
evolution of the DNA/RNA sequences. Those nucleic acid sequences and proteins which
are best suited to the environmental conditions will be preferentially replicated and
will eventually dominate. Natural selection is already important at this level, and is absolutely
crucial for the gradual emergence of life. Mutations in the genetic templates, which
enable the systems to seek for even better or more advantageously adapted configurations,
and the metabolism of these replicating molecules are also essential for evolution.
Many researchers have investigated the ways in which the formation of necessary
prebiotic molecular components for self-replicators could have been accomplished on
the primitive Earth. They have suggested possible mechanisms for the synthesis of most
amino acids, sugars and nucleic acids. A few of the required components are more difficult
to account for, particularly ribose and the pyramidines, and some necessary processes
are difficult to fit into the overall scenarios. But it seems likely that further work
1 Cf. PAUL DAVIES, “Teleology without Teleology: Purpose Through Emergent Complexity,” and
WILLIAM R. STOEGER, S. J., “The Immanent Directionalitiy of the Evolutionary Process, and Its Relationship
to Teleology,” both in Evolutionary and Molecular Biology: Scientific Perspectives on Divine Action,
edited by ROBERT JOHN RUSSELL, WILLIAM R. STOEGER, S. J., and FRANCISCO AYALA, Vatican Observatory
Publications, Vatican City State and the Center for Theology and the Natural Sciences, Berkeley, CA,
1998, pp. 151-162, and pp. 163-190, respectively.