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Author | Topic: All species are transitional | |||||||||||||||||||||||||||||||||||||
Parasomnium Member Posts: 2224 Joined: |
Creationists often hail the lack of transitional fossils as damning evidence, if not the death blow for the theory of evolution. Such arguments are often countered by pointing out that the fossil record is bound to be incomplete, is not the only evidence, is in fact a minor part of the evidence, etc, etc. Also, evolutionists explain, absence of evidence is not evidence of absence.
But I think a very important point is often overlooked when considering the argument of transitionals, when in fact it could be a very powerful weapon in the debate, if it is properly understood. What I am talking about is that the concept of 'transitionals' is a bit misleading. It is misleading in that it forces upon us - but mostly upon the undiscerning creationist mind - the distinction between "finished" and "unfinished" creatures. Thus the finished creatures belong to a species, while the unfinished creatures are deemed somewhere "in between" species. Also, a transitional creature is supposed to exhibit useless features, or even defective features, because they are not the "finished product". But this is a false picture. The reality is that all species are transitional. There is no such thing as a "finished species". It's a mirage, for two reasons. First, the term 'species' is an arbitrary, man-made concept. The system of classification in biology, of which 'species' is a layer, has been revised more than once, to accomodate new insights in the relatedness of newly found creatures to ones already known. Also, there are several definitions of the term 'species'. One definition takes interbreeding as its criterion. Ernst Mayr defines 'species' as:
quote: But interbreeding assumes sexual reproduction. So what about all those creatures that reproduce asexually? How are they classified into species? Enter the concept of a "morphological species", that is to say, when two creatures are similar enough, we call them a species, and when they differ too much, they are "clearly" two species. But what is "similar enough"? When do they "differ too much"? All in all, it seems obvious that the concept of 'species' is a bit problematic. Second, the term 'finished' presupposes a plan. Something can only be called 'finished' if it is known in advance what the thing is going to look like. But evolution advances by random mutation and natural selection, making it logically impossible for there to be a plan. And if there is no plan, then a species cannot rightly be called 'finished' or 'unfinished'. It simply is what it is: a species in its own right. To illustrate the point that all species are transitional, here's a thought experiment. Let's create a row of numbers, by following a simple rule: we start with the number 1 and create each following number by adding 1 to the preceding number. Let's repeat this until we have reached 1 million. Now we have a long row of numbers, with small numbers at one end, and large numbers at the other. Everyone will probably agree that 1 is a small number, and a million is a large number. The number 2 is also a small number, as are 3, 4 and 5. At the other end there are more large numbers: 999,999 is large, so are 999,998 and 999,997. However, the row is continuous, so the question is: where in the process that created the row did a small number give rise to a large number? Whatever boundary is taken as the point of transition, the numbers on both sides of the divide differ by only one, so it is a bit difficult to maintain that the one is a small number and the other is a large number. A solution could be to introduce 'intermediate' numbers, which are neither small nor large, but, obviously, intermediate. But is that really a solution? Actually, no. Because now we have not one, but two boundaries to determine. When is a number still small, and when is it intermediate? What intermediate number gave rise to a large number? We find we still have the same problem, only twice. And introducing still finer gradations just adds to our problems, until... Until we come to the point where each number is in its own division, and the dilemmas disappear all of a sudden. But now our divisions no longer provide us with more information about the numbers than the numbers themselves do, effectively making the divisions obsolete. This means that there are no discrete dividing lines to be drawn. The transition takes place along the entire range of numbers. Each number is itself a transitional, from small to large. What we need to realise is that we are trying to impose an arbitrary system of discrete divisions on a continuous set of elements. With species it is no different. If you translate the example of the numbers to species, you can imagine a continuous sequence of intermediates from any ancestor you'd care to start with, right up to yourself. You are the same species as your parents, and they the same as theirs. At the other end of the line, the ancestor you started with is the same species as its offspring, and they are the same species as their offspring. But if you went back far enough in the lineage so that the ancestor you start with is a tree-dwelling primate, then obviously this ancestor is not the same species as you. There must be transitionals. But wherever you look in the lineage, locally you cannot pinpoint any real transitions. That's because the transition takes place all over the lineage. Each and every one of your ancestors is a transitional. And if you have children or plan on having them, you are a transitional yourself. The next time a creationist asks "Where are the transitionals?", you can answer "Look around you."
{edited for spelling} This message has been edited by Parasomnium, 30-Dec-2005 02:08 PM Did you know that most of the time your computer is doing nothing? What if you could make it do something really useful? Like helping scientists understand diseases? Your computer could even be instrumental in finding a cure for HIV/AIDS. Wouldn't that be something? If you agree, then join World Community Grid now and download a simple, free tool that lets you and your computer do your share in helping humanity. After all, you are part of it, so why not take part in it?
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Parasomnium Member Posts: 2224 Joined: |
JustinC writes: if a creature dies without breeding then it isn't transitional That's why I specifically mentioned ancestors, and not just any odd creature:
quote: If a creature dies without breeding, it can't possibly be one of your ancestors.
JustinC writes: Or, if we are using "species" as a valid classification then a species that goes extinct, without some of it's populations evolving into another species, is not transitional. Now you have point. A trivial point, by your own admission, but a point nevertheless. Thanks for sharing it, I hadn't thought of it. We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
Brad McFall writes: There is so much biology lost by not being able to relate deaths to genetic biophysics conceptually. Well, normally we say that evolution is directed by natural selection. But we could easily rephrase that as "evolution is directed by non-random death." They are two sides of the same coin. To assess your wealth, you can either consider what you've got left, or you can count your losses. The nett result is the same. But that may not be what you mean. The problem is that I don't understand what you mean. Could you explain?* Please concentrate on this phrase from your other post: "species like dying individuals".
* Preferably in green-grocer speak. We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
NosyNed writes: This, like so much else, depends on the definition. [...] At some point in time there were probably 100's or 1,000's of species that were all cousins and all part way along the path from dinosaur to bird. It may be that exactly one of these species gave raise to all modern birds or certainly only a handful of them. But I'd claim that ALL of them were transitional -- that is straddling the gap between the two higher taxa. It's all a matter of where we draw the boundary between taxa, like I illustrated in my opening post. Popularly, you could say that "the birds descended from the dinosaurs". You'd be right, in a very loose sense of the word 'descended'. But if you zoom in, so to speak, you find that some, if not most subtaxa of "dinosaurs" did not give rise to the taxon "birds" at all. Some dinosaurs may have been birdlike and gone extinct without leaving a continuous lineage resulting in birds. They cannot have been the ancestors of modern birds, but you could call them transitional because they are part of the blurry taxon "birdlike dinosaurs", which we could imagine between dinosaurs and birds. So, zooming out again - but not all the way - we get: "the birds descended from birdlike dinosaurs which in turn descended from dinosaurs". In that sense, "birdlike dinosaurs" are the ancestors of birds, even if some of the birdlike dinosaur species went extinct.
JustinC writes: I always considered a transitional to be a direct link between two species. So it would have to fit in the timeline between the two species and share features of the oldest species while showing characteristics of the later one. That's also how I would define a transitional, at least for the sake of the purpose of this topic, which is specifically targeted at the creationist argument of the "missing" transitionals. I'm sure a more elaborate discussion can unfold if we allow a more relaxed definition of transitionals, but I would like to engage a particular creationist misconception first. This message has been edited by Parasomnium, 05-Oct-2005 12:13 PM We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
Any objections to the above?
No objections. Now that that's out of the way, could we agree on a notion of 'transitional' that addresses the creationist argument of the missing transitionals? I think the problem they have with speciation is the reason they always talk about missing transitionals. The purpose of the argument in my opening post is that if it can be shown that transition is a very gradual, locally almost imperceptible process, then perhaps speciation is a bit less of a problem. This message has been edited by Parasomnium, 06-Oct-2005 10:31 PM We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
robinrohan writes: When a gene pool gets isolated is not, I would think, an arbitrary designation. "Isolation" seems pretty definite to me. First of all, reproductive isolation comes in several flavours and they aren't all as dramatic as it sounds. It can just as well take place over a longer period of time and in one and the same habitat, as it can take place instantaneously, effectively creating two separate habitats for two populations. Please bear this in mind when I mention "the moment of isolation" in what follows. What you are forgetting is that the transition takes place over time. Up until the moment of isolation, the combined gene pools are still uniform enough to allow interbreeding all over the gene spectrum of both populations. It's because the isolated populations do not interbreed from that moment on - allowing each gene pool to follow its own path through mutation space - that both gene pools start to differentiate. Long after both populations have grown so far apart that interbreeding has in fact become impossible, you can still perform the thought experiment I described in my opening post. Only now you have a row of ancestors that splits into two rows at the moment of isolation. In each of the resulting two gene pools, you can pick an individual and trace back an unbroken chain of ancestors until you come to an ancestor in the original pre-isolation gene pool. You can do this for both chains. But wherever you look in either chain, locally you will not find a transition to another species, not even at the moment of isolation. It is only when you compare individuals from either population, and from well after the moment of isolation, that you will see significant differences, leading you to suspect that you may be looking at different species. We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
Mammuthus writes: [...] in addition to not being able to look at small steps and recognize discrete transitionals..the "transition" has not even necessarily been unidirectional with tendencies towards isolation being reversed and then reversed again until much later you look at two clearly distinct species that may have had several false starts in getting to a point where they are recognizeabley members of distinct gene pools. Which goes to show that nature is usually much more intricate and beautiful than we can imagine in even our wildest fantasies. How boring and banal it would be, had it merely been created by humanity's gods. Thank you for this informative addition to my somewhat simplistic and idealized picture of the workings of evolution. We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
Mammuthus writes: I don't think that simple models that may be off are not useful. Maybe it's the very fact that they are off that makes them useful. It forces us to think about the discrepancies between the model and reality, thereby refining our understanding of the latter.
Mammuthus writes: [...] if you had access to the finer details (say at the level of the Darwin's finches study) you might find that beaks got shorter, then longer then shorter and it would not look like a progression at all. I suppose my model would be like looking at a subset, where, for example, beaks would change from long to short, period. On the other hand, if one would look at the genes behind a sequence of beaks undulating from long to short to long again, one might see no undulation at all, since the genes for the early long beaks need not to have been reverted to, in order to produce the later long beaks. In fact, I'd be very surprised if that would be the case. Then again (he added enigmatically) I wouldn't be surprised if you surprised me... This message has been edited by Parasomnium, 11-Oct-2005 10:19 AM We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
Brad McFall writes: Perhaps I just misunderstand your notion of "transition" or how we define "species" After all I have written in this thread, you still "perhaps misunderstand"? How can that be? Short of hyphenating the long words, I cannot write anymore clearly than I have, sorry. Speaking of clear writing, I think I'll pass on your essay and wait for the polished version. We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
Brad McFall writes: Is "transition" univocal with "missing link"?I need to know. You can look up 'transition' in a dictionary to find out what I mean by it. Same with 'missing' and 'link'. But I'll oblige you with a description of both: a transition is a change from something to something else; a missing link is what used to hold two parts of a chain together, but no longer does. Why does everything have to be so difficult with you?
If you are only obviously waiting for the "day after" to respond, not only is that hardly fair but it is not a material response I have more things to do. Your posts mainly have me try and parse their structure. I rarely, if ever, get to the point of understanding what you are saying. From now on, I will only respond to those fragments I can understand - if I can spare the time.
Are you saying specifically that there is NO comprehensibility of the "adaptive landscape" figuration of Wright either because he had graphed it either with gene frequencies OR gene combinations on the axes? I need to know quite specifically. Well, obviously not specifically, since I didn't even mention Wright. Maybe, if I have time, I will look into it, but don't hold your breath.
to say that you or I can not "find" the transition "to" another species given the trace back to former gene pool at "isolation" seems gratuitous. Indeed it is, given everything I have written about it so far. That's precisely the point.
I consider your reponse well informed for older biology but to simply make your language of a single isolated mating pair and a continent to be placed in the same space is harder for me to imagine than the small ex nihlio probablity that God eixsts. It's equally hard for me too. Language? Continent? What are you talking about?
If you wait for me (oh probably a couple more weeks) it might be too late. You wont be able to swim across tangled bank by then. Too bad then.
I took it that "locally you will not find a transition to another speices" to mean that I will not be able to predict from any given pill bug that a particular pill bug population is headed for extinction relative to its neighbors. I meant no such thing. I just meant that if you took a pill bug and compared it to its mummy and daddy, you would not conclude that you were looking at two different species.
So are you detailing incomprehensibility of ME or Sewall Wright? You tell me. We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins
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Parasomnium Member Posts: 2224 Joined: |
Got to go. Talk to you later.
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Parasomnium Member Posts: 2224 Joined: |
Brad, I have become convinced that you are not human.
You are an algorithm which produces pseudo-intelligent messages by regurgitating texts from a limited pool in a semi-random way. Here's your challenge: prove me wrong. Consider it your own personal Turing test. This message has been edited by Parasomnium, 12-Oct-2005 08:46 AM
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Parasomnium Member Posts: 2224 Joined: |
Annafan writes: It is unlikely that there exists a better way to express how I personally felt about Brad's posts. Thank you. I liked it myself, it has all the necessary elements, doesn't it?
Well, there's also the alternative that I (we?) are just too dumb, lol. Definitely "we". In my optimistic years I've dabbled endlessly and to no avail to make some sort of start with an AI. And now here's this brilliant but unknown programmer from Ithaca, just deploying his Brad 1.0 It's just not fair.
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Parasomnium Member Posts: 2224 Joined: |
robinrohan writes: The most human-like response I've noted is the memorable phrase, "I don't chat." That's funny, I'd interpret that in the opposite direction: maybe it's a pre-programmed response to avoid giving the game away. I think we'll have to wait for at least Brad 2.7.0.1 before an add-on ("BradChat"?) can be downloaded. Only after we've visited http://www.brad.com to register ourselves as Brad users, of course.
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Parasomnium Member Posts: 2224 Joined: |
nwr writes: We might have trouble understanding Brad. But it is clear that Brad understands us. And no AI system has ever been able to achieve that. This is an interesting remark. It set me thinking about yet another permutation of Brad, us, AI, and 'understanding'. I asked myself: would an AI understand Brad? To find out, I did an experiment. I searched for online chatbots on the internet and looked for the first one I didn't have to buy before I could try it. It was called Ella. I fed it one of Brad's sentences and pressed enter. Here's the result.
Brad writes:
Try to see that Waddington's "canalization" actually spreads beyond any Freudian projectionisms no matter the circle of perceptrons you might have applied.Ella writes: No one is perfect. Communication can be tough. This may look funny, but it's also an astonishingly apt assessment of the situation.
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