Darwin's Dangerous Idea - Evolution and the Meaning of Life

162 PRIMING DARWIN'S PUMP The Laws of the Game of Life 163
and synthesis, show that sequences rich in G and C are best at self-replication
by template instruction without the help of enzymes" (Eigen 1992, p. 34).
This is, you might say, a natural or physical spelling bias. In English, "e" and
"t" appear more frequently than, say, "u" or "j," but not because "e"s and "t"s
are harder to erase, or easier to photocopy, or to write. (In fact, of course, the
explanation runs the other way around; we tend to use the easiest-to-readand-write
symbols for the most frequently used letters; in Morse code, for
example, "e" is assigned a single dot and "t" a single dash.) In RNA and
DNA, this explanation is reversed: G and C are favored because they are the
most stable in replication, not because they occur most frequently in genetic
"words." This spelling bias is just "syntactic" at the outset, but it unites with
a semantic bias:
Examination of the genetic code [by the "philological methods"]... indicates
that its first codons were rich in G and C. The sequences GGC and
GCC code respectively for the amino acids glycine and alanine, and because
of their chemical simplicity these were formed in greater abundance
... [in the prebiotic world]. The assertion that the first code-words were
assigned [emphasis added] to the most common amino acids is nothing if
not plausible, and it underlines the fact that the logic of the coding scheme
results from physical and chemical laws and their outworkings in Nature.
[Eigen 1992, p. 34]
These "outworkings" are algorithmic sorting processes, which take the
probabilities or biases that are due to fundamental laws of physics and
produce structures that would otherwise be wildly improbable. As Eigen
says, the resulting scheme has a logic; it is not just two things coming
together but an "assignment," a system that comes to make sense, and makes
sense because—and only because—it works.
These very first "semantic" links are of course so utterly simple and local
that they hardly count as semantic at all, but we can see a glimmer of
reference in them nevertheless: there is a fortuitous wedding of a bit of
nucleotide string with a protein fragment that helped directly or indirectly to
reproduce it. The loop is closed; and once this "semantic" assignment system
is in place, everything speeds up. Now a fragment of code-string can be the
code for something—a protein. This creates a new dimension of evaluation,
because some proteins are better than others at doing catalytic work, and
particularly at assisting in the replication process.
This raises the stakes. Whereas at the outset, macro strings could differ
only in their self-contained capacity to self-replicate, now they can magnify
their differences by creating—and linking their fates to—other, larger, structures.
Once this feedback loop is created, an arms race ensues: longer and
longer macros compete for the available building blocks to build ever big-
ger, faster, more effective—but also more expensive—self-replicating systems.
Our pointless coin-tossing tournament of luck has transformed itself
into a tournament of skill. It has a point, for there is now something for the
succession of winners to be better at than just, trivially, winning the cointoss.
And does the new tournament ever work! There are tremendous "skill"
differences between proteins, so there is plenty of room for improvement
beyond the minuscule catalytic talents of the proteinoids. "In many cases,
enzymic catalysis accelerates a reaction by a factor between one million and
one thousand million. Wherever such a mechanism has been analysed quantitatively,
the result has been the same: enzymes are optimal catalysts"
(Eigen 1992, p. 22). Catalytic work done creates new jobs to be done, so the
feedback cycles spread out to encompass more elaborate opportunities for
improvement. "Whatever task a cell is adapted to, it carries out with optimal
efficiency. The blue-green alga, a very early product of evolution, transforms
light into chemical energy with an efficiency approaching perfection" (Eigen
1992, p. 16). Such optimality cannot be happenstance; it must be the result of
a gradual homing-in process of improvement. So, from a set of tiny biases in
the initial probabilities and competences of the building blocks, a process of
snowballing self-improvement is initiated.
3. THE LAWS OF THE GAME OF LIFE
This most beautiful system of the sun, planets, and comets, could only
proceed from the counsel and dominion of an Intelligent and Powerful
Being.
—ISAAC NEWTON 1726 (passage translated in
Ellegard 1956, p. 176)
The more I examine die universe and study the details of its architecture,
die more evidence I find diat die universe in some sense must have
known diat we were coming.
—FREEMAN DYSON 1979, p. 250
It is easy to imagine a world that, though ordered, nevertheless does not
possess the right sort of forces or conditions for the emergence of
significant depth.
—PALI DAVIES 1992
Fortunately for us, the laws of physics vouchsafe that there are, in the Vast
space of possible proteins, macromolecules of such breathtaking catalytic