Common Design vs. Common Descent

I promised John Harshman for several months that I would start a discussion about common design vs. common descent, and I’d like to keep my word to him as best as possible.

Strictly the speaking common design and common descent aren’t mutually exclusive, but if one invokes the possibility of recent special creation of all life, the two being mutually exclusive would be inevitable.

If one believes in a young fossil record (YFR) and thus likely believes life is young and therefore recently created, then one is a Young Life Creationist (YLC). YEC (young earth creationists) are automatically YLCs but there are a few YLCs who believe the Earth is old. So evidence in favor of YFR is evidence in favor of common design over common descent.

One can assume for the sake of argument the mainstream geological timelines of billions of years on planet Earth. If that is the case, special creation would have to happen likely in a progressive manner. I believe Stephen Meyer and many of the original ID proponents like Walter Bradley were progressive creationists.

Since I think there is promising evidence for YFR, I don’t think too much about common design vs. common descent. If the Earth is old, but the fossil record is young, as far as I’m concerned the nested hierarchical patterns of similarity are due to common design.

That said, for the sake of this discussion I will assume the fossil record is old. But even under that assumption, I don’t see how phylogenetics solves the problem of orphan features found distributed in the nested hierarchical patterns of similarity. I should point out, there is an important distinction between taxonomic nested hierarchies and phylogenetic nested hierarchies. The nested hierarchies I refer to are taxonomic, not phylogenetic. Phylogeneticsits insist the phylogenetic trees are good explanations for the taxonomic “trees”, but it doesn’t look that way to me at all. I find it revolting to think giraffes, apes, birds and turtles are under the Sarcopterygii clade (which looks more like a coelacanth).

Phylogeny is a nice superficial explanation for the pattern of taxonomic nested hierarchy in sets of proteins, DNA, whatever so long as a feature is actually shared among the creatures. That all breaks down however when we have orphan features that are not shared by sets of creatures.

The orphan features most evident to me are those associated with Eukaryotes. Phylogeny doesn’t do a good job of accounting for those. In fact, to assume common ancestry in that case, “poof” or some unknown mechanism is indicated. If the mechanism is unknown, then why claim universal common ancestry is a fact? Wouldn’t “we don’t know for sure, but we believe” be a more accurate statement of the state of affairs rather than saying “universal common ancestry is fact.”

So whenever orphan features sort of poof into existence, that suggests to me the patterns of nested hierarchy are explained better by common design. In fact there are lots of orphan features that define major groups of creatures. Off the top of my head, eukaryotes are divided into unicellular and multicellular creatures. There are vetebrates and a variety of invertebrates. Mammals have the orphan feature of mammary glands. The list could go on and on for orphan features and the groups they define. Now I use the phrase “orphan features” because I’m not comfortable using formal terms like autapomorphy or whatever. I actually don’t know what would be a good phrase.

So whenever I see an orphan feature that isn’t readily evolvable (like say a nervous system), I presume God did it, and therefore the similarities among creatures that have different orphan features is a the result of miraculous common design not ordinary common descent.

3,738 thoughts on “Common Design vs. Common Descent

  1. colewd,

    One of the advantages of the limitation of the ID argument is that it keeps it coherent.

    Limitation? Not from what I’ve seen. You’ll whip it out at the drop of a hat.

    So, to get it straight, evolution is incoherent because it contains – say – selection and drift. But ID is coherent because it keeps within limits. Chortle.

  2. keiths: Guided common descent permits large variations within a single generation and large amounts of horizontal transfer. Under those circumstances, we would not expect to be able to infer a single, objective hierarchy, even though one exists. The IDer’s only recourse is to assume that the Designer is an evolution mimic, either by inclination or by limitation. I have yet to meet an IDer who can justify that assumption.

    True enough. The problem in arguing againsts design is that it encapsulates a great number of possibilities, including the one you postulate. But John is correct that there are versions of design theory which are compatible with common descent, i.e. those where the designer is limiting itself to inserting novel characters into single lineages (apomorphies), so the issue of common descent is distinct from the natural origin of mutations.

    Now, you argue that this is an unjustified and ad hoc assumption because it simply mimics the natural process, but what of that? Wouldn’t you like to see the creationists here defending versions of their theory that are at least compatible with common descent?

  3. The “guided” part touches the heart of the matter though; I get the impression that it is the thought of evolution chugging along without divine intervention that makes evolutionary theory unbearable to the anti-evolution crowd here. But in my view common descent as such is perfectly compatible with guided evolution, so why the reluctance to accept?
    Of course, if the mere thought of being distantly related to gibbons appalls you, I can understand.

  4. Corneel,

    Now, you argue that this is an unjustified and ad hoc assumption because it simply mimics the natural process, but what of that? Wouldn’t you like to see the creationists here defending versions of their theory that are at least compatible with common descent?

    Guided evolution is an improvement over creationism, sure, but why stop there? The biological evidence allows us to reject ID even of the guided evolution sort, just as the meteorological evidence allows us to reject the Rain Fairy as an explanation of the weather.

  5. Corneel,

    But in my view common descent as such is perfectly compatible with guided evolution, so why the reluctance to accept?

    For most creationists, it’s all about scripture. Common descent contradicts scripture and must therefore be fought against tooth and nail.

  6. keiths: Guided evolution is an improvement over creationism, sure, but why stop there? The biological evidence allows us to reject ID even of the guided evolution sort, just as the meteorological evidence allows us to reject the Rain Fairy as an explanation of the weather.

    Because I think that a lot of the unwillingness to accept common descent here at TSZ comes from it being part of the larger “evolution package” . If we are clear about separate issues, some people may realize it is not an issue they are emotionally involved in, and become willing to drop the more ridiculous objections.

  7. keiths: For most creationists, it’s all about scripture. Common descent contradicts scripture and must therefore be fought against tooth and nail.

    Creationists are a bit of a motley crew in my opinion, with some being more prone to biblical literalism then others, but my impression is that very few seriously consider special creation to be true.

  8. Corneel,

    Creationists are a bit of a motley crew in my opinion, with some being more prone to biblical literalism then others, but my impression is that very few seriously consider special creation to be true.

    You may be using a different definition of “creationism” than I am, then.

    It may also be because you’re European. Lots of people accept special creation here in the States.

  9. Corneel:

    Because I think that a lot of the unwillingness to accept common descent here at TSZ comes from it being part of the larger “evolution package” . If we are clear about separate issues, some people may realize it is not an issue they are emotionally involved in, and become willing to drop the more ridiculous objections.

    I’m very much against the “accommodationist” stance taken by the NCSE and others, in which the implications of the science are downplayed so as not to scare away the religious.

    There might be short-term benefits to doing so, but I think it’s a mistake. Better to be honest: Science rules out guided evolution as well as creationism.

  10. keiths: It may also be because you’re European. Lots of people accept special creation here in the States.

    That’s it, I suppose. Creationism is not wide spread here. The creationists I am aware of adopt “guided evolution” arguments of some sort, if they are not just being anti-evolution.

  11. keiths: I’m very much against the “accommodationist” stance taken by the NCSE and others, in which the implications of the science are downplayed so as not to scare away the religious.

    In what way is separating the discussion of common descent from that on within-lineage evolutionary change an accommodationist stance? Argue for both as fiercely as you can, just do it in separate threads so as not to confuse the two. I am just saying that the chance of somebody accepting common descent is greater when he is not forced to swallow natural selection as well.

  12. Corneel,

    Argue for both as fiercely as you can, just do it in separate threads so as not to confuse the two. I am just saying that the chance of somebody accepting common descent is greater when he is not forced to swallow natural selection as well.

    What he swallows is up to him. I’m just saying that we shouldn’t hide the implications of the evidence. Guided evolution is an improvement over creationism, but the objective nested hierarchy is fatal to both. To deliberately hide that, just to coax someone into accepting common descent, seems dishonest to me, and more than a little condescending. In effect, it amounts to saying “I knew you weren’t ready for the whole truth, so I hid the full implications of the ONH from you.”

  13. keiths: Guided evolution is an improvement over creationism, but the objective nested hierarchy is fatal to both. To deliberately hide that, just to coax someone into accepting common descent, seems dishonest to me, and more than a little condescending. In effect, it amounts to saying “I knew you weren’t ready for the whole truth, so I hid the full implications of the ONH from you.”

    Haha, I am sure the creationists here at TSZ are delighted to hear that you have such high expectations of them. They will learn the whole truth!

    I confess that my ambitions are somewhat more modest, but I don’t think I am being condescending to creationists by keeping some focus on the topic at hand. If you are constantly mixing up the discussion of common descent with other topics, people are bound to get confused. I am sure you’ll agree that it takes very little to confuse some of the people here.

  14. Allan Miller: Limitation? Not from what I’ve seen. You’ll whip it out at the drop of a hat.

    Well, sure, but I think that Bill does almost realize that ID doesn’t really say anything except “it’s designed (by God),” and not incoherent in that sense.

    It’s incoherent as science, however, because it takes the brute fact of the functional complexity of life as evidence that life is designed. Complexity is obverse of the coin, design the unquestioned reverse of the same coin, rather than complex life being something that requires a discovered explanation. It’s like saying that earthquakes simply prove that there’s an earthquake god, based on nothing but the fact that there are earthquakes.

    ID is coherent as religion, since much religion simply takes certain phenomena as signs of God.

    Glen Davidson

  15. keiths: Our ability to infer an objective nested hierarchy points not merely to common descent, but to unguided common descent, in which variation is incremental and inheritance is primarily vertical.

    Guided common descent permits large variations within a single generation and large amounts of horizontal transfer. Under those circumstances, we would not expect to be able to infer a single, objective hierarchy, even though one exists. The IDer’s only recourse is to assume that the Designer is an evolution mimic, either by inclination or by limitation. I have yet to meet an IDer who can justify that assumption.

    Guided common descent certainly permits large variations and horizontal transfer, but so does unguided common descent. Nor does guided common descent require anything of the sort. Nor is the designer assumed to be an evolution mimic, just an evolution tweaker. If the tweaks don’t involve creation of new individuals, just ordinary reproduction, that’s common descent, and it unavoidably produces a nested hierarchy. So the nested hierarchy isn’t evidence for unguided common descent, just common descent.

    What you need to argue for unguided evolution is data on the mutations themselves, not the pattern. If differences between species are limited to the same sort of thing we see in mutations within populations, that argues for unguided evolution. If the path followed by evolution shows no evidence of forethought or planning — suppose, for example, that a middle ear were constructed by repurposing pieces of a jaw, and that a jaw had been constructed by repurposing pieces of a filter-feeding mechanism — that too would be evidence for unguided evolution. Yes, you are confusing what different sorts of evidence can show.

  16. The problem of guided vs. unguided evolution is that it really depends on what sort of evolution is going on.

    On the one hand, there are similar sorts of evidence of evolution of languages and manuscripts via common descent as there is of the evolution of life by common descent. That’s because possibilities for change are practically limited in manuscripts and in languages, much as they are in biologic evolution, even if they are affected by intelligence, and even design. So evolution needn’t be unguided in order to leave evidence of objective hierarchy.

    On the other hand, the differences between language and manuscript evolution vs. biologic evolution are striking–plus the intelligence that supposedly is causing “guided evolution” of life is effectively God–unlimited intelligence. Language evolution is extremely fast compared with biologic evolution, and it has limits involving understood rules. Words horizontally transfer much more readily than does genetic information, and even in manuscripts you can get considerable transfer of unrelated material. That said, human limits (inherent and deliberate) have largely kept the evolution signal of languages intact for at least thousands of years in most cases, although English is the kind of hybrid of once-separate languages that has no real counterpart in biology (except for possible very early fusions).

    The thing is that in languages and manuscripts you do get the effect of intelligent manipulation and violation of the objective hierarchies, even if the latter are still observable. In biology, apparently not, save for our own rather meager genetic engineering capabilities. But maybe the guidance of evolution isn’t as great as the mental faculties affecting languages? Well, there are two problems with that. One is that we all know that the Designer is in fact God, who should be able to get around the limitations that languages and manuscripts have for change, and the other is that, according to ID, miracles are necessary in order for certain changes to occur. And yet, the “miracles” involve a whole lot of conserved genetic sequences, not the kind of de novo changes that one might expect of God, or at least of very advanced aliens who could cause major shifts in life.

    Some kind of guided evolution presumably would be possible, although it seems implausible. It would be strange that an intelligence is guiding the changes of life, but somehow it never manages to noticeably transcend the limits that unguided evolution would be stuck with. Common descent of languages is visible despite intelligence being involved, however, intelligence does leave its marks both in the mental rules affecting languages and in violations of those same rules. Neither is visible in biology, outside of our own manipulations.

    So common descent needn’t be unguided to be visible. The thing is that guidance should generally be visible where it exists, at least if it’s any sort of guidance that we understand (with ID, supposedly we can understand it). Guidance that we don’t understand could be affecting biologic evolution, naturally, but the very fact that we don’t understand it renders that issue moot.

    Glen Davidson

  17. Plants have ovaries. They appear to be called ovaries since they have correspondence in function to mammalian ovaries.

    How much of that similarity is due to common descent? Plant pollen are haploid. So did sexual reproduction in animals and plants that involve haploid gametes arise by common descent or convergence?

    https://en.wikipedia.org/wiki/Ovary_(botany)

    In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the pistil which holds the ovule(s) and is located above or below or at the point of connection with the base of the petals and sepals. The pistil may be made up of one carpel or of several fused carpels (e.g. dicarpel or tricarpel), and therefore the ovary can contain part of one carpel or parts of several fused carpels. Above the ovary is the style and the stigma, which is where the pollen lands and germinates to grow down through the style to the ovary, and, for each individual pollen grain, to fertilize one individual ovule. Some wind pollinated flowers have much reduced and modified ovaries.

    A fruit is the ripened ovary or ovaries—together with seeds—from one or more flowers. The fruits of a plant are responsible for dispersing the seeds that contain the embryo and protecting the seeds as well. In many species, the fruit incorporates some surrounding tissues, or is dispersed with some non-fruit tissues.

    So is the similarity by common descent? If not, this is evidence similarity does not necessarily imply common descent.

    Flowering plants, by the way, were Darwin’s abominable mystery.

  18. stcordova,

    Sal, what’s your explanation for both angiosperms and humans having ovaries?

    My explanation is that “ovary” is a name we give to an organ in which large gametes are produced. Ovaries are as homologous between plants and animals as the tree habit is homologous among different plant families. It’s just a word, just a surface resemblance, not anything deep or detailed enough to be considered homology. And it’s certainly not a conundrum for biology as you seem to imply. Why all this dodging around the central question? Why won’t you confront it directly?

    Once again, the central question: how does common design account for the nested hierarchy of life? I’ll even answer it for you: it can’t; only common descent can. OK, now deal with that, directly, forthrightly, and without oblique little asides.

    Oh, let me point out that the angiosperm “ovary” is also the angiosperm “womb”. Where’s your similarity now?

  19. stcordova: [..] this is evidence similarity does not necessarily imply common descent

    Yes, it is. Well done, Sal.

    Now, you may be surprised to learn that no biologists actually believe that angiosperm and vertebrate ovaries are homologous structures.

  20. stcordova: If not, this is evidence similarity does not necessarily imply common descent.

    But nobody says mere similarity implies common descent.

    Oh god, how can it be necessary to repeat this still?

    The evidence for common descent is either that the data has statistically significant levels of hiearachical structure, or the statistically significant consilience of independent phylogenies.

    These two terms have precise, well-defined meanings, and neither of them reduces to something like mere similarity.

    Did any of you ever read Nicholas Matzke’s Panda’s Thumb reviews of Meyer’s book Darwin’s Doubt?
    Here are some links:
    Meyer’s Hopeless Monster, Part II.
    Meyer’s Hopeless Monster, Part III.

    In both posts, Nick goes over both the concept of the Consistency Index (CI) as a measure of hiearchical structure, and the consilience of independent phylogenies.

  21. stcordova: So is the similarity by common descent? If not, this is evidence similarity does not necessarily imply common descent.

    Oh, if only we had known this.

    Well, we have since the 19th century.

    Please try to get up to speed with the science of the 1800s, at least.

    Glen Davidson

  22. Corneel: Wouldn’t you like to see the creationists here defending versions of their theory that are at least compatible with common descent?

    gpuccio over at UD does this quite well, but keiths can’t manage to mind his manners over there and so gets banned.

  23. Corneel,

    Haha, I am sure the creationists here at TSZ are delighted to hear that you have such high expectations of them. They will learn the whole truth!

    It’s not about my expectations of them, but rather about my treatment of them. I won’t deliberately downplay the implications of the ONH just to coax them into accepting common descent.

    I confess that my ambitions are somewhat more modest, but I don’t think I am being condescending to creationists by keeping some focus on the topic at hand. If you are constantly mixing up the discussion of common descent with other topics, people are bound to get confused. I am sure you’ll agree that it takes very little to confuse some of the people here.

    Well, it is condescending to say “Don’t mention that — you’ll confuse the creationists”, though that’s true in some cases.

    As for “focus”, you’re relatively new to TSZ, so you may not have noticed this yet, but the only threads that stay strictly on topic are the ones that are stillborn or peter out after a few comments. If any of our commenters are confused by meandering threads, then they are doomed to confusion at TSZ.

    If you’re really concerned that people will conflate an acceptance of common descent with a rejection of divine guidance, then just state categorically that they are not the same thing. That’s true enough, but I’ll add that anyone who understands why the ONH supports common descent is just a hair’s breadth away from understanding why it undermines guided evolution.

  24. keiths: The biological evidence allows us to reject ID even of the guided evolution sort…

    No it doesn’t. You have no explanation for why the search space is constructed in just the right way to allow life to evolve, nor why life when it began was placed in just that spot in the search space from which it could then further develop.

    Wagner doesn’t help you keiths.

  25. Now, you may be surprised to learn that no biologists actually believe that angiosperm and vertebrate ovaries are homologous structures.

    No I’m not surprised, because for the similarities to be due to homology a gap has to be overcome.

    There are other similarities I pointed to that have similar X’s, but gaps have to be overcome like say

    prokaryote

    XXXXXXXX

    vs.

    eukaryote

    iiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiii

    Now did the processing of haploid gametes in animals and plants arise by common descent, or did that evolve independently.

  26. keiths: For most creationists, it’s all about scripture. Common descent contradicts scripture and must therefore be fought against tooth and nail.

    This PRATT has been previously refuted a thousand times. Even young earth creationists accept common descent.

  27. Corneel: If we are clear about separate issues, some people may realize it is not an issue they are emotionally involved in, and become willing to drop the more ridiculous objections.

    I don’t know. I still don’t understand why, if monkeys evolved into humans, why there are still monkeys.

  28. Corneel: Haha, I am sure the creationists here at TSZ are delighted to hear that you have such high expectations of them. They will learn the whole truth!

    According to keiths, The Book of TRVTH is a science book.

  29. John Harshman: Guided common descent certainly permits large variations and horizontal transfer, but so does unguided common descent.

    Exactly. keiths is just making up his “limits” on unguided evolution to reach the outcome he wants. There is no science behind it.

    Wishful thinking is not science, keiths.

  30. Mung: gpuccio over at UD does this quite well, but keiths can’t manage to mind his manners over there and so gets banned.

    Even well mannered can be banned at UD.

  31. Mung: This PRATT has been previously refuted a thousand times. Even young earth creationists accept common descent.

    No that one’s a fact. They only believe in very limited common descent from some thousands of original biblical “kinds”. If that’s what you mean, you should point that out so as to avoid the confusion between common descent and universal common descent. And yes, that one’s on you. There’s no way keiths post could seriously be taken to mean anything other than universal common descent except by a deliberately hostile reading.

    You could have elected simply to respond with “I presume you mean universal common descent when you write ‘common descent'”. But you didn’t do that, you responded as if keiths had made some colossal error that has been “refuted”.

  32. Mung: You have no explanation for why the search space is constructed in just the right way to allow life to evolve

    First of all, how do you know the search space is “constructed” to allow life to evolve? How do you know there aren’t even better, more life-conducing “speach spaces” possible? This one could be pretty crap for all we know. It might be possible for life to originate much more frequently, and evolve much faster, and produce intelligent moral agents more often, with a different and superior set of laws. Do you know for a fact that this isn’t the case? No you don’t.

    Regardless, we do have explanations, but just like you we don’t know whether those explanations are correct.
    Here are some options:
    A) It could be due to chance.
    B) It could be due to necessity (like the laws can’t be any other way, or they are explained by a deeper physical law from which they emerge).

    nor why life when it began was placed in just that spot in the search space from which it could then further develop.

    Same as above.

    You are in no better position for these than anyone here.

  33. keiths: It’s not about my expectations of them, but rather about my treatment of them. I won’t deliberately downplay the implications of the ONH just to coax them into accepting common descent.

    I know keiths, I just thought it was funny you told me not to be condescending to creationists, given the colourful language in some of your discussions with them 🙂

    keiths: As for “focus”, you’re relatively new to TSZ, so you may not have noticed this yet, but the only threads that stay strictly on topic are the ones that are stillborn or peter out after a few comments.

    Believe me, I noticed allright.

    keiths: If you’re really concerned that people will conflate an acceptance of common descent with a rejection of divine guidance, then just state categorically that they are not the same thing.

    …repeatedly.

  34. Allan Miller,

    Limitation? Not from what I’ve seen. You’ll whip it out at the drop of a hat.

    So, to get it straight, evolution is incoherent because it contains – say – selection and drift. But ID is coherent because it keeps within limits. Chortle.

    It is limited because it does not explain how the design was implemented. That appears to be part of the inference of common descent.

    The incoherence comes from making claims that are difficult to support. An example is selection and drift creating a complex adaption.

  35. stcordova: Now did the processing of haploid gametes in animals and plants arise by common descent, or did that evolve independently.

    I assume you mean sexual reproduction by this. Did you see Allan’s OP a while back?

  36. stcordova: No I’m not surprised, because for the similarities to be due to homology a gap has to be overcome.

    There are other similarities I pointed to that have similar X’s, but gaps have to be overcome like say

    prokaryote

    XXXXXXXX

    vs.

    eukaryote

    iiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiiiiiiiiXiiiii

    Now did the processing of haploid gametes in animals and plants arise by common descent, or did that evolve independently.

    Those are the miraculous gene insertion into the tree of life Harshman admitted musta happened, which obviously evolution predicts… 😉

  37. Mung,

    Even young earth creationists accept common descent.

    Some, perhaps, but one need look no further than Erik for contrary evidence.

  38. colewd,

    It is limited because it does not explain how the design was implemented.

    Nor anything else.

    That appears to be part of the inference of common descent.

    Since when?

    The incoherence comes from making claims that are difficult to support. An example is selection and drift creating a complex adaption.

    That’s a completely different take on ‘incoherence’ from Mung’s. Perhaps you two could compare notes and get back to me.

    I think it’s just one of those instances where, if you stare at a word long enough, it loses all meaning. Incoherent. Incoherent. Incoherent.

  39. Mung: Corneel: If we are clear about separate issues, some people may realize it is not an issue they are emotionally involved in, and become willing to drop the more ridiculous objections.

    I don’t know. I still don’t understand why, if monkeys evolved into humans, why there are still monkeys.

    That was EXACTLY the one I meant. Thank you, Mung 🙂

  40. stcordova,
    Corneel,

    I assume you mean sexual reproduction by this. Did you see Allan’s OP a while back?

    Yep, the evidence is that it arose once only*** – or only once that left modern descendants. (I spy another derail!).

    *** [eta – in an organism without ovaries, of course!]

  41. Corneel,

    I know keiths, I just thought it was funny you told me not to be condescending to creationists, given the colourful language in some of your discussions with them 🙂

    There’s nothing wrong with condescension in general, particularly when it’s based on an accurate assessment of one’s opponent. 🙂

    My objection was rather more specific:

    Guided evolution is an improvement over creationism, but the objective nested hierarchy is fatal to both. To deliberately hide that, just to coax someone into accepting common descent, seems dishonest to me, and more than a little condescending. In effect, it amounts to saying “I knew you weren’t ready for the whole truth, so I hid the full implications of the ONH from you.”

    It’s one thing to condescend after your interlocutor fails to understand something. It’s another thing entirely to deliberately hide something because you’ve decided ahead of time that your interlocutor won’t understand it and you wish to manipulate them into a position they wouldn’t take if presented with the whole truth.

  42. Allan Miller,

    According to this discussion with John.

    John Harshman October 1, 2017 at 2:50 am
    colewd:
    John Harshman,

    Colewd :It means there is not external assistance to the process.Reproduction and the things that result from that process is responsible for diversity.

    John: What would you propose as “external assistance”?

    Colewd: For common descent to be true reproduction must be able to create new genes.As large sequential space is a potential obstacle to this is process it should be relevant.

    John: I’m afraid that you don’t understand what “common descent” means. Once again you have confused common descent with the causes of mutations. Even if every mutation, every new gene, is lovingly crafted by Jesus, that’s still common descent as long as species are ancestral to other species. You are arguing about the wrong thing.

  43. Allan Miller,

    That’s a completely different take on ‘incoherence’ from Mung’s. Perhaps you two could compare notes and get back to me.

    I await Mung’s take but my thoughts are that if you strip out all the unsupported claims then the theory would move toward coherence by breaking up into subjects that are much easier to comprehend like population genetics.

  44. Yep, the evidence is that it arose once only*** – or only once that left modern descendants. (I spy another derail!).

    Did multicellularity precede or arrive after the emergence of haploid recombination.

    Which raises the question, when did diploidy emerge? Was it haploidy first (which seems more reasonable), then diploidy?

  45. colewd,

    I await Mung’s take but my thoughts are that if you strip out all the unsupported claims then the theory would move toward coherence by breaking up into subjects that are much easier to comprehend like population genetics.

    In which case I think ‘incoherent’ is too far too vague a term to be of any use. If you mean X, say X, not ‘incoherent’.

    I’m sure the people in the pews lap it up. “Evolutionary theory is incoherent? Well, I always suspected as much! What do I mean by incoherent? Who cares!”.

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