The Modern Synthesis as a Limited Consensus 573
general trend: "In recent years the analysis of these rules has shown that, as we
stressed earlier, all phenotypes are compromises among a variety of conflicting
selection pressures. As a result, there are many so-called exceptions to such rules,
where a new selection pressure takes over and adjusts an organism or a local
population in a different way" (in Tax and Callender, 1960, volume 3, p. 138).
In another example of victory by virtual definition, Tinbergen acknowledged
that randomness might provide a theoretical alternative to adaptation in the
evolution of a behavior. But since he construed randomness only as an absence of
evidence for selection, and since he regarded the variety of conceivable
adaptationist explanations as effectively inexhaustible, how would one ever
validate randomness in any particular case? "This task [of explaining the results of
evolution] really amounts to an assessment of the relative importance of the
contribution made by random variation, on the one hand, and by adaptation
directed by selection, on the other. Since randomness is, per definition, detectable
only by elimination of every conceivable directed-ness, it is natural that this
approach should lead to a quest for directedness" (Tinbergen, 1960, p. 602).
Adaptation pervades Tinbergen's discourse and world of thought. He even
proposes a turnabout from Darwin's own, eminently sensible, view that non-
adaptive features of conservative inheritance (deep homologies) provide optimal
characters for taxonomic definition, since more recent adaptations tend to be
homoplastic (as easily convergeable with similar features in independent lineages)
and nondistinctive. Tinbergen, on the other hand, states that his paper will focus
upon "the extent to which taxonomic characters must be assumed to be due to
natural selection" (1960, p. 595). He then carries his adaptationist paean even
further by arguing that evolutionists (as opposed to other scientists who might need
to classify for different reasons) must divide organisms and designate their
characters in terms of adaptive complexes, thus assuring his preferred
interpretation by predefining the structure of observation itself:
The conclusion that adapted features are systems of functionally related
components forces us to reconsider once more the question What is a
taxonomic character? The answer is, of course, that it depends on the aims,
which the scientist has in mind. The classifier is fully entitled to use, e.g.,
the tameness of the kittiwakes, their nest-building behavior, the black
neckband of their young, and their nidicolous habits as four separate
characters. But the evolutionist is not entitled to treat them as four
independent characters. To him, the correct description of the
characteristics of the species would be in terms of adapted systems, such as
(1) cliff breeding; (2) pelagic feeding; (3) orange inside of the mouth and
related characteristics of posturing (Tinbergen, 1960, p. 609).These symposia not only featured adaptation as the centerpiece of the
biological world, but also extended the concept to all other fields included within
their program of lectures. Robert McC. Adams, then a young anthropology