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Author | Topic: "Microevolution" vs. "macroevolution." | |||||||||||||||||||||||||||||||||||||||
EZscience Member (Idle past 5182 days) Posts: 961 From: A wheatfield in Kansas Joined: |
ptman writes: I would contrast this to what I think is generally called "emergent properties" where differences of scale result in observations of small scale that do not explain observations on the larger scale. You have a valid parallel here.Ernst Mayr did a good job of discussing the emergent properties of biological systems in his book Toward a New Philosophy of Biology. Thus complete knowledge of cellular functions would really tell us nothing about what to expect from organismal behavior, and complete knowledge of organismal behaviors would tell us nothing about population behavior, etc. etc. The parallel is that observations of microevolutionary change, and even complete understanding of the forces and processes at work, were it possible, would really tell us nothing about patterns of macroevolutionary change and the forces and processes that guide the divergence of taxa at species level and higher. (Thus I would take issue with Jar's idea expressed below that we might find macro to be just the accumulation of a lot of micro if we had all the intermediates). Granted, similar forces such as natural selection will likely prove to be important in both cases, but they will act differently on separate gene pools than they do on connected gene pools. I see this as further functional justification for the biological species concept, simply because macroevolutionary changes cannot begin to accrue until speciation and blockage of gene flow between populations. Macroevolution requires separate gene pools as a starting point, and yet the most initial stage of macroevolution (a speciation event) is probably the only 'macro' process we are ever likely to be able to observe directly.
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
Faith writes: {ABE: OK, I went back to the original statement and here's what I said:
Nobody ever thought there could be variation beyond whatever a kind is until Darwin, and all Darwin did was suggest how it might be possible, which was nothing more than observing that the principles of domestic breeding occur haphazardly in nature. Yes, I quoted this when I replied in Message 15. I understand now from your clarification that you intended to say only that Darwin's proposal of natural selection was just casting onto nature what domestic breeders were already doing. And you are correct. There's actually a deeper picture here that is hinted at when you say that domestic breeding argues against cross-kind change, but this isn't the thread for that discussion. In the interest of accuracy, the first part of your passage about nobody considering the possibility of change across kinds before Darwin is incorrect. That idea wasn't actually original with Darwin. The idea, though not the word, for evolution was already in the air, and Darwin's grandfather, Erasmus, had dabbled with the idea decades earlier, and it was still an idea in the naturalists' collective repertoir when Darwin came on the scene. But the idea garnered little serious consideration because there was no known mechanism for this type of change. It was Darwin's contribution to provide the mechanism, not the idea, of evolution. --Percy
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Chiroptera Inactive Member |
quote: I'm going to second PaulK's answer. Macroevolution is evolution that creationists will not accept. "Religion is the best business to be in. It's the only one where the customers blame themselves for product failure." -- Ellis Weiner (quoted on the NAiG message board)
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Faith  Suspended Member (Idle past 1472 days) Posts: 35298 From: Nevada, USA Joined: |
Yes, I quoted this when I replied in Message 15. I understand now from your clarification that you intended to say only that Darwin's proposal of natural selection was just casting onto nature what domestic breeders were already doing. And you are correct. I'm glad you now understand what I meant to say.
There's actually a deeper picture here that is hinted at when you say that domestic breeding argues against cross-kind change, but this isn't the thread for that discussion. Just to clarify again, it wasn't so much that it "argues against" cross-kind change (unless that is perhaps implied) as that since it can be strictly controlled to produce variations faster than most natural processes do, it ought to be the standard, and if macroevolution cannot be proved by domestic selection then it can't be proved by natural selection either.
The idea, though not the word, for evolution was already in the air, and Darwin's grandfather, Erasmus, had dabbled with the idea decades earlier, and it was still an idea in the naturalists' collective repertoir when Darwin came on the scene. But the idea garnered little serious consideration because there was no known mechanism for this type of change. It was Darwin's contribution to provide the mechanism, not the idea, of evolution. Yes, again I misspoke. I knew that but I had in mind the general public or the Zeitgeist, not the few thinkers who had that idea. Now everybody thinks it. Darwin changed the world by coming up with the mechanism that could possibly make macroevolution happen (even if as I said it is really no better as a mechanism for that purpose than domestic selection already was). This message has been edited by Faith, 04-03-2006 04:42 PM
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ptman Inactive Member |
Thus complete knowledge of cellular functions would really tell us nothing about what to expect from organismal behavior, and complete knowledge of organismal behaviors would tell us nothing about population behavior, etc. etc. I agree that behavior is an emergent property of cellular function, at least in general, but I don't think that clarifies Micro/Macro. I'm more with Jar in this sense, If you did have a complete set of intermediates, you would only be able to define arbitrary breakpoints between them and the sum would be Macro but the individual changes would be Micro. As with species, I think the distinction is only really there in terms of convenience of categorization.
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Brad McFall Member (Idle past 5061 days) Posts: 3428 From: Ithaca,NY, USA Joined: |
I doubt "emergence" is existant. It is an emergency default for those anti-apriorists who think that it was always too late for the NYTIMES to capitlaize the "N"word. While it might be biologically argued that race growth is a social fiction, I tend to reason to biogeography rather than new levels of organization ornamentally because of a lost discussion of the body. Feelings of surpassing Lysenkoism/Larmakianism does not keep hierarchy out of biology necessarily. Emergence simply and easily (too easily I feel) justifies the rear offensive guard of an otherwise WEB DuBois dubius ontology. Sure, there is no purpose to natural selection but as Faith said...
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EZscience Member (Idle past 5182 days) Posts: 961 From: A wheatfield in Kansas Joined: |
ptman writes: If you did have a complete set of intermediates, you would only be able to define arbitrary breakpoints between them and the sum would be Macro but the individual changes would be Micro. Your thinking is rather linear and evolution is not.Think in terms of a heavily pruned tree with only a few branches extending to give rise to others. The branch points are speciation events. Looking at terminal branches on different sides of the tree (extant species in disparate orders, for example) they can all be traced back to a common branch deep in the tree, a branch that now represents the divervence of some higher order taxon, even though it was originally only a speciation event. The tree represents macroevolutionary structure, or phylogeny. This is the only useful application of the concept. The tree structure doesn't really hinge in any way on the presence or absence of 'intermediates' - remember these are only defined a posteriori as forms that apparently fit well between an earlier form and a later form. They are not in any way essential to make sense of higher evolutionary processes. We now have far more powerful molecular tools to infer the structure of the tree than simply searching for fossil intermediates. And the branch points, or 'breakpoints' as you call them, are not in any way arbitrary. That is incorrect. They are inferred speciation events that *had* to occur at certain points in order for taxa to diverge, unless you reject outright the idea of commonality of descent. Just because we may not know the exact details about how and when particular speciation events occurred in phylogenetic history, this does not make inferences of their occurrence in any way arbitary.
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Omnivorous Member Posts: 3991 From: Adirondackia Joined: Member Rating: 6.9 |
Faith writes: Darwin changed the world by coming up with the mechanism that could possibly make macroevolution happen (even if as I said it is really no better as a mechanism for that purpose than domestic selection already was). Natural selection was (and is) vastly superior to domestic breeding as a mechanism for "macroevolution" because of the roughly contemporaneous realization of the earth's great age and natural selection's lack of any need for purposeful direction: the time scale of domestic breeding is a blink of the eye compared to that of natural selection, and domestic breeders seek particular traits, not survivability in a changing environment, or new species. Domestic breeding was (and remains) a useful illustration of how any selective force, whether natural and contingent or human-directed, can create genetic change, but the analogy ultimately fails at the boundaries of time and intentionality: time as described above, and intentionality because natural selection "seeks" nothing and domestic breeders do not seek to create new species but rather to modify traits within species. The question of domestic breeding is more illuminating in the context of cultural evolution: the peoples of Eurasia found themselves surrounded by a bounty of readily domensticated animals and plants, in contrast to Africa and the Americas, and the Eurasian advantage encouraged the rise of larger populations, greater social complexity, formal agriculture, and related techologies. Darwin's contribution, his great synthesis, was not only the idea of natural selection but the meticulous observations (the Galapagos finches which speciated rapidly as they inhabited the islands being among the most well known) which illustrated its effects and supported his theories. This message has been edited by Omnivorous, 04-05-2006 02:43 PM
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Faith  Suspended Member (Idle past 1472 days) Posts: 35298 From: Nevada, USA Joined: |
Natural selection was (and is) vastly superior to domestic breeding as a mechanism for "macroevolution" because of the roughly contemporaneous realization of the earth's great age and natural selection's lack of any need for purposeful direction: the time scale of domestic breeding is a blink of the eye compared to that of natural selection, and domestic breeders seek particular traits, not survivability in a changing environment, or new species. Yes, of course. That is the theory. But my argument is about what it would take to PROVE it, and since we are at a disadvantage in that we cannot witness the supposed changes over those aeons of time, my point was that even with this possible mechanism for it that Darwin supplied, it brought him no closer to an actual proof that (macro)evolution had occurred than we'd been without it.
Domestic breeding was (and remains) a useful illustration of how any selective force, whether natural and contingent or human-directed, can create genetic change, but the analogy ultimately fails at the boundaries of time and intentionality: time as described above, and intentionality because natural selection "seeks" nothing and domestic breeders do not seek to create new species but rather to modify traits within species. I don't think time can affect the principle involved. Microevolutionary variations don't automatically become macroevolutionary ones simply with the introduction of lots of time. This is an assumption of the ToE but there is no proof for it. We've always known about the micro level variations. As for intentionality I don't think that affects my point. I'm only talking about the processes of change, and any change that survives and reproduces, whatever particular mechanisms brought it about (natural selection is hardly the only one -- all the population splitting events do the same), serves the point.
Darwin's contribution, his great synthesis, was not only the idea of natural selection but the meticulous observations (the Galapagos finches which speciated rapidly as they inhabited the islands being among the most well known) which illustrated its effects and supported his theories. Yes, and I thoroughly enjoyed Darwin's reasoning when I first read the book, and that part of his work is valid. However, all he observed was the already familiar processes of what is now called "microevolution" via natural selection. He did not prove macroevolution, he simply had the intuition that natural selection would be the mechanism that would allow it, if it occurs. But there is no reason yet to think it occurs. To summarize: Time cannot possibly guarantee the kind of changes postulated, and intention is just one more way change is established, and as long as the change survives and reproduces it's all the same thing for the purpose of my argument. -------------------------By the way, Omni, I still plan to send you some CDs from the theology class. Sorry it's taking so long. It may be three, it may be five. PS: Sorry to hear about your harrowing brush with death and glad you came through it. This message has been edited by Faith, 04-05-2006 06:51 PM
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Omnivorous Member Posts: 3991 From: Adirondackia Joined: Member Rating: 6.9 |
Of course, I continue to believe that deep time makes all the difference: only vast amounts of time turn the winds that blow across the earth into a force that can level mountains; only a great deal of time will turn my pitiful 401K contributions into an above-poverty-level retirement fund; only millions of years could permit the lion, the tiger, the leopard, the lynx, the bobcat and my three dear kitties to evolve from the ur-cat: once the former did not exist, but now they do; once the saber-toothed tiger existed, and now it does not. Deep time has turned seas into prairies and mountaintops, and savanna and jungle into oceans and artic ice. Given enough time, the work of giants can be done by the smallest hands.
When Darwin developed his theory of natural selection, he did not just hand us an untestable abstraction. Rather, he outlined a mechanism that could be tested by observations in nature via changing populations and extinctions, by observations of the fossil record which showed species that no longer exist and the lack of species that now do exist, and by the development of such powerful technologies as molecular genetics. Through these technologies we know that genetic novelty emerges in populations, and by observation we know that these novelties succeed or fail to varying degrees depending on the environment in which they are expressed. Certainly, if we can manage to maintain a history-recording civilization long enough, we will have proof one way or another as to the reality of "macroevolution." I mean no disrespect when I say that the evidence is already overwhelming to anyone who has not rejected it out of hand for philosophical or theological reasons.
By the way, Omni, I still plan to send you some CDs from the theology class. Sorry it's taking so long. It may be three, it may be five. No problem, Faith: I never doubted you would.
PS: Sorry to hear about your harrowing brush with death and glad you came through it. Thanks--me too! Life seems even sweeter now. Maybe my guardian angel will protect me until I listen to your CDs... I've been at that particular threshold more often than I care to remember: being a glass-half-full person, I consider myself extraordinarily fortunate to have survived so many times; though I sometimes am told, "You've had so much misfortune!", it has never seemed that way to me. The experience of my mother's presence by my hospital bedside has been followed by a sense of peace about her death several years back that had eluded me--curiously enough, she died from the same problem I was experiencing. But she was nearly 80 and had already survived more than most. This message has been edited by Omnivorous, 04-05-2006 07:49 PM
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
Faith writes: That is the theory. But my argument is about what it would take to PROVE it... In a scientific context the question becomes, "What is the evidence supporting this theory?" At any point during the presentation of evidence you can say, "But you still haven't *proven* the theory," and of course in a technical sense you would be correct because in science theories are never proven, only supported by evidence. So in a scientific context you would have to instead say, "I don't find that evidence convincing," and would hopefully go on to explain why.
...and since we are at a disadvantage in that we cannot witness the supposed changes over those aeons of time,... Yes, we are at a disadvantage, analogous to the police detective trying to solve a crime that has no witnesses but which does have evidence.
I don't think time can affect the principle involved. Microevolutionary variations don't automatically become macroevolutionary ones simply with the introduction of lots of time. The key problem for you is the absence of anything preventing the accumulation of microevolutionary changes. Almost every reproductive act creates errors, and in sexual reproduction there's the mixing of alleles. You can take the chimpanzee genome and come up with a sequence of microevolutionary changes that eventually arrives at the human genome. If I were to present you that hypothetical sequence, how would you go about identifying the microevolutionary change that would somehow be prevented from happening and keep the chimp forever a chimp?
However, all he observed was the already familiar processes of what is now called "microevolution" via natural selection. That might be all he observed of "evolution in action", but it is only a tiny part of his evidence.
He did not prove macroevolution... Yes, that's true, of course he didn't prove macroevolution. And Newton didn't prove gravity and Einstein didn't prove relativity. But just as Newton and Einstein supported their theories with evidence, Darwin supported his theory of evolution with evidence drawn from artificial and natural selection, hybridism, geological distributions, the fossil record, instinct, morphology, embryology and vestigial organs. Since Darwin's time the evidence has only grown, and in the 1920's the work of population geneticists enabled Darwin's theory to be combined with the science of genetics to form the modern synthesis, otherwise known as the synthetic theory of evolution, which is what most evolutionists actually have in mind when talking about evolution.
To summarize: Time cannot possibly guarantee the kind of changes postulated... Yes, you are right, time cannot guarantee. But that's because nothing is guaranteed in science. The process requires supplying evidence, not guarantees, and in the case of evolution there is much available evidence. Just as there is nothing to prevent seconds from accumulating into millennia, which no one person can observe, there is nothing to prevent microevolution from accumulating into macroevolution, and this theoretical framework is consistent with the evidence. --Percy
Fix typo. --Percy This message has been edited by Percy, 04-06-2006 09:12 AM
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Faith  Suspended Member (Idle past 1472 days) Posts: 35298 From: Nevada, USA Joined: |
Of course, I continue to believe that deep time makes all the difference: only vast amounts of time turn the winds that blow across the earth into a force that can level mountains; only a great deal of time will turn my pitiful 401K contributions into an above-poverty-level retirement fund; only millions of years could permit the lion, the tiger, the leopard, the lynx, the bobcat and my three dear kitties to evolve from the ur-cat: once the former did not exist, but now they do; once the saber-toothed tiger existed, and now it does not. Thousands of years do it for me. And yes, it would take astronomical amounts of time if we explain it all as evolution does, but that doesn't PROVE it happened that way. Actually NO amount of time would suffice. That's the real objection to the time scenario.
Deep time has turned seas into prairies and mountaintops, and savanna and jungle into oceans and artic ice. Given enough time, the work of giants can be done by the smallest hands. CAN, but excuse me if I have to say that I find the Flood sufficient explanation for the landscape changes you mention.
When Darwin developed his theory of natural selection, he did not just hand us an untestable. Rather, he outlined a mechanism that could be tested by observations in nature via changing populations and extinctions, by observations of the fossil record which showed species that no longer exist and the lack of species that now do exist, ... Yes, and given the science of his day that was all a great contribution. And I can see why it dazzled everybody. But in the end there is nothing in all his work that proves that evolution actually happened. He proved that selective processes work in nature and account for the great variety we observe, and genetics has shown the way it happens internally. But none of that proves macroevolution. All of that is quite consistent with microevolution, or the ordinary processes by which it has always been known that life forms are capable of change, but it doesn't get you one notch closer to macroevolution. And I have no problem at all explaining the fossils and the extinct species by the Flood, and the new "species" by microevolution.. ...and by the development of such powerful technologies as molecular genetics. Through these technologies we know that genetic novelty emerges in populations, and by observation we know that these novelties succeed or fail to varying degrees depending on the environment in which they are expressed. But all of that is quite consistent with microevolution, or the ordinary processes by which it has always been known that life forms are capable of change, but it doesn't get you one notch closer to macroevolution.
Certainly, if we can manage to maintain a history-recording civilization long enough, we will have proof one way or another as to the reality of "macroevolution." I mean no disrespect when I say that the evidence is already overwhelming to anyone who has not rejected it out of hand for philosophical or theological reasons. And I mean no disrespect when I say that the evidence that appears overwhelming to you has been seriously rejected by me and not out of hand. I was already frustrated long before I became a Christian with the answer "time, time and more time" I always got to my serious doubts about how evolution could possibly work. Because if it can't work it can't work, and aeons of time isn't going to make something work that just can't work. The main objection I always had was that evolution seems to imply a teleology. This is denied, but what the theory actually posits seems to imply it. How do you get anything at all that functions, let alone functions in the complex ways living things function, out of a process that randomly affects genetic material? My doubts tended to focus on the increments of development that would have to occur before you had a fully functioning organism or organ, the millions of years of stubby-to-middling antlers before the five-point stag could exist for instance (I spent hours thinking about the evolutionary requirements to arrive at the antlers mounted on the wall at a place I was visiting once when I was 20. I wasn't a Christian until I was 45). And since those degrees of antlerdom wouldn't be lethal, why aren't there a bazillion of similar kinds of increments of development across many different species found in the fossil record? Why does everything appear finished? The number of mistakes before you got a viable option would have to be beyond astronomical. It boggles the mind to think of blind evolution coming up with the most rudimentary organized creature. And all you guys can say back is, well, it doesn't boggle YOU, it just had to have happened. And the genetic system itself from which all this develops would have had to have been formed by the same means. That alone would have had to take a few bazillion years of trial and error. But I know this is a familiar objection, and basically is the same question as How much time would it take a million monkeys to type the works of Shakespeare? Answer: It can't happen. And that will just be dismissed as "the argument from incredulity" as if that means anything. I know you guys think the evidence is there. I don't, and I didn't before I had a reason to "{reject} it out of hand for philosophical or theological reasons." Long answer but the point is no, I'm not dismissing it out of hand. On another note, wondering if the experience of your mother's presence did anything to influence your ideas concerning the supernatural?
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Alasdair Member (Idle past 5778 days) Posts: 143 Joined: |
When you pass the random chance of mutation through the non random filter of natural selection, you can easily get order. Go and grab yourself a bucket of 100 pennies. Pour them out on the table. Take all the pennies that land "tails" up and pour them again. Within 10 pourings you'll have 100 pennies all heads up. By random chance alone, that has a chance of .5^100 or .000 000 000 000 000 000 000 000 000 000 789 of happening - not going to happen in other words. Hope this clears things up.
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Wepwawet Member (Idle past 6137 days) Posts: 85 From: Texas Joined: |
quote:Faith: Science does not prove anything. You've been told this time and again, yet you always come back to saying that this or that has not been proven. Science never has and never will prove anything because our knowledge can never be absolute. Science can only provide explanations that fit our current understanding, as that understanding grows science follows suit. Please drop the whole idea that science must provide proof. Could you perhaps explain your assertion that no amount of time will suffice for evolution? You seem to acknowledge micro-evolution, so I'm rather curious why you can't simply see that process continue given adequate time.
quote:(setting aside the proof/prove issue) Here you admit that genetic change occurs and that these are filtered by selective processes to produce organisms better suited to their environment. Basically you are acknowledging The Theory of Evolution. All the pieces are in place for macro-evolution if we add time for the changes to accumulate. No, this doesn't prove macro-evolution, but the available evidence makes macro-evolution and common descent a more reasonable inference than believing that there is some undiscovered mechanism in place which prevents it. quote:In a scientific context, evidence consists of observations and measurements of real (natural) things. Evidence that is reliable (meaning it may be gathered openly and freely) may not be dismissed at all. A theory must account for all the evidence, or at least enough of the evidence as to provide a practical foundation for experimental prediction. An example might be Newtonian physics which is known to be wrong in many respects, but practical for use at the level where observations can be easily made. The idea of geologic time can be difficult to grasp. At some point millions and billions just start to blur and...like the proverbial congressman said...pretty soon you're talking about real money. In this case pretty soon you're talking about real time. A prokaryote may reproduce every twelve and a half minutes. The earlies fossils show that life existed on Earth about 3.8 billion years ago at the latest(these fossils are from the Ishua group discovered in Greenland). That's a whole lot of time for the process which you've acknowledged to work...how do you figure it isn't enough?
quote:Here you're making a crucial mistake. Evolution as posited by the ToE is not a random process. Step through the process in your mind and hopefully you'll see that the moment you apply a selective filter (natural selection) the process begun by a random event (mutation) is no longer random. By the way, there's quite a bit of work that's been done on antler evolution. There's plenty more to be done, but simple observation of deer can tell you that antlers are not primarily deadly weapons and there's no reason to assume they were selected as such. quote:Argument from incredulity does indeed mean something. An argument from incredulity simply asserts that because I can't imagine that something is possible/true/real/whatever that it is not possible/true/real/whatever. Our beliefs are not necessarily in tune with reality. Your assertion "It can't happen" above is a statement of belief which, while it may or may not be true, can not be affirmed just because you believe it. quote:From a scientific standpoint you are dismissing the evidence out of hand. The evidence is there to be seen and you must account for it in order to participate in a scientific discussion. Philosophy and theology reasons are not sufficient if you wish to discuss science. The real world does not go away because we want it to...look at the evidence and account for it. When science and the Bible differ, science has obviously misinterpreted its data. - Henry Morris, Head of Institute for Creation Research
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DominionSeraph Member (Idle past 4782 days) Posts: 365 From: on High Joined: |
Faith writes: And yes, it would take astronomical amounts of time if we explain it all as evolution does, but that doesn't PROVE it happened that way Nothing would. Say I come upon you laying on the floor bleeding from a hole in your leg. There's a gun on the floor in the doorway, and I dig around in your leg and extract a bullet.Now, is it possible that you were shot? Let's test it. I take the gun and shoot you in your other leg. Result: Bloody hole with a bullet in your leg. So, we have the same outcome. Does that prove that your first wound was caused by you being shot? Nope. It could've been magically created by the Bloody Hole Fairy, with a follow-up call by the Bullet-in-Bloody-Hole Fairy. You being shot may be the most reasonable explanation, but it's not the only one that'll work.
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