1212 THE STRUCTURE OF EVOLUTIONARY THEORY
long-step jumping to higher, but distant, adaptive peaks (contrasted with different
rules for simple expansion to adjacent peaks) doubles after each successful transition,
thus forecasting, for example, that if a first success emerges from two tries on
average, the tenth will require a mean wait equal to the time needed for more than
1 000 attempts. In this manner, and very sensibly in my opinion (see Gould, 1989c),
Kauffman tries to account for the origin of all fossilizable metazoan phyla in the
Cambrian explosion, followed by more than 500 million years featuring no further
origin of body plans of such distinctly different design. But this level of generality
offers no insight into the particular historical questions of taxon and time that have
always defined the guts and soul of biology: why arthropods, and why then rather
than a billion years before or after (with the latter, contingently plausible, scenario
precluding my writing and your reading this book, among other differences between
our actual world and innumerable sensible, but unrealized, alternatives).
In explicating this feature of broad generality for the legitimate realm of
physical imposition and predictability, Kauffman (pp. 13-14) draws an apt analogy
that cannot be denied, but that also identifies the limits of his favored approach:
There is no doubt that our awareness of historical contingency is proper. The
question we must address is whether there might be statistical order within
such historical processes. A loose analogy makes this point. Imagine a set of
identical round-topped hills, each subjected to rain. Each hill will develop a
particular pattern of rivulets, which branch and converge to drain the hill.
Thus the particular branching pattern will be unique to each hill, a
consequence of particular contingencies in rock placement, wind direction,
and other factors. The particular history of the evolving pattern of rivulets will
be unique to each hill. But viewed from above, the statistical features of the
branching patterns may be very similar. Therefore, we might hope to develop
a theory of the statistical features of such branching patterns, if not of the
particular pattern on one hill.An ironic solution to controversy between this form of timeless structuralism
and historical particularism could emerge from a treaty that rigidly relegated each
domain to its proper space within the analogy. But such a clearly defined and well-
patrolled truce would also deprive biology of much interest and legitimate
skirmishing, for our deepest puzzles and most fascinating inquiries often fall into a
no-man's land not clearly commanded by either party—while we must also admit
(and treasure) our human inclination to expand the domains of personally favored
explanations ("pushing the envelope" in a favored cliche of our times). Historicists do
claim that much of what we have often interpreted as timeless and predictable
generality (with evolutionary "progress" towards some form of consciousness as a
prominent example) truly falls into the domain of contingent, but still fully
explainable, good fortune in the particular history of this specific planet (whatever the
percentage of inhabited worlds that eventually evolve consciousness in some form).