962 THE STRUCTURE OF EVOLUTIONARY THEORY
as punctuated equilibrium must not be construed as an argument against
predictable trends, but rather as a different mechanism for the episodic production
of such trends, so too might the punctuational origin of hydrothermal ore deposits
be reconceptualized as directional but episodic. He writes (p. 168): "Recognition of
the quasi-cyclic and episodic nature of these events within the lifetime of a
hydrothermal system could be described as leading to more 'catastrophic' models.
There are similarities to the concepts of punctuated equilibrium recently proposed
in paleontology and biological evolution... these concepts emphasize the
importance of specific events which are of random occurrence on a short time scale
but statistically predictable on a longer scale."
TWO CONCLUDING EXAMPLES, A GENERAL STATEMENT, AND A CODA.
As final examples in this chapter, two recent authors have used punctuated
equilibrium as the central organizing principle for books on subjects of different
scale, but of great importance in human life and history—Kilgour (1998) on The
Evolution of the Book, and Thurow (1996) on The Future of Capitalism. Moreover,
each author uses punctuated equilibrium not as a vague metaphor, but as a specific
model of episodic change offering casual insights through the identification of
structural homologies as defined in this chapter.
Kilgour notes that a theme of greater efficiency marks the history of book
making (and might be misread as evidence for anagenetic gradualism, just as
trends in the evolutionary history of clades have often been similarly misconstrued
when a punctuational model of successive plateaus defined by discrete events of
branching actually applies). He writes (p. 4): "Form aside, the major change
throughout the entire history of the book has been in the continuous increase in
speed of production: from the days required to handwrite a single copy, to the
minutes to machine-print thousands of copies, to the seconds to compose and
display text on an electronic screen."
But, as Kilgour knows, and adopts as the major theme of his book, form
cannot be put "aside." When one probes through these progressive improvements
in function to underlying bases in form, the history of the book becomes strongly
punctuational. In a pictorial summary for his central thesis (Fig. 9-36), Kilgour
views the evolution of the book—defined (p. 3) as "a storehouse of human
knowledge intended for dissemination in the form of an artifact that is portable, or
at least transportable, and that contains arrangements of signs that convey
information"—as a sequence of four great punctuations: the clay tablet, the
papyrus roll, the codex (modern book), and the electronic "book" (with no
canonical form as yet since we are now enjoying, or fretting our way through, the
rare privilege of living within a punctuation), with three "subspeciational"
punctuations within the long domination of the codex (Gutenberg's invention of
printing with movable type in the mid 15th century, and the enormous additional
increases in production made possible first by the introduction of steam power at
the beginning of the 19th century, and then by the development of offset printing in
the mid 20th century).
As I have emphasized throughout this discussion of human cultural and