More Denton: Denton on Types (Introduction)

by David Turell , Thursday, March 03, 2016, 05:13 (2977 days ago) @ David Turell

A brief explanation by Denton on his structuralism theory:-http://www.evolutionnews.org/2016/02/the_types_why_s102569.html-"One of the major achievements of pre-Darwinian biology was the discovery that the living world is organized into a hierarchy of ever more inclusive classes or Types, each clearly defined by a unique homolog or suite of homologs possessed by all the members of the Type and which in many cases have remained invariant in divergent phylogenetic lines for tens or hundreds of millions of years.-***-"There is currently a widespread impression that pre-Darwinian biologists derived their discontinuous-typological conception of nature from all sorts of discredited metaphysical beliefs. This view has been severely criticized by recent researchers and shown to be largely a myth created by twentieth-century advocates of the neo-Darwinian evolutionary synthesis1 -- what Ron Amundson calls "Synthesis Historiography."2 As Amundson shows, whatever their metaphysical leaning, pre-Darwinian biologists did not derive their view of the Types as changeless components of the world order from any a priori metaphysics but from solid empirical observations. -***-"Today, 150 years after Darwin, Owen's "biological atoms" are as distinct as ever. The vast majority of all organisms can be assigned to unique classes based on their possession of particular defining homologs or novelties that are not led up to via Darwin's "innumerable transitional forms." -"For readers subjected to popular and pervasive claims by evolutionary biologists that there are innumerable transitional forms of organisms, it might come as something of a surprise that there are unique taxon-defining novelties not led up to gradually from some antecedent form, and that remain invariant after their actualization for vast periods of time. 
There is indeed something incongruous about the very notion of distinct taxa and genuine immutable "taxon-defining novelties" in the context of the functionalist Darwinian framework, which implies that all taxa-defining traits should be led up to via long series of adaptive transitional forms! On such a Darwinian model, taxa-defining novelties should not exist; neither should distinct Types in which all members possess unique defining novelties not shared by the members of any other taxa.-"Let me reiterate: If evolution has occurred as conceived of by Darwin, invariant taxa-defining novelties, not led up to via long sequences of transitional forms from some antecedent structure, should not exist.
Ironically, it is only because organisms can be classified into distinct groups on the basis of their possession of invariant unique homologs that descent with modification can be inferred in the first place. If it was not for the invariance of the homologs and the Types they define, the common descent of all the members of a particular clade from a common ancestor would be in serious doubt. The living realm would conform to a chaotic network rather than an orderly branching tree. -"Types are still as distinct today as they were for Richard Owen, Agassiz, and the other typologists and structuralists in the pre-Darwinian era and even for Darwin himself.3 They are still clearly defined by homologs or synapomorphies that are true evolutionary novelties without antecedent in earlier putative ancestral forms. "-Comment: An apt comment on the Cambodian forms, no antecedents.