Re. Wings

Richard Hall hall at deleteme.ns.utk.edu
Fri Sep 18 14:15:07 EDT 1998


John Grehan wrote:
> 
> Alex Netherton notes Darwin' s intrest in Lamark, as well as natural
> selection., but there are
> altogether three elements to Darwin's philosophy of mechanism. The third,
> which evolutionists
> (at least those who write the textbooks and promote evolution against
> creationism) generally ignore,

Perhaps you should check out _Phenotypic_Evolution_ by Schlichting and
Pigliucci as well as the numerous journals devoted to evolutionary
theory.  Laws of growth, ie. chromosomal organization, the
genotype-phenotype gap, norms of reaction, ontogeny, these are all
extremely active topics among those who study evolution.

These things are probably not discussed in arguments with Creationists
since those kind of arguments rarely reach a level of sophistication,
rationality, or pertinence which might allow these more subtle issues to
come up.  Likewise with textbook writing, which is a highly politicized
process.

But sure, there are plenty of biologists out there who wonder why
butterflies haven't evolved a gene that will keep them out of the road,
while not pausing for a second to consider where and how a gene could
act to accomplish such a task.  They aren't our brightest bulbs.  Still,
I think that it is absurd to say that evolutionists ignore laws of
growth.

>These mechanisms, proposed by molecular geneticists change
>the whole concept of mutation from as "random" to oriented process >(i.e.
>there may be a bias in the mutation process in consequence of current
>genetic structures

Just because mutation is biased does not mean that mutations don't still
happen by chance.  It just means that the probability distribution
function is not uniform across the DNA molecule.  That is problematic
for people doing molecular phylogenies, where a constant mutation rate
is primary assumption, but it is hardly surprising or disrputive of
evolutionary biology as a whole.

> As such it is quite possible from a molecular genetic context, to consider
> that much, if not the
>  primary content, of novelty in evolution has arisen without requiring or
> involving natural selection
> as a driving force.

The "force" of natural selection is reproduction and birth.  Nothing
alive gets here except by the force of natural selection.  I don't
understand what you are saying.  Perhaps you could provide an example of
a novelty arising by this other force you allude to.  That way we could
move from possibly considering your point to actually considering it.

 
> The concept of orthogenesis in its broadest context (i.e. to encompass the
> historical development of concepts behind the term) provides the
> interesting possiblity that in terms of structural origin, the wing of a
> butterfly, and the leaf of a tree, may have more in common than just a
> poetic
> similarity (and I don't mean 'just' in a derogatory sense as poets can and
> do have insightful
> contributions to make about the nature of the real world).

Wings and leaves may have a common structure due to the ways in which
one tissue type grows into another during development, but this is
completely irrelevant in terms of the evolutionary origin of either
structure.  I think that you are conflating the developmental origin of
a structure with its evolutionary origin.

Rikki Hall


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