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Author | Topic: When does microevolution turn into macroevolution? | |||||||||||||||||||||||||||
Taz Member (Idle past 3292 days) Posts: 5069 From: Zerus Joined: |
After having read through the responses already made, I think people ahve already covered what is necessary. I would like to give another analogy that might help you understand the difference between the two terms.
Just look at history. We generally divide human history up into large intervals like the stone age, the bronze age, the iron age, etc. There are individual moments in history when it is bleedingly obvious to us what era it belonged to. Alexander the Great was clearly in the late bronze age. The Crusades were clearly in the Iron Age. It's like looking at the color spectrum that jar presented. There are areas where it's bleedingly obvious if it's blue, red, or yellow. However, asking the question of when microevolution becomes macroevolution is like asking exactly when did the world turned from the Bronze Age to the Iron Age. Noone could answer that. Very tiny changes in the way tools and weapons were made and used eventually added up and gave rise to the Iron Age. But can anyone actually say the exact year, date, hour, or minute the world emerged into the Iron Age? In a way, microevolution is just referring to very tiny changes in the allele frequency of a species. Say that you start with generation 0. Generation 1 is still almost genetically identical to generation 0. Generation 2 is still almost genetically identical to generations 1 and 0. We jump to generation 300 where the allele frequency is now noticably different than generation 0 and 1, but they are still the same species. We jump to generation 3000 and the differences are a little more noticable if we compare to generation 0. But notice that generations 3000, 3001, and 2999 are almost genetically identical to one another. It's when you compare them to generation 0 or 1 that you notice a difference. But again, they are still the same species. Fast forward in time and now we are at generation 300,000 and we already have a new species because this generation is genetically different than generation 0 and that they can no longer interbreed. But hang on a second, when did this population make the "transition" that changed to a new species? Was it generation 102,845? Was it generation 142,893? Generations 100,000 and 100,200 are still almost genetically identical. But when you compare generation 100,000 to 0, there are very noticable differences. Compare generations 300,000 to 0 and they are obviously different species. Now, saying that we can't know what's what in the past is simply silly. We can look at archaeological evidence and determine about what age so-and-so city was burned to the ground. We can look at the tools, art, houses, etc. left behind by people long gone and determine how these people lived and died. In similar ways, we can look at the fossil record and determine things that were far far in the past.
Neutralmind writes:
From what I've seen from you in other threads and this particular sentence, I can tell that you still hold a grossly deformed idea of what evolution is all about. "Macro"evolution doesn't mean a fish one day decides to grow 4 legs and become a lizard or a cow one day decides to grow a pair of wings and become a bird. Despite the fact that we've been trying to explain the very slow and tiny progression of changes that over millions of years would add up to very large changes, people like you and Ann Coulter continue to make arguments like how come we don't find a fossil of an animal half cow and half eagle as a transition. I recently read Coulter's new book and she made almost the exact same stupid and grossly uninformed argument against evolution. If you've seen frustration somewhere along the line from one of us, please understand that it's very frustrating for us to repeat the same thing over and over to the same goddamn people and a few months later see the same bogus arguments from the same goddamn people. Ann Coulter contributed a whole chapter essentially calling all scientists dumbasses, and I think she and her ilk shouldn't be shot... flu shot that is. Also, I want all of you to write more questions because I'm seriously not a specialist in this. Disclaimer: Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style. He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!
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Archer Opteryx Member (Idle past 3598 days) Posts: 1811 From: East Asia Joined: |
Nuggin:
the two types of plants do not (can not) interbreed - they are therefore different species. That's macro-evolution. This is close to how creationists define it, yes. Speciation, though, has been observed. Creationists admit this. They just deny (their 'breeding' criterion not withstanding) that the observed change is 'macro' evolution. The logical consequence of this denial is that 'macro-evolution' is not speciation at all. It necessarily involves some additional evolutionary change beyond the species level. What sort of change that might be--and why additional speciation events of the kind already observed aren't adequate to drive them--is something creationists have never explained.
microevolution is easily demonstrated in labs and even the fundamentalists can not deny that it exists. Therefore the reason the two terms are at play is that they accept micro-evolution, but do not believe in macro-evolution. Speciation has also been observed, though, and creationists admit this. They just admit the speciation while deying any 'macro' evolution. Change 'within a species' is thus irrelevent to the question. The issue really comes down to this: What is the difference between the evolution of one species to another that creationists admit (speciation) and the evolution of one species to another creationists deny ('macro-evolution')? Archer All species are transitional.
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Taz Member (Idle past 3292 days) Posts: 5069 From: Zerus Joined: |
I think the issue really is how can one directly observe evolution on a level that is obviously on a macro level, like from amphibian to reptile. And from the example I posted above, this is like asking to directly observe the world's transition from the bronze age to the iron age. This, of course, is an impossible task. Such changes on such a scale requires very long periods of very tiny changes, and unless one is both immortal and all-seeing, there really is no way one can directly observe changes on such a scale.
Disclaimer: Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style. He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!
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Allopatrik Member (Idle past 6187 days) Posts: 59 Joined: |
Creationists define 'macroevolution' as the earliest point in the process of divergence that cannot be observed by human beings.
Edited by Allopatrik, : No reason given. Natural Selection is not Evolution-- R.A. Fisher
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fallacycop Member (Idle past 5521 days) Posts: 692 From: Fortaleza-CE Brazil Joined: |
Creationists define 'macroevolution' as the earliest point in the process of divergence that cannot be observed by human beings. That's right. And then they say the TOE can't be right because macroevolution isn't observed. Kinda nuts, ain't it??
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Fosdick  Suspended Member (Idle past 5500 days) Posts: 1793 From: Upper Slobovia Joined: |
TD wrote:
I think the issue really is how can one directly observe evolution on a level that is obviously on a macro level, like from amphibian to reptile. And from the example I posted above, this is like asking to directly observe the world's transition from the bronze age to the iron age. This, of course, is an impossible task. Such changes on such a scale requires very long periods of very tiny changes, and unless one is both immortal and all-seeing, there really is no way one can directly observe changes on such a scale.
Yes, that's one POV. But another is that macroevolution must have been highly punctuated. Some macroevolutionary events could NOT have been gradual, such as the separation of deuterostome from protostome branches in the animal kingdom. If macroevolution entailed mutated Hox genes, for example, it could have happened in a geological instant. On the other hand, the evolution of reptiles to birds was apparently not instantaneous, according to fossil records. Some biologists have said that birds are just different kinds of reptiles with feathers instead of scales, and that no macroevolution was ever involved”only speciation. And then the trouble ensures over whether or not speciation IS macroevolution. Even celebrated Harvard biologists do not agree precisely on the difference between macroevolution and microevolution and where speciation fits in. ”HM
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Some macroevolutionary events could NOT have been gradual They were certainly gradual - just because they happened more quickly than the background equilibrium does not change that. Gradual has several definitions - in evolutionary terms, gradualism is mostly contrasted with saltation. I assume you are not proposing that some macroevolutionary events must have occurred saltatory? The alternative definition of gradualism is phyletic gradualism - a constant rate of small changes. This kind of gradualism is what people not entirely familiar with evolutionary history believe is the reason given for macroevolution - however not even Darwin believed this kind of gradualism...its a misundersanding of his position and no more. TD seems to have misunderstood this position, but by saying that some macroevolutionary events are not gradual, you seem to be perpetuating this misunderstanding. All evolutionary events are gradual.
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Fosdick  Suspended Member (Idle past 5500 days) Posts: 1793 From: Upper Slobovia Joined: |
Mod says:
TD seems to have misunderstood this position, but by saying that some macroevolutionary events are not gradual, you seem to be perpetuating this misunderstanding.
Please explain to me how the deuterostomes separated from the prototomes gradually. That macroevolutionary event involved an either-or situation. The blastopor on an animal's embryo can become either the mouth or the anus of the developing organism, not both.
All evolutionary events are gradual.
You know, Mod, even fertilization can be seen as a gradual event. What are your temporal criteria that legimitize gradualism and dispatch punctuated equilibrium theory? ”HM Edited by Hoot Mon, : No reason given.
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fallacycop Member (Idle past 5521 days) Posts: 692 From: Fortaleza-CE Brazil Joined: |
Please explain to me how the deuterostomes separated from the prototomes gradually. That macroevolutionary event involved an either-or situation. The blastopor on an animal's embryo can become either the mouth or the anus of the developing organism, not both. Is it a fact that all non-macroevolutionary change must be gradual? To answer the question above you would have to have a consistent meaningfull definition of what macroevolution is. As it is, macroevolution is useless ill-defined pointless term. Makes the topic question "When does microevolution turn into macroevolution?" sound kinda stupid doesn't it?
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Nuggin Member (Idle past 2493 days) Posts: 2965 From: Los Angeles, CA USA Joined: |
I know I'm drifting off topic by posting this here but...
Guys! You wanna know why Fundies never come around? YOUR discussion is why. I see it on EVERY thread here. Fundy: "I don't understand the concept of X"Evo1: "Okay, let me try and explain it to you. blah blah blah." Evo2: "Actually evo1, you missed out on sub-sub-sub-point 7. You said blah, but really its bllah" Evo3: "You are both wrong. Recent studies show that "bllah" is mearly "balh" Evo1: "Fine, but that doesn't address what I was saying" Evo2: "Well, the implications of sub sub sub point 7 are that if bacteria blah blah blah" Evo3: "Here we go again about bacteria. Once again I want to address your issue with minute detail 23." Fundy: "Geez, there's no concensus among the Evos they much all be wrong about everything." STOP trying to impress one another and focus on the issue at hand - A fundy wants information. They don't have an advanced degree in Bio-genetics, don't treat them like they do. Keep it simple, and keep the nitpicking to the nitpicking threads.
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Please explain to me how the deuterostomes separated from the prototomes gradually. I don't know a great deal about that specific event. I ask again, are you suggesting it happened saltatory?
What are your temporal criteria that legimitize gradualism and dispatch punctuated equilibrium theory? You are talking like gradualism and punctuated equilibrium are mutually exclusive, right after I explained to you why they are not. I do not accept phyletic gradualism, which is what I believe you mean here when you say 'gradualism'.
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
The problem is that if we try and gloss over the whole topic as simple, then it is simply shown to be false.
I will not dilute the truth. I will certainly tailor my answers to the person with whom I am discussing something with, gradually increasing the complexity of the discussion. I will not pretend that I agree with everybody here, just to provide the illusion of overwhelming consensus on all issues since that would be a lie. It would be a lie easily seen through, and I will not insult those who do not grasp evolution fully by pretending that there is no legitimate scientific debate. As it turns out, the gradualist vs saltationist point of view was sort of a genuine controversy. If somebody comes away from this discussion thinking there is no consensus amongst evos about gradualism, then I know exactly who to blame. It seems a little off because Gould is dead, but he is the one that pretended that people believed in phyletic gradualism just so he could shoot it down (conveniently forgetting that Darwin had already discussed punctuated equilibrium as part of his gradualist vision). When a person says 'This could not happen gradually', I feel obliged as someone who is passionate about the truth to correct the statement. If somebody who doesn't know there arsole from their pyrrole I will help them out. However, I will not supress debate just so that we can attract 'Fundies' so we can subsequently bash them around the head with their own ignorance. There are plenty of places we can feel good about ourselves by beating an unarmed opponent. I come here to try and stoke up some quality debate. The information has been provided for the original poster, and I'm sure any further questions will continue to be answered. I almost posted something near the start of this thread, but you seemed to be doing a competent enough job of it so I backed away.
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Fosdick  Suspended Member (Idle past 5500 days) Posts: 1793 From: Upper Slobovia Joined: |
Mod, I take notice that Gould (in Ontogeny and Phylogeny, 1977) defines "macroevolution" this way:
quote:He gives your side of our argument a lot of support. So that's one for you. But I still don't know why ALL evolutionary events must be necessarily gradual. I still think some very big events could have been quite sudden. There are good arguments, for example, that larval stages may have served as radical points of departure in certain evolutionary bursts. And it is well known that small changes in the Hox genes of an organism can produce huge changes in its deveopment”some heritable. E. O. Wilson (in Sociobiology, 2000) defines "macroevolution" only as a default term for "evolution," both of which he enfolds into his definition of "microevolution":
quote: Ernst Mayr (in What Evolution Is, 2001) defines "macroevolution" as:
quote: So the Harvard heavies may be more on your side than on mine. But I'm holding firm for a while with my assertion that very big evolutionary changes can ocur in a geological blink”maybe requiring only a few generations. ”HM
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Nuggin Member (Idle past 2493 days) Posts: 2965 From: Los Angeles, CA USA Joined: |
He asked a very simple question. It deserves a simple response.
There is no "proving it to be false" because he's not asking for a falsifiable statement. He just wants to better define the two terms. I'm not saying you should gloss over the truth, what I am saying is that this sort of scientific dick measuring HURTS the cause. If two people who speak Spanish are arguing over a minor dispute - all I can tell you is they are arguing, because I don't speak Spanish. The Fundies don't speak science. When you guys dicker about sub-issue 33, all they hear is disagreement. The entire reason there is even a debate going on politically about Creationism and Evolution boils down to one EXTREMELY simple fact. The Fundies can walk in lock step. They all say the exact same thing, quote the exact same source. 100 people shouting the same thing can very easily be wrong, but they get heard over 100 people shouting different things each one of which is correct.
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NosyNed Member Posts: 8996 From: Canada Joined: |
But I still don't know why ALL evolutionary events must be necessarily gradual. I don't think anyone says they must all be gradual. Since we have observed instances in plants and animails (IIRC) of "instant" speciation then obviously they can not say that. However, there is good reason why the vast majority of evolutionary events must be pretty darned gradual (however you quantify that). The changes are random events. A large random event has a very high probablity of producing something very dead if it manages to get beyound a cell or two in gestation. An analogy is a drunk's random walk. If he takes small steps he may be caught before he steps into traffic. If however, he can somehow teleport 10's or 100's or 1000's of meters randomly he has a significant probablity of ending up inside solid rock, a kilometer in the air, in front of a truck or out to sea. If he takes small steps he will stay not to far from where he is unless there is some enouragement to go in a particular direction. If the direction is toward less danger he will be fine. You do the same thing walking in a very dark room. You take small steps and correct you path when you feel something in your way -- your path is random and then selected for. If you start taking big steps you will be flat on your face very quickly.
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