564 THE STRUCTURE OF EVOLUTIONARY THEORY
A world of difference separates the negative view held by most synthesists—
that speciation merely iterates (and therefore buffers) adaptations produced by a
different, anagenetic process—from Mayr's recognition that adaptations may be
pieced together through accumulated events of speciation, each chancy in itself and
not directed towards the eventual novel phenotype. In this sense, Mayr's view
becomes the root for those branches of modern macroevolutionary theory that treat
speciation as a higher-order analog of organismic birth—leading to a concept of
trends as the product of differential sorting within the multitude of units thereby
produced, and not as the extrapolated result of organismic selection within
anagenetic lineages.
If most of the synthesists viewed speciation as trivial, they didn't grant even
this modicum of concern to the counterpart process of extinction. Although they
acknowledged the death of species (for a process affecting 99 percent of all species
that ever lived can't be entirely ignored), they viewed extinction entirely in a
negative light—as a loss of adaptation, and therefore as a failure in evolution,
something to be recognized but not extensively discussed in polite company. Even
Ernst Mayr, who understood so clearly how speciation could enter a higher-level
process of sorting, didn't grasp the logical corollary—that any selective process
must pair survivals with eliminations, and that "defeats" can therefore teach us as
much as "victories." Instead, Mayr professed puzzlement as to why such a
profoundly negative phenomenon should be so common:
We find so many cases of extreme sensitivity of natural selection, doing the
most incredible and impossible things; and yet the whole pathway of
evolution is strewn left and right with the bodies of extinct types. The
frequency of extinction is a great puzzle to me (in Tax, 1960, volume 3, p.
141).
Natural selection comes up with the right answer so often that one is
sometimes tempted to forget its failures. Yet the history of the earth is a
history of extinction, and every extinction is in part a defeat for natural
selection... Natural selection does not always produce the needed
improvements (1960, pp. 375-376).The Synthetic approach to macroevolution can be encapsulated in a few dicta:
view life as stately unfolding under adaptive control; depict trends as accumulative
and anagenetic within lineages according to the extrapolationist model; downplay
or ignore the macroevolutionary calculus of birth and death of species. These
propositions leave little role for the actual archives of life's history—the fossil
record—beyond the documentation of change. The causes of change must be
ascertained elsewhere, and entirely by neontologists (my profession's term for the
folks who study modern organisms). Thus the Synthesis held paleontology at arm's
length. (I suppose we deserved this denigration in retaliation for the plethora of
poorly conceived, anti-Darwinian assertions and speculations that so many earlier
paleontologists had falsely based upon the fossil record—see Chapter 4. In this
sense, our later demotion, however unfairly extended, became part of the salutary
cleansing accomplished