The Structure of Evolutionary Theory

(Michael S) #1

tives—for the diversity of organs growing off the stems and roots of plants. He
viewed cotyledons, and all the standard parts of flowers (sepals, petals, stamens
and carpels), as modifications of a leaf archetype.



  1. The famous early 19th century argument, culminating in the public debate
    of 1830 between Georges Cuvier and Etienne Geoffroy St. Hilaire (and analyzed
    by Goethe in his final paper before his death), did not, as commonly
    misinterpreted, pit evolutionary theories against creationist accounts (although
    Geoffroy favored a limited theory of evolution, while Cuvier remained strongly
    opposed), but rather represented the most striking and enduring incident in this
    older and persistent struggle between formalist (Geoffroy) and functionalist
    (Cuvier) explanations of morphology and taxonomic order. Geoffroy advocated the
    abstract vertebra as an archetype for all animals, beginning (largely successfully)
    with a common basis for anatomical differences between teleosts and tetrapods,
    moving to the putatively common design of insects and vertebrates (still with some
    success, partly confirmed by the Hoxology of modern evo-devo, but also including
    some "howlers" like the homology of arthropod limbs with vertebrate ribs), and
    crashing with the proposed homology of vertebrates and a cephalopod doubled
    back upon itself (the comparison that sufficiently aroused Cuvier's growing ire into
    a call for public debate). Geoffroy's theory of dorsoventral inversion between
    insects and vertebrates was not a silly evolutionary conjecture about "the worm
    that turned" (as later caricatures often portray), and did not represent an
    evolutionary explanation at all, but rather expressed a formalist comparison based
    upon a common underlying structure, ecologically oriented one way in vertebrates
    (central nervous system up), and the other way in arthropods. The common
    impression of Cuvier's victory must be reassessed as a complex "draw," with
    Geoffroy's position abetted by the fortuity of his longer life and his courting of
    prominent literary friends as supporters (including Balzac and Georges Sand).

  2. Adaptationist preferences have enjoyed a long anglophonic tradition,
    beginning with the treatises of Ray and Boyle, in Newton's founding generation, on
    final causes; then extending, in creationist terms, through Paley and the
    Bridgewater Treatises; and finally culminating in the radically reversed
    evolutionary explanations (but still retaining the same functionalist and
    adaptationist commitments) of Darwin, extending forward to Fisher and the
    Modern Synthesis. By contrast, continental traditions have favored formalist and
    structuralist explanations of morphology, from the creationist accounts of Agassiz,
    through the transitional systems of Goethe and Geoffroy, to the fully evolutionary
    accounts of Goldschmidt and Schindewolf in the mid 20th century. Interestingly,
    the complex views of Richard Owen, so widely misunderstood as an opponent of
    evolution (when he only rejected the predominant functionalism of traditional
    British approaches to morphology), may best be grasped when we understand him
    as a rare anglophonic exponent of a predominantly formalist theory. Owen,
    following Geoffroy, tried to explain the entire vertebrate skeleton, including the
    skull and limbs, as a set of modifications upon a vertebral archetype.

  3. Darwin maintained a genuine interest in formalist constraints upon


66 THE STRUCTURE OF EVOLUTIONARY THEORY

Free download pdf