The Modern Synthesis as a Limited Consensus 551
can only produce adaptations for the genetic survival of individuals. Many
biologists have recognized adaptations of a higher than individual level of
organization. A few workers... postulate that selection at the level of
alternative populations must also be an important source of adaptation, and
that such selection must be recognized to account for adaptations that work
for the benefit of groups instead of individuals. I will argue... that the
recognition of mechanisms for group benefit is based on misinterpretation,
and that the higher levels of selection are impotent and not an appreciable
factor in the production and maintenance of adaptation (1966, pp. 7-8).This statement includes several interesting features, suggesting useful
definitions and frameworks that I will follow throughout this book (while often
disagreeing with Williams's own conclusions): (1) The term natural selection shall
refer only to Darwin's process at the organismic level; selection at higher levels
requires a different name. (2) The logic of group (and higher level) selection
cannot be denied; we may only reject the process as impotent relative to natural
selection, not as inconceivable. (3) The criterion advanced by group selectionists—
the existence of properties that work for the benefit of groups, but at the expense of
individual organisms—may be sound in theory but inapplicable in fact, for
virtually all proposed cases either have been misinterpreted or remain subject to
recasting in terms of advantages for organisms alone.
Williams then states his "doctrine," frankly so designated: "The ground rule—
or perhaps doctrine would be a better term—is that adaptation is a special and
onerous concept that should be used only where it is really necessary. When it
must be recognized, it should be attributed to no higher a level of organization than
is demanded by the evidence. In explaining adaptation, one should assume the
adequacy of the simplest form of natural selection, that of alternative alleles in
Mendelian populations, unless the evidence clearly shows that this theory does not
suffice" (1966, pp. 4-5).
Williams's doctrine then serves as a hammer against group selection. This
higher-level process poses no problem in theory, for "there can be no sane doubt
about the reality of the process. Rational criticism must center on the importance of
the process and on its adequacy in explaining the phenomena attributed to it"
(1966, p. 109). But group adaptation is both methodologically onerous (more so
than Darwinian adaptation, which is onerous enough already), and theoretically
impotent (though potentially operative).
If there are many adaptations of obvious group benefit, which cannot be
explained on the basis of genie selection, it must be conceded that group
selection has been operative and important. If there are no such adaptations,
we must conclude that group selection has not been important, and that
only genie selection—natural selection in its most austere form—need be
recognized as the creative force in evolution. We must always bear in mind
that group selection and biotic adaptation are more onerous principles than
genie selection and organic adaptation. They