Evolution Requires Reduction in Genetic Diversity

No, RAZD, you have misunderstood my point. I'm not talking about VARIATIONS being reduced, variations or phenotypes or new traits actually increase due to population splits and reproductive isolation, it's GENETIC DIVERSITY that gets reduced as new phenotypes or varieties are developed.Also I try to keep it clear but it's not easy, that by "selection" I don't necessarily mean "Natural Selection." That is one form of what I'm talking about. I keep trying to use a collection of phrases such as Reproductive Isolation, Population Reduction, Population Split, Geographic Isolation, to make clear that I'm talking about the effect of reducing the numbers of a population and keeping the new population isolated as the way new phenotypes or varieties get formed, which is ALWAYS accompanied by a reduction in genetic diversity. This process can go as far as what is known as Speciation and sometimes does.Otherwise you are making the same claim about mutations that I've already answered here. This is not like money in, money out as DWise put it, selection in its many forms actually changes gene frequencies so that you have more of some alleles, fewer of others and if the population is small enough (or if natural selection IS involved so that the unadapted ones die off or are eaten or whatever) none at all of some alleles. The overall effect is a reduction in genetic possibilities which is what gives you a new variety or phenotype.Also I'm quite aware of the Greenish Warbler ring species, as I am of other ring species which I use as examples for my own purposes. There is a ring species of chipmunks around the Sierra Nevada, a ring species of salamanders around the Central Valley of California, and a ring species of seagulls around the Northern Atlantic.The thing about ring species is that they demonstrate the effect of geographic isolation from one "species" to another. Each new population split off from an earlier population and because of its new mix of alleles which always involves reduced genetic diversity produced a new phenotype. This continued all around the ring.According to my argument there should be much less genetic diversity in the last of the populations than the first. But I'm also aware that the first will have undergone reduced numbers and hence phenotypic and genotypic change as well so pinning this down isn't always easy.Sometimes there is gene flow that continues between populations so that you get a gradation of phenotypes or you get hybrid zones, sometimes there is a complete isolation and the separate phenotype will be more strikingly defined.In any case it takes the elimination of alleles that underlie the other phenotypes in order to form any given phenotype and that's what I mean by reduced genetic diversity.Mutations are absolutely unnecessary to this as simple sexual recombination of existing alleles in the original population is all that is needed to form all the new varieties or phenotypes. But again I'd make the point that even if mutations are involved all they do is form the collection of alleles from which the new phenotypes are created, and in order for that to occur they have to undergo the same processes of selection, isolation, and concomitant reduced genetic diversity I'm talking about.I think there is a common problem with evoljutionist thinking that often the great variety of phenotypes that can occur both in nature and in domestic breeding gets confused in your minds with the genetic substrate or genotype. You really do not need mutations at all to producde all the variety we see. All you need is a good mix of alleles for many genes that govern many traits, the reduction of numbers of individuals that interbreed, and normal sexual recombination will produce all the wonderful variety we see in nature.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Hallelujah, another one to hang on my wall!I have to thank the Lord for this because I prayed that SOMEONE would appreciate the content of this argument and at least to this point and this degree HBD has done so. So thank You Lord and thank you HBD.If I were more faithful at praying for God's guidance I'd probably do a better job with the argument, so I'll try to take my advice here more often.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Of course not. But confirming it would. Though it's not exactly a "theory of evolution." Clearly said what, that this is MY theory? I would have thought that was pretty clear, but if it helps I'm glad if it is clearer now. Just curious: What did you THINK I was talking about?As for terminology, it is never easy to talk about phenomena from within a new explanatory framework when those phenomena already have terms attached to them from the framework you're trying to answer. You can't use NEW terminology or nobody will know you are talking about familiar things. I've worked on this a long time off and on, and done the best I can with the terminological problems. I nevertheless still sometimes forget to make a necessary distinction or I use a term in a sense that can be misconstrued. Just have to hope that over much repetition the basic idea will get across. I kind of think that was done with the cheetah, but never mind, that will take us too far off course and sure, the emphasis on a perfect specimen is a human concern. But when it was said that mutations always increase diversity as if that applied to domestic breeding as well, I had to answer that mutation would only interfere with the breeding objective -- and it doesn't, meaning it doesn't occur as you think it would. Even in the wild nature seems to do a pretty good job of maintaining its well delineated "species" without much interference from constantly occurring mutations.And I feel I need to say for the sake of terminological clarification that although I use the term "selection" a lot I usually use it in a much broader sense than "Natural Selection" and this is no doubt one of those places where the terminology can get confusing. By selection I mean ANY way a smaller gene pool is "selected" from a larger, or "isolated" and especially "reproductively isolated." Natural Selection is one of the ways that happens as some alleles are preferred to others and come to dominate the phenotype while the nonadaptive ones are reduced or even eliminated from the gene pool. But even in random "selection" of a smaller gene pool from a larger, as by migration and geogrphical isolation, the exact same processes occur: you get some alleles making up a new phenotype while others are left behind in the old population. In this case the "selection" is random but it works just the same way. Any "failure to remove new variations" is talking about failure to remove PHENOTYPES, but this is not GENETIC diversity you are talking about. This is the same mistake RAZD made and it is an easy one to make and I try to be alert to catch it when it happens. You are apparently talking about an increase in PHENOTYPES or VARIETIES, but my point is that when that occurs the alleles that don't support that particular phenotype are reduced or eliminated from the gene pool and that's a reduction in GENETIC diversity. This is ALWAYS the case. You ALWAYS get genetic reduction when you get new phenotypes.Again the "selection" I am talking about isn't natural selection, isn't necessarily focused on any particular variation but can be quite random and yet produce a new phenotype from a new isolated gene pool -- while reducing the genetic diversity of the gene pool. I've got plenty of those but they all amount to the same thing functionally: a new gene pool from an old with reduced numbers of individuals, reproductive isolation, perhaps other kind of "selection" as well including Natural Selection, but the reduction in numbers plus the reproductive isolation is quite sufficent for the purpose -- the purpose being the establishment of a new population with a new phenotype, which requires the reduction of GENETIC diversity within that population's gene pool.In answering your post my main objective is to try to clarify terminology, which you recognize is a problem. I hope I've been somewhat clearer here.Edited by Faith, : No reason given.

I sincerely doubt it. All it takes for a new phenotype to develop and come to characterize a new species is the isolation of a portion of a population so that it inbreeds among its own members apart from the original or parent population until its own set of alleles are thoroughly mixed in its own gene pool. That would take some number of generations, perhaps a few hundred years if we're talking about a population of cattle that reproduce every year, that started with say 100 individuals, but not more than that. If the new gene pool contains much fewer individuals it will take much less time. As long as reproductive isolation is maintained a new "species" ought to be fairly rapidly formed in any case. Not of wild species but perhaps of domestic species. Cattle breeds for instance. I think some have taken only a hundred or so years to develop.And if the same conditions are met in the wild, which they could be, since all it takes is the isolation of a small portion from the principla herd for enough time to mix its gene pool through all its members. the Wildebeest, or Gnu, describes two separate "species" -- the black and the blue, and it dates their divergence to a million years ago, which I find rather laughable knowing that breeds take a lot less time to develop. Because all that is needed is enough generations to work all the offspring of all the original individuals through the new gene pool. No, it isn't and this is another factor in this discussion that will have to get considered in some thoroughness eventually. Certainly you can have whole populations of creatures that are all phenotypically similar and the underlying genetic diversity can be anything from high to low in such populations. There will always be new traits, new variations showing up in the population but they don't really affect the overall character of the population unless they get isolated in small numbers and form a new population.When I'm talking about the reduction of genetic diversity I'm talking about the situation where "evolution" is actively occurring, where a reduced number is reproductively isolated and inbreeds for some number of generations to produce its own characteristics as a population. The actual genetic diversity may remain quite high in a given new population depending on how many members are involved and how high the original diversity was. It's only when the diversity is already quite low that you begin to get anything that could be described as genetically "impoverished" -- the point is that it will always be genetically reduced with respect to the original population. It could still remain quite high. But the process of developing a new phenotype WILL reduce it, whether it maintains a pretty high diversity or not.When you get out to "speciation" or the actual loss of ability to interbreed with former populations THEN you can talk genetic impoverishment and that IS the natural ultimate ending point of these processes if they continue that far.NEVERTHELESS even such genetically impoverished poulations may maintain a surprising amount of vitality such as the elphant seals thyat increased to great numbers after nearly being completely killed off, and even the cheetah, which does surprisingly well considering its genetic limitations.(Here I will insert the remark from my Creationist perspective that if death had never entered the Creation, which occurred at the Fall, then all lines of natural variation or breeding could safely proceed to the genetic condition of the cheetah and the elephant seal without endangering them. The original Creation I believe was meant to produce myriads upon myriads of beautiful variations on animals and plants. It still manages to do just that though only to a tiny degree of its original potential because now death endangers those that are genetically depleted.)Must end this post here. Perhaps will pick up the rest later.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

I've been waiting for someone who actually knows how this stuff works to drop by, but as they haven't yet, I'll stick my oar in.I can't see any reason why this should be true at all. A new feature - such as a small or larger beaked finch could be an addition to the genotype, a deletion, a duplication or simply a change.Not only that, a change without speciation would increase the genotype at the species level and a change at the species level, by definition, increases the genetic variation of the genus. (Now two species instead of one.)You seem to be falling into the 'if I evolved from monkeks, why do monkeys still exist' trap. In the finches example, where once we had single type of finch, we now have many - a large increase in both phenotype and genotype diversity.

The alleles that bring about the different beak, if isolated and selected to characterize a new subpopulation ...
-- or if you think some other genetic condition than alleles for the trait are responsible, then put it this way: the genetic condition that gbrings about the different beak, if isolated and selected so that it proliferates and comes to characterize a new subpopulation ...
will of necessity DISPLACE all the other genetic conditions for other kinds of beaks. Those conditions will be left behind in the previous population or die out or one way or the other reduced or eliminated. THIS IS WHAT I MEAN BY REDUCED GENETIC DIVERSITY.You do not get new features characterizing a whole population or "species" or "subspecies" without eliminating all the competitors. If this beak is to be established as a trait of its own species all the others have to get lost from the gene pool. That's genetic reduction.Where a feature is clearly determined by a particular allele or set of alleles it's probably clearer but I think the same principle applies. It actually wouldn't. Not sure why you think it would. It comes about merely by the mixing of existing alleles, nothing new is added. If it's brought about by a mutation, if that's what you are thinking of, that's still just an allele that has been changed by the mutation, nothing has been added, there is no increase in the genotype just a variation on that particular gene, which is the same thing a pre-existing allele is too. And the mutation still has to be selected for it to become a trait in a new "species" or population and that means the elimination of all the competitors which is the reduction in genetic diversity I'm talking about. Well, no, it doesn't increase the GENETIC variation, it only increases the SPECIES or PHENOTYPIC variation. Oh nonsense. Read through this thread to find out what I think. The problem is that it isn't easy to think this through and keep all the levels in their proper place. It wasn't easy for me when I first started thinking through all this either, so i expect others not to have an easy time with it.But do at least make an effort rather than assuming the usual. Edited by Faith, : No reason given.

Sorry Faith, you're wrong - but it'll take someone with a proper genetics education to explain it to you.

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I sincerely doubt it. All it takes for a new phenotype to develop and come to characterize a new species is the isolation of a portion of a population so that it inbreeds among its own members apart from the original or parent population until its own set of alleles are thoroughly mixed in its own gene pool. That would take some number of generations, perhaps a few hundred years if we're talking about a population of cattle that reproduce every year, that started with say 100 individuals, but not more than that. If the new gene pool contains much fewer individuals it will take much less time. As long as reproductive isolation is maintained a new "species" ought to be fairly rapidly formed in any case.

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But we're NOT talking about just the formation of a species. To become successful that small population must expand outwards, and that's a prime time for expanding genetic diversity.You see, the important issue is the strength of selection. When a species is under pressure every little advantage counts That's when you'd get reduction in genetic diversity. When the species is expanding, fitness is "easy" and even small disadvantages can spread. Even when the population is stable neutral mutations can and will spread through drift, and some may become beneficial or provide the basis for future beneficial mutations.

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Not of wild species but perhaps of domestic species. Cattle breeds for instance. I think some have taken only a hundred or so years to develop.

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I don't think you'd have any records for any domestic breed that would let you single out the number of mutations that have occurred.

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And if the same conditions are met in the wild, which they could be, since all it takes is the isolation of a small portion from the principla herd for enough time to mix its gene pool through all its members.

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Given the aggressive level of selection and forced inbreeding I don't think that such conditions will often be encountered in the wild - and if they do I doubt that they would often be survivable. And let us note that breeds are not species. Obviously there's something more to speciation than what the breeders have done.

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the Wildebeest, or Gnu, describes two separate "species" -- the black and the blue, and it dates their divergence to a million years ago, which I find rather laughable knowing that breeds take a lot less time to develop. Because all that is needed is enough generations to work all the offspring of all the original individuals through the new gene pool.

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Firstly the time it takes for the split to happen doesn't dictate how long ago it happened. Even if it took only a year to occur it could still have happened a million years ago.Also they aren't breeds (the blue wildebeeste has five subspecies)

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No, it isn't and this is another factor in this discussion that will have to get considered in some thoroughness eventually. Certainly you can have whole populations of creatures that are all phenotypically similar and the underlying genetic diversity can be anything from high to low in such populations. There will always be new traits, new variations showing up in the population but they don't really affect the overall character of the population unless they get isolated in small numbers and form a new population.

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OK. So we're going to need actual measures of genetic diversity.

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When I'm talking about the reduction of genetic diversity I'm talking about the situation where "evolution" is actively occurring, where a reduced number is reproductively isolated and inbreeds for some number of generations to produce its own characteristics as a population. The actual genetic diversity may remain quite high in a given new population depending on how many members are involved and how high the original diversity was. It's only when the diversity is already quite low that you begin to get anything that could be described as genetically "impoverished" -- the point is that it will always be genetically reduced with respect to the original population. It could still remain quite high. But the process of developing a new phenotype WILL reduce it, whether it maintains a pretty high diversity or not.

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Yes, a small group split off a successful species will almost certainly have lower genetic diversity. But that's really not the whole of the story because the process needs the variation to recover, and it does.

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When you get out to "speciation" or the actual loss of ability to interbreed with former populations THEN you can talk genetic impoverishment and that IS the natural ultimate ending point of these processes if they continue that far.

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Which leads to the question of why isn't it normal for species to be as genetically impoverished as breeds ? If forming a new species involves reducing genetic diversity below that of a breed, shouldn't species all have really low genetic diversity ?

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NEVERTHELESS even such genetically impoverished poulations may maintain a surprising amount of vitality such as the elphant seals thyat increased to great numbers after nearly being completely killed off, and even the cheetah, which does surprisingly well considering its genetic limitations.

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And let us remember that these are bottleneck situations and - certainly at the level of DNA - the cheetah is recovering diversity.Edited by PaulK, : No reason given.

I suggest that in the finch chart I posted, the 14 species that developed from the common ancestor species collectively have far more genetic diversity than the common ancestor. That's why there are 14 species!Now take that chart and extrapolate back a few hundred million years. From a common ancestor you have all the chordates that we know, both fossil and living--I haven't looked it up, but there are probably hundreds of thousands of species.I see no way you can claim that there is no increase in genetic diversity in that situation without ignoring massive amounts of real world evidence.(And don't try to cram all of that into 6,500 years. That battle was lost years ago.)

I don't see how you can type stuff like that quoted above and not see the inherent problems.Yes it is true that selection removes individuals who vary from the favored species. But that does not mean that evolution removes diversity overall. For example if a mutation is created that adds diversity, even if the original species goes extinct, the new species is exactly as diverse as the original species. So the net diversity before and after the mutation and selection is exactly the same.Secondly, the assumption here is that if selection causes the original species to die off, that must inevitably remove some trait from existence. There are a number of things wrong with that assumption.First, the parent, grandparents, and cousins of the original species might well still exist, and those species contain almost all of the diversity of the species from which the new species comes. Couple that with the fact that the new variant may differ from the originating species in ways that are different from the way that the originating species differs from its parents, grandparents and cousins.Th net result is that even if this originating species gets outcompeted and dies out in favor of the mutants, there is no overall loss of diversity. All of the original traits still exist in either the new variant or the cousins and parents of the species in question.Finally speciation need not result in the loss of any species at all.Now the situations I outline above do not happen every time, and of course some ancestor and cousin species might be evolutionary dead ends. But the discussion above is sufficient to show that evolution does not inevitably result in a decrease in overall diversity.The jeer button is the button on the left bearing the minus sign.Finally, what's the difference between this thread and the 670+ message thread from three years ago.

As walkists admit (such as the notoriously pro-walkist Wikipedia): "In humans and other bipeds, walking is generally distinguished from running in that only one foot at a time leaves contact with the ground and there is a period of double-support."This means that walking requires leaving the right foot fixed in one place. Because I am not very bright, I shall now insist that this means that walking requires the right foot must be fixed in one place all the time. This means that someone walking cannot move from the spot, but can only turn around in circles.On this principle, I shall assert that micro-walking (for example to the shops and back) is perfectly possible, even though this flatly contradicts what I've just said. I'm not big on logical consistency. However, macro-walking, for example hiking the Appalachian trail, is clearly impossible, because you could not do that by merely revolving on the spot, which as I've explained is all a person can ever do when walking.Now, I know that some of you will point out that walking also involves moving the right foot, and that micro-walking, the existence of which I admit, definitely involves moving the right foot and indeed allows one to travel from place to place. How do I know that you will say that? Because it's what you said last time I raised this damnfool argument, and the time before that.However, I'm sure I can ignore these obvious facts for the rest of this thread, and also for the duration of the other thread I'll start in another couple of months to say exactly the same thing. Instead I shall repeatedly assert that the process of walking requires the right foot to remain stationary, focusing obsessively on this one aspect of the process of walking and ignoring everything else about it, as though this somehow proved my point.What I lack in intelligence, I make up for in the tenacity with which I can maintain an argument the deep unfathomable stupidity of which is completely obvious to every single person I try it out on.Edited by Dr Adequate, : No reason given.

Mutation doesn't stop after a selection event. It is going non-stop in every single generation. Each time a new individual is born in the population you get an increase in the genetic diversity of the population because that individual will be born with a genome sequence that has never existed before in the entire history of that lineage.You might as well be arguing that rivers should run dry in a year's time because rivers only flow downhill, they can't flow uphill to replenish the water flowing downhill. Just as rain replenishes the water needed to flow downhill. so too does mutation produce the new genetic diversity that flows through selection.

Prior to that point, you had an increase in the genetic and phenotypic variation within the species. So at one time you had the A allele. A mutation produces the B allele. The B allele becomes more common to the point that 50% of the population has allele A and 50% has allele B. So you started with just allelel A, and then you had A and B. That is an increase in genetic diversity.

New mutations occur in reproductively isolated and inbreeding populations as well. New mutations will occur in each of these new species which will increase the total genetic diversity of the clade given that these mutations will not be lineage specific due to different selective pressures.

I'm answer this post out of all the others attacking my argument because it's the most absurdly far from understanding anything I've said on this thread. All of them look like straw man arguments but this one looks like the strawiest of them all. Well you are certainly off to a bad start here. In most of the scenarios I mention I'm not even talking about selection in the sense of Natural Selection but I gather you didn't bother to read enough to find that out. And in most of the scenarios it's quite a benign situation of alleles / individuals being left behind in the original population as the new population randomly forms, in which new phenotypes emerge from the new gene frequencies. "Removes diversity overall?" Where are you getting that? I'm talking about how diversity is REDUCED (sometimes eliminated but ALWAYS reduced) by the fact that alleles that don't contribute to the new phenotype simply are not present in that gene pool or the phenotype would not develop. Usually there's nothing active about their removal, they are just left behind in the original population as the new one forms. I consider Natural Selection to be a rare occurrence, and that new varieties form normally from accidental factors, such as migration away from the main population. Not genetically it isn't. Whether the original population goes extinct or not is utterly beside the point but just for the record nowhere in my discussion has any population gone extinct. The phenotypes of the new "species" can only form because the alleles for old phenotypes are not present to interfere, and it doesn't matter if the new phenotype includes the mutation or excludes it, the overall effect of its formation requires that competing alleles be removed from the gene pool, and again, that's reduced genetic diversity. And here I'm trying to hard to keep my terminology simply and uniform and you still can't get it. Well, I knew it wouldn't be easy but I did think people here were better readers than you turn out to be. "Diversity" isn't what I'm talking about, I'm talking about GENETIC diversity. I suspect that as with at least three others here you are confusing the diversity of phenotypes with GENETIC diversity. If you are talking about INDIVIDUALS that is certainly what you have in mind. GENETIC diversity is NOT the same as phenotypic diversity and I've been very very careful with my terminology on this point. Since you aren't talking about any assumption of MINE the number of things wrong with it are wrong in YOUR thinking.I don't think you have a clue how I've been using the term "selection" either, not having bothered to read the thread where I've been at pains to discuss its use many times.I've said nothing about "causing the original species to die off." Where on earth are you getting this stuff? Traits are removed FROM A POPULATION by simply being LEFT BEHIND in the parent population. Uh could be. The genetic diversity of the original population which could include all those relatives is not at all affected by the situation in the new population where the genetic diversity is being reduced by the formation of NEW phenotypes. All the original genetic diversity could even be contained in a full collection of all the daughter populations put together as I suggested concerning the finch varieties on Coyote's chart. Even all the ring species separate populations put together. IT's possible for that to be the case while each individual "species" or population has reduced genetic diversity WITH RESPECT to the other populations that preceded it. "COUPLE THAT WITH?" NN, you do not have Clue ONE about what I'm talking about here. All the populations should vary from one another in their own unique ways. What ARE you thinking? How much of this thread did you read? Did you stop and think AT ALL? I know this isn't an easy argument to follow, it takes a little work, but I did myself do a lot of the work of keeping the terminology as accessible as possible. Sheesh. Again you are hallucinating something about species "dying out" that has absollutely nothing to do with anything I've said. Again I think your problem is at least partly confusing the phenotype with the genotype. I The loss of GENETIC diversity, get that, [size=5]GENETIC All of the original traits still exist in either the new variant or the cousins and parents of the species in question. [/qs]If the divergence isn't drastic the same alleles and their traits may all be present in the new population but in new frequencies, but if the divergence is greater then some alleles will most likely not be present at all. But the point I'm making is that this is a TREND, and that over many population splits the trend to reduced genetic diversity will show up most dramatically though in the first population splits it won't be as dramatic. But in order to get this argument you have to get at least a minimum of what I'm saying and you've missed the whole ballpark. I never said it did. But the speciated species itself will certainly have lost a ton of alleles for characteristics it does not possess while it retains only those alleles that support its own traits. Most of those alleles will still exist in the previous populations, they are only LOST to the speciated species. Hardly. If I could banish everybody from this thread who doesn't even get the first thing about what I'm arguing I would do it in a flash, and you'd be the first to go. Yes, I've noticed it. A very handy little item. Oh I've improved my argument since then, and extended it into new areas, not that you'd have any way of judging.Also my own contribution to that thread stopped far far short of that 670, after which the thread devolved into pure destructive idiocy.