>Comment: Does natural selection do nothing more than remove "bad"
>sequences? I don't think most evolutionary authors would be satisfied with
>that, including Darwin, Mayr, Dawkins, Dennett, among others. As I
>understand Darwinian theory, natural selection is the critical process that
>drives evolution and adapts organisms to their niches.
Natural selection does two things. Kills badly adapted genomes and allows
well adapted genomes to reproduce. Natural selection is not the thing that
"adapts organisms to their niches" The genome is what does that. Natural
selection is the test, not the adaptor. Those genomes adapted to the
environment reproduce well; those that aren't don't.
>You now seem to be
>substituing concepts from information theory, which I obviously do not
>understand, such as, "pathway", "sequence space" "billions of dimensions",
> "mathematical space". Natural selection no longer plays a role, as far as I
>can see.
Information theory is something that needs to be understood if someone is
going to criticize modern views of evolution. Researchers like Stuart
Kaufman are dealing in this type of modeling of evolution.
> You say, "But as long as there is a path through the
>sequence space from one sequence to another in which all sequences allow a
>living being to exist and reproduce, then mutation can move from one species
>to another....If there is a path into that point, *it can be found by random
>mutation, given enough time*." Are you saying that random mutation can do it
>by itself, without the shaping role of natural selection?
No. The best analogy I can draw is to a ball on a water bed. As waves of
water travel under the plastic, a ball on the bed finds itself pushed and
pulled in different directions depending upon what part of the wave the ball
finds itself. Similarly, natural selection acts on a genome pushing and
pulling it in various directions within the sequence space.
> This lack of a
>role for natural selection (except to remove "bad" sequences) leaves
>information theory quite unsatisfactory as far as I'm concerned; and I see
>little empirical confirmation of the computer simulation.
>
You keep saying that there is no role for natural selection in spite of the
fact that I keep saying that there is a role in information theory. Since
you admit that you are not conversant with information theory and nonlinear
dynamics, how can you say that these theories leave natural selection out of
the picture? Is this what you want to believe or what the study of the area
has convinced you of?
Yockey states,
"Let us consider evolution as a communication system from past to present.
At some time in the history of life the first cytochrome c appeared. As a
result of drift, random walk and natural selection, this ancestor genetic
message was communicated along the dendrites of a fractal representing a
phylogenetic tree. Most organisms that lived once are now extinct and, of
course, their protein sequences are lost. Some dendrites lead to modern
organisms, the sequence having changed with time. Thus the original genetic
message of the common ancestor specifying cytochrome c, regarded as an
inpute, has many outcomes that nevertheless carry the same specificity.The
evolutionary processes can be considered as random events along an ergodic
Markov chain that have introduced uncertainty in the original genetic
message." Information Theory and Molecular Biology, Cambridge Univ. press,
1992, p. 132
Explanation of terms.
dendrite- a tree-like branching path. Published phylogenies look like trees
and are dendrites
Markov chain--a sequence of decisions in which the future probability
depends upon the present state of the system. Our genome is unlikely to
mutate at once to that of a bird, but it is likely that some position will
be mutated from C to T. Each future probability has its own probability of
occurence.
Notice the inclusion of natural selection. If you won't believe me that
natural selection has a role, then believe Yockey.
>You wrote, "The nature of a lot of mutation is that it changes a whole lot
>of things all at once. To assume that mutation produces small change and
>another mutation produces another small change is an outdated view of how
>mutation and development work." You go on to quote Gould, "Genetic systems
>are arranged hierarchically; controllers and master switches often activate
>large blocks of genes. Small changes in the timing of action for these
>controllers often translates into major and discontinuous alterations in
>external form."
>
>Comment: How do these concepts apply to the transition between fins and
>legs. What are these "large blocks of genes" that Gould posits? Where do
>they come from?
You answer your own question below. Like the switches that supply
electricity to my computer, some switches are more important than others.
The switch from the generator to the power grid, if it is turned off would
turn off a whole city full of lights. the switch at my substation, if it is
turned off, costs my neighborhood its electricity. The switches at my fuse
box turns off only a room or two in my house. The surge protector on my
computer has a switch that if it is off prevents my computer, printer, EZ
drive/TV/VCR from runing. The switch on my computer only prevents the
computer from running. Genetic developmental switches are exactly like
that. Vestigial that you mention below, does not in and of itself make
wings. It is the switch between the generator and the power grid. Lots of
other switches are needed to make wings successfully.
>Let me suggest that they may constitute *developmental
>programs* that I believe lie unexpressed in the phyletic germ line until
>activated by controllers and master switches. Perhaps they are the
>"developmental patterns" that Vermeij suggested were the products of the
>Precambrian putative formation of phyla, that I referred to in a previous
>post.
>
>On the other hand some times a single gene does it all. A single gene--not
>several--is enough to spark the formation of a major structure like wings in
>Drosophila according to Carroll in Nature, July 11, 1996. The gene called
>*vestigal* caused wings to grow in tissue that doesn't normally form wings,
>such as eyes, heads, antennae, or legs. So genes apparently work in various
>ways. Incidentally, such a single gene as *vestigal* which does so much
>makes it at least possible to think that the original genome of a lineage
>could hold a great deal of structural genetic material in suppressed form for
>future phyletic development.
>
>You wrote, "As I noted, 3 mutations perform most of the morphological change
>between two species of monkeyflowers."
>
>Comment: In my humble opinion, your example is not relevant to how fins
>were transformed into vertebrate legs. The major innovation represented by
>the transition from aquatic to terrestrial life is not explained by
>microevolutionary change of one species to another. The transition from
>aquatic to terretrial life happened far upstream when major changes were
>being made. The change from one species to another pales in comparison.
>
>I wrote in my last post that "Development also works on a sliding scale. It
>starts out high, and ends low. NS starts low and ends high." To which you
>replied, " There is none of theis high and low business. None of this higher
>and lower animals as far as I can see."
Let me suggest that natural selection starts out very, very high for the
next generation. If the parents are unable to reproduce, development of the
next generation has no chance.
>
>Comment: I was not referring to higher and lower animals.
I misunderstood you last time. Sorry.
[snip]
>On the other hand our exchange of notes has not permitted me to provide other
>evidence for the developmental framework. And this is not the best format
>for presenting it. As I said earlier I am in the process of preparing a
>summary of the theory, which when I complete I will be glad to share with
>you, if you wish, for your comments and questions.
I will look forward to it.
glenn
Foundation, Fall and Flood
http://www.isource.net/~grmorton/dmd.htm