The abstract says,
"Desent with modification, however, renders design unnecessary only if it is
due entirely to naturalistic mechanism. Two such mechanisms ahve
beenproposed, genetic programs and developmental pathways, but neither one
fits the evidence." (p. 12)
The authors go on to knock down genetics as the basis of homology by stating:
"According to the neo-Darwinian synthesis, a genetic program encoded in DNA
directs embryonic development; the process of reproduction transmits this
program to subsequent generations, but mutations in the DNA sometimes modify
it ('descent with modification'); thus descendants of the original organism
may possess structures which are similar but not identical ('homologies').
No design is required, so the explanation is thoroughly naturalistic." (p. 14)
So I have a question of the authors if I can get them to reply. Why does a
DNA program exclude a designer having written the program? The designer
very well may have written a program that is able to mutate itself like many
computer viruses can do. This may have been intentional on the part of the
designer so that different living forms can arise and thus amuse the designer.
They then conclude the "genetic program as the cause of homology" section with
"The underlying assumption that a genetic program directs embryonic
development has been seriously questioned by developmental biologists.
Sydney brenner, who originally proposed genetic programs in 1970, repudiated
the idea when he realized that the information required to specify the
neural connections of even a simple worm far exceeds the information content
of its DNA." (p. 15)
I would point out that I performed a similar calculation for the information
content of the human brain with similar results.
http://www.calvin.edu/archive/asa/199710/0403.html
http://www.calvin.edu/archive/asa/199710/0405.html
But this of course raises a question for the Intelligent design position.
If there is not enough information in DNA to account for brains of even
small worms, then why all the fuss about information theory and all in this
movement?
The second suggestion for explaining homology concerns developmental
pathways. They state:
"Efforts to correlate homology with developmental pathways, however, have
been uniformely unsuccessful. First, similar developmental pathways may
produce very dissimilar features.' p. (15)
"Secondly, and more dramatically, similar features are often produced by
very different developmental pathways." (p. 16)
They conclude by saying
"Without a naturalistic mechanism to account for homology, however,
Darwinian evolution cannot claim to have demonstrated scientifically that
living things are undesigned, and the possibility remains that homologies
are patterned after non-material archetypes." (p. 17)
The authors propose no explanation at all of homology. So the question I
have here is:
If I agree that homology is not due to genetics nor due to developmental
pathways, fine. Now that you have told me what does not work, what does
explain homology? Is it the archetypes?
If naturalism cannot explain why homology occurs, does this mean that you
are taking a position in which God Himself personally fashions each living
creature according the the Platonic archetype and He provides the
information for homology?
What is the mechanism for the transference of information from the archetype
to the developing critter?
If DNA has no role in producing homology nor in the developmental pathway,
then why do we have DNA systems at all?
glenn
Adam, Apes, and Anthropology: Finding the Soul of Fossil Man
and
Foundation, Fall and Flood
http://www.isource.net/~grmorton/dmd.htm