Tiers of Time and Trials of Extrapolationism 1329
throughout this book, but primarily in Chapters 2 and 9) that such phyletic trends be
explained, by simple extension and extrapolation, as adaptive anagenesis carried
further through time's geological fullness. I shall not here rehearse the lengthy
arguments and documentation of Chapter 9, but I believe that punctuated equilibrium,
as the dominant pattern and process of the second tier during millions of
"background" years between pulses of mass extinction, undoes the first tier's vector
of progress by supplying a radically different general explanation for phyletic trends:
the differential success of certain species within clades, with each species treated as a
stable individual during the several million years of its average geological existence.
Since the reasons for differential success of species extend so far beyond (while also
including) the traditional citation of adaptive biomechanical advantages for
constituent organisms; and since several of these reasons tend to run orthogonal, or
even counter, to general expectations of organismal progress; the crafting of trends by
punctuated equilibrium derails extrapolation from the first tier, thus providing the
second tier with a different set of explanations for its central phenomenon of cladal
trending.
This barrier at the second tier would be sufficient, by itself, to resolve the
paradox of the first tier, but even the second tier's rules for trending do not ac-
cumulate through broader realms of time to explain, by smooth extrapolation, the
patterns of waxing and waning for major taxonomic groups. That is, the causes of
cladal trends through long geological intervals of "normal" time do not accumulate to
patterns of success and failure through the full Phanerozoic range. For, as the
preceding section of this chapter documented, the "random" and "different rules"
models of differential success in episodes of catastrophic extinction then derail the
phyletic trends of the second tier for the same basic reason that these cladal trends
previously undid the anagenetic accumulations of the first tier: that is, by introducing
new patterns and rules at these rare moments of maximal impact. Thus, in summary,
adaptive anagenesis of a single lineage at the first tier cannot be extrapolated to cladal
trends within a monophyletic group of species at the second tier; and these cladal
trends of the second tier then cannot be extrapolated through episodes of mass
extinction to explain patterns of differential success for life's higher taxa throughout
Phanerozoic time. Punctuated equilibrium undoes anagenesis, and catastrophic mass
extinction derails punctuated equilibrium.
As with the workings of hierarchical levels in selection, the effects of adjacent
tiers of time may interact in all possible ways. Higher tiers do not automatically
counteract lower tiers. Adjacent tiers may also reinforce each other to intensify a
signal in life's history—as I illustrated, for example, in reporting Jablonski's claim
(1987) that species selection on species-rich subclades at the second tier often
reinforces the adaptive advantages gained by the organisms of these species in
Darwinian selection at the first tier. Similarly, if only for exaptive merits at the higher
tier, diatoms flourished by virtue of the same features at both the first and third tiers
(if my argument on page 1319 holds)—as