On the third branch of scope, my contribution cannot claim much novelty, if
only because I have not worked professionally in this area of paleontological
research. But I do explicate, perhaps more fully than before, both the historical and
conceptual reasons for regarding catastrophic mass extinction, and catastrophic
mechanics in general (within their limited scope of validity), not as anti-
selectionist per se, but rather as fracturing the extrapolationist premise of
Darwinian central logic, and requiring that substantial aspects of phyletic pattern
be explained as interaction between temporal extensions of microevolution and
different processes that only become visible and effective at higher tiers of time. I
try to resolve "the paradox of the first tier" (the empirical failure of Darwin's
logically airtight argument for a vector of progress) by arguing that punctuated
equilibrium at the second tier of phyletic trends, and mass extinction at the third
tier of faunal overturn, impose enough of their own, distinctive and different,
patterning to forestall the domination or pure imprint of extrapolated
microevolutionary results upon the general pageant of life's history.
Finally, at the third level of those lovely details (where both God and the devil
dwell, and where, ultimately, both the joy and power of science reside), I trust that
any originality I have introduced at "higher" levels of theoretical structure gains
primary expression and utility in the resolution of previously puzzling details, and
in the identification of "little things" that had escaped previous notice or explicit
examination.
For example, most original analyses and discoveries in the historical first half
of this book flow directly from my organizing theme of identifying essential
components in Darwinian logic, and then tracing both the early attempts to defeat,
and our later efforts to modify and expand them through time. I was thus able to
discover and identify Darwin's major encounter with higher level selection not in
his recognized discussion of group selection for human altruism, but in his
previously unexplicated admission of species selection to resolve the problem of
diversity (see Chapter 3, pp. 246-250). In this case, I "lucked out" through an odd
reason for previous ignorance of such an important textual revision—for Darwin
omitted this material in his compressed and hasty discussion of diversity in
Chapter 4 of the Origin (on this subject, the only Darwinian source generally
known to professional biologists, who would immediately highlight the importance
of any acknowledgment of species selection). But Darwin agonized over levels of
selection at explicit length in the unpublished "long version" that only saw the light
of printed day in 1975 (Stauffer, 1975), and that virtually no practicing biologist
has ever read (whereas historians of science who do study this longer text usually
lack sufficient knowledge of the technical debate about levels of selection to
understand the meaning of Darwin's passages or to appreciate their import).
The same context led me to appreciate the previously unanalyzed
development of a full hierarchical model by Weismann in his later works (Chapter
3, pp. 223-224), a formulation that Weismann himself identified as the most
important theoretical achievement of his later career. Previous historians had
written about his much longer and earlier explications of lower level selection
Defining and Revising the Structure of Evolutionary Theory 51