On Tue, 18 Jul 1995 16:07:17 -0500 (EST) you wrote:
LH>There have been several posts lately following this pattern: Glenn
Morton
>quotes an experiment in which a "control" gene was altered in an organism,
>or a small surgical procedure performed on a developing embryo, which
>resulted in a large morphological change in the adult organism ("B") IN
>THE DIRECTION OF the putative ancestral form "A." Glenn offers this as
>evidence in support of evolutionary development from A to B. Stephen Jones
>and Jim Bill criticized this by saying (1) Since the alterations were
>performed by an intelligent agent, this is more like evidence for
>Progressive Creation; and (2) What about all the OTHER mutations required
>to transform creature A into creature B?
LH>Maybe we can agree on some common points. Let me suggest:
>
>1) The experiments Glenn cites are evidence for common ancestry, or at
>least the strong appearance of common ancestry. (This fits into either
>theistic evolution or progressive creation. The experiments themselves
>cannot tell whether the new developmental genes in creature B arose from a
>sequence of "natural" mutations, or _ex_nihilo_ creation of a new gene
>SIMILAR to A's, or anything in between.)
Disagree about blanket "common ancestry" claim. Gould points out that
homeosis is only applicable the arthropods and other segmented
organisms.
What Jim and I protest about is the constant extrapolation from
special cases to a general theory. As Jim points out, if atavism was
that significant it would be chapter 1 page 1 of evolutionary biology.
My daughter's 1990 university Biology text has about a quarter page
(at page 684) in an 800 page book, dealing with homeotic genes. It
says (inter alia):
"Evidence for the existence of homeotic genes comes from experiements
with Drosophila, in which a single gene mutation can have bizarre
consequences...Homeotic genes have been discovered in other segmented
animals with body parts that repeat." (Mader S., "Biology", 3rd Ed.,
1990, Wm. C. Brown, Indiana, p684). The book draws no evolutionary
implications from this despite having a strong evolutionary emphasis
in other places (there are 5 whole chapters devoted solely to aspects
of evolution).
LH>2) The fact that the experiments were performed by an intelligent
>agent is a moot point. Both T.E. and P.C.-with-common-ancestry
>predict the same result from the experiment, so the experiment
>doesn't preferentially support one or the other in that respect.
LH>3) In order to "prove" evolutionary development from A to B
>(insofar as any such hypothesis can be "proved"), we would have to
>find a mutational pathway through viable genomic phase space which
>was sufficiently "short" (to allow for a realistic rate of mutations
>and substitution into the population). To _disprove_ evolutionary
>development, we would have to show that there is NO "sufficiently
>short or viable" pathway. The experiments which Glenn cites are just
>a begining, sort of a signpost on the path. They show that a small
>part of the pathway is shorter than we might otherwise have expected,
>but a lot more work will have to be done to settle the issue. Is
>that reasonable, or am I just starting a new argument? :-)
I am not qualified to evaluate Glenn's mathematical arguments. My
understanding is that the total genetic combinations of all
organisms is unimaginably large, exceeeding by far all the
electrins in the universe. So I remain unconvinced that a random
search could discover them.
Besides, I have seen no evidence that Glenn's arguments are accepted
in mainstream Darwinism.
LH>p.s. No more posts from me for two weeks. Vacation!!!)
Happy holiday. It's mid-winter here down under! :-)
Stephen