Intelligent Design

Chimeras and Transitional Forms: Examining the ID Position

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Many people who argue against Intelligent Design’s position on transitional forms often don’t have any clue what it is that is actually being said. I’d like to take a moment to clear it up. If anyone disagrees with my commentary (especially ID’ers — I’d hate to misrepresent other’s opinions), please post below. My main point in writing is not so much a defence of the concept (though I do attempt that) but rather to show why it makes sense even in the absence of special creation, and why its use is not limitted to people who agree with special creation, but anyone who believes in a telic form of evolution.

What is a transitional form? If the generative force of evolution is atelic, then we should be able to detect many forms of organs and organisms on their way to being stable forms. If natural selection is acting on changes which are atelic, then we should see a gradual progression from one form to another in a gradual succession. Each individual change must be small (or else the search space would be too huge) and beneficial (or else it would be selected against). Likewise, it requires quite a bit of reproductive excess for this to occur, so there should be plenty of evidence in the fossil record of the dead animals required to make these changes. So, by transitional form, it is meant a midway point between organism X and organism Y.

Remember, ID is not an argument against evolution itself, but rather an argument for teleology as the prime mover in organismal form. This means that evolution may be coherent, but Darwinian evolution, where the substrate for change which is selected is atelic, is incoherent. It is fully within the bounds of ID for a basal organism to have pre-coded, fully-formed adaptations ready-to-go, and be able to assemble itself piece-wise at certain periods or in response to certain stressors.

What is found in the fossil record primarily is not transitional forms. What is found is transitional habitats and chimeras. A chimera should not be confused with a transitional form. A chimera is an organism which has fully-formed features put together in a unique way.

The fundamental question is how do novel body plans and tissue types arise? This is the fundamental question that needs answering. These things function in holistic ways in the present. What is the origin of such features? If the answer is Random Mutation + Natural Selection (RM+NS), then one has to figure out how such a process was able to find such remarkable, holistic structures. There are two possibilities as far as I can see — either all-at-once or a step-at-a-time. If it occurred a step-at-a-time, then where are the steps? We should see them massively in the fossil record, as each step requires reproductive excess to occur. If it was all-at-once, then how is that distinguishable from a miracle? And if it happens over and over again in the fossil record, can the generative mechanism really be random mutation?

Darwinists like to think that the fossil record shows random mutation + natural selection occurring. But there is no way to tell from a fossil what mechanism produced it. All you have are very discontinuous organisms at every step of the way. The question is, what best accounts for the pattern we see?

When a Darwinist claims a transitional fossil, the best questions to ask are, “what two specific species is this a transitional between?” and “in what ways are the features intermediate between them?” Most of the time, transitions are listed as between very large groups. But transitions can’t occur between large groups. They only occur between specific species. If something has “transitional features” between large groups, that isn’t saying much, given the large amount of variability among large groups. If something is claimed as a transitional between fish and amphibian, that is a huge range of features on both sides that someone could take from to claim intermediacy, despite the fact that for it to be evidence of Darwinian evolution it would have to be transitional between two specific species.

If multiple “transitionals” are found, with the lineages all mixed up in a chimeric way, this provides evidence against Darwinian evolution. How does descent work in a way in which would allow for crossing over of body parts? Instead, such is evident to me of either a preprogrammed set of features to diversify, an interventionist change, special creation for intermediate habitats, or hybridization.

There are a few examples of possible transitions. But the number of potential transitions is dwarfed by the number of humongously large gaps, which would be unexpected by a non-telic form of evolution.

29 Replies to “Chimeras and Transitional Forms: Examining the ID Position

  1. 1
    DaveScot says:

    there should be plenty of evidence in the fossil record of the dead animals required to make these changes

    I don’t see why this should be. See here.

  2. 2
    Scott says:

    Dave raises a point. When I present the lack-of-transitional-fossils argument to Darwinists, I repeatedly get two responses:

    1. We haven’t been looking long enough.

    2. Fossilization is rare because…

    Johnnyb, do you think these are valid counter arguments?

  3. 3
    jerry says:

    Each time I see the question “what are the transitional sequences in the fossil record” I wait for the response. In the last year I have mostly seen the “dinosaur to bird”, land animal to whale and just a few days ago supposedly the best of them all, the “reptile to mammal.” The first two seem easy to deal with. The third appeared in the criticism of Coulter’s book by Robert Savillo and references a website run by something like the Gulf Coast Society for Paleontology and Minerals that has a technical discussion of this sequence. Also Talk Origins has a long and also highly technical discussion of this transition sequence claiming it is very complete.

    I find it very interesting that this is the best they have but maybe someone can supply a lay description of the problems with the reptile/mammal transition since it has come up. Or point out a discussion of this in a book or on the internet.

  4. 4
    russ says:

    If there is little or no evidence of transition in the fossil record, and Darwinists’ defense for this lacuna is that fossilization is rare, then would it be fair to state that paleontology doesn’t have much to offer in proving Neo-Darwinian Evolution?

    If you did a poll of ordinary people, I think they would be surprised to hear that this is the case, since lots of us think Dr. Leaky/dinosaur bones/archaeopterix when we think of evolution.

  5. 5
    eebrom says:

    If ID is not an argument against evolution itself, then it would be an argument for evolution itself, or it would be an argument that says nothing about evolution itself.

    If ID is an argument, then it has premises and at least one conclusion. If evolution is an argument, then it also has premises and at least one concluson.

    Premises are normally bolstered with evidence. If two opposing arguments use conflicting evidence, or lack evidence, then surely there is opposition of one argument to the other.

    Saying that ID is not an argument against evolution itself, it seems, throws doubt on the overwhelming evidences, which support teleological inferences, which support ID arguments.

    Evidence of one viable, transitional form weakens the ID argument. Continuing lack of that evidence destroys the putative certainty in the evolution argument.

    Presumably the evolution argument conclusion is that the prime mover is step-at-a-time, whereas the ID argument conclusion is that the prime mover is all-at-once. Again, the argument of one reasoning is against the argument of the other reasoning.

    ID is an argument that says certain patterns in nature are best explained as the result of intelligent agency and that some of these patterns are visible in living things. If your definition of “evolution” precludes any possibility of intelligent agency being involved at one or more points then ID has an argument with it. If not then there is no argument. -ds

  6. 6
    gpuccio says:

    johnnyb, thank you for your very clear post, with which I agree completely. I would like to add some personal thoughts.
    First of all, I think it should always be stressed that ID is not necessarily against “evolution” (although some IDers can certainly be), but in general against a “mechanical”, non telistic cause of evolution (RM + NS). Practically all the evidence which “supports” darwinism is, at best, evidence of some continuity in biological being, not of the cause. Evidence of continuity is completely compatible with a telistic point of view, and therefore with ID. From the point of view of computer programming, we know well that the fundamental way to write code, now, is object oriented, that is that a programmer tries to write software in “objects”, which can be easily reutilized in different contexts when necessary. So, no wonder that windows xp, for instance, utilizes some GUI objects which are similar, or equal, to those we had in windows 98. Is that evidence of mechanical progression from one version to another? Obviously not. Partial reutilization of the software may just be proof of an efficient, intelligent, tidy programmer.
    In that case, it is perfectly natural that one can find some continuity, especially at molecular level, in a scenario which is generally discontinuous, and that proteins from humans may be similar even to proteins from archea. Or that a few proteins from the flagella may be similar to those from a pump system. Reutilization of the code. But the main code, the real program, which makes the great difference between species, is still by far unknown (see the debate about junk DNA, especially the data from Mattick).
    About the lack of fossils, in reality I find johhnyb’s argument very intuitive. May be fossils are rare, but here we are speaking of thousands, or millions, of transitions, say from A to B (two completely different species). According to standard darwinian theory, if A is stable, each new transition towards B should be stable (at least as stable as A), and gain a selective reproductive advantage so that it will not be confined to one individual and its small progenies, but rather expand so that it can, at least partially, substitute to A competing for available resources. We must remember that, if a first random mutation happens in one individual of a species of, say, one million individuals, and if it stays confined to that individual and its descendants (that is, one millionth of the species, if the species is at equilibrium), then there is no reasonable chance that a second, compatible mutation may happen in that small fraction of genetic material. The concept of natural selection is that each favourable mutation must reasonably expand before becoming receptive to a second, and then a third, useful and pertinent mutation. So, if we need 20 aminoacid substitutions to go from A to B, each step should bring meaningful advantage, and each step should have the same chance to become a fossil. Multiply that for the thousands of aminoacidic changes necessary to go from species A to species B. Do you still find that it is realistic that we find, say, 10 fossils of A, 5 fossils of B, and nothing else?

    Very good up until the point you start talking about fossils. Darwinian theory in no way requires transitionals to be stable. It only requires that they reproduce. They need not have any selective advantage either. The weakest members of the herd aren’t always the ones to die young. The unlucky members of the herd are the ones that die young. They may be unlucky by genetic misfortune or just by the circumstance of being in the wrong place at the wrong time. In the Darwinian world most evolution takes place in small isolated populations and large populations tend to remain stable. This can be seen most vividly in island species which tend to diverge rapidly from the mainland species they once were. -ds

  7. 7
    johnnyb says:

    “This can be seen most vividly in island species which tend to diverge rapidly from the mainland species they once were.”

    But again, we have no evidence that this is because of RM+NS. It could just as easily be precoded adaptation to new environment. There is a lot of data that says that organisms can “sense” the other organisms in the area during development, and develop adaptations appropriate to them (eco-devo, not to be confused with evo-devo). After a certain number of generations, these become fixed (genetic assimilation).

    Likewise, the establishment or disestablishment of symbioses can cause speciation to happen very, very rapidly.

    As for the fossil record, if it is a stochastic sampling, we _should_ see the transitions, for they would be many, and they would need increased reproduction in order to overtake the others. If it is not a stochastic sampling, then what is it that the fossil record tells us? It certainly wouldn’t tell us about evolution, because there would be no reason to suppose that it is even in the right order. In fact, what’s really amusing about the fossil record is the fact that it appears to not be stochastic. For instance, you usually have trace fossils before you have body fossils. Grass appears in dino poop 30 million years before it appears as vegetation. Coelacanths disappear for tens of millions of years without a trace. How long were they missing before that? If they were missing for 60 million years afterwards, do we have any reason to not think they weren’t there but missing from the fossil record 60 million years before?

    What, exactly, the fossil record signifies is not as cut-and-dry of an issue as _anyone_ says it is. There are features that baffle nearly every theory concocted about it, including Darwinists, YECs, OECs, everyone! Most people know that I am a YEC, but I’m not going to pretend that the evidence is cut and dry. While I have posted evidence against the old earth views on my blog, it wasn’t to pretend as if the YEC view has answered all of the questions against it. The point being, anyone who says the fossil record supports their view alone simply isn’t being honest with it. There are many features one can point to that scream “earth-wide catastrophe”, but then there are other parts which make you say, “how can such a catastrophe produce X?” All camps presume that the outstanding issues can be resolved with further study. Perhaps someday they will. But I think that for any side, open communication with honest skeptics helps everybody more than entrenched diatribes where noone is listening.

  8. 8
    johnnyb says:

    As for the reptile/mammal transition, I haven’t studied it much myself, but from what I’ve heard you have several chimeric groups, all independently increasing their mammalness for a period, and then a sharp discontinuity between them and mammals.

    Here’s the question — if this transition was not telic, how were multiple groups, none of which seem to be related to each other, doing this at the same time? Where did these chimeric organisms come from in the first place? Now, reptile/mammal transitions cause difficulties for other theories, too. However, the issues that they raise for Darwinism are not as widely known.

  9. 9
    DaveScot says:

    The evidence missing from the fossil record isn’t transitions per se. The missing evidence is gradual transitions. Comparative rarity of fossils in rapidly changing small isolated populations is a good explantion for the missing evidence. Not the only explanation but a good one. Saltation is another good explanation. The problem is that gradual transitions are not just missing from the fossil record but are also missing in the living record. In that case, saltation appears to me to be the best explanation that reconciles both the living and fossil records. The one thing I refuse to take seriously is lack of continuity. Life comes from life is something that has been observed billions of times without exception. When something in nature is observed that many times without exception it is a law not a theory. The continuity of life is a law as far as I’m concerned until falsified by empirical evidence. Therefore any scientific explanation for the fossil and living records must accomodate as a given everything that ever lived was descended from another living thing until such time as extraordinarily strong empirical evidence is provided to the contrary.

  10. 10
    DaveScot says:

    JohnnyB

    The thing about island species is an island bird that differs markedly from a mainland species is it is still a bird with no non-bird anatomy about it. There are limits in what allelic evolution has actually been observed doing. These limits are basically constrained to modification in scale and cosmetics and are best exemplified by what has been attained in artificial selection of dogs over the past 20,000 years. This is why I demand empirical evidence of a mechanism capable of generating novel cell types, tissue types, organs, and body plans. All of those must be accounted for by any mechanism or mechanisms that purport to explain all of evolution and there is simply no empirical evidence of any capable mechanism. All candidate mechanisms to date are hypothetical. -ds

  11. 11
    jerry says:

    By the way there is a full assault going on by some people from PT against anything that is anti-Darwinism over at the Cornell course site on Evolution and Design.

    Today’s thread is http://evolutionanddesign.blog.....an-update/

    Included are re-writes of the Cambrian explosion and evidence of many intermeidaries in the human brain size and discussions of what gradualism is really about.

  12. 12
    Mung says:

    Wikipedia: A transitional fossil is the fossil remains of a creature that exhibits certain primitive (or basal) traits in comparison with its more derived descendants.

    Unless we know who the descendants are, we cannot ascertain that the fossil “exhibits certain primitive (or basal) traits in comparison with its more derived descendants.”

    Since we are unable to identify ancestors and descendants in the fossil record, we have no basis upon which to classify any fossil as a transitional.

    And this doesn’t even address the issue of basal and derived traitns and how to tell which is which, or even if.

    I know what a unicorn is too. Whether or not unicorns are anything other than imagined is a different argument. Of course unless the descent is actually observed we can’t prove what descends from what but we can make reasonable assumptions based on similarity and circumstance that any reasonable person should accept as a given for the sake of argument. After all, we’ve never observed a living thing coming from anything but another living thing. If that is a given then it follows that we don’t question descent from the something, the question is just what is mostly likely to have descended from what. -ds

  13. 13
    Ryan says:

    “The one thing I refuse to take seriously is lack of continuity. Life comes from life is something that has been observed billions of times without exception. When something in nature is observed that many times without exception it is a law not a theory. The continuity of life is a law as far as I’m concerned until falsified by empirical evidence. Therefore any scientific explanation for the fossil and living records must accomodate as a given everything that ever lived was descended from another living thing until such time as extraordinarily strong empirical evidence is provided to the contrary.”

    I don’t think anyone is arguing that spontaneous generation is true. In fact, it was disproved years ago. The problem with saying that some form of macro-evolution (guided or not) must be true because only life comes from life is that such an argument ends up in infinite regression. What about the first cell? Dave: If you are a proponent of ID and believe that it took an intelligent agent to form the first cell, then why is it so hard to believe that an intelligent agent made every type of biological form out there. The fossil record lacks the continuity for Darwinian gradualism to be true, and so, should we eliminate the belief that every form was made seperately from science just because that belief isn’t mechanistic?

    If you are a proponent of ID and believe that it took an intelligent agent to form the first cell, then why is it so hard to believe that an intelligent agent made every type of biological form out there.

    If the first cell had all the information required to evolve then the intelligent agent *did* make every form. The molecular evidence doesn’t fit a designer that created each form individually at about one new species a year for a billion years. For instance, evidence of retrovirus infections are shared across different species in a way that strongly suggests the infection occured in a common ancestor. Proteins are different in ways that suggest common ancestry. What scientific evidence makes you think common descent from one or a few common ancestors isn’t true? Why is THAT so hard to believe? -ds

  14. 14
    russ says:

    “After all, we’ve never observed a living thing coming from anything but another living thing. If that is a given then it follows that we don’t question descent from the something, the question is just what is mostly likely to have descended from what.” -ds

    Dave, why would it be bad logic to change your statement by inserting what I’ve put in brackets?:

    “After all, we’ve never observed a living thing coming from anything but another living thing [of the same species]…”

    And going back in time, don’t you eventually reach a place where some living thing didn’t come from another living thing?

    Sorry Russ, I thought I answered earlier. Nothing wrong with your change. It is true. The problem is there are estimated to be about a billion species that have ever lived, 99.9% of them now extinct. We have to explain the origin of about 1 new species a year for a billion years. A designer could do this by creating one organism a billion years ago that was programmed to diversify into a billion species by saltation or the designer could have hung around for a billion years creating one new species each year (on average). It seems to me Occam’s Razor forces us to choose the simpler case (one point of design input) instead of a billion cases. As for going back in time, we eventually reach a place where the whole universe appeared out of nothing. So no, you can’t conclude that at some point life had to come from non-life. Maybe life in some form has been around longer than the observable universe. We don’t have the means to answer that question. Some things will always remain a mystery. But maybe we can get back at least as far as when life first appeared on this planet. We may never know where it came from or how. -ds

  15. 15
    jonabbey says:

    What is this theory of pre-coded adaptation? How would one distinguish pre-coded adaptation from non-precoded adaptation?

    Kirschner and Gerhart’s “The Plausibility of Life” advances the thesis that living organisms are structured in such a way as to facilitate adaptation, in that the genetic recipe for developing the organism must be very flexible to deal with relatively unpredictable circumstances during development, and that this same flexibility allows the developing organism to adapt to differing developmental enviornments also permits the organism to adapt to differing genetic variations that are expressed during development.

    The issue of ‘pre-coded adaptation,’ though, seems to be attempting to make a more ID-ish point, that an intelligence somehow placed prophetic (?) knowledge into the organism’s DNA, waiting for it to unfold at some point in the future.

    Is this a correct reading of the point? If not, what is intended by pre-coded adaptation, and how would such a pre-coded adaptation be discovered, or distinguished from RM+NS?

    What is this theory of pre-coded adaptation? How would one distinguish pre-coded adaptation from non-precoded adaptation?

    The presence of complex specified information. Saltation. Things coded into genomes but not used in the present or past by the owner or its ancestors. Your reading of the point is correct. -ds

  16. 16
    johnnyb says:

    “Is this a correct reading of the point?”

    Basically. It doesn’t need to necessarily be “prophetic” knowledge, however, as much general knowledge of possible standard variations and heuristics. For instance, for the Nylon bug, for example, it needn’t know specifically about Nylon, but rather be able to detect certain classes of polymers, and have the information to develop a suitable gene. I like to think of these as semi-specific knowledges.

    The way they are distinguishable from RM+NS is fairly simple in theory (in practice, it is difficult to get a handle on genome-wide mutation statistics). Look at the distribution of mutations in given circumstances. Are they clustered? Do they consistently yield more beneficial changes than would be expected under a genome-wide stress? Do they consistently yield the same or similar changes?

    To see one highly-specified instance, see Transposable elements as activators of cryptic genes in E. coli.. For a very reliable but not quite-so-well specified mechanism, see A Biochemical Mechanism for Nonrandom Mutations and Evolution.

    There’s lots of papers on this. We recently reviewed one review paper here on UncommonDescent.

  17. 17
    Jeffery Keown says:

    Dave, you actually seemed reasonable in this discussion. Bravo.

    You must have actually understood it then. Bravo to you too. -ds

  18. 18
    jonabbey says:

    The presence of complex specified information. Saltation. Things coded into genomes but not used in the present or past by the owner or its ancestors. Your reading of the point is correct. -ds

    It seems that demonstrating that stuff in a genome was not used in an organism’s past or present would be precisely as difficult as proving the every-mutation-documented-as-randomly-occurring materialistic chain of evidence that Behe calls for from Darwinists. How could anyone ever demonstrate such a thing?

    It seems like precoded information of the type that you seem to be implying would be theologically unnecessary for an intelligent designer who acted to create miracles at will upon the earth, besides.

  19. 19
    johnnyb says:

    “How could anyone ever demonstrate such a thing?”

    I think the existence of change strategies within the genome is enough. While I think that such a system would be icing on the cake, I don’t think it’s necessary.

  20. 20
    BarryA says:

    DaveScot says “Life comes from life” or as our long-dead Latin friends would have said, “Omne vivum ex ovo” (all life from eggs).

    Russ asks: “If there is little or no evidence of transition in the fossil record, and Darwinists’ defense for this lacuna is that fossilization is rare, then would it be fair to state that paleontology doesn’t have much to offer in proving Neo-Darwinian Evolution?”

    The answer is “yes.” Mark Ridley says: “In any case, no real evolutionist, whether gradualist or punctuationist, uses the fossil record as evidence in favour of the theory of evolution as opposed to special creation.” Mark Ridley, “Who Doubts Evolution?” New Scientist 90 (June 25, 1981): 830-1, 830-32.

  21. 21
    bFast says:

    “The problem is that gradual transitions are not just missing from the fossil record but are also missing in the living record. In that case, saltation appears to me to be the best explanation that reconciles both the living and fossil records.”

    I think I have found on good example of a transitional formin living creatures. The last time I saw a manatee at a zoo I noticed that it had a few partial fingernails. Its interesting that its cousin, the elephant, also seems to have fingernails of minimal use.

    What I find intriguing about this phenomenon is that transitionals are a viable possibility. However, they certainly aren’t common.

    In general, JohnnyB, I fully agree with you that chimeras fundimentally do not qualify as transitional forms. There’s got to be something somewhat awkward about a transitional, like the awkward partial fingernails on the manatee.

    Further I do recall that Darwin expected that there should be many transitional forms. Unless evolution has wound down to a halt as some have suggested, we should see many transitional forms alive today.

    Actually Darwin offered an explanation for why we don’t see transitionals today. He basically said that most living species have been “perfected” and that perfected species quickly drive their inferior predecessors into extinction. Thus we don’t see living transitionals from one perfected species to another. -ds

  22. 22
    jonabbey says:

    I think the contention that there are no gradual transitions in the living world is simply unsupportable. In fact, we see graduated transitions all over, even to the spectacular extent of ring species, in which we find a continuum of variation within a species that becomes effectively speciated from one end of the variation range to another. Species borders in general can be very fuzzy, especially in plants, which are given to hybridize at the drop of the hat, given the opportunity.

    Further, I don’t think it’s at all true that there needs be something ‘awkward’ about living transitionals. Remember that transitionals are generally evaluated in the fossil record over geologic time. Evolutionary theory would posit that all individuals in an ancestral chain would have themselves been fit on their own terms, and not necessarily observably different from other conspecifics, even if the slightest changes were eventually amplified through successive mutations, population dividing events and extinction of intermediates.

    I agree that a lack of comprehensive gradualism in living things would be a damning argument against evolutionary theory, but I just don’t think that’s what the evidence shows.

    Eldredge and Gould disagree with you about what the evidence shows. They didn’t need to come up with Punctuated Equilibrium if there were lots of fossil evidence of gradualism. Ring species only show that variants of a single species can lose the ability to interbreed. Gradualism in variants isn’t under dispute. Gradualism leading to novel cell types, tissue types, organs, and body plans is in dispute. -ds

  23. 23
    Doug says:

    Hmmm. What happened to my comment? Am I wrong? Whatever the fossil record does show, it doesn’t give conclusive proof that there is no meaning to life and that the bible is wrong.

    Your comment was so uncivil it even made me pause. -ds

  24. 24
    Scott says:

    BarryA recently had an interesting post on the issue of transitional forms: http://www.uncommondescent.com.....hives/1177

  25. 25
    Joseph says:

    Has anyone else listened to “The Incorrigible Mr Berlinski”? He figured there should be at least 50,000 “transitional” forms for cetacean evolution alone! And what have we found? 5 or 6

    Fossils cannot tell us anything about a mechanism. We cannot differentiate between convergence and divergence with fossils or between phenotypical plasticity and a change brought on by mutations. The important parts- reproductive systems for example- are not preserved.

    Evo-devo (“hopeful monsters” revisted) may be an “out” for the “missing” fossils…

  26. 26
    Ryan says:

    “A designer could do this by creating one organism a billion years ago that was programmed to diversify into a billion species by saltation or the designer could have hung around for a billion years creating one new species each year (on average). It seems to me Occam’s Razor forces us to choose the simpler case (one point of design input) instead of a billion cases.”

    Such a series of saltations requires large amounts of information increases including irreducibly complex systems which would still require information input from an intelligence anyway.

    No it doesn’t. It can all be loaded into a large genome. Organisms can carry very large genomes. Amoeba dubia for instance is 200 times the size of the human genome. Read the archives where I talk about it. -ds

    “For instance, evidence of retrovirus infections are shared across different species in a way that strongly suggests the infection occured in a common ancestor. Proteins are different in ways that suggest common ancestry.”

    I’m kind of new to ID/Darwinist debate, but if the retrovirus infections/proteins argument is anything like the homologies argument, then it suffers from the same fallacies.

    If you don’t know anything about what retrovirus infections leave behind when they happen to infect a germ cell then I suggest you learn about it before making judgements. That is if you want to continue commenting here. -ds

  27. 27
    jonabbey says:

    Eldredge and Gould disagree with you about what the evidence shows. They didn’t need to come up with Punctuated Equilibrium if there were lots of fossil evidence of gradualism. Ring species only show that variants of a single species can lose the ability to interbreed. Gradualism in variants isn’t under dispute. Gradualism leading to novel cell types, tissue types, organs, and body plans is in dispute. -ds

    Isn’t the systemic inability to interbreed one of the primary definitions of speciation? Ring species show that gradualistic modification can lead to species-level breeding barriers, and can be viewed as evidence of incomplete or incipient speciation under the most conservative definition of speciation, I should think.

    Assuming that you concede that new species can arrive through RM+NS (or at least M+NS, if you want to preserve telic activity in the generation of the mutations), it seems that we have agreed on principle and can begin haggling over price (or, over what quantum of modification becomes under dispute).

    I’m not expert enough in biology to say that there is no evidence of recent arisal of novel cell and tissue types, organs, and body plans, but my understanding of the theory is that such major modifications would take much longer to arise than would simple speciation, and therefore we should not be surprised if we were not to see much obvious evidence of such modifications over the course of a century or so.

    As far as Gould and Eldridge, they don’t disparage gradualism so much as a flattened first derivative of gradualism. That species might tend to stay near a stable optimum until such time as environmental stress and population separation drives members of the species out of the local optimum and into new ones doesn’t contradict continualism in the fossil record.

    None of this argument should be taken as an argument for the lack of an intelligent designer, of course, though I would say that I am arguing against the evidentiary requirement for one, which may amount to the same thing for the purposes of present company, I guess.

    In any event, very nice talking with you, here.

    Eldredge and Gould weren’t really discounting gradualism, although evolution is ostensibly accelerated in small isolated populations so it certainly isn’t as gradual as it would be in large populations. What they were doing is offering an explanation of why there is hardly any evidence of gradualism in the fossil record. The fossil record is primarily of large stable populations because large stable populations have greater time and numbers to become fossilized. -ds

  28. 28
    j says:

    jonabbey: “Ring species show that gradualistic modification can lead to species-level breeding barriers, and can be viewed as evidence of incomplete or incipient speciation…”

    Instead of “incomplete or incipient speciation,” how about “generation of varieties or races”?

    Quite a few cases are known in which a long chain of populations curves around, resulting in an overlap of the ends of the chain. Not surprisingly, the ends of the chain had become so different genetically that they do not interbreed, in other words, they behave toward each other like two different species… Should such a chain be considered a single species in spite of the sympatry of the ends, or should it be broken into two (or more) species (sic)? Much new information favors the second choice. This information comes from a fine-grained analysis of the entire chain. Invariably, it shows that the chain only appeared to be continuous, but actually had a number of breaks or remnants of former isolation. When these are recognized as species (sic) borders, the “ring” consists of several species (sic) and there is no longer any sympatry of the two populations of the same species. Two well-analyzed cases are those of the gull Larus argentatus (Mayr 1963) and the salamander Ensatina (Wake 1997). [boldface added]

    [Ernst Mayr, What Evolution Is: Now Sit Down and Shut Up (2001)]

    I presume Mayr would have said “cannot interbreed” if he could have.

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    jonabbey says:

    I used ‘incomplete or incipient’ out of an abundance of caution, actually. I think the lack of ability to interbreed marks the species boundary as it is commonly understood, so it’s more than a variety or race.

    Regarding Mayr, I would not myself seek to parse his words so closely, but even if we acknowledge that he is seeking solely to make a point about behavior, behavioral separation into non-breeding populations should be adequate enough to allow further mutations to accumulate in the separate populations, tending to drive them towards a clearer delineation of species.

    Thanks for the reference.

    As long as it “should”, that’s as good as “did” in Darwin-speak. Real scientific there, sport. 🙄 -ds

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