Species as Individuals in the Hierarchical Theory of Selection 633
must be evaluated on the basis of its success in explaining and predicting material
phenomena. It is equally true that replicators (codices) are a concept of great
interest and usefulness and must be considered with great care for any formal
theory of evolution, either cultural or biological." Williams's statement agrees
completely with the position that I have advanced in this book— an attitude that,
by general consensus, leads logically and directly to the hierarchical model of
selection, and the invalidity of single-level, gene-based views. Williams allows that
interactors represent the "concrete realities" confronting biologists (and chapter 4
of his 1992 book eloquently defends the concept of legitimate interactors at several
hierarchical levels of increasing genealogical inclusion). He admits that both the
"truth and usefulness" of a biological theory, natural selection in this case, depends
upon the explanation of material phenomena—that is, interactors operating as
agents. He does not include replicators—the basis of gene selectionism—in this
category, for his last sentence grants them a separate but equal status in
evolutionary theory: "It is equally true that replicators (codices) are a concept of
great interest" needed "for any formal theory of evolution." Now, if replicators are
not causal agents, but are vital for any full account of evolution—then what are
they? I suggest that we view gene-level replicators as basic units for keeping the
books of evolutionary change—as "atoms" in the tables of recorded results.
Williams did not slip or misspeak in the quotation cited above. He repeats this
separation of a causal agent from a basis of hereditary transmission— with
interactors as agents and replicators as transmitters—in several other passages,
including (1992, p. 38) "Natural selection must always act on physical entities
(interactors) ... It is also necessary that there be what Darwin called 'the strong
principle of inheritance'..."
Whereas Williams makes valid separations and defines proper roles, but then
seems unwilling to own the theoretical consequences, Dawkins, on the other hand,
seems merely confused. In discussing group selection (1982, p. 115), for example,
Dawkins writes: "The end result of the selection discussed is a change in gene
frequencies, for example, an increase of 'altruistic genes' at the expense of 'selfish
genes.' It is still the genes that are regarded as the replicators which actually
survive (or fail to survive) as a consequence of the (vehicle) selection process."
By putting the word "vehicle" in parentheses, as a reminder of selection's
intrinsic nature rather than a mere modifying adjective, Dawkins admits that
interactors (vehicles in his terminology), not replicators, operate as agents of
selection. He describes the differential survival of replicators as a consequential
result of this causal process—therefore as units for bookkeeping rather than agents
of causality—but he then fails to disentangle these two different aspects of
evolution, while continuing to grant favored status to genes.
We may indeed, and legitimately as a practical measure, decide to keep track
of an organism's success in selection by counting the relative representation of its
genes in future generations. (In large part, we count at the genie level for the
reason always emphasized by Williams and Dawkins—because