Quite apart from any factual errors, about which I’m not at all qualified to judge, here is what seems to me to be Meyer’s fundamental logical error IMO:
According to Darwin’s theory, the differences in form, or “morphological distance,” between evolving organisms should increase gradually over time as small-scale variations accumulate by natural selection to produce increasingly complex forms and structures (including, eventually, new body plans). In other words, one would expect small-scale differences or diversity among species to precede large-scale morphological disparity among phyla.
(Darwin’s Doubt, Chapter 2)
He illustrates this by asking us to comparing this figure, which he says is what we do see:
With this (appallingly badly drawn) one:
Which he claims Darwin’s theory says we ought to see.
And he says:
The actual pattern in the fossil record, however, contradicts this expectation (compare Fig. 2.12 to Fig 2.11b). Instead of more species eventually leading to more genera, leading to more families, orders, classes and phyla, the fossil record shows representatives of separate phyla appearing first followed by lower-level diversification on those basic themes.
Well, of course it does, Dr Meyer! You have just, in Chapter 2 of your fat book made an absolutely fundamental error of understanding of the entire principle of phylogenetics and taxonomy. No, of course you wouldn’t expect phyla to follow “lower-level diversification on those basic themes”. How could it possibly? And how could you possibly so fundamentally misunderstand the entire point of Darwin’s tree and its relationship to the nested hierarchies observe by Linnaeus?
All branching events, in Darwin’s proposal, whether the resulting lineages end up as different phyla or merely different species, start in the same way, with two populations where there once was one, and a short morphological distance between them. It is perfectly true that the longer both lineages persist for, the greater the morphological distance will become. But that isn’t because they started different, or because the phyla come later. It’s because what we call phyla are groups of organisms with an early common ancestor, whose later descendents have evolved to form a group that has a large morphological distance from contemporary populations who descended from a different early common ancestor.
So when a phylum, or a class, or even a kingdom first diverges from a single population into two lineages, the “morphological distance” from the other lineage will be very short. We only call it a “phylum” because eventually, owning to separate evolution, that distance becomes very large.
I’ve amended the drawings in the book as below, and, instead of labeling the trees by what a contemporary phylogeneticists might have called them, I’ve called each tree a phylum, and I’ve drawn round the organisms that constitute various subdivisions of phyla in colours from orange to green to represent successive branchings. Rather than the little bunch of twigs marked “families” by Meyer, I’ve indicated the entire clade for each subdivision, or tried to.
In Meyer’s version, he called the early sprout “ONE SPECIES”, which a contemporary phylogeneticist (Dr Stephen Chordata perhaps) would have called a “species”. But by the time of the next tree (which I think is supposed to incorporate the first), and Dr Chordata’s distant descendent comes along, she may call it an entire “genus”, and become rather more interested in the “species” that she observes it contains. Move along one to the next tree on Meyer’s time-line and an even more distantly descendent will call the whole tree a “family” containing “genera” and “species”. What was a “genus” to her great^10 grandmother will be several genera to her, and so on. And with each multi-generation of palaeontologist, the descendents of what were close relations in her ancestral palaentologist’s day are now separated by a wide “morphological distance.
So of course, if we look at the fossil record as these speciation-events were happening and try to categorise the organisms in terms of their modern descendents, we will find a great number of different phyla, and far fewer species. Of course they have different body plans, because they lived at a time when many different lineages from the first populations of rather amorphous multi-cell colonies were still around, some with not much symmetry, some with bilateral symmetry, some with five-fold symmetry, and many that didn’t go very far and left no extant lineages. Because of course Meyer also forgets the big extinction events, which are the other part of the answer to why one particular branch “exploded” while the others were never seen again. It’s even in his terrible Figure 1.11. Which he may not have been responsible for drawing, but he should at least have looked at.
ETA: the other drawing, fixed:
ETA2:
Another extraordinary example of Meyer’s complete failure to understand what a clade is, or that the words “phyla” and “class” refer to clades. Coloured emendations are mine (orange/red for Meyer’s “phyla”, blue for Meyer’s “class”):
I’d have expected an urbane, Cambridge-educated guy like Meyer to know the [ETA: spot the erroneous] singular of “phyla” but that’s minor compared to his crashing howler of an attempt to demonstrate what the term means.
ETA:3 Note: As Mung has pointed out, Meyer shows that he does know the singular of “phyla”, he just doesn’t get it correct it in this particular diagram. However, as I have said elsewhere (and above), this error is minor compared with the howler of including only a group of of descendents in his circled “phyla”, not the whole branch, which as I’ve said, undermines his entire argument.
William j Murray, beacon of clarity, use your mind powers to change this reality! Then she’ll get it. Or ID will be right. Or whatever you want!
It means that the only way to get from a universal common ancestor to different phyla, under darwinistic evolution, is for that universal common ancestor to diversify into, presumably, different species, and for those different species to diversify, presumably, into different genus, etc., until somewhere down the road you have a new phylum. Although we classify genus and species under phyla taxonomically, the only way for the universal common ancestor to get from it’s own phylum to the point of being a different phylum (or producing different phyla) is to diversify to the point of disparity.
Otherwise, you’d have to have a dog give birth to a cat, or more accurately phylum A (original ancestor) giving direct birth to phylum B, and then either A or B giving birth (directly) to phylum C. That’s a no-no under current evolutionary theory.
Sure. And that’s what we observe.
William, it’s not a mark. It was a period of 70 or 80 million years, during whichthere was a great deal of diversification, and at the end of which, there were more phyla than when it started. Each of those new phyla started off as a subgroup or a bifurcation in a superphylum present at the start.
Not if you understood what you first said. Body plans must come come first, diversifying thereafter into variations.
Think of origami. Take a piece of paper, and fold it diagonally. There are lots of origami pieces that start that way. Take another piece, and fold it down the middle. There are lots of origami pieces that start that way too. Those folds are the equivalent of the earliest varieties of body plans – and they aren’t that different. A piece of paper folded diagonally once is “morphologically close” to a piece of paper folded vertically once. But they will give rise to a very different set of finished pieces.
And this is exactly what we see in the fossil record. The first radiations are into different patterns of basic body plan with not much else – some bilateral, some radial, some developing anus first, some developing mouth first.
As time goes on, each of those simply body plan schemes radiates into complex variations. Exactly what we’d expect, and exactly what we observe. So much so, that it didn’t happen that way round – it was because that was what was observed, that Common Descent became obvious.
Nope. Firstly, there isn’t a “CE point”; secondly, we see many phyla starting to emerge from their ancestral superphyla during the cambrian, and thirdly, of those phyla present at the start of the Cambrian, ancestral phyla are also evident in earlier strata, including the Ediacaran. But the evidence is patchier the further back you go, because earlier organisms fossilise less readily. There’s a lot of it, nonetheless.
Why don’t you actually read about what is known about the Cambrian period? And perhaps find out a little about how taxonomy and phylogeny are related? Then read Meyer, and you will see his mistake.
But trying to tell me that Meyer didn’t really say what he not only said, but got someone to draw, on the basis of some half-baked notion of a “CE mark” at which point lots of “phyla” appeared from nowhere, fully formed, is ridiculous.
If you want to base an argument on “what we see” then first find out what we do actually “see” and what a phylum is.
What?!!
No it does NOT. Where are you getting these ideas? Duane Gish?
William, this makes no sense whatsoever. Could you at least use the terms in the way that biologists use them? Even if you don’t accept common descent, could you at least acknowledge that in biological taxonomy, a species is a subset of a genus, which is a subset of an order, which is a subset of a class, which is a subset of a phylum.
It’s because, as Linnaeus noted, that organisms can be grouped into these nested categories that common descent was hypothesised to explain the pattern.
Presumably you are not denying the pattern? Then why not use the terms as they are used to denote the nests of the pattern?
And if you do, then it is perfectly clear that phyla mustprecede order, which mustprecede class, which must precede genus which mustprecede species, if common descent is true.
Why would later generations of a lineage all independently come up with anus-first development, if it weren’t the thing that they all started and then diversified from?
Of course it is. That’s because you are using the terms wrongly. What is proposed to happen makes perfect sense: a superphylum diversifies into two or more phyla, which diversify into two or more classes, which then diversify into two or more orders etc, except that we now have to invoke lots of sub-classes and superorders because branches don’t neatly split off in nice sequential waves.
Seriously William, both you and Meyer need to first learn what terms are used to denote in biology before you start saying that there’s a problem. As I keep saying – Meyer’s problem isn’t a problem at all – it’s just a mistake.
William doesn’t understand the basic ideas behind classification in evolution. This is a typical problem with ID/creationists, even the ones who purportedly have PhDs. When you check closely, they fail at concepts taught in high school. William’s and Meyer’s problem is a dramatic example.
The notions of orders, genera, phyla, etc. are “upstream” from species. As you group species together, you then go farther upstream and group groups. And then groups of groups of groups, etc. It is a nested hierarchy.
New species are the “flowering end” of the bush of evolution.
The fact that you are begging the question here (pushing back the “ancestor to phylum” problem with “ancestor to superphylum”) indicates you are still not addressing the issue.
There’s no way around it. If you start with a universal common ancestor, you must then diversify from it to build new body plans. IOW, while you are agreeing that diversification of the original body plan into new body plans occurred before the CE, You say we shouldn’t see any such diversification into new body plans after the CE. That makes no sense.
BTW, if diversification to new body plans requires body plans to work on, where did the first body plan come from?
I’m not telling you he didn’t say what he said; I’m telling you that, like in so many other cases, you don’t understand what he said.
As for whether or not a 30-80 million year span is a “mark”, I would say that in a 3.8 billion year (or so) history of life on earth, 30-80 million years is indeed well represented by the terms “point” and “mark”, representing 2% of available evolution time. That’s pretty much all known phyla popping up in 2% of available time and then evolution creating nothing taxonomically novel (phyla-wise) for the next 500 million years.
From Wiki:
Your evolutionary bluffs are duly noted and dismissed.
It’s not an argument about classifications according to a taxonomic chart per se, it’s an argument about what you’d expect to find in the fossil data – ever increasing diversity from a universal common ancestor towards disparate sets of morphologies we call phyla. You’d expect to find, leading chronologically away from the universal common ancestor (forward in time), something taxonomically divergent such as a different species, a different genus, diversifying to the point of disparity – a new phylum.
But this is not darwinism. If, as in origami you start with differents body plans you do not have a tree anymore. That means that there was a the common ancestors of all fishes is not the common ancestor of the anphibians, because the body plan of anphibians come first of the diversification of the fishes. If yu go down with your idea the body plan of all life forms was ready in the LUCA meaning that LUCA wasn´t an homogeneus population but a big number organism with different genomes that will evolve to the different body plans.
I agree that this view fits better the data. Tell that to darwinists.
Which is what we see.
because a “phylum” describes some feature shared by all the organisms within it, putatively inherited from a common ancestor.
Yes, but in the reverse order, using the standard nomenclature. You’d expect to see the features common to all members of a phylum to appear first, those common only to a subset, e.g. an order, next, and so on.
You are simply using the wrong terms. Like Meyer, you think “phylum” only refers to the group of organisms that descended from the common ancestor of that branch, not the whole branch. It doesn’t – refers to the whole branch. The reason the twigs at the end look so different from the twigs at the end of a different branch isn’t because they only became a “phylum” at the end, but because they have a different common ancestor.
The pair of common ancestors themselves looked pretty similar. For instance, two anus-developing-first deuterostome, one with a two-ended nerve, one with a five-ended nerve. There were probably three-ended-nerve and four-ended-nerve and six-ended nerve deuterostomes too, but the 2 and five ended ones were the ones that led to lineages that still survive today.
You are falling in negation mode. This is not true, what exists are the individuals and the populations. Biologists arbitrary define species, group species in something defined as genera then in other abstractions called families, phyla etc..
Taxonomy starts with the description of the individual and then fit it in the arbitrary classification.
You can even get rid of the words “species” “genera” and “phylum” and say that you’d expect to find greater and greater diversification, chronologically, from some universal common ancestor towards new phyla – but we don’t see that in the fossil record. What we find is the sudden appearance of disparity first at the CE, then nothing but diversity from those basic forms afterward, leading to no new disparity in 500 million years.
Of course. And we aren’t even talking about the universal common ancestor here, but the common ancestor of multicellular organisms, which was probably a fairly amorphous colony of one-celled critters. From that amorphous ancestor, various lineages with more or less symmetrical structures diverged, some with bilateral symmetry, some with radial symmetry.
There was no “CE”. The Cambrian so-called explosion, as I said was a period of tens of millions of years, over which diversification occurred. And many new variants of body plan have occurred since then, as you must know. Or are you wondering why those amorphous mats haven’t kept on generating yet more weird and wonderful lineages since the rest of the biological world took over? Probably because the rest of us occupied their niches rather effectively.
But you certainly wouldn’t expect a bilaterian to give birth to a sextuplanarian. Bilaterians will tend to produce a lineage of bilaterians, and do.
What part of “he mislabeled his tree diagram” don’t you understand?
What part of “I’ve read the book and you haven’t” don’t you understand?
How the hell do you know that I didn’t understand what he said, when you haven’t read the book, and you seem as confused as he is about the nature of taxonomic groups?
Or do you really think a “phylum” only includes the late generations of a lineage, not the entire lineage?
If so, I suggest you read a high school biology text book.
William,
Given that you’ve now solved the riddle of free will and explained how Darwinism fails at explaining the Cambrian explosion don’t you ever wonder if you don’t actually know as much about all of this as you think you do?
So write a paper about “what you’d expect to find” and get it peer reviewed and published? If your argument is as strong as you seem to believe it is then fame and fortune (well, grants) await!
Well, that might help, seeing as neither you nor Meyer seem to know what they mean.
It’s exactly what we see in the fossil record.
As Meyer notes. He seems to think it’s a problem for Common Ancestry. It isn’t, because it is, as you note, exactly what you’d expect.
Explain how you are distinguishing “disparity” from “diversity”.
And even if that was the case, so what? At one point there was nothing, then something then lots of something. And so?
What would you expect to see if Darwinism was true?
What would you expect to see if ID was true?
Can’t you say? lol.
The problem his argument addresses is where those different common ancestors came from that leads to the diversity afterward.
Without some twigs at the end of some branching phylum becoming a new phylum, you can’t get new phyla, unless your argument is that new phylum appear in whole without any predecessors.
What was the phyla of the universal common ancestor? Are all current phyla subphyla of that phylum? Or are modern phyla different phyla than the universal common ancestor? Where did new phyla come from, if not at the end of branchings from that universal common ancestor phyla?
rofl
I’m just talking about the quote above, of course.. You have obviously misunderstood that quote by comparing your argument and characterization of the quote to the quote itself.
As I said in an earlier comment, this is the classic creationist misunderstanding.
I use a garden tree as an example. So let me rephrase that example as a paraphrase of what you just wrote:
it’s an argument about what you’d expect to see in that background tree — ever increasing diversity toward those parts of the trees we call branches
You are saying that we should find the branches at the tips of the tree. But the name “branch” doesn’t apply to a newly grown twig. Rather, it applies to the whole subtree starting where it branched off. Likewise the name “phylum” does not apply to individual organisms, but to a whole large class of organisms starting where it branched off.
Fortunately we aren’t limited to phenetic classification. Phylogenetic classification – which necessarily assumes common ancestry/descent – indicates genetic continuity right through these assumed divisions, entirely in accord with the divergence occurring at lower levels, and implying cumulatiove divergence by exactly the same mechanisms in operation here at the twigs. So whatever you might think the fossils say (biased as they are towards organisms with hard parts), the DNA clearly indicates a cryptic common ancestor not preserved in sediments (or not yet located).
‘Body plan’ classification tends to mean things that happen in early embryogenesis that have a whole bunch of downstream consequences. Subsequent amendments lead to the different morphologies we actually see in juvenile and adult stages. These fix the basic ‘body plan’ – which end the anus goes and which the mouth; which tissue becomes the outside, etc. These are not amendable to produce a new ‘body plan’ at that level. ‘Darwinian’ (sic) evolution does not predict that the anus will gradually migrate to where the mouth is, or the organism will turn inside out. It’s ‘stuck like that’, as my mum used to say. To get a new phyum at that level you’d have to start with an organism of some simplicity, where downstream consequences were not so critically dependent on early embryology. So WJM’s expectation – a continuing production of new phyla – needs to take account of these considerations.
Well, have you looked at the diagrams he supplies to support his quote?
Do you think they are correct?
Of course not, and that you ask me this demonstrates that you still do not comprehend the argument. If you start with phylum A, at some point down the branching path a new phylum must emerge. There’s no place else for the new phylum to emerge from. Generally speaking, you’d expect some section of twigs to be so divergent from the originating phylum that it can no longer be considered of the originating phylum, but must be considered a new phylum.
From the 2nd phylum’s perspective, increased diversity (into different species, genus, order, etc.) from the first phylum gave rise to the 2nd. Now, you have a new phylum and one species (let’s say) that represents it, that houses the defining new body plan; what does it make next, chronologially speaking. A new sub-phylum? A new order? A new genus? No, it just evolves a new species. That diversity then leads to what we will later call new orders, genera, etc., but not because the species representing a new phyla then branches off directly into a sub-phyla or different class, but rather it speciates, speciates some more, until there are what we would call different classes and genera of that phylum. If those different genera, classes, etc. become divergent enough, evolution has then created what we would classify as a new phylum.
IOW, in current evolutionary theory, new phyla are built from the bottom up, from a prior phylum species to divergent species to divergent genera to divergent order until you have enough divergence to classify one of the divergent species, or a group of them, as a new phyla. They are classified top-down, but are built (supposedly) bottom up from divergent speciation.
There is nothing amusing there, William.
If you are going to use words like “disparity” and “diversity”, please explain what you mean by them.
Because on the basis of your total misunderstanding of the words “phylum” and “species”, plus the fact that Meyer define the words in terms of his misunderstanding of “phylum” and “species”, I have no confidence that you have any clue as to what you are talking about.
Please tell me what YOU mean by those words.
Not in any accepted meaning of the word “phylum”.
Please consult a biological glossary.
Please learn what the theory of common descent actually proposes, and what the terms used to describe the various levels of the taxonomic hierarchies actually refer to.
Then you will be in a position to critique it if you don’t find it persuasive. Until then, this mangling of the theory, with its disastrous misunderstanding of taxonomic terminology, gets a failing grade at HS level. Seriously, it’s laughable, William.
No.
They are classified according to the nested hierarchy of characters they show. It is neither bottom up nor top down, but nested. Superphylum: everything that develops anus first; phylum; all the anus-first organisms with bilateral symmetry; subphylum: all the anus-first organisms with bilateral symmetry that have a backbone; superclass: all the anus-first organisms with bilateral symmetry that have a backbone and four limbs
etc.
And clearly, the fact that organisms can be so nested according to their inherited features strongly suggests that those that share any one feature descended from a common ancestor with that feature. If that feature is anus-first development, it will be shared among a great many organisms, including sub groups that don’t have backbones, and don’t have four limbs; these sub groups have different names such as “order” or “class” or “genus”.
You don’t get a new phylum from the diversification of an old one. You get a new something, but it won’t be a phylum, by definition.
WJM, do I correctly understand the situation you wish argue?
[ For the sake of brevity adfd(2 – 6) means: anus-developing-first deuterostome, with a (two, three, four, five, six)-ended nerve. ]
Suppose we had a time machine and and could watch life during the pre-Cambrian/Cambrian eras. Further, suppose the adfd2 population appears first. Among its offspring are the eventual mutant populations adfd3, adfd4, adfd5, and adfd6. Shortly after this initial diversification, populations adfd3 and adfd6 die off, but adfd4 survives long enough to produce offspring populations adfd4A and adfd4B before all three (adfd4, adfd4A, adfd4B) die off. Thus for a brief time (geologically speaking), there were five lineages (adfd2,adfd3, adfd4, adfd5, and adfd6) before collapsing to two.
From our limited perspective in the present, we would say adfd2 and adfd5 are separate phylums (based on the fossilized evidence of many, many descendent species) and speculate on the existence of others. From “God’s” perspective we would clearly see five phylum with only two surviving into the present. But from the perspective of the time traveler (who does not know the future), he sees one genus with five species or perhaps sees one species with four subspecies.
We just about all mammals, including thee and me, evolved from shrew-like varmints in that amount of time.
Then where did new phyla come from?
Perhaps William and most ID/creationists are not even able to grasp the concept of branching; things like icicles, trees and bushes, branching water flows, stalactites, and percolation.
If one doesn’t understand concepts that even little children can understand, then concepts like the tree of evolution would be incomprehensible.
The persistent game-playing and word-gaming are also symptoms of something not so good.
There is little question that ID/creationists have a lot of pent up fear and loathing of the secular world. They certainly make no secret of it within their churches.
From what are called “superphyla”.
And if a phylum bifurcates, the resulting branches are called subphyla.
We are running out of words now, because the nesting is so much deeper than the early taxonomists imagined. That is, of course, because the tree model fits so well.
There isn’t such a thing as a “new” phylum.
I don’t know if this will help, but I’d like to know if this fits with what the biologists here understand.
My sense of the situation is that, considered in terms of evolutionary theory, only the species is real. But the reality of the species is construed in anti-essentialist terms, as the distribution of traits across a population. (So a species is real in the sense that a sports-team is real — it’s the same team, even if the players change.) But above the species-level, all the other taxonomic orders are merely nominal — they are labels we use to represent the degrees of similarity and difference between species. So there’s no real kind of thing designated by the term “phyla”, and the question, “where did the phyla come from?” is a pseudo-problem.
Right, that is the whole point Lizzie is unable to see. Darwinism needs to immagine intermediate forms existed and didn´t left ny trce during CE.
Now that are you explaining that instead of me, maybe Lizzie realize that were making nonsense arguments.
I think that’s a common view. I’m inclined to say that not even the species is real, at least for some meanings of “real”.
Imagine a lake, with a ring species of frogs as we go around the lake. There are 7 different species in that ring. But maybe it could just as easily have been divided into a ring of 6 species, or a ring of 8 species. So I’d say that there is something a bit arbitrary even about the species boundary.
I am a physicist; not a biologist. However it is not as “nominal” as you suggest; at least as greater amounts of common features are brought into the picture.
Earlier classification schemes relied on visible morphological features to group species. Going up the levels of the classification scheme, one would expect to see features that would be common to every organism beneath that particular level of classification.
However, as more data become available, some of the members of a group have to be moved to other groups.
These days we don’t just rely on morphological features; we include detailed genetic information from the genomes where we can get it. Where we cannot, some questions are left open or are answered indirectly until further data become available.
There is a somewhat similar classification scheme with the periodic table. Atoms are listed by atomic number, but they are grouped by their chemical properties, in particular by how many valence electrons in their outer shells or by the electrons that actually exchanged in chemical reactions.
Early on – before the advent of quantum mechanics and more detailed knowledge of the shell structure of atoms – chemistry was primarily the guide for how to place atoms in the various columns of the periodic table. However, once the quantum mechanics and structure of atoms became understood, we discovered that the chemistry did a pretty good job of putting elements in the proper columns of the table.
We are finding similar correlations with genetics confirming many of the classifications that were done by morphology; but it isn’t as clean and neat as it was with the periodic table. Plus a lot of intermediates are missing.
The higher taxa are simply the set of descendents from an ancestral.population. dead and alive. Extant species and extinct. The oldest known ancestral population would have been a species. But we can’t know the ancestry all the way back, so it’s just a label.
The only thing real in biology is geneology. Every living thing is at least a cousin of every other living thing.
um, Blas, it’s Meyer who is making the argument about how phyla should come after genera, not before.
As you say, it’s a nonsense argument.
Blas,
So you think the fossil record should be perfect if ‘Darwinism’ (sic) were true? Everything that ever lived should be in there somewhere?
Indeed. Just not at what you hoped.
My own suggestion for visualising the issue would be to consider a set of branching pipes. Start with a single pipe which divides ; subsequent pipes divide further, though some pipes ultimately become capped.
There is a flow through these pipes – analogous to the flow of genetic sequence from parent to offspring. Looking at the current ends of the pipes, one can name each separately. But if one injected radioactive markers at various points in the branching network, one would receive a collection of such markers at any given end. These represent injections which are serial along the length of any given sequence of flow, but this series is ‘flattened’ on sampling the ends. But, if each injection is unique, a given marker will appear in only a subset of pipes. One can name the subsets containing any given marker. Another marker, appearing earlier in the flow, will be present in sets of these subsets. One can use this information to classify, and to reconstruct the branching pattern.
But as time passes, the pipes continue to branch. New markers appear. The classification scheme one used when the pipes were x meters long starts to group larger and larger sets of pipe ends as they get to 2x, 3x, 4x. What was the lowest level of classification becomes ever higher.
The difference between any two pipe ends would be expected to be proportional to the distance to their common branching node. If one thinks of the pattern as the letter Y, and the stem and both arms are the same length x, the genetic distance between the ends of the arms is 2x, which is also the genetic distance between the end of either arm and the base of the stem. Does this mean that we could classify the serial difference base-to-tip as a change of exactly the same taxonomic rank as the divergent one? No. The taxonomic classification is due to the divergent differences between arms, not the amount of difference per se. If one determines that the ends of the Y are different [taxonomic category x] this does not mean that each end is also a different [taxonomic category x] to the base – that a serial change process should be continually throwing out by change alone new instances of one’s branching class as the amount of change increases. We do refer to historic species and genera, of course. But really, classification systems are discrete (possible at a moment in time because gene lines remain largely discrete above the species, and in palaeontology because the record is jerky) but the process is continuous.
No, but darwinist have to admit that there is a big part of you call evidence is only in your head.
No, you are making the point that the problem is how understood Meyer the definition of phyla and genera that is nothing more than, as Kantian said, a pseudo problem instead of focusing in the real problem of CE.
It’s either amusing or sad that after probably a score of posts where I have detailed exactly what I mean by “diversity” and “disparity”, you ask me this. I prefer to see it as amusing.
Again,rofl.
If “phyla” means “disparate sets of morphologies”, then in order to avoid the terminological and categorical mental block Liz and others appear to be beating their semantics against, please tell me how these disparate sets of morphologies came to exist? Where did they come from, if not from a previous “morphological set”?
Did they not come about as one morphological set (represented by the universal common ancestor) branched out and, over time, gradually, generated a (or more than one) sustainable population of organisms with a very different – a disparate, if you will – morphological set?
So that if we went back in time to that point, we would classify those organisms with the original morphological set as “morphological set 1”, and its disparate descendant species line “morphological set 2”?
Isn’t that what we are necessarily doing when we classify any morphologically disparate sets? After all, they all were produced – supposedly – via common descent, right? So all “morphological sets” came from prior (even if still existing) morphological sets, which is how you get from a bacteria-like morphological set to a tetrapod-like morphological set. Right?
Yes, the clade of all living organisms is split into Bacteria and Archaea. There is some argument about whether the clade of eukaryotes split from archaea, bacteria, or a symbiogenetic amalgam of an archaean, a bacterium and a virus. Once you get to the eukaryotes, the cladistics are much more settled, with the two main clades of animals and plants. Multicellularity appears to have arisen in both clades independently after the separation of plants from animals.
ETA
It might be worthwhile you glancing here for an overview of stem groups and crown groups.
ETA
I’d avoid “morphological sets” when discussing evolution as the phrase seems to be used more in mathematics. Try clade which is a monophyletic group of a species and all its descendants.
Phyla doesn’t mean “disparate sets of morphologies”.
Still trying to make up your own pet definitions I see. How long before you figure out that silly rhetorical game just won’t work in science?