nested heirarchies as evidence against darwinian evolution

If a new phyla popped up tomorrow, that would hardly be a nested hierarchy would it? In a nested hierarchy, the names we give to groups of parent nodes (phyla) shouldn't be applied to groups of their child nodes. I have a maternal line and a paternal line. I'll never find myself with a third parental line, so why would we find new parental lines of extant life forms popping up to the extent you suggest?Evolution didn't stop producing new phyla:- we just started calling the nested groups within phyla subphyla and then superclasses and classes etc etc.

The names of the groupings is manmade and arbitrary - this is understood, yes? Why do you consider phyla special? Why not Kingdom or 'life'? Oh wait, you already went there: "If abiogenesis is possible, wouldn't it happen all the time?" The answer is straight forward: Any children nodes of phyla will be called a subphyla, and then superclasses and then classes and so on. We wouldn't call the descendants of a superclass a new phyla.If a new phyla did crop up - it wouldn't be a nested hierarchy. You haven't explained why they should.

Yes, the groupings are based on analysis. The names of the groupings is manmade and arbitrary. "If we evolved from apes, why are there still apes around?", you've just moved the old silly argument back a few orders of magnitude. Why not push it back further:- why are there still non-animals around?

You agree that 'if we evolved from apes, why are there still apes' is a silly argument, yes?What makes your argument that 'There are still, for example, non-vertebrates around." significantly different? Well, most of our debate comes down to this. We could just accuse each other of dodging arguments or we can try to understand each other, ask pertinent questions and try and move things forward. If
you feel the avenue is not fruitful we can simply stop.Here is my position again:Any children nodes of phyla will be called a subphyla, and then superclasses and then classes and so on. We wouldn't call the descendants of a superclass a new phyla.If a new phyla did crop up - it wouldn't be a nested hierarchy.You haven't explained why new phyla should have to crop up according to evolution or taxonomy. All you've said is that it has been a long time.If you feel that is avoiding your argument then there really isn't any advancing of the discussion to be made as far as I can see. Perhaps you can expand a little and a light bulb will go on and we can take a new direction.

So you agree it's a silly argument. Great. Now, how is your argument about how invertebrates exist not just the same argument, but moving back the focus a few orders of magnitude? There is no phyla-creating-mechanism. There is just evolution of life. There are some distant ancestral nodes, from which all extant animal life has descended from and we call this group of nodes 'phyla' for the purposes of classification.Edited by Modulous, : No reason given.

You think that 'if we evolved from apes, why are there still apes?' is not silly? OK, I thought we could at least agree on that but if not, we'll try to move on. Right. However, evolution isn't a random process. And the question I'm asking is - why should this be the case? If there is no reproductive advantage to be found in rejigging an established body plan then it won't get selected for. Think of it in terms of a fitness landscape - if a population is at the top of a hill, it is improbable that an animal could 'jump' onto another hill without taking a massive hit in reproductive fitness. The only realistic way it would happen is if there is a gradual uphill slope to another hill and there is no necessity for that to be the case. The process hasn't stopped - there's just no going back to the drawing board. We're stuck on the path our ancestors have tread upon. To get to the point where an animal would improve its fitness by evolving a spine, they may well have to go back down the fitness slope (decreasing their fitness) and start climbing up another one. This is completely against what evolution would predict as probable.Just because some primitive invertebrates were more successful with primitive notochords and the like it doesn't mean all would have been more successful and it doesn't mean that modern invertebrates would likewise find that this is the case. If competition is stiff to be the best in their niche - it might be that in order to get to a better solution they would first need to go through a period of taking a reduction in fitness. Clearly something that natural selection would not favour.This is more of a question of 'macroevolution' than it is about nested hierarchies. You must accept that evolution predicts nested hierarchies, surely? If we were sat in the lab and we witnessed a nematode evolve something which we could reasonably call a backbone it wouldn't jump from the nematode phylum to the chordata phylum and nor would a new phylum be created for them. They'd be in the nematode phylum. We'd just have to not say that all members of the nematode phylum are missing a backbone.Edited by Modulous, : No reason given.

Because primitive life has more opportunities. Think about the most worst kind of life. The kind of life that only just gets by - it is hanging on a thread of existence and its continuing survival is a miracle. There are only two ways it's offspring can vary. They will either be dead or they will be better. The better ones, by definition will be the ones that reproduce yet again.So - when life was very primitive there was a lot of scope for change. Now animal is on the whole highly specialized. To evolve away from this specialization would usually entail a reduction in fitness. To evolve away from the primitive condition does not necessarily imply a reduction in fitness. Correct. And evolution doesn't suggest they should. New ancestral clades don't just pop up ex nihilo. Any new evolutionary paths that are taken today will face stiff opposition from highly advanced specialists in the niche. If they managed to dig themselves in and get established, they would still not be classified as a new phylum. In 500my time, maybe what we call 'families' will be as broad as what we call classes or phyla today. Maybe not. There's no reason it has to go either way. Because you inherit things from your ancestors. That is an inherent constraint in the evolutionary model.In simple terms, at first there was just life. Then there were a variety of life forms which for our convenience we have called various kingdoms. Those kingdoms split up and those subgroups we have called phyla. Each one of those phyla were subgroups of a kingdom. The phyla split up, and each branch would forever be part of the phyla its ancestors were part of. Either those things which were still part of a kingdom with no phyla died off, or they later became part of their own phyla. Once this occurred there could never be 'new' phyla. Maybe we might get a bit confused in our classifications and what we have previously called a 'phylum' are actually subgroups of another group after kingdom. So we create a classification between phyla and kingdoms.No matter what bizarre life forms evolve now, there will never be a new phylum - unless the life form is part of a previously undiscovered phylum. It is unlikely there are any life forms around now that are members of a kingdom but are not members of a phylum. Every one of their descendants will be thus part of that phylum. It didn't stop, it just got more and more specialized so we invent new names for the subgroups of the earlier broad groups. We could say the same thing for the kingdoms or for the classes. That's what a nested hierarchy is. Hypothetically there could be a period when all extant life has reached its equilibrium all at the same time. Maybe we are in a period of total or broad equilibrium now. What difference would that make to nested hierarchies as evidence against evolution? However, Grasse is hardly an authority that is likely to sway my opinion on this alone: If you want to convince me that evolution is winding down, you'll need to do better than quote a single zoologist who was born in the 19th century and was anti-Darwinian whose replacement ideas for Darwinian evolution have not really gone anywhere.

I'm suggesting that it may require a drop in fitness for a specialist to change its general body plan significantly enough to satisfy what you are after. One possibility that it might require a drop in fitness is because of the fact that all of the specialists they will be competing with are likely to outcompete them. I'm arguing that new evolution continued after the Cambrian, but not that new phyla have evolved. The subgroups of the phyla are broadly called Class, Order, Family, Genus and Species - though further subcategories are used where necessary. Not at all. I am simply saying that there is no reason to expect large fundamental changes such as a modern invertebrate developing a backbone. Plenty of evolution has happened since chordata came around and the window of opportunity to evolve these structures may simply have passed. That does not mean I am implying that other windows might not be opened. I have made no such claim. I simply said that the descendants of the first members of any given phylum will all be members of that phylum. I went on to say that there is no necessity in biology for backbones to evolve in a population of non-backboned entities. This may be because the opportunity has never arisen in any members of this lineage or it may be because it has but that lineage went unfortunately extinct by bad luck - or maybe it went extinct because it could not compete with its backboneless competition. These are just possible reasons as to why we have not seen backbones appear in other entities.The easiest way of putting is that things (including other life forms and extant genes) were different then. When we have different conditions, we expect different outcomes. If you can tell me about an extinction event that put the earth into a condition much like that during the Cambrian period, we'll talk about it. If it wasn't much like the Cambrian period, I don't see any reason to assume that these things have to have happened. The chordata phlyum did, but there is also the Hemichordata phylum, whose members have a notochord that is proposed to be independently evolved to the more famous chordata, although some propose that they both inherited their notochords from an earlier common ancestor. I'd still like to know what is unreasonable about the proposition that some events can only happen under certain conditions, and in an environment of constantly changing conditions it is possible that that some events may never happen, or only happen once or twice.Sometimes rand, you can't get there from here. Modern genomes may simply not be able to change in the ways you are thinking of within the realms of reasonable probability - and even those that can, it might require several hundred generations of increasingly less fit organisms, which would also render it improbable.I don't know why this has happened (I can only think of a few reasons why it might be the case - and thus argue why it doesn't need to be the case), but you think you know that it should have happened if modern evolutionary theory is true. If you are right, then I will concede the point.You'll need to show how evolutionary theory, and the evidence from genetics and zoology/paleontology demands that invertebrates should evolve vertebrae more than a small number of times (or once). To do that, you'll need to draw upon the literature to weave a theory that explains why this should be the case if evolution were true. I doubt you'll do that so we'll just have to rely on argumentation.Thus: You claim it should have happened. I claim that it might have happened, but there are any number of factors that could prevent it. Where would you like to go from here?Finally, this is still irrelevant to nested hierarchies. Perhaps you should change the OP, or at least the title, to reflect the evolution of the phyla or whatever it is you wish to actually discuss? As I previously explained, if we discovered a family of nematodes with backbones - they wouldn't get a new phylum. They'd still be in the nematode phylum.

First issue: neither Dad nor his brothers are capable of evolving. His lineage might evolve across the generations. No, Dad died over 500 million years ago. Reproduction requires being alive. Some of his descendants survive to this day.Let me explain this.Dad has sons who have sons who have sons. These children of children of children form families of their own, some being more closely related to each other than they are other lineages. These family lineages begin to evolve apart from each other and exploit different niches and face different challenges that require different evolutionary solutions.These families become so big and different that we give them a special group name: the families are the phyla one of which is called 'chordata'. In turn these families have offshoots of their own, each evolving down different paths. These offshoot families are then given another name: Classes (for example: Mammalia). This sub family or Class known as Mammalia are a specific sub family of the phylum Chordata. Dad no longer has any children so there will never be a new Phylum groupings. No - the first batch was the only batch that existed, and a new batch cannot be created since the batch producer...Dad...is very much dead.

If you read my post, which talked about evolution of populations over the course of generations, you'd not have made such a statement. You stated that he was a common ancestor, not an ancestral population so I went with that. If you refer to an ancestral population then the argument still stands as in my corrected version of the analogy. If you want to say that the surviving members of 'Dad' are still 'Dad', then we can say that 'Dad' has significantly changed since 500mya - so we would not expect 'Dad's' offspring to be the same today as they were 500mya - nor would they face the same environmental problems/predators/parasites/prey etc etc. The ancestral population that produced the lineage that lead to us, for example, is long gone.The various lineages of Dad are very different from one another, but they are still 'Dad'; there will still be no new 'Dads' popping up (Dad will never have any new brothers). You propose that new Dads should pop up. (Where, for convenience, I have demoted 'Dad' to be the common ancestor of one of the phyla). That is clearly in line with some kind of special creation, not descent with modification style evolution.Moving back to Dad as the father of the phyla, his sons were called the phyla, their sons were called Classes, their sons were called Orders, their sons were called Families and so on and so forth. Since the ancestral population is no longer one population, and since it has evolved in many different directions - we would not expect it to start producing offspring like the first sons. Dad is in a sense is no longer reproducing. Once his sons came about, Dad stopped reproducing - his sons were doing all the reproductions.You cannot find reproducing Dad's son today, only Dad's sons of sons of sons of sons... If you can point me at a living reproducing population that does not belong to any of the existing phyla I will concede the point. The chances are - you will not be able to produce any living reproducing sons of Dad. You will have to go all the way down the species level to find living reproducing members - none of these are the son of Dad though - they are sons of sons of sons of sons of Dad. It would be clearly madness to expect a son of a son of son of a son of Dad to create a new uncle, which is what you propose we should see if evolution is accurate.What we see - a nested hierarchy is what we'd expect if life were related to one another. New phyla appearing is what we'd expect to see if life was periodically specially created. Like birds?But more pertinently, why should 'new and improved' dinosaurs evolve? The dinosaur's ancestor is long dead, so the 'proto'-dinosaur genome was no longer around. Relatives of the dinosaurs did evolve into 'new and improved' organisms. Edited by Modulous, : No reason given.

Not a new complaint from you, it seems redundant for you to repeat it so often. Perhaps you are right. Perhaps you are not. Let me answer every question in your post. It might be that you simply do not understand the counter-argument. It might be that I do not understand your argument. Instead of complaining about it, let's debate about it and try and find out what is what! If you genuinely think that your questions are not being answered and the procedure is futile then simply stop responding to posters that you don't feel are moving discussion forward. Because the ancestral population from which the phyla evolved no longer exists. It has split into a variety of lineages most of which are extinct and the rest of which has evolved. Evolved means that it has changed. If something has changed it is different. If something is different that means it isn't the same. Thus: the descendant populations are not the same as the ancestral populations. Thus: there is no reason to think that the descendant populations would have descendant lineages in the same way at the ancestor populations did. We would not expect sons to have their own uncles as offspring. If we are going to be specific, then a population evolved into the population that we later called the common ancestors of animalia or metazoa. Correct. It did evolve more - look at all the animals today and compare with the proposed early ancestors of metazoa. However, the population that evolved into what we see today no longer exists as the same thing it did then: Most of it went extinct. The rest of it evolved - rather dramatically. Today it is very very different. Thus: there is no reason to expect its offspring to be in the same area of 'design-space' as the ancestral population's offspring. There is no reason to think that the selection pressures acting on the ancestral population are the same selection pressures acting on animals today. Indeed, it should be extraordinarily obvious that contemporary animals have many different pressures to contend with. There is no rule which says that they wouldn't. They just didn't. I could ask why wouldn't Hitler's assassins successfully kill him? They hypothetically could have, but they didn't. There is no necessity for every possibility to be tried out, and most experiments that were tried out never made it this far.I have said this at least twice already, and it's an important point: if a nematode was to develop a notochord it would still be in the nematode phylum. It might be theoretically possible for something like this to happen. Maybe at this time, it is simply too improbable for the current nematode genome to change in such a way as to result in the evolution of something notochord like. The genes that the metazoan ancestor had that developed into the notochord in one lineage might have been used for some other purpose in nematodes for example and has now changed so much that the probability that it would be co-opted for notochord use is vanishingly small. Maybe it isn't improbable, has been tried out, but is not positively selected for. Maybe it isn't improbable, is positively selected for but dumb luck has ended up with any populations with notochords as going extinct without leaving any evidence (that we have so far found).Evolution does not predict that descendant populations will have offshoot branches that will likely evolve along similar lines as their ancestral populations once did. What we'd expect to see is that populations that have changed over time, will be different and will in turn have different offspring. We'd expect that different selection pressures existed in distance ancestral species and that ancestral species have a different gene pool as the descendant species and will thus be likely to evolve in different ways.

What happened was that A branched into B and C. A ceased to exist. Thus A will never diverge again, since extinct populations don't reproduce by definition.

What I said has nothing to do with "hyper-gradualism" and nor is that relevant the topic at hand.

There are two ways it might happen. Cladogenesis and Anagenesis. Anagenesis is sometimes referred to as gradual evolution and yes it does occur and no, 'evos' have not moved away from thinking that anagenesis occurs.

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When enough mutations reach fixation in a population to significantly differentiate from an ancestral population, a new species name may be assigned. A key point is that the entire population is different from the ancestral population such that the ancestral population can be considered extinct.

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(wiki)If a new group diverges from A called B we might call that cladogenesis.If A proceeds to evolve away from its ancestral population we might say that anagenesis has occurred and the current population should be called C.If A splits into B and C then what happens to A? It either continues splitting cladogenesis style, evolves away from its ancestral population anagenesis style or it goes extinct.Since we know there are no ancestral populations hanging around, we know that the continuing splitting of the of the ancestral metazoa population into animal phyla cannot continue. Either the ancestral population went extinct or it itself evolved to such a degree away from its starting to point that it warranted being called a new phylum.

Or it did exist but it wasn't ancestral it was actually a descendant gone back in time to father itself. That isn't evolution as it is understand by science though, which is what I was describing. There were ancestral populations similar to the first that arose and split into phyla. I have no idea why there wouldn't be, without resorting to crazy nonsense. It might be extinct because the niche no longer existed, or there was something more fit competing for that niche. Niches change over time depending on the environment and the environment includes other life which changes with time partially because niches are changing over time as a partial result of life changing over time. That isn't a rule, it is a theory. There is nothing within the theory which demands that backbones cannot evolve multiple times. There is historical evidence that they didn't (well, I mentioned another possible evolution of notochords but let's not get complicated). The reason new phyla don't emerge has been explained. I don't feel like repeating it everytime you repeat yourself.