Don't worry too much about definition
by MikeGeneOkay, we've seen that the important concept of "˜species' comes with a fuzzy definition that does not seem to apply to the majority of organisms on earth, so what about the concept of life? After all, biology is the study of life. How is it defined:
SHAPIRO: There was a wonderful paper written by Chris Chyba and Carol Cleland about three years ago about definitions of life, and how even defining what definition is can get you into philosophical doo-doo. And it's best to look for phenomena that by their properties we would be happy to classify as alive, and to not worry too much about definition.
One could borrow from this logic and also argue, "it's best to look for phenomena that by their properties we would be happy to classify as intelligently designed, and to not worry too much about definition."
January 31st, 2008 at 7:14 am
And let's not forget definitional problems with natural selection and the associated concept of fitness. It seems to be one of those "I know it when I see it" deals for most folks. The terms can be more precisely defined in terms of reproductive survival, but that robs them of their practical insight vis a vis Darwinian evolution.
So I have no problems with folks demanding hard definitions, but I merely expect they play by the same rules they try to impose on me.
Comment by RogerRabbitt — January 31, 2008 @ 7:14 am
January 31st, 2008 at 9:24 am
Would that include intelligently designed by man?
Comment by The Pixie — January 31, 2008 @ 9:24 am
January 31st, 2008 at 11:16 am
We're talking about assigning a definition to a known phenomena, but one which has a chaotic edge. Some things we know fit well within the boundary (puppy dogs), and some things we know fit well outside the boundary (brass door knobs). Sometimes, especially when those edges are chaotic, we might try to work with a partially defined category, and by doing so, help define that edge. Notice that Shapiro is not rejecting any definition, just allowing for some flexibility.
It's called a working definition.
To extend this concept to Intelligent Design, you need a reasonable working definition of intelligence, but it might allow for some flexibility on the edges. However, Intelligent Design typically doesn't posit a quasi-intelligent process (evolutionary processes might be considered quasi-intelligent), but definitive intelligence.
Also, keep in mind that this you are referencing an expansive discussion, not a philosophical or scientific tract.
Comment by Zachriel — January 31, 2008 @ 11:16 am
January 31st, 2008 at 1:24 pm
Often the arguments about the definition of specific terms are about the definition of "definition." I criticize your language and request (or demand insistently) that you define your terms more precisely. But I will hold you to a factitious, arbitrary, and undefined standard of precision.
These arguments hardly ever rise above the level of general concepts, which are also our least well defined terms. The argument raises a doubt about anyone's ability to convey any meaningful information or understanding about anything in general. IOW the argument implicitly cast into doubt science itself. Such is the defense of true science! LOL
But there is more to the argument than that. There's a sinister side. I call it the "Orwellian argument." The argument is predicated on a theory: Control language, control thought.
The argument is like a scene out of Kafka. If you thought I was grilling you for a precise definition of your terms you have not understood the rules of the game (which, of course, are the rules I decide):
Only I am allowed to define your terms.
Gives one a definite sense of empowermnet. I can literally define into or out of existence anything. You can only hope that I use my powers for good…
[Insert maniacal laughter here.]
Comment by Rock — January 31, 2008 @ 1:24 pm
January 31st, 2008 at 2:22 pm
I do loves me some Rock!
The "Kafka-esque" analogy…
…resonated with me as I pondered Zachriel's previous post.
Notice how Zachriel makes a demand that ID proponents define intelligence.
Notice how Zachriel then graciously provides us his guidelines for defining intelligence, by invoking "quasi-intelligence" and "definitive intelligence" (whatever those might be).:roll:
Care to define THOSE terms, Zach?:lol:
Comment by chunkdz — January 31, 2008 @ 2:22 pm
January 31st, 2008 at 2:49 pm
I think it reasonable to consider that a simple filter is a quasi-intelligent agent. Natural selection is a simple filter. Is natural selection sufficient intelligence to explain life as we know it? I don't think so.
I think that "sufficiently intelligent" to explain life as we know it needs at least one very clear attribute: forethought — intention.
Natural selection has no future goal in mind. Future goals, advancement, however is evident in life. I don't see advancement as a possible product of a quasi-intelligence that is not in any way seeking advancement. I look at the nuclear pore that is being discussed on UD. I don't think that such a contrivance can come about without forethought — intention.
Comment by bFast — January 31, 2008 @ 2:49 pm
January 31st, 2008 at 3:13 pm
Rock:
The older I get the more I appreciate the wisdom of the Rock. Ya ever think about running for president Rock?
Comment by Bradford — January 31, 2008 @ 3:13 pm
January 31st, 2008 at 4:28 pm
I asked for a "reasonable working definition".
'The question is,' said Alice, 'whether you can make words mean so many different things.'
'The question is,' said Humpty Dumpty, 'which is to be master - that's all.'
Comment by Zachriel — January 31, 2008 @ 4:28 pm
January 31st, 2008 at 9:30 pm
The concern I have is with definitions that are too broad "Evolution is change over time" or too narrow "A species is an isolated breeding group"
These definitions are operational, but they skirt the fundamental issue pertaining to novel genetic or morphological structures and their origin.
Comment by David — January 31, 2008 @ 9:30 pm
February 1st, 2008 at 12:00 am
Most scientists are careful in their use of terminology, because the purpose of publication is to communicate so that other scientists can replicate and extend their results.
Let's start with the definition of evolution you provided, the change in heritable traits (alleles) over time. The Theory of Evolution is the scientific theory that explains the mechanisms of evolution.
We define variation as heritable differences within a population. Natural selection is the causal relationship between the environment and evolution, or the result of competition for resources or mates due to heritable traits. Adaptation is the process or result of evolution by natural selection.
A species is an interbreeding population, with speciation a process that occurs over time. That there is a fuzzy or chaotic edge to a species does not make the definition meaningless or without utility, and this gradation of fertility is actually important evidence cited by Darwin. There are several known mechanisms of speciation.
Common descent refers to the fact that species diverged incrementally from common ancestors.
When we combine these disparate concepts, we have a Theory of Evolution. That is, we have incremental divergence from common ancestors, and robust mechanisms of evolutionary change that can be observed and studied.
Novel structures are incremental adaptations of existing structures. Fins to legs to arms to wings to fins.
Comment by Zachriel — February 1, 2008 @ 12:00 am
February 1st, 2008 at 12:11 am
Hi RogerRabbit,
Exactly. I should add that I have no problem with the difficulties when it comes to these definitions, as my 3 posts are not some form of critique. On the contrary, we can learn from the fact that scientists are exploring a fuzzy reality with fuzzy concepts.
Comment by MikeGene — February 1, 2008 @ 12:11 am
February 1st, 2008 at 1:14 am
David, I think you have a point that is not addressed in full by Zachriel. I'm going use the molecular level to illustrate a point. Enzymes are important components of living organisms. We have identified groups or families of enzymes which share similar structures and functions within their goups and vary accordingly from group to group. For example, isomerases catalyze racemization of optical isomers, transferases catalyze the transfer of carbon, phosphate or nitrogenous groups and ligases catalyze bonds between carbon and oxygen or nitrogen. There's more but the point is these enzyme groups differ and it is unreasonable to assume a gradual process would have simultaneously generated all of them.
At some point in time identifiable structures at any level were novel and it is legitimate to inquire about the origin of novelty. This includes the matter of definitions.
Comment by Bradford — February 1, 2008 @ 1:14 am
February 1st, 2008 at 8:26 am
Scientists don't think they arose simultaneously, but incrementally.
Pertinent to the discussion, these microbiological structures evolved billions of years ago and left no direct evidence. They do form a reasonably consistent nested hierarchy, a prediction from common descent. But because we don't have direct evidence, it can be difficult to untangle their evolution. We would normally start with what we have more evidence about, such as macroscopic adapations. Or does everyone accept the Theory of Evolution from eukaryotes to elephants?
In any case, the question at issue is whether we can provide reasonable definitions to construct a valid scientific evolutionary theory.
Comment by Zachriel — February 1, 2008 @ 8:26 am
February 1st, 2008 at 12:36 pm
Well, the first such criterion is simplicity. Known designers create things with smooth surfaces, continuous lines, sharp edges, shapr contrasts, etc. Mt. Rushmore looks designed, the Man in the Mountain does not, because the surface of the first is smooth, even, and has sharply delinated features, while the second is craggy, uneven, and fgeatures that don't have a concrete border. The fact that categories in biology are uneven and without concrete borders resembles a lack of design.
Comment by One Brow — February 1, 2008 @ 12:36 pm
February 1st, 2008 at 3:23 pm
Bradford:
Has Zachariel ever addressed anything in full? Maybe it is my engineering mind set (after all, that is what I do for a living) but I get frustrated when someone makes a scientific claim and can't back it up with any real evidence.
Instead of identifying specific chemicals and specific processes Zachriel simply gives us vague general assertions like: "Novel structures are incremental adaptations of existing structures. Fins to legs to arms to wings to fins.." Or, "Scientists don't think they arose simultaneously, but incrementally." Never mind giving an incremental, specific and detailed explanation how any of that happens.
I think, in science, we can get bogged down arguing over definitions. Are definitions really necessary for the advancement of science? Sometimes things are just hard to define. Matter, energy, space and time, for example, are concepts that are also notoriously difficult to define, but that certainly hasn't hindered the advance of modern physics. What is important in science (as it is in engineering) is figuring how something happens. And, I guarantee you that explaining how something happens always involves detailed and specific kinds of explanations. IOW we need detailed explanations not definitions. Leave the definitions to people who write dictionaries.
Comment by JOHN_A_DESIGNER — February 1, 2008 @ 3:23 pm
February 1st, 2008 at 3:49 pm
Penguins are not a generality.
I was agreeing with Bradford concerning the hypothesis that these structures just came together in a single, simultaneous step.
In any case, when you actually look, there are a number of lineages with fairly obvious transitionals, such as horse evolution. Indeed, if you actually look at some fossils, they tend to fall into fairly regular families of incremental adaptations. After all, an elephant tusk is just a long tooth, even though it no longer functions as one.
Comment by Zachriel — February 1, 2008 @ 3:49 pm
February 3rd, 2008 at 11:28 am
Zachriel says:
Zachriel provides a more than reasonable definition of NS for folks actually interested in discussing NS and related issues. But also notice the conflict between "causal" and "result" that are destined to become a source of conflict between folks of differing POV's on these issues as exemplified by the discussions here and at other sites.
It is easier to see my own ambiguities as innocent or even inevitable, but the other guy's as evidence of dishonesty, intellectual weakness, hidden agendas, etc.
Comment by RogerRabbitt — February 3, 2008 @ 11:28 am
February 4th, 2008 at 8:05 am
Zachriel you are not understanding the problem. I agree that there is quite a lot of evidence for species level change. However, that is not where the more problematic gaps exist. Denton explains the problem quite accurately. In his book he writes:
Denton, by the way, isn't a creationist and believes, like Behe, in Common Descent. He does however argue that the standard Darwinian and Neo-Darwinian explanations do not hold up to closer scrutiny.
Comment by JOHN_A_DESIGNER — February 4, 2008 @ 8:05 am
February 4th, 2008 at 7:28 pm
Do you accept common decent? If not, we have to start with that. You can't hardly argue about the rate of morphological changes between nodes of the nested hierarchy, otherwise.
I'm fully aware of what you think is the problem, that historical morphological changes occurred too quickly to be accounted for by natural evolutionary processes.
Classic handwaving. What is the calculated rate of morphological change in these historical transitions? What is the observable rate of morphology evolution?
Comment by Zachriel — February 4, 2008 @ 7:28 pm
February 4th, 2008 at 10:52 pm
Zachriel,
The rate of change is only a part of the story.
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. If you want to be accurate, let's talk about the limits of evolution, not just the rate.
Comment by chunkdz — February 4, 2008 @ 10:52 pm
February 5th, 2008 at 7:27 am
And you know this how exactly?
Accepting Common Descent, then we know that dogs evolved from even smaller, and morphologically very different, mammalian ancestors, and share that ancesetor with mice and elephants. 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.
Comment by Zachriel — February 5, 2008 @ 7:27 am
February 5th, 2008 at 1:42 pm
I am open minded on the subject. However, I think there are empirical reasons to be skeptical as well as logical ones. Assuming your primary premise has to be true is question begging.
Denton is arguing that there are gaping holes in the fossil record just where there is the greatest morphological change and the greatest increase of innovative novel features. Shouldn't the emergence of these innovative novel features: flight feathers in birds, The development of wings in both birds and bats, diaphragms and mammary glands in mammals etc take a long period of time? Shouldn't there be an abundance of fossil evidence? Oh yes that's right we can only make such inferences from skeletal remains. However, even there the fossil record is not very helpful. The hand-waving is really the Darwinist side who, whenever they are confronted with an anomaly or problem, retreat to their a priori belief that somehow unguided RM + NS did it. I am not convinced that nature is sufficient in and of itself to create a high degree of novel change.
Comment by JOHN_A_DESIGNER — February 5, 2008 @ 1:42 pm
February 5th, 2008 at 7:15 pm
No. I'm not trying to prove the premise from the argument. Note you just cited Denton's argument saying,
Hence, the argument based on that precept.
Comment by Zachriel — February 5, 2008 @ 7:15 pm
February 5th, 2008 at 7:16 pm
However, if you wish to discuss the evidence for Common Descent, I would be happy to oblige.
You have to start with a particular pattern called the nested hierarchy. You are probably somewhat familiar with this pattern as the Tree of Life. The vast majority of taxa and traits can be organized into a *singular* nested hierarchy. This hierarchy even extends into geologic time. This is the expected pattern resulting from common descent of uncrossed lineages, and leads to specific, testable predictions.
Comment by Zachriel — February 5, 2008 @ 7:16 pm
February 5th, 2008 at 7:51 pm
Zachriel,
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.
You make a common error in extrapolating the results of artificial selection to natural selection. The two are extremely different, and yield different results.
In truth, if we extrapolate artificial selection for a particular trait out over deep time, we generally get death. If we extrapolate RV + NS over deep time we generally get stasis. The most probable explanation lays somewhere in the middle. Something like RV + NS + (?) = Novel Morphology.
Comment by chunkdz — February 5, 2008 @ 7:51 pm
February 5th, 2008 at 8:29 pm
If there is some natural limit, it has nothing to do with the selection being artificial as opposed to natural. There are usually short-term physiological limits to evolutionary diversification, but I was curious as to your reasoning. (You might want to consider the recently discovered one-ton 'rat' when pondering physiological limits.)
Those are unsupported claims in lieu of argument or evidence.
As human selection is a rather new phenomena, I have no idea why you would make such a claim concerning "deep time".
Upon what do you base this assertion? On the contrary, we know the observed rates are much, much faster than required to explain the historical record, while the differences in long-term stasis and directional change are determined by environmental factors, *not by any intrinsic rate* (Gingerich 1993, 2001).
What happens is that life quickly diversifies to fill the available niches, then changes little unless the ecosystem is perturbed. There are many excellent examples of adaptive radiation, including in the Galápagos Islands.
Comment by Zachriel — February 5, 2008 @ 8:29 pm
February 5th, 2008 at 10:50 pm
The more I read that statement, the less it makes sense. Have you ever bred animals?
Comment by Zachriel — February 5, 2008 @ 10:50 pm
February 6th, 2008 at 12:36 pm
Zachriel,
Not true. Inbreeding reduces fitness. Artificial inbreeding for particular traits greatly reduces fitness.
What are those short term physiological limits that you speak of? And why do we hit these limits when we attempt to artificially breed for a particular phylogenic trait?
I seriously doubt that artificial selection had anything to do with the rat's size.
Fossils, mitochondrial DNA.
I didn't make any claim about intrinsic rates. I said that you were ignoring some obvious limits, and making some rather weak assumptions. Your assumption about rate of change is similar to saying that because my car can do 100 miles an hour that I should be able to reach the peak of Everest from base camp in about 15 minutes. You are ignoring a whole set of difficulties and limits to what the vehicle can accomplish.
Did you see the word 'extrapolate'? It means to infer about the unknown from the known. But we do know that inbreeding and isolation generally cause genetic degradation, disease, smaller brains, etc. If you are unable to see the trend, then I probably can't convince you otherwise.
Thanks. I watch the Discovery Channel too.
Comment by chunkdz — February 6, 2008 @ 12:36 pm
February 6th, 2008 at 1:59 pm
Zachriel: The point I was trying to make about common descent, it's really secondary to whether Darwinism or neo-Darwinism (RV + NS) are good theories. Both Denton and Behe believe Common Descent but doubt the RV + NS is able to adequately account for novel morphological change. Ironically all you have are trivial examples change of size and shape of breeds primarily with in a species or family. Even Young Earth Creationists accept this kind of variation. In their literature they refer to it as micro-evolution. Darwin made key discoveries that explain this kind of variation and he deserves credit for those discoveries.
However, what Darwin didn't explain very well is the novel change we see that differentiate different classes of animals: amphibians emerging from fish; reptiles from amphibians; birds and mammals from reptiles etc. Consider for example what it takes for mammals to evolve from reptiles.
I think Michael Denton summarizes the problem nicely. All members of the mammal class, he writes:
Notice what this implies. All mammals are derived from a common ancestor. Fossil evidence such as there exists implies that the last common ancestor came from a fairly small population. This small population had a lot of evolution probably in a fairly short time span before diversifying into modern mammals. That simply doesn't fit the slow gradual process required by Darwin's theory.
Chunkdz makes a good point:
Why not consider (?) if the evidence points you in that direction?
Comment by JOHN_A_DESIGNER — February 6, 2008 @ 1:59 pm
February 6th, 2008 at 3:36 pm
Um, artificial selection does not necessarily entail excessive inbreeding. But that does explain your previous confusion. Where you see "death", I see race horses and corn on the cob.
There are natural limits to everything. In terms of the evolution of physiology, there are always tradeoffs, and every choice (decision node) can act to limit choices. That's why highly specialized organisms tend to be more prone to extinction.
In the case of dogs, I would think their hip design might act as a temporary limit to further increases in size. This hasn't been a problem historically because many canines are cooperative hunters, and use intelligence more than sheer bulk to kill.
But keep in mind that we know that dogs and other mammals share a common ancestor. That means some canine cousins grow as big as elephants"”or rather, they are elephants. And there is no reason to believe that dogs might not evolve to be much larger given the opportunity.
Exactly. Lots of changes to rodent physiology had to occur before the rodent could get that big.
Sure you did, assuming by "RV + NS" you mean natural evolutionary processes.
You say there are limits. I reread your comments on this thread. I don't see where you described those so-called limits other than vague references to fossils and mtDNA.
Comment by Zachriel — February 6, 2008 @ 3:36 pm
February 6th, 2008 at 4:24 pm
Common Descent is an integral component of the Theory of Evolution and has been since Darwin.
Then you have to be willing to engage that argument. The argument is that mice and men share a common ancestor and that known mechanisms are not sufficient to account for this diversification. That is a vastly different position than saying that mice and men are not related by common descent.
There is substantial evidence concerning how each of these transitions occurred. Vertebrates do leave occasional skeletal fossils. And there is nothing that substantially calls into question incremental adaptation and evolution.
Why did you have trouble admitting this before?
That is not necessarily certain. Fossils may not provide a complete picture of an ecosystem. Even if the precise ancestor comprised only a small population, there may have been a robust ecology of many closely related varieties.
What you call a "short time span" may have been millions of years. Most people just can't comprehend the vast stretches of time involved.
In any case, it is now known from direct observations that evolution is a much more rapid than previously understood. Whenever a new niche becomes available, organisms will quickly adapt to fill the niche. This is often followed by a long period of relative stasis unless and until the system is perturbed.
Chunkdz's premise is faulty, but we can consider anything you want. But to have scientific validity, the assertion has to lead to specific and distinguishing empirical predictions.
Comment by Zachriel — February 6, 2008 @ 4:24 pm
February 6th, 2008 at 6:36 pm
Zachriel,
Um, why did you choose to insert the qualifier 'excessive' into my argument?
Look, selective breeding, whether it includes inbreeding, line breeding, or outcrossing, or a combination of all three, limits genetic diversity thereby reducing fitness. Race horses and corn are no exceptions.
Right. Like how big you can breed a dog to become.
Sorry, I still don't remember making a claim about intrinsic rates. Perhaps you were merely expecting me to do so, and so proceeded to argue as if I had.
And thankfully, now so do you.
Did you miss the part where I said that dogs cannot be bred to be the size of elephants?
Perhaps you should start over by explaining what it is you think that I am saying.
Comment by chunkdz — February 6, 2008 @ 6:36 pm
February 6th, 2008 at 8:14 pm
Let's revisit your statement.
False as artificial selection does not necessarily entail inbreeding. For instance, we might outbreed a preferred trait. We may visit Farmer Ahmed and ask to hire his stud animal. That single act is artificial selection.
False again in that not all inbreeding reduces fitness, especially when combined with outbreeding. Only *excessive* inbreeding has dire effects on a population, something that most breeders avoid.
Outbreeding increases genetic diversity. Your statement is largely muddled with the issue of inbreeding. But let's assume a single, finite population under selection (artificial or natural). Your point would be that the degree of variation on the one trait has been reduced. And that would be a reasonable point to make.
We have a standard distribution representing the Mendelian variation of a trait in the population. Through selection over several generations, the lower end (least desirable) end of the curve is reduced, and the distribution narrows across the upper end (most desirable). Most animal husbanders are not selecting for a single trait, of course, but also for the general vitality of the stock. Hence, they can only select to a point and maintain the population, perhaps even sell a few back to Farmer Ahmed.
But over time *novel* variations occur! And the standard distribution spreads across this new higher value. This takes time, typically many generations. Indeed, some *novel* variations in domestic plants and animals can be traced to specific genetic mutations.
Just repeating your claim doesn't lend it strength. You have offered no reason why dogs would necessarily be limited in size given a few million years of evolutionary selection for that trait. And we know that close relatives of dogs do grow to the size of elephants. They are called "elephants".
Yes, you're saying that "dogs cannot be bred to be the size of elephants" assuming sufficient time and selection.
Comment by Zachriel — February 6, 2008 @ 8:14 pm
February 6th, 2008 at 8:46 pm
FalseIrrelevant 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.
Comment by Zachriel — February 6, 2008 @ 8:46 pm
February 7th, 2008 at 1:53 pm
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.
Comment by chunkdz — February 7, 2008 @ 1:53 pm
February 7th, 2008 at 2:45 pm
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.
Comment by Zachriel — February 7, 2008 @ 2:45 pm
February 7th, 2008 at 3:00 pm
These are some of the claims you have made on this thread.
Comment by Zachriel — February 7, 2008 @ 3:00 pm
February 7th, 2008 at 4:08 pm
Zachriel:
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?
Comment by JOHN_A_DESIGNER — February 7, 2008 @ 4:08 pm
February 7th, 2008 at 4:41 pm
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.
Comment by Zachriel — February 7, 2008 @ 4:41 pm
February 7th, 2008 at 4:52 pm
Zachriel wrote:
Hmmm. What known rates did you mention in this thread?
And…
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?
Comment by chunkdz — February 7, 2008 @ 4:52 pm
February 7th, 2008 at 7:11 pm
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.
Yes, many domesticated animals have smaller brains *and* smaller teeth. I wonder why.
Consider a world with one-ton 'rats'.
This is the result, after centuries of artificial selection, when such an organism is let loose in the wild.
Comment by Zachriel — February 7, 2008 @ 7:11 pm
February 8th, 2008 at 1:21 pm
Zachriel:
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:
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.
Comment by JOHN_A_DESIGNER — February 8, 2008 @ 1:21 pm
February 8th, 2008 at 7:32 pm
I did think about your question and thought I had answered it, but perhaps not as directly as I might have.
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.
Variation and selection. Incomplete does not mean unsupported.
Now why do you think your cited experts would so strenuously reject Intelligent Design?
Comment by Zachriel — February 8, 2008 @ 7:32 pm