Terry writes:
>Irrelevant! This is the common fallacy that asks of modern "fine-turned"
>(canalized) organisms something that was only possible at an earlier time,
>before the canalization occurred. The viability of modern homeotic mutants
>is just not relevant.
Then maybe you can describe a non-canalized, non-fine-tuned organism
that nevertheless undergoes development to a viable adult phenotype.
As far as I can tell, such organisms are entirely hypothetical constructs,
postulated by evolutionary theory because it needs them, not because
any evidence for them exists.
The viability of modern homeotic mutants couldn't BE more relevant, if
evolutionary theory is to be a testable -- not speculative -- explanation.
>Nor is the criticism that they aren't good candidates for adaptive change.
>I don't know of anyone who points to antennapedia as a transitional form
>to some new species.
Again: please describe a viable homeotic mutant. If current experimental
examples don't work, come up with one of your own.
>The point is that there are genes that regulate bodyplan and that these
>genes are found in all metazoans
True.
>and that small changes to these genes can result in
>largescale changes in bodyplan.
Also true. But these "large-scale" changes are not viable, and therefore
are not heritable. Evolution needs viable, heritable change.
>All these things suggest in a very powerful way a solution to a
>longstanding problem--i.e. the pre-Cambrian explosion and the origin
>of metazoan bodyplans.
Nope. Not unless large-scale change is heritable. Why do you think
Erwin, Gould, McKinney, and others postulate a "golden age" of metazoan
evolution -- a happy time before canalization? Because it's so damned
hard to get the complex metazoans we actually observe to move off the dime,
morphologically speaking.
>Sorry Paul. As for professional biologists, you are in the minority on
>this one.
Pleased to be in the minority, Terry.
Paul Nelson.