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Denton, Still a Theory in Crisis, Part 2

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This is the second of a series of posts reviewing Michael Denton’s new book Evolution: Still a Theory in Crisis.

“Gaps among known species are sporadic and often small.  Gaps among known orders, classes, and phyla are systematic and almost always large.”  George Gaylord Simpson, “The History of Life,” in ed. Sol Tax, Evolution After Darwin (Chicago:  University of Chicago Press, 1960), 1:149.

“Unfortunately, the origins of most higher categories are shrouded in mystery; commonly new higher categories appear abruptly in the fossil record without evidence of transitional ancestral forms.”  D.M. Raup and Steven M. Stanley, Principles of Paleontology (San Francisco:  W.H. Freeman and Co., 1971), 306.

“The known fossil record fails to document a single example of phyletic evolution accomplishing a major morphologic transition and hence offers no evidence that the gradualistic model can be valid.”  Steven M. Stanley, Macroevolution:  Pattern and Process (San Francisco: W. H. Freeman, 1979), 39.

As I noted in part one of this series, Dr. Denton has no doubt that Darwinian evolution occurs.  Nor should he.  The term “bauplan” comes from the German “building plan” or “building scheme,” and is often translated in biology as “body plan.”  In chapter 2 (entitled Galápagos), Denton explains that the biosphere is replete with examples of minor variations of bauplans – such as the beaks of the finches of the Galápagos islands made famous by Darwin – that are doubtless due to purely Darwinian processes.  These minor variations of bauplans are often classified under the term “microevolution.”

Before we go any further, let us anticipate an objection.  Darwinists who post in these pages often howl in indignation over the term “microevolution.”  They say the term is never used by “real” biologists.  Perhaps they do not consider George Gaylord Simpson to be a “real” biologist:

“Micro-evolution involves mainly changes within potentially continuous populations, and there is little doubt that its materials are those revealed by genetic experimentation.  Macro-evolution involves the rise and divergence of discontinuous groups, and it is still debatable whether it differs in kind or only in degree from microevolution.”  George Gaylord Simpson, Tempo and Mode in Evolution (New York: Columbia University Press, 1944), 97

Or Stephen Jay Gould:

“As a Darwinian, I wish to defend Goldschmidt’s postulate that macroevolution is not simply microevolution extrapolated . . .”  Stephen Jay Gould, The Return of Hopeful Monsters, Natural History, 86 (June/July 1977), 24, 30

Or Douglas H. Erwin and James W. Valentine:

“Explanations of the Cambrian radiation of invertebrate marine phyla and classes have focused on species selection or traditional microevolutonary processes.”  Douglas H. Erwin and James W. Valentine, “‘Hopeful Monsters,’ Transposons, and the Metazoan Radiation,” Proceedings of the National Academy of Sciences, USA 81 (September 1984): 5482-5483

Eminent biologists have recognized and referred to the distinction between microevolution and macroevolution for nearly one hundred years.  Let us hope that we can dispense with the “real biologists don’t use the term ‘microevolution’” canard once and for all.

Denton uses the Galápagos finch beaks as an example of microevolution.  The finches of the various islands are closely related in terms of nest architecture, egg coloration and DNA.  Yet in other respects, including their beak morphology, they can be quite different.  Denton quotes Darwin’s correct inference regarding the origin of these differences: “Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.”  Darwin was also correct about the causal mechanism that resulted in these changes: “Darwin also inferred (again rightly, as the work of subsequent researchers on Galápagos has amply confirmed) that the major causal mechanism responsible for their adaptive divergence—the shaping of their beaks for example—is the simple mechanism of natural selection.”

Denton concludes that evolution on this scale is caused by purely Darwinian mechanisms:

As far as the evolution of finch beaks is concerned, there is no need either at the morphological or genetic level to call for any causal agency other than cumulative selection. Here I concur with classic Darwinism. The beaks are clearly adaptations and their evolution is entirely explicable within a classic functionalist framework. . . . The lesson of the Galápagos, and one of the repeated mantras of Evolution: A Theory in Crisis (see Chapters 2 and 4) is simply this: Cumulative selection will work its magic as long as the novelty of interest is adaptive and there is a functional continuum (at the morphological or genetic level) leading from a putative ancestor species or structure A to a descendant species or structure B.

(emphasis in the original)

In summary, Denton has absolutely no problem with attributing evolutionary change to Darwinian mechanisms so long as the two conditions Darwin himself asserted are necessary are in place:  (1) the novelty is adaptive (otherwise there is nothing for natural selection to “select” for); and (2) there is a functional continuum – there can be no “gaps” in functional intermediates.

This brings us to another  important term: “saltation.”   In Origin of Species Darwin quoted six times the Latin sentence natura non facit saltus.  It means “nature does not take jumps.”  The word saltus means “leap” or “jump,” and in evolutionary theory a drastic or sudden change in a line of organisms (a “jump”) is called a “saltation.”  Thus, Darwin himself asserted that his theory does not allow for saltations. Stephen Jay Gould added in his 2002 The Structure of Evolutionary Theory  that Darwinian evolution requires variation for natural selection to act upon, AND that variation must, by definition, be very small.  Otherwise, it would be the variation itself, and not natural selection, that would account for the evolutionary change.

Thus Darwinists, beginning with Darwin himself, have always insisted that the theory absolutely requires the “functional continuum” to which Denton alludes.  Saltations are not possible under the theory.  Gould goes so far as to say “For this reason . . . saltationist (or macromutational) theories have always been viewed as anti-Darwinian.”  Stephen Jay Gould, The Structure of Evolutionary Theory (Cambridge, MA: Belknap Press [Harvard], 2002), 111.

Functionalist evolutionary theory demands a continuous chain of functional intermediates for natural selection to work at all:

Darwin’s interminable series of transitional forms is necessary for straightforward mechanistic reasons (how else can one get from A to B by cumulative selection?), but it is also essential if the sole agency of change is to be natural selection.  Where a complex adaptation—no matter how complex—can be reached in a series of tiny adaptive steps, then natural selection can indeed function, in Dawkins’s description, as a blind watchmaker and change A into B no matter how complex the transition, without any other causal agency being involved.

But what if the continuous chain of functional intermediates is missing?  Here we get to the nub of the matter, because Denton claims that

many of the taxa-defining homologs actualized during the course of evolution have never been shown to be adaptive and even in the case of those homologs which are apparently adaptive, functional continuums are either unknown or very hard to envisage.

And if this is the case, certain conclusions follow ineluctably:

To acknowledge their absence [i.e., the absence of a continuous chain of functional intermediates] is to acknowledge that the paths of evolution must have been ordered and directed by additional causal factors, i.e., that cumulative selection is not the sole or even the major directive agency.

Denton writes that this “need for adaptive continuums brings us to the nub of the problem, the core contention of Evolution: A Theory in Crisis, and the major point defended here: Practically all the novel, taxa-defining homologs of all the main taxa are not led up to via adaptive continuums.  Moreover, as argued later in this book, many of these novel Bauplans do not convey any obvious impression of being adaptive . . .”

Denton concludes the chapter with this delightful observation of fine irony:

It is ironic that the very evidence for believing that microevolution has indeed occurred in cases like the finches—an empirically known or readily envisaged continuum of forms leading from an ancestral form A to descendant form B—is precisely the evidence that is lacking when attempting to account for macroevolution and the origin of the defining features (feathers, hands, mammary glands, hair, the placenta, flowers, body plan, etc.) of the major taxa.

Comments
Eric you are right. I should have explained my concept of ORDER first. Please get the following quote from Aquinas (Commentary on Nichomachean Ethics) 1. As the Philosopher says in the beginning of the Metaphysics (Bk. 1, Ch. 2, 982 a 18; St. Th. 2, 41-42), it is the business of the wise man to order. The reason for this is that wisdom is the most powerful perfection of reason whose characteristic is to know order. Even if the sensitive powers know some things absolutely, nevertheless to know the order of one thing to another is exclusively the work of intellect or reason. Now a twofold order is found in things. One kind is that of parts of a totality, that is, a group, among themselves, as the parts of a house are mutually ordered to each other. The second order is that of things to an end. This order is of greater importance than the first. For, as the Philosopher says in the eleventh book of the Metaphysics (Bk. XII, Ch. 10, 1075 a 15; St. Th. Bk. XII, Lect. 12, 2629-2631), the order of the parts of an army among themselves exists because of the order of the whole army to the commander. Obviously by order I don´t mean a pattern of physical arrangement of particles or molecules. I mean a value, a meaning, a function, an intentional behaviour, directedness, goals, ends, the existence of a good; I mean a significance that can´t be reducible to the mere effect or expression of physycal laws. Life is order, and order is the hallmark of an intelligent cause.Anaxagoras
February 18, 2016
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@15 second paragraph: What does that even mean?Eric Anderson
February 17, 2016
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Anaxagoras @12:
But I consider that we shouldn't concede that Darwinian mechanisms are at work when they are not.
Exactly. I wish people (including Denton) wouldn't concede so much, but I understand why they sometimes do from a practical debating standpoint. But it would at least be preferable to make it clear that it is a concession for purposes of discussion, not because the Darwinian claim has been verified in actual fact. Indeed, the more we learn about biology the less relevant Darwin's ideas become. Nevertheless, I too agree that there are cases, mostly minor and at the fringes, where bona fide RM+NS Darwinian evolution operates. ----- Your points about causation and teleology are well taken. The only caution I would suggest is a definitional one. Specifically, mere "order" is not what we are interested in for purposes of intelligent design. Complex functional organization, yes. Complex specified information, yes. But mere order is very commonly the result of purely natural and material causes -- crystal formation being a classic example. I believe you were referring to the correct thing, so I'm not arguing with you substantively. Just wanted to give you a heads up that using the word "order" will cause no end of confusion and send discussions down endless rabbit holes. One of the key debating tricks of materialists is to purposely conflate mere order with complex functional organization and then play dumb and endlessly claim that there is no difference. Some pro-Darwinist propagandists on this forum are wont to do that on a regular basis, so be on the lookout.Eric Anderson
February 17, 2016
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So who wants to go first and show how to use your "theory of intelligent design" to demonstrate the cause of macroevolution? I believe it is possible. The problem seems to be from the ID movement's reliance on the philosophy of Naturalism, which makes whatever created us "supernatural" and in turn scientific theory to explain how our creator works is blindly believed to be impossible.GaryGaulin
February 17, 2016
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Anaxagoras: An study that analyzed different species of Galapagos´s finches was published in 2014 showing that epigenetic differences were more important among species than genomic alteration. Actually, the study indicates that "epigenetic and genetic changes may jointly regulate genome activity and evolution". Epigenetics may give evolution a bit of a look-ahead capability, similar to how errors during protein synthesis can give a look-ahead. jerry: So there is essentially one species of Finches on the Galapagos. Nearly all ornithologists consider them separate species, but it is a characteristic of evolutionary divergence that such dividing lines will be difficult to draw.Zachriel
February 17, 2016
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Darwinian mechanisms are great for creating diseases and deformities.Virgil Cain
February 17, 2016
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Mung @ 4 Eric Anderson @ 8 I have nothing against admitting that random mutations occur and that these occurrences might shape to some extent biological forms and mechanisms. But I consider that we shouldn´t concede that Darwinian mechanisms are at work when they are not. The difference between epigenetics regulatory mechanisms and genetic mutations is important as far as causation is concerned. The essence of Darwinism is to dispense of final causes, teleology and goals in Nature. Teleology and final causes are the key point in arguing for an intelligent cause. If changes in living organisms can be presented as directed responses to environmental challenges (like in phenotypic plasticity or many epigenetic alterations) these changes, even at microevolutionary level are a manifestation of ORDER in Nature and constitute a good ground for an inference to an intelligent cause. It is not only that the extrapolation from microevolutionary events to the emergence of the big novelties (macroevolution) has never been observed (this is not enough for an ID argument) It is that ORDER and FINALISM pervades life and Nature and we are legitimated to proclaim it as the hallmark of an intelligent cause.Anaxagoras
February 17, 2016
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Eric,
it would be better to be more clear about the term “evolution”
I believe a lot of what we see in the natural world is "devolution" and not "evolution." Here is something I wrote over 8 years ago on this and I believe explains most of what we see in nature. https://uncommondescent.com/the-design-of-life/darwin’s-tree-of-life-vs-real-life-the-curious-case-of-the-beefalo/#comment-164650
PaV and I and some others have been debating a similar idea in the last couple months on different threads. Here is part of a post I sent to someone on another site when one of the posters brought up the artificial selection of a pet fox and the extraordinary number of beetles in the world.
“The currently accepted theory of the mechanism for evolution is called the modern synthesis. Now this theory was originally developed in the 1930’s and 1940’s to take care of many of the flaws in Darwin’s arguments but before anything was known about DNA, a genome and all the information on how this genome might change. So the modern synthesis has been modified many times. But essentially it consists of two basic processes, (1) development of variation and (2) genetic mixing of alleles from one generation to the next.
Within the second process is included the well known process of natural selection. However, to better understand the differences between these two processes it essential to introduce the concept of a gene pool. Here is the definition of gene pool from Wikipedia and it will suffice for here:
“In population genetics, a gene pool is the complete set of unique alleles in a species or population. A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity (see inbreeding and population bottlenecks) can cause reduced biological fitness and an increased chance of extinction.”
So lets look at our gene pool and the two basic processes of the modern synthesis. The variation process increases the set of unique alleles by modifying the gametes in organisms in the population. There are a multitude of different ways this is supposed to happen from a SNP (single nucleotide polymorphism - a mutation to one nucleotide in a DNA sequence) to massive reorganizations of the genome of the gamete. There are several processes that will change the DNA sequences in the gametes from duplication, insertion, deleting, changing the order of nucleotides, introduction of retro viruses, etc. Let’s just say there are a lot of processes proposed. But the gene pool has not been modified yet since all the changes are in the gametes only. Now once the gametes have been changed, the genetic processes will decide if these changes enter the gene pool or get rejected. If the change is harmful, then the organism may not be able to reproduce and the change has been eliminated and not entered the gene pool. If the change is neutral and has no effect on the organism then it may enter the gene pool and be accepted or rejected purely on a random chance basis. If a change is beneficial in some way in some environment then the percentage of organisms in a population having that gene will increase especially if the population or part of the population enters such an environment. This is simplified but essentially the basic process. If no changes to the gene pool ever take place can one have evolution. The answer is yes. Because within the gene pool is the potential for a lot of variation without the gene pool ever expanding. To give you an example, I will use your artificial selection process you described (wild feral fox turning into a friendly lap fox in 50 years of breeding). The cute friendly fox is available within the gene pool of the feral grey fox. And so is the chihuahua available within the gene pool of the wolf. If one saw the wolf and the chihuahua in the fossil record no one would say they are the same species but according to some definitions of species they are. The wolf and the chihuahua can mate and produce another variant. Now I do not know how the chihuahua could impregnate a wolf or vice versa but if it could there would be a viable offspring. Now is the gene pool of the chihuahua a wholly contained subset of the wolf. Probably not because in the process of artificial selection, some mutations probably took place for body size, hair length, shape etc. that was not in the wolf gene pool but which does not prevent them from breeding. That is how a lot of artificial breeding takes place, by preserving mutations but most is just a refinement of the gene pool to a smaller wholly contained subset so you get your friendly lap fox. Now rather than go on and on, I will cut it short and say that most of what passes as evolution is just refinements of the gene pool with the occasional small mutation. So the example of 60,000 beetles may be just slight variants of each other brought on by simple mutation events but mainly refinements of an original gene pool based on environmental pressures. This is indeed evolution but it is simple micro evolution and what one would have to do is isolate the gene pools of these beetles and see which allele differences represent real novelty in the species or just simple changes. An interesting research project but massive to do it well. There is little argument about the genetic half of the modern synthesis and while they do not understand how everything works in mixing up the alleles during reproduction, this side does not produce much that is new that isn’t already in the genome or the gene pool. All (nearly all) the novelty is produced by the other process, namely variation generation. And Michael Behe’s book cast severe doubt on just how much variation can arise through naturalistic processes. So most species arise through the genetic processes that are mostly straightforward and do not represent real novelty or much addition to the gene pool. And this type of evolution is micro evolution and not very controversial. It was within this uncontroversial area that Darwin provided all his examples on his trip on the Beagle. When a Darwinist invokes beetles and artificial selection, they are not appropriate examples. They are/may only be refinements of the gene pool and as such trivial. There may be some significant mutations but I guess that most are not and could be solved by examining the genomes. Essentially they are probably examples of devolution and I believe we should use this term more frequently. However, to support this hypothesis, 60,000 beetle or 2,000 cichlid genomes have to be mapped (or a substantial subset) and this is a daunting project.” If bisons and cows come from the same gene pool, how many other so called species differences are not just devolution of gene pools. This could change our understanding of just what a species is and is one of the ID predictions that should be put forward to support Behe’s Edge of Evolution.
There is an incredible amount of variation in nature and it has to accounted for somehow. So maybe what we are mainly seeing is devolution not evolution. If I were a designer, I would want to have in place natural processes that could handle all the different environments the world would throw at a gene pool. The important thing is the ecology which is a coordination of thousands of gene pools. This process would allow various populations to devolve as needed into new populations that in essence are just sub-populations of a much larger gene pool. The result would be the millions of ecologies we see in the world. This is just speculation but fits a lot of the data. As far as Denton is concerned, the millions of novelties are in the various original gene pools and over time get modified slightly but remain within the specific taxa or gene pools. What Denton can not do is explain the original gene pools. He just speculates there are forces that form these taxa and essentially begs the questions of how the gene pools arose.jerry
February 17, 2016
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But what if the continuous chain of functional intermediates is missing? Here we get to the nub of the matter, because Denton claims that
many of the taxa-defining homologs actualized during the course of evolution have never been shown to be adaptive and even in the case of those homologs which are apparently adaptive, functional continuums are either unknown or very hard to envisage.
And if this is the case, certain conclusions follow ineluctably:
To acknowledge their absence [i.e., the absence of a continuous chain of functional intermediates] is to acknowledge that the paths of evolution must have been ordered and directed by additional causal factors, i.e., that cumulative selection is not the sole or even the major directive agency.
Denton writes that this
“need for adaptive continuums brings us to the nub of the problem, the core contention of Evolution: A Theory in Crisis, and the major point defended here: Practically all the novel, taxa-defining homologs of all the main taxa are not led up to via adaptive continuums. Moreover, as argued later in this book, many of these novel Bauplans do not convey any obvious impression of being adaptive . . .”
Denton concludes the chapter with this delightful observation of fine irony:
It is ironic that the very evidence for believing that microevolution has indeed occurred in cases like the finches—an empirically known or readily envisaged continuum of forms leading from an ancestral form A to descendant form B—is precisely the evidence that is lacking when attempting to account for macroevolution and the origin of the defining features (feathers, hands, mammary glands, hair, the placenta, flowers, body plan, etc.) of the major taxa.
So the evidence is missing and hard to visualize. Whether or not it exists or really happened, we don't really know. We can take Denton's position and assume it did happen and come up with a way to make it happen - NREH. 1) Seems like the ID interpretation of the data to me. Or, since it is missing, we could take that as evidence that it does not exist - since it is missing in so many different areas, that does not seem unreasonable. 2) This view would doubt common descent and be more in line with the creationist interpretation of the same data. Or, you could take the evolutionary view that it has to exist and sometime we'll find it. Just give us a little more time. We're sure it's there. 3) This would be the Materialist interpretation of the data.tjguy
February 17, 2016
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Talking about enucleated RBC - which was his Ph.D theis, Denton says:
Even more challenging is the fact that red cells in birds, which have a higher metabolic need for oxygen than mammals, retain their nucleus. Anyone who has watched a hummingbird sucking nectar from a flower, with its heart beating sixty times per second, or watched geese flying over the Himalayas, under greatly reduced oxygen partial pressure at 8,000 meters, will have been struck by the incredible ability of birds to deliver oxygen to their muscles to empower flight. If birds get by with nucleated cells, perhaps the enucleate state is not quite as specifically adaptive for oxygen transport to the tissues as is widely assumed!
Any one with rudimentary knowledge of fluid dynamics will know that according to Poiseuille's law, size of radius has dramatic effect on flow of blood (remember there is 4 fold effect of radius - r^4). The unpliable nucleus occlude the blood vessel,effectively reducing the diameter of blood vessels.Thus if a bunch of nucleated RBC occlude the blood vessel by just 10%, the flow rate will drop by 34% 1-.90^4 .For humans, imagine the pressure which would be required to restore normal flow rate of blood and thus supply the required oxygen.Me_Think
February 17, 2016
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Interesting discussion. My understanding is similar to jerry's in terms of finch species and the epigenetic factors. So it may not be a good example of Neodarwinian evolution. But it could still be an example of Darwinian evolution, depending on how we define it. Why do I say that? If we forgive for a moment Denton's sloppy reference to natural selection as a "mechanism" of evolution and we think back to how Darwin framed things in The Origin, we recall that Darwin did not propose any mechanism for the source of variations. Neither he nor anyone else at the time had any idea what could be the actual biological cause of morphological differences. We're just starting to scratch the surface now, and 150 years ago it was simply impossible to know what could be causing these changes. As a result, in The Origin Darwin did not propose any mechanism as the source of biological variation. Rather, he simply observed that some variation did take place, and then hypothesized that these small-scale insignificant changes would, with passage of time, add up to large-scale significant changes. Yet these large-scale significant changes have never been observed. Hypothesized, yes. But never observed. In more than 150 years of dedicated research, despite thousands of lab experiments, untold numbers of observations in the wild, and billions of dollars spent, this claim that small-scale changes can add up large scale changes has never been observed. Thus, the essential part of Darwin's theory -- the critical claim he put forward -- has never been observed. In that sense, we would be well justified to say that Darwin's theory has never been confirmed. Not by the finches or anything else. On the other hand, if we take a very ample view of what Darwin was saying, then we can argue that there are many examples of Darwinian evolution. Whether finches are a good example or not, even most hardened evolutionary critics would accept Behe's example of sickle cell trait/malaria as an example of the kind of thing that can be accomplished by the vague Darwinian claim of trial-and-error-plus-time. Thus, because Darwin provided very little in the way of substantive information about how variations arise, and because he framed the result of those variations over time in an essentially circular concept of natural selection, it is quite easy indeed to see evidence of this variation+selection "mechanism" in nature.* Indeed, it is all around us -- after all, everything we see in the whole of nature is the result of some biological feature that has, until now, been preserved. Incidentally, this kind of thinking -- vague references to variations coupled with an essentially circular concept of preservation -- is precisely why evolutionary proponents are so overwhelmed with all the evidence they think they are seeing. I don't know that Denton is in that category. My sense is that Denton, like many evolutionary critics, is content to concede for purposes of argument that natural selection is meaningful and that Darwin was right in a general sense. This is because debates about whether Darwin had any clue what he was talking about, or whether natural selection is meaningful or circular, and the like, inevitably turn on nuances and details and definitions that only the most pedantic among us have the stomach for. Much easier to concede all of that and then argue, in essence, "Even with all that, the broader evolutionary claim that these minor variations add up to large-scale changes doesn't hold water." Most have taken this approach, including Behe, Meyer and Dembski. From my perspective, it would be better to be more clear about the term "evolution". Paraphrasing Philip Johnson when he was talking about the peppered moths, "You can call it 'evolution' if you like. But the tremendously deceptive thing about calling it 'evolution' is that you also use that same word to describe the whole grand creative process that brought the peppered moth into existence in the first place." In other words, as I have noted multiple times, much of the confusion around these issues comes from the fact that the word "evolution" is used to describe very different phenomena, from the obvious and the well-supported on one end of the spectrum to the outrageous and wildly-speculative on the other end. But that is a topic for another day . . . Yes, there is a fair amount that could be criticized in Denton's reference to the finches, in his uncritical acceptance of Darwinian evolution at the micro level, in his sloppy use of terminology about natural selection and "mechanisms." But in the broader context, I think he is willing to concede those things to make a larger point. One that definitely needs to be made. ----- * Variations due to both genetic and epigenetic factors are both captured in Darwin's original idea. He had no way of knowing the difference and, as pointed out, did not say much of anything about the mechanism of variation. He simply made the broad observation that variations occur. So whatever the source of a variation, it falls within his general observation that such things occur.Eric Anderson
February 16, 2016
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Evolution is okay as long as it doesn't cross biblical boundaries or the very obvious need for new information to make a important new population. This mutation thing is not plausible or within probability options. We see peoples looks and so know there is change from within. Denton is all about showing its unlikely to have great information change. If simple selection pressures act on a pop then its unrelated to the great claims of Darwin.Robert Byers
February 16, 2016
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The Teaching Company or now called The Great Courses have several courses on evolution. In none of them do they show how macro-evolution or how the appearance of novelities developed. They beg the question in several places and just say/imply that it happened by some form of gradualism due to natural selection or what Denton calls functional adaptation. Denton shows there has never been such a continuum but did suggest the Finches. In one of the Teaching Company courses titled "Theory of Evolution: A History of Controversy" by Edward Larson, the lecturer said there was doubt about Darwin's theory till the Galapagos Finches were shown to be separate species arising due to natural selection. http://bit.ly/1XwBQJW Ironic, now that they are not separate species and the morphological differences are not due to natural selection.jerry
February 16, 2016
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Are Galapagos´s Finches a good example of Darwinian evolution?
They can all interbreed. They don't but there is no biological reason why they cannot. So there is essentially one species of Finches on the Galapagos.
An study that analyzed different species of Galapagos´s finches was published in 2014 showing that epigenetic differences were more important among species than genomic alteration
The Grants admitted this in a presentation at Stanford for the 200th anniversary of Darwin's birth in 2009.jerry
February 16, 2016
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Anaxagoras @ 1. Nice point. But Denton could probably have come up with other examples where epigenetics was not involved. What do you think?Mung
February 16, 2016
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“For this reason . . . saltationist (or macromutational) theories have always been viewed as anti-Darwinian.” Over at TSZ they think a saltation means some feature spread instantly throughout the entire population. LoL.Mung
February 16, 2016
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Denton needs to read Spetner :cool:Virgil Cain
February 16, 2016
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Are Galapagos´s Finches a good example of Darwinian evolution? I feel certainly uncomfortable about the way in which Denton accepts they are. Two conditions are, according to Denton, sufficient for that: a) the novelty is adaptive, and b)there is a functional continuum. But Denton seems to forget the most important condition for an evolutionary event to be considered an example of darwinism: the emergence of the novelty must be a random event, a chance occurrence, something that can not be presented as finalist or teleological. The event can not take place as a response to a specific environmental challenge. It is not clear that this is the case as far as finches´s beaks are concerned. An study that analyzed different species of Galapagos´s finches was published in 2014 showing that epigenetic differences were more important among species than genomic alteration. https://gbe.oxfordjournals.org/content/6/8/1972.full Denton himself acknowledges in his book (p. 34) that the diversity in finch beak shapes is the consequence of the differences in the pattern of expression of certain genes; some genes might be expressed earlier on time at a higher level in development . If Epigenetetics and regulatory mechanisms are the cause of the changes experimented by the organisms, then it is difficult to present the events as darwinian evolutionary processes.. To regulate the expression of genes is something that the cell does, is a manifestation of cell´s teleological agency. This seems to be more a finalist response to a change in the environment than a random unguided event. If this is the case, nothing to do with darwinism.Anaxagoras
February 16, 2016
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