The Structure of Evolutionary Theory

576 THE STRUCTURE OF EVOLUTIONARY THEORY

constructive side, Olson could offer nothing. He ventured a few comments about
cytoplasmic inheritance as a possible mechanism that might not follow all
synthetic rules, but such a limited and inadequate speculation could not fuel such a
comprehensive set of doubts! Revisionists would gain no hearing until they could
propose an extensive and positive set of extensions or alternatives—and I write this
book because I believe that such an affirmative program has now been formulated.
Olson's critique achieved no currency, and the hardened version descended from
the empyrean academy into the vernacular world of textbooks, the ultimate test of
establishment by social imposition as well as by professional consensus.

ALL QUIET ON THE TEXTBOOK FRONT

Professional writing tends to be nuanced and judicious. Even the strongest partisan
finesses his commitment and adds at least a footnote or tangential comment, so that
any charge of oversimplification or dogmatism may be countered by stating: "but
look on page 381 (in the small print); you see, I raised that caveat myself."
To learn the unvarnished commitments of an age, one must turn to the
textbooks that provide "straight stuff" for introductory students. Yes, textbooks
truly oversimplify their subjects, but textbooks also present the central tenets of a
field without subtlety or apology—and we can grasp thereby what each generation
of neophytes first imbibes as the essence of a field. Moreover, many textbooks
boast authorship by the same professionals who fill their technical writings with
exceptions, caveats, and complexities.
I have long felt that surveys of textbooks offer our best guide to the central
convictions of any era. What single line could be more revealing, more attuned to
the core commitment of a profession that bathed in the blessings of Victorian
progressivism, and aspired to scientific status in Darwin's century, than the
epigram that Alfred Marshall placed on the title page to innumerable editions of his
canonical textbook, Principles of Economics: "natura non facit saltum."
The changing foci of 20th century textbooks provide direct insight into the
history of evolutionary thought and the eventual triumph of Darwinism. In
particular, if the Synthesis truly hardened, as I have argued, then texts following
the 1959 centennial celebrations—the apogee of strict selectionism— should
describe evolution in unambiguously panadaptationist language, and should extol
the sufficiency of natural selection to craft the entire range of evolutionary
phenomena at all scales, ecological to geological.
This section does not present a systematic survey of texts, though I have
consulted everything I could find, including nearly all-major American books for
introductory college biology (and several high school textbooks as well). A more
complete search, extended back in time to cover the early days of the Synthesis,
and the pre-synthetic period as well, would provide a fascinating topic for a
dissertation in the history of science or education. This field of vernacular
expression has been neglected by scholars, though the subject would