I don't think Brian Goodwin would shed any tears if universal
common descent (the theory that all organisms, recent and extinct,
share a common ancestor) turned out to be false. In his work over
the past couple of decades, he has carefully defined his central
terms -- e.g., homology -- to be independent of any necessary
historical assumptions. "If a genealogical assumption is built
into the definition of homology," he wrote in 1988 (158) "then
contradictions and absurdities arise."
In the most extended discussion of common descent that I can find
in Goodwin's writings, he evinces a distinctly "take it or leave
it" attitude to the theory. Please pardon the long quote, but it
helps to have the full context (from "The origin of species: a
structuralist approach," _Journal of Social and Biological
Structures_ 5 [1982]: 15-47, co-written with Gerry Webster).
The first paragraph is the "OK, we can take it" statement:
It will be apparent that we regard the theory of
evolution, and in particular neo-Darwinism, as having
extremely limited explanatory power with respect to
the problem of form to which it was originally
addressed. This limitation arises as a consequence of
the absence of any adequate theory of the means of
production of 'typical forms' and is such, we would
maintain, as to render debatable the claim that neo-
Darwinism is 'the unifying theory in biology' (Maynard
Smith, 1975). These remarks are not to be construed
as either a rejection of Darwinist functional
explanations in biology, or of a historical theory of
descent, the claim that existing species are 'blood
relations' which have arisen by the evolutionary
transformations of a smaller number of pre-existing
species. The structuralist position we adopt is
perfectly consistent with a theory of historical
descent (though not dependent upon it) and, by
providing a conceptual framework within which a theory
of transformations can be produced, both clarifies
some of the issues raised by such a theory and
provides a picture of the evolutionary process which
is somewhat different to that of the neo-Darwinists.
(p. 44)
The next paragraph, which follows immediately in the original, is
the "yeah, but we just might leave it" statement:
The plausibility of the theory of descent as
representing an actual series of events requires (1)
that organisms have the power of reproducing
themselves so that offspring are materially continuous
with parents, (2) that this reproduction is not
necessarily exact so that offspring can differ from
their parents, and (3) that the diversity of species
constitutes, at least empirically, a system of system
of transformations. The significance for the theory
of (1) and (2) is recognized by all neo-Darwinists;
their demonstration means that evolutionary change
must occur. The significance for the theory of the
third requirement, while not ignored by neo-
Darwinists, does not seem to be given the same weight
as the first two. Yet, what we take to be the
supposed (if merely empirical) unifying nature of the
theory, its postulate that the diversity of species,
as a matter of fact, constitutes a 'unity of blood
relations' depends upon it. However, this
demonstration is as problematic today as it was in the
early nineteenth-century when Geoffroy and Cuvier
argued over the question of 'one animal' or four
distinct 'types'. Whereas it would probably be agreed
that, supposing gross anatomical criteria to be
adequate, a major group such as the vertebrates does
comprise an empirical system of transformations, the
continued uncertainty over the relation of the major
groups suggests that there may be more than one such
set. If this is so then the 'unification' provided by
the theory of descent would appear to be partial and
speculative. (pp. 44-45)
You'll never find Goodwin putting much weight on common descent.
To his mind, it represents exactly the wrong kind of theory for
biology. One postulates unknown common ancestors as the original
loci of typical forms, where (say) the vertebrate body plan "just
appeared in a common ancestor" (1994: 146).
Of course -- to be tough-minded about all this -- it doesn't
really matter what Brian Goodwin thinks about common descent.
What matters is whether the theory is true.
Paul Nelson
Goodwin, B. 1988. Morphogenesis and heredity. In _Evolutionary
Processes and Metaphors_, eds. M.W. Ho and S.W. Fox
(London: John Wiley).
Goodwin, B. 1994. _How the Leopard Changed Its Spots_ (New York:
Scribners).
P.S. to Denis L.:
Dear brother, you're making it hard for me to pray that you finish
your dissertation without a hitch (as I hope you're praying that I'll
finish mine), even though I continue to do that because we need your
expertise and critical skill, and because I can't help liking
tremendously despite our many differences. (Remember praying in
Montreat?)
But please stop throwing your weight around as an "expert" and
lecturing people about the primary literature, etc. Yes, it's
important that amateurs get the science right and do their best to
educate themselves. But my diss. keeps me up to my neck in the
primary literature -- the same literature you're citing -- and I
just don't read the evidence as you do. I looked up all those
references you sent to Plantinga (cost me a whole morning). A lot
of good information about signalling molecules (e.g., sonic
hedgehog), but nothing about how one viably transforms distinct
complex morphologies. And the latter problem, I think we'll agree,
is what evolution is all about.
So, come on: a moratorium on the speeches about the superiority of
those at the bench vs. the hoi polloi. Let's stick to the evidence and
how best to understand it.