710 THE STRUCTURE OF EVOLUTIONARY THEORY
imply increasing dominance of such species within the clade, for this positive trait
can be counterbalanced by the higher speciation rates of shorter-lived
nonplanktotrophic species. Moreover, Jablonski also showed that selective forces
can change radically during episodes of mass extinction. In the great dying at the
end of the Cretaceous period, geographic range of species shows no correlation
with survivorship through the event. But, interestingly, geographic range of entire
molluscan clades (though not of their component species) does correlate positively
with persistence through the mass extinction— a potential example of clade
selection.)
I freely admit that well-documented cases of species selection do not
permeate the literature. But I regard this infrequency as a great opportunity, rather
than a restrictive limitation or an indication that the phenomenon scarcely exists.
We have barely begun to acknowledge (much less to define or operationalize) this
process, and we have still not entirely agreed upon criteria for recognition. We face
the tradition of a full century spent not considering causes at this level (indeed,
actively denying the existence of such levels at all). We are just learning how to
look—or, to state the issue more incisively; we have just begun to recognize that
we should be looking at all! We face all the promise of a rich but unploughed
field—and (to commit two literary barbarisms of mixed metaphors and parodied
quotations at the same time), we should summon up the courage of John Paul Jones
and recognize that we have not yet begun to think.
I regard the second, or theoretical, objection as even more unfair in its purely
traditionalist grounding in the parochialism of viewing organisms as exclusive
agents of evolutionary interest or importance—more an aesthetic defense about
comfort or preference than an intellectual argument about mechanisms. Several
Darwinian strict constructionists, Richard Dawkins and Daniel Dennett in
particular, hold that almost everything of interest in evolutionary biology either
inheres in, or flows from, natural selection's power to craft the intricate and
excellent design of organisms—"organized adaptive complexity," in Dawkins's
favorite phrase. "Biology is engineering," Dennett tells us again and again in his
narrowly focussed book (Dennett, 1995).
I do not deny either the wonder, or the powerful importance, of organized
adaptive complexity. I recognize that we know no mechanism for the origin of
such organismal features other than conventional natural selection at the
organismic level—for the sheer intricacy and elaboration of good biomechanical
design surely preclude either random production, or incidental origin as a side
consequence of active processes at other levels. But I decry the parochialism of
basking so strongly in the wonder of organismic complexity that nothing else in
evolution seems to matter. Yet many Darwinian adaptationists adopt this narrow
and celebratory stance in holding, for example, that neutrality may reign at the
nucleotide level, but still be "insignificant" for evolution because such changes
impose no immediate effects upon organismal phenotypes; or that species selection
can regulate longstanding and extensive trends in single characters, but still
maintains no "importance" in