The Fruitful Facets of Galton's Polyhedron 351
Now for another metaphor, taken from a more complex system of forces.
We have all known what it is to be jammed in the midst of a great crowd,
struggling and pushing and swerving to and fro, in its endeavor to make a
way through some narrow passage. There is a dead lock; each member of
the crowd is pushing, the mass is agitated, but there is no progress ... At
length, by some accidental unison of effort, the dead lock yields, a forward
movement is made, the elements of the crowd fall into slightly varied
combinations, but in a few seconds there is another dead lock, which is
relieved, after a while, through just the same process as before. Each of
these formations of the crowd, in which they have found themselves in a
dead lock, is a position of stable equilibrium and represents a typical
attitude (1869, 1884 edition, pp. 369-370).Formalism, as the preceding chapter documents, boasts a long and
distinguished pedigree, well antedating both Darwin and any explicit discussion of
evolution. Darwinism rendered many formalist concerns irrelevant, but key
features of the structuralist agenda could not be encompassed, or even well
addressed, by natural selection and its functionalist mechanics. Galton's
polyhedron provides a strikingly apt metaphor for the two great themes of
formalism that continue to demand attention within evolutionary theory, and that
the Darwinism of his day could not adequately comprehend—discontinuous
evolution, and internally generated pathways: in other words, saltation and
channels. Both themes express the more general conception that internal properties
of organisms "push back" against external selection, thereby rendering evolution,
as dialectic of inside and outside—that organism, in other words, must be
conceived as polyhedrons, not billiard balls.
I shall show, in the rest of this chapter, that formalist, or structuralist,
evolutionary thought, from the immediate post-Darwinian years to the codification
of the Modern Synthesis, continued to emphasize the twinned concepts of saltation
and channels—for these notions represent two sides of the same conviction that
internal structure can set and constrain the pathways of change. The modern plea to
put history and organic integrity back into evolutionary theory echoes the same
call. If "constraint" has become a buzzword of contemporary evolutionary theory,
then I must assume that the shades of Galton and Geoffroy are smiling, for the
structure of their thought has withstood the formalist's ultimate test of timelessness.
Orthogenesis as a Theory of Channels and One-Way Streets:
The Marginalization of Darwinism
Misconceptions and Relative Frequencies
The German zoologist Wilhelm Haacke devised the word "orthogenesis" in 1893
(see Kellogg, 1907; Bowler, 1983); but the concept implicitly motivated the entire
formalist tradition that sandwiched Darwin (in a chronological sense) between
Goethe and Geoffroy on one side, and searchers for the