260 THE STRUCTURE OF EVOLUTIONARY THEORY
contribution by adding a dimension for history, and by formulating a theory that
granted controlling relative frequency to adaptation. But he did not invent the
issues, or the scheme of classification. The triumph of Darwinian functionalism
did, however, erase much historical memory for the old alternative of constraint.
The next two chapters sink their rationale in a simple premise: Our current need to
reinvigorate constraint as a vital topic in evolutionary explanation (see Stearns,
1986; Maynard Smith et al., 1985; Gould, 1989a, 1992b)—based upon advancing
knowledge of genetic architecture, development and macroevolution—requires
that we rediscover this legacy of structuralist thought, * and recognize that the
entire history of evolutionary theory has been pervaded by an issue that simply
would not disappear, if only because the dialectic of inside and outside, structure
and function, design and adaptation, must be resolved at some fascinating interplay
and synthesis, not as a victory for either pole in a debate without true sides.
Two Ways to Glorify God in Nature
We cannot comprehend the past from the vantage point of a newly constructed
present reality. Once the 19th century had discovered evolution as the primary
cause of relationships among organisms, the historical axis not only sprang into
being as a pole of explanation, but quickly assumed a primary status (Figs. 4-2 to
4 - 6). More than a century later, we can hardly imagine biology without this theme.
What kind of questions could be posed before history became an option for
resolution? What kinds of explanations could be rendered when a biologist couldn't
ask (or even conceptualize): "How has this feature changed from an ancestral state;
what do its differing forms in various species tell us about phyletic relationships;
what are the causal bases for both the origin and later alterations of this feature?"
Immediate appearance in a fully formed state provides the only alternative to
history—whether such "creation" is achieved by the direct hand of a divine agent,
or by spontaneous organization from elements according to some unknown law or
principle of nature. If basic taxa originated as we find them now, then the range of
theoretical explanation remains wide. Species might be purposely ill designed to
suit the black humor of a diabolical creator; or they might be cobbled together with
no rhyme or reason by forces of universal randomness. The list of possibilities
continues ad infinitum.
But, in fact, Western cultural traditions greatly limited the range of acceptable
*I shall discuss, in subsequent sections of this and the next chapter, the functionalist
(Paley) vs. structuralist (Agassiz) versions of natural theology, the central role of laws of
form in the pre-Darwinian evolutionary debates (particularly the struggle between the
structuralist Geoffroy Saint-Hilaire and the functionalist Cuvier), Darwin's own treatment
of constraint and correlation of growth, alternatives to Darwinism based upon the
centrality of constraint (Galton's polyhedron, various theories of orthogenesis, Bateson on
homeosis, de Vries on saltation, Goldschmidt on jumps within channels). The
structuralist alternative has always been pursued as an active option by some of the finest
thinkers in our field.