The Fruitful Facets of Galton's Polyhedron 405
and seeks to explain form in terms of chemical and mechanical forces now
operating through development. (Structuralists do not deny, of course, that history
sets the presence of one mechanics, rather than another, in any particular lineage.
But the analysis of immediate causes for current anatomies must still invoke
present and intrinsic workings.)
Bateson best illustrates his full allegiance to the structuralist program by
interpreting a range of putatively historical phenomena in terms of contemporary
mechanics. He admits, for example, that highly variable parts, like mammalian
third molars, often have little functional utility—and may therefore be "permitted"
to range widely by a history of failing function. But Bateson still seeks a primary
explanation in terms of current construction: "The oft-repeated statement that
'useless' parts are specially variable, finds little support in the facts of variation,
except in as far as it is a misrepresentation of another principle. The examples
taken to support this statement are commonly organs standing at the end of a
meristic series of parts, in which there is a progression or increase of size and
degree of development, starting from a small terminal member" (1894, pp. 78-79).
Similarly, the features that we call atavisms and attribute to past echoes
should be viewed as alternate mechanical pathways. In this case, a Darwinian
might invoke both styles of explanation, for even a historical vestige must be built
along a current developmental route. But Bateson did not seem to grasp this
necessary duality, and he often used the second aspect (mechanical pathway of
building) to castigate the first (adaptational basis)—thus illustrating, by his error,
the near exclusivity of his structuralist interpretations. Bateson uses simple
mechanical analogs to make his point:
But all that we know is that now and then it shoots wide and hits another
mark, and we assume from this that it would not have hit if it had not aimed
at it in a bygone age. To apply this to any other matter would be absurd. We
might as well say that a bubble would not be round if the air in it had not
learned the trick of roundness by having been in a bubble before: that if in a
bag after pulling out a lot of white balls I find a totally red one, this proves
that the bag must have once been full of red balls, or that the white ones
must all have been red in the past (1894, p. 78).EVOLUTIONARY CONCLUSIONS AND IMPLICATIONS FOR DARWIN-ISM. The
central thesis of Materials can be stated positively and succinctly: much variation
(or at least the evolutionarily significant fraction) is discontinuous, mechanically
and chemically built through heredity, and often well formed (and therefore
potentially useful) by intrinsic construction. The primary cause of evolution, a
process that also tends to be discontinuous, must therefore be located directly in
the rules, patterns and directions of variation: "Is it not then possible that the
discontinuity of species may be a consequence and expression of the discontinuity
of variation?" (1894, p. 69 ).
But Bateson makes few positive claims in this mode. Rather he presents