The Fruitful Facets of Galton's Polyhedron 355
selection as deprived of power but not contravened; to the "hard liner" Hyatt on
one side, who interpreted the orthogenetic drive as contrary to selection; to the
conciliatory Whitman on the other, who hoped to find appropriate and mutually
reinforcing status for all viable contenders in a pluralistic evolutionary theory.
I present orthogenesis as a spectrum grounded in relative strength and
frequency because I believe that a potential role for modern versions of such
structuralist theories should be judged in the same manner. A mild formalism of
constraint, akin to some ideas within the unfairly reviled theory of orthogenesis,
may now enrich our Darwinian world (see Chapters 10 and 11)—and the potential
fusion, in its richest form, would not be designated as strict selectionism with a
little bit added, but would be recognized as a potentially integrated theory of a new
kind (with a persistent Darwinian core). In this light, an understanding of the
original formulations of orthogenesis and their varying relationships with
Darwinism may enlighten us in our current struggle to integrate structuralist and
functionalist approaches to evolutionary causality.
Theodor Eimer and the Ohnmacht of Selection
Theodor Eimer's evolving views followed a channel every bit as directional
(though inadaptive by current, and perhaps transient, standards) as the constraining
orthogenetic pathways that he ascribed to organisms. His empirical work of the
1 870's, on coloration of lizards from Capri, presented a predominantly functionalist
argument, with a boost from internal channels to foster movement through
incipient stages, and to reinforce the process along the way. In the first of his two
volumes on orthogenesis—published in German in 1888 and translated into
English in 1890 as "Organic evolution as the result of the inheritance of acquired
characters according to the laws of organic growth"—Eimer stressed internal
channels, relegated Darwin to a periphery, but still sought a genuine fusion (as the
title proclaims) of formalist and functionalist perspectives. The second and last
volume (for Eimer died soon thereafter)—published in 1897 as Orthogenesis der
Schmetterlinge: ein Beweis bestimmt gerichteter Entwickelung und Ohnmacht der
Naturlichen Zuchtwahl bei der Artbildung—presents an anti-selectionist polemic
(directed more at his sparring partner Weismann than at Darwin) and a defense of
internal direction as preeminent. Its title proclaims Eimer's change of emphasis
from fusion to exclusivity: Orthogenesis of butterflies: a proof of definitely
directed development and the weakness of natural selection in the origin of
species.
Gustav Heinrich Theodor Eimer (1843-1898) was born near Zurich and
eventually became professor of zoology at Tubingen, Germany. He imbibed the
late 19th century mechanistic tradition that so permeated German science (in such
movements as Entwicklungsmechanik)—an attitude strongly opposed to
speculative phylogenizing, the main thrust of the "Darwinian" (read Haeckelian)
tradition in Germany (see Gould, 1977b, chapter 6). But Eimer also expressed
sympathy for "our great philosopher Oken" (1890, p. 433),