JOHN_A_DESIGNER: You answered my 2nd question, but but I'm still not clear what you think about the first.

I did think about your question and thought I had answered it, but perhaps not as directly as I might have.

JOHN_A_DESIGNER: I asked whether or nor you agreed that "the weakest point in Darwin's theory is the origin of novelty and the sufficiency of random change?"

I have several problems with the construction of your query. "Darwin's Theory" is rather nebulous. Are you referring to the historical theory? Or are you conflating various biological theories?

Leaving that quandary aside, the concept of "weakest point" is problematic. Darwin proposed a valid theory of evolution and yet had no idea how the variation arose. But natural variation within populations is a fact. The Theory of Common Descent is so strongly supported that there is no reasonable scientific doubt concerning its validity; while variation, evolution and natural selection can be directly observed.

The source of variation is certainly an important area to investigate. Variation is not purely random. Even if the variation turned out not to be random with respect to fitness, it wouldn't represent any threat to the fundamental basis of the Theory. Many sources of biological variation have been found, and many more sources will probably be identified. But there is still a lot to learn.

Kirschner and Gerhardt: Though modern scientists may have questioned the completeness of the Theory of Evolution, few believed that the fundamental principles of variation and selection would not in the end explain the diversity of life. Certain groups, however, .. have exaggerated and fabricated weaknesses in evolution theory in order to discred it.

Variation and selection. Incomplete does not mean unsupported.

Now why do you think your cited experts would so strenuously reject Intelligent Design?

You answered my 2nd question, but but I'm still not clear what you think about the first. I asked whether or nor you agreed that "the weakest point in Darwin's theory is the origin of novelty and the sufficiency of random change?" This is a question that even some non ID-ists find interesting.

For example, in their book, The Plausibility of Life: Resolving Darwin's Dilemma, Marc Kirschener and John Gerhardt comment that:

"Without some account of how complex novelty arises, mere refuge in the sufficiency of time is unconvincing. To comprehend fully how genotypic change generates phenotypic change, one needs an understanding of how the genotype generates the phenotype. A degree of understanding is coming where none was before, giving us a sense of the ultimate map between genotype and phenotype. That map should provide a way to estimate the feasibility of evolutionary change. The existing phenotype of the organism biases the realm of possible phenotypic variation: that much is self-evident. But how, how much, and in what direction it biases novelty in evolution remain difficult and crucial questions." (p 33)

Their theory of "facilitated variation" was prompted by questions of how complex novel change occurs. Though they repudiate both ID and creationism they agree that questions about complex novel change are interesting, important and still largely unanswered.

chunkdz: What known rates did you mention in this thread?

Gingerich (1993, 2001), but there are many other studies and methodologies.

Gingerich, P. D. 1993. Quantification and comparison of evolutionary rates. Functional morphology and evolution, American Journal of Science.

Gingerich, P. D. 2001. Rates of evolution on the time scale of the evolutionary process. Contemporary Microevolution: Rate, Pattern, and Process.

chunkdz: For instance, dog brains have generally shrunk by about 20% compared to their wolf ancestors.

Yes, many domesticated animals have smaller brains *and* smaller teeth. I wonder why.

chunkdz: So, in the end, I can see your point. A 9000 lb., blind, obese, disease ridden dog that can't walk and has a brain the size of a flea seems perfectly plausible.

Consider a world with one-ton 'rats'.

chunkdz: … artificial selection comes with a trade-off. Selection vs. viability. At some point, (I don't know exactly where) the selected trait will beget unviability.

This is the result, after centuries of artificial selection, when such an organism is let loose in the wild.

"I'm not extrapolating from artificial breeding, but from known rates of natural evolutionary processes."

Hmmm. What known rates did you mention in this thread?

Wolf breeds vary in weight from about 30 to 70 kg (e^0.8 deviation); while dogs vary from 1 to 100 kg (e^4.6 deviation). This in a few tens of thousands of years. The rate of evolution in dogs is consistent with what is expected over the time-scale involved.

And…

…there is no reason to believe that dogs might not evolve to be much larger given the opportunity.

Sounds to me like you are taking the relative weight deviation of domestic dogs and making an extrapolation about what natural selection can do.

Ok, ok. Extrapolate away.

But don't neglect the other obvious extrapolations. For instance, dog brains have generally shrunk by about 20% compared to their wolf ancestors. Extrapolate that out for about 15 million years.

And let's not forget to extrapolate the limited genetic diversity that dogs possess, along with it's deleterious effects. Joint problems, thyroid malfunction, eye problems, gut problems, bone problems, breathing problems, congenital illness, lower life expectancy, susceptibility to sickness, etc. etc. Let's be sure to extrapolate those rates out for 15 million years.

So, in the end, I can see your point. A 9000 lb., blind, obese, disease ridden dog that can't walk and has a brain the size of a flea seems perfectly plausible.

Isn't extrapolation fun?

JOHN_A_DESIGNER: So you would disagree with the statement, that the weakest point in Darwin's theory is the origin of novelty and the sufficiency of random change. You think all the major problems have been resolved. Is that your opinion?

I think there is still quite a lot to learn about the origin of novelty.

As to "Darwin's theory", Darwin didn't have a theory of genetics and proposed a poorly devised, non-random theory of variation called Pangenesis. In any case, mutations are now largely understood to be random with respect to fitness, but mutations are not purely random, nor are their phenotypic changes purely random.

There are a variety of mathematical relationships concerning the evolution of complex networks. Older structures tend to be more essential and more stable. That's because they act as hubs for a great many other interactions, so even minor changes cause repercussions throughout the network requiring many simultaneous changes. Newer structures tend to be less essential and more pliable. That leads to another general rule, minor changes happen frequently, major changes happen infrequently, revolutionary changes happen very rarely. This means we will see long periods of relative stasis unless the system is perturbed externally.

chunkdz: Dogs have artificially evolved at a relatively fast morphological rate. Yet they will never be bred to be as large as elephants, no matter what the rate of morphological change.

chunkdz: In truth, if we extrapolate artificial selection for a particular trait out over deep time, we generally get death.

chunkdz: I said that you were ignoring some obvious limits

chunkdz: The point is that the rate of change is only a tiny part of the story, so it is incorrect for you to extrapolate the results of artificial breeding to reflect what natural selection can accomplish.

I'm not extrapolating from artificial breeding, but from known rates of natural evolutionary processes.

We know that mice and elephants share a common ancestor. We know that the observed rate of naturally occurring evolution is sufficiently robust to account for the historical changes (constituting a confirmed prediction from theory). We do not know all the twists and turns of that evolutionary change, though we do know some of the intermediate stages indicating (along with other such transitions) that the process was incremental. Meanwhile, you claim there is some sort of limit, but there is apparently no barrier preventing a primitive shrew-like mammal to elephant transition and substantial evidence as to the mechanisms involved.

chunkdz: Perhaps you should start over by explaining what it is you think that I am saying.

Zachriel: Yes, you're saying that "dogs cannot be bred to be the size of elephants" assuming sufficient time and selection.

I kind of figured that you had missed the point. I might just as easily have said that dogs cannot be bred to be the size of gnats, but I suppose you would have questioned that as well.

The point is that the rate of change is only a tiny part of the story, so it is incorrect for you to extrapolate the results of artificial breeding to reflect what natural selection can accomplish.

chunkdz: Because artificial selection comes with a trade-off. Selection vs. viability. At some point, (I don't know exactly where) the selected trait will beget unviability.

Zachriel: If there is some natural limit, it has nothing to do with the selection being artificial as opposed to natural.

chunkdz: Not true. Inbreeding reduces fitness. Artificial inbreeding for particular traits greatly reduces fitness.

False Irrelevant as artificial selection does not necessarily entail inbreeding.

Just to make sure the context is clear. Chunkdz was responding to a statement concerning artificial selection conflating that with artificial inbreeding.