Seeds of Hierarchy 177
long as organisms maintain their steady state of abundance, these raw materials
will be taken up again and redeposited as new rocks fashioned from the products of
life.
In summary, if lineages could not become extinct, if climate and geology
changed in a continuous and insensibly gradual manner throughout geological
time, and if the forms and functions of organisms always matched the features of
their local environments, then gradual, adaptive evolution becomes a logical
necessity.
But by what mechanism will this ineluctable evolution occur? In particular,
since steady, continuous alteration of environment provides the impetus for organic
change, how does information flow from new environments to modify the old
forms of organisms? Lamarck's answer to this riddle—building only one corner of
his complete system—invokes the familiar ideas that later generations would call
"Lamarckism" when the rest of his edifice had been forgotten. Lamarck begins by
formulating the central principle of his functionalist credo—the counterintuitive
statement, later embraced by Darwin as\J well, that form follows function as the
order of life's history. When we contemplate any adaptation of an organism, and
consider the intricate correlation of form with function, we naturally assume (or so
Lamarck asserts) that form comes first, and that function can only follow. (God
makes a wing, and a bird can then fly, to cite a nonevolutionary example.) But
Lamarck advanced the paradoxical reverse order as his key premise: new habits
lead to altered structures. *
In Lamarck's proposed mechanisms, environment changes first. Indeed,
environment changes slowly and continuously on our uniformitarian planet. "Every
locality," Lamarck writes (1809, p. Ill), "itself changes in time as to exposure,
climate, character and quality, although with such extreme slowness, according to
our notions, that we ascribe it to complete stability." Organisms must
accommodate to these changes by alterations in their habits— chewing with
greater strength if the food gets tougher, moving more vigorously if the
temperature gets colder. These altered habits, if long sustained, must feed back
upon the organism in the guise of altered morphology or physiology—a thicker
beak to crack the harder seeds, longer hair on a tougher skin to resist the cold.
At this point in the argument, the famous "Lamarckian" theory of inheritance
finally enters. As many scholars have documented, "soft," or "Lamarckian"
inheritance represented the folk wisdom of Lamarck's time, and cannot be regarded
as an innovation of the Philosophic zoologique. Therefore, the restriction of
"Lamarckism" to this relatively small and non-distinctive corner of Lamarck's
thought must be labeled as more than a misnomer,
*This reversed order does not constitute a general claim for evolution against
previous creationist models. This reversal represents, rather, one major style of
evolutionary argument—the functionalist response. The alternative, structuralist stance—
the evolutionary version of function following form—sets a major theme of this book,
both in the historical precedents of Goethe, Geoffroy, Bateson and others, and in modern
notions of constraint and exaptation.