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furshur
SFN Regular
USA
1536 Posts |
 Posted - 07/19/2005 : 07:27:22 [Permalink]
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Welcome Larry Boy!
quote:
I do not think that facts alone are ever compelling enough to force the adoption of specific theories (though they might force rejections) and wish to understand what is a sufficient reason for accepting a theory as compelling.
Facts alone are the only thing that leads to the adoption of a theory. Science starts with a hypothesis based on some set of observations. Succesful experimentation, observations that support the hypothesis and successful predictions based on the hypothesis lead to the adoption of the theory from the original hypothesis.
Maybe I do not understand the point you are trying to make in the above statement.
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If I knew then what I know now then I would know more now than I know. |
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larry_boy
New Member
14 Posts |
Posted - 07/19/2005 : 10:34:31 [Permalink]
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quote:
Originally posted by furshur
Facts alone are the only thing that leads to the adoption of a theory. Science starts with a hypothesis based on some set of observations. 1) Succesful experimentation, 2) observations that support the hypothesis and 3) successful predictions based on the hypothesis lead to the adoption of the theory from the original hypothesis.
Maybe I do not understand the point you are trying to make in the above statement.
Well, Persig (Zen and the art of motorcycle maintenance, not a scholarly work, but whatever) asserted that an infinite number of (ad-hoc) hypothesis could be envisioned to bring any fact into agreement with any theory, essentially invalidating the scientific method. I am not sure that the real world problem is quite as bad as Persig asserts, but clearly a form of logical analysis of the theory itself is just as important to the theories survival as are the empirical facts which directly impact the theory.
To rephrase Persig's problem: If we follow the internal logic of a theory, people (empirically) follow it in different ways and make predicts that are different, and sometime opposite. Clearly the claim that a theory predicts both a set of observation or their opposite is non-senses, and these observations cannot be used to support the theory itself, unless one set of predictions can be rigorously demonstrated not to follow from the central logic of a theory.
The barring on N.S. is that Darwin did predict extrapolative gradual evolution of species, and most ToE followed this pattern until recently. Gould attacked this assumption by asserting that modern genetical N.S. should predict punctuation. Now, neither punctuation nor gradual change could be used to support an N.S. ToE. (whee. Maybe I should stop using abrvs.?)
To worsen problems, many times the most important predictions of a theory are experimentally untestable. For instance, no practical experiment could test the theory of common descent, because it is an historic claim, in the same way as I cannot conduct an experiment to discover if Roosevelt met with Church hill on august 12, 1939. (I am not making the contention that common descent incorect (yet) or unknowable.)
So 1) experimentation, is right out (accept to validate N.S. as a theory of evolutionary change [Proving that there is at least one valid mechanism.] and establishing that DNA can specify an arbitrary organism and is arbitrarily alterable under mutation [Proving that it is possible that some organism are descended form radically different ancestors, but not that all, or even most are.].).
And 2) and 3) are essentially restatements of each other, from my way of thinking, and the problem with accepting a theory on their basis I just discussed, I think.
Now, I am not stating that we should reject the ToE or Theory of Common Descent [or ToCD!] on this basis, nor even that the evidence which is generally accepted as validating both is unacceptable.... To be continued. |
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furshur
SFN Regular
USA
1536 Posts |
Posted - 07/19/2005 : 11:15:23 [Permalink]
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quote:
The barring on N.S. is that Darwin did predict extrapolative gradual evolution of species, and most ToE followed this pattern until recently. Gould attacked this assumption by asserting that modern genetical N.S. should predict punctuation. Now, neither punctuation nor gradual change could be used to support an N.S. ToE. (whee. Maybe I should stop using abrvs.?)
Punctuated Equilibrium does not negate gradual change. Check out this link if you haven't already:
http://www.talkorigins.org/faqs/punc-eq.html
Pucnctuated Equlibium says (taking some liberties) that isolated populations change slowly and then these better adapted species spread out displacing their less well adapted precursors. This results in the fossil record indicating relatively sudden dramatic changes in animals.
edited for spelling. |
If I knew then what I know now then I would know more now than I know. |
| Edited by - furshur on 07/19/2005 11:17:03 |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 07/19/2005 : 11:40:13 [Permalink]
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quote:
For instance, no practical experiment could test the theory of common descent, because it is an historic claim,
This is false.
Let me send you to the TO site dealing with the molecular evidence for evolution. Specifically ERVs.
http://www.talkorigins.org/faqs/comdesc/section4.html#retroviruses
Strong expirimental evidence with a very clear way to falsify the hypothesis, that supports common descent.
And ERVs are just one bit of molecular data that supports common descent. There are many experiments you can do to test common descent and as our understanding of the molecular basis of life continues to expand I remain confident that the methods will gain greater sophistication and produce even more reliable evidence.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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larry_boy
New Member
14 Posts |
Posted - 07/19/2005 : 11:43:56 [Permalink]
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quote:
Originally posted by furshur
Punctuated Equilibrium does not negate gradual change.
sorry, I wasn't trying to argue that it negated gradual change, simply that neither the empirical evidence of gradual change nor the empirical evidence of punctuated change can be used to validate general evolutionary theory. So I cannot use the argument, "The fossil record shows a slow, continues, change in the morphology of X into Y over 2 million years, clearly validating the predictions of the ToE" Nor can I say "In a near perfectly preserved fossil strata of place A, we see that there are no morphologicaly intermediates forms between X and Y, clearly validating the predictions of the ToE." because it is not clear which predictions the ToE makes at this point in time. At least, not clear to me.
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| Edited by - larry_boy on 07/19/2005 11:44:37 |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 07/19/2005 : 12:13:19 [Permalink]
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| Actually, neither gradualism nor punk-eek are predictions of evolution. Yes, evolution predicts that change occurs, but both gradualism and punk-eek are only theories predicting the rate of that change. Only if we found no change whatsoever would there be a failure of the real evolutionary theories. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 07/19/2005 : 16:00:28 [Permalink]
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quote:
"In a near perfectly preserved fossil strata of place A, we see that there are no morphologicaly intermediates forms between X and Y, clearly validating the predictions of the ToE."
This may be nitpicking...
But you won't see morphological intermediates in the same strata. When you compare fossils from many strata, oldest to newest, you see the morpholigical progression from form to form.
But that might be what you are trying to say.... hehe. Not sure, exactly, what you are getting at with that post.
And did you take a look at TO's summary of the molecular evidence for common descent yet?
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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| Edited by - Dude on 07/19/2005 16:02:04 |
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Hawks
SFN Regular
Canada
1383 Posts |
Posted - 07/19/2005 : 16:06:49 [Permalink]
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quote:
To worsen problems, many times the most important predictions of a theory are experimentally untestable. For instance, no practical experiment could test the theory of common descent, because it is an historic claim, in the same way as I cannot conduct an experiment to discover if Roosevelt met with Church hill on august 12, 1939. (I am not making the contention that common descent incorect (yet) or unknowable.)
It is true that we can never know for sure that all of todays life forms only had one common ancestor. One can, for example, imagine that two early ancestors (separately "created") have been evolving side by side and exchanging genes from time to time. So, all we can do as scientists is to go by the evidence that we do have, and form our hypotheses/theories based on this (Occams razor would make us disregard the two ancestor hypothesis I mentioned). While we might be wrong, it is the best we can do.
Regarding the impossibility of using experiments here, it is important to remember that an experiment is just another way to get observations (ie evidence). And the evidence that mother nature has left behind strongly supports the idea of common descent. |
METHINKS IT IS LIKE A WEASEL
It's a small, off-duty czechoslovakian traffic warden! |
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larry_boy
New Member
14 Posts |
Posted - 07/19/2005 : 22:21:42 [Permalink]
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Ok, replaying to two in one on this post, and then, finally (hopefully), moving on to what you have all, no doubt, been waiting for, and I hope it doesn't disappoint too much :)
quote:
Originally posted by Dude
quote:
For instance, no practical experiment could test the theory of common descent, because it is an historic claim,
This is false.
I agree about the strong evidence, I was just not viewing this as experimental evidence. Though perhaps making the distinction is somewhat arbitrary, but let me clarify by saying that the history of the world could never be recreated and that creation observed. So ToE cannot be tested by manipulating experimental variables.
Now moving on...
quote:
Originally posted by Dude
This may be nitpicking...
But you won't see morphological intermediates in the same strata. When you compare fossils from many strata, oldest to newest, you see the morpholigical progression from form to form.
But that might be what you are trying to say.... hehe. Not sure, exactly, what you are getting at with that post.
And did you take a look at TO's summary of the molecular evidence for common descent yet?
Ok, you are right, in that my example was in error. I was confusing two studies, in addition to making an error in words. I had meant to say an area with particularly fast sedimentation continuously for an extremely long amount of time while reasonable exhausting a clades geographic range. I don't know if such a wonderful study exists, but there are studies that look at entire clades geographic range and find predominant or exclusive punctuation and stasis. I.E. Species do not change in a cumulative fashion over time, and new species originate abruptly. (There are also studies conducted with particularly fine temporal resolution to validate interpretations of stasis, but they are not geographically exhaustive.) Anyway, this is just to reiterate the often ignored/trivialized central claims of Punctuated Equilibrium, that morphological change is very correlated closely with speciation (originally postulated as a causal relation ship, though evidence for this has weakened.)are left to be found. Anywhere. (say oh, 10,000 years.)
What I was getting at is that the fossil evidence for gradual anagenic change of species, aside from being nearly absent, cannot be taken as a validation of Evolution by Natural Selection because it is no longer clear that what Darwin expected, gradual anagenic change, should actually occur with sexually maintained species. (Though clearly it would support a theory of Common Descent, as would Punctuated Equilibrium, so for that aspect of the ToE, it is of no consequence.) So to rephrase once more, While it is true that seeing an organism's fossils change into a closely related organism's fossils over millions of years supports the idea that all organism are related, it is not true that such a transformation indicates that the organism has changed as a result of differential mortality among various traits.
K.
Now, this whole belabored example was just to point out that starting it is not always clear what predictions a Theory actually makes, so one has to be very careful about what is taken as supporting evidence for a theory.
Once again for old times sake. Starting from the positions that Natural Selection is the driving force behind evolution, Dawkins asserts that specialization should not be particularly associated with morphological change and that environmental pressures tend to transform whole population simultaneously. (I.E. Peppermoths.) Gould, form the same starting possition says that Natural Selection should only change morphologies when speculation is occurring. (I.E. Whooops, the peppermoths changed back.)
So, What conclusions about Natural Selection as THE driving force behind evolution can we reach from the data that P.E. is or is not a pattern in evolutionary history? None. (At least until it is made clear whether Dawkins or Gould was right.)
Now (sorry if some people got board a long time ago back there.) I am trying to emphasize that the logical interpretation of theories and of data is important. That the data does not stand on it's own, that science is not made of facts, but of theories shaped by facts.
*drum roll please*
Now all of this has been building up to the idea that Natural Selection may not be vindicated as the driving force behind Evolution by the fossil record when properly interpreted.
Now, I will, (for now *mwhahahhaha*) assume common descent. Most of the replies so far of focused on how creationist might attack the theory of common decent, and aspect of the theory of evolution to be sure, but not the only one that creationist might object to. Now let us not try to take a young earth view, because it is simply too very very hard to defend, and grant a history of the earth as presented by scientific texts. Objections are often raised to the blindness, the randomness, of evolution that focuses only on the biological fitness of the end organism, and is obtained only through a hecatomb of the slightly less fit.
Several features of the fossil record, might attack a traditional N.S. based evolution effectively:
If it was found that there was no correlation between generation times and evolutionary rates.
Why? Because logically the frequency of the selection/mutation cycle has changed, and the maximal rate of evolution is dictated by this cycle. A contention can be made that this signal could be over ridden by environmental considerations, but this will pose significant problems further down the line, I think.
If it was found that life did not approach a point of fitness asymptotically.
Why? Because the strength of selection should diminish as well as the availability of new mutation, acting together to slow evolutionary change as organism become more fit.
Less certainly I would think that diversity two should increase asymptotically under N.S. because of the number of available rolls for an organism being slowly filled through out time.
Now, all three of these observations are evidence against Natural Selection as the driving force of Macro-Evolution because of it is observed in the fossil record that there is little or no correlation between the rapidity of morphological change and generation times.
Not only is there not an asymptotic approach of complexity in organism, but if anything it appears to be exponential, organisms appearing to evolve faster when there is less material available to evolve from, or places to evolve to.
And we will leave that diversity argument behind until it is more well developed.
I realize these arguments are rather inchoate, but I hope they are clear enough to warrant further discussion.
-Edited for Spelling |
| Edited by - larry_boy on 07/20/2005 05:45:46 |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 07/20/2005 : 00:15:28 [Permalink]
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quote:
So ToE cannot be tested by manipulating experimental vatiables.
Some aspects of it surely can, especially in organism with short generation times. Many of our prokaryotes have generation times measured in minutes, under ideal conditions.
quote:
let me clarify by saying that the history of the world could never be recreated and that creation observed.
No one has ever (to my knowledge) said that it could. But how is that relevent?
quote:
What I was getting at is that the fossil evidence for gradual anagenic change of species, aside from being nearly absent, cannot be taken as a validation of Evolution by Natural Selection
If you only examine fossils, this would be correct. All the fossil record would show is change over time, and it would not be evidence for natural selection as the driving force of evolution.
However, when you incorporate geology and include the record of various catastrophic events and drastic changes in climate, you can see a direct correlation to extincion and the appearance of new species in conjunction with these events. That is evidence, in the fossil record, for natural selection. Species adapt and change, or die out, due to environmental changes.
quote:
Dawkins asserts that specialization should not be particularly associated with morphological change and that environmental pressures tend to transform whole population simultaneously. (I.E. Peppermoths.) Gould, form the same starting possition says that Natural Selection should only change morphologies when speculation is occurring. (I.E. Whooops, the peppermoths changed back.)
The statements by these two eminent scientists are not mutually exclusive. One says speciation doesn't have to cause morphology changes (not that it can't), the other says that morphology will only change when speciation occurs.
The peppermoth is not a morphological change anyway, it was a shift in the dominant color phenotype of the population due to an environmental change (industrialization and the resulting pollution).
quote:
So, What conclusions about Natural Selection as THE driving force behind evolution can we reach from the data that P.E. is or is not a pattern in evolutionary history? None
I'm not sure that anyone claims that natural selection is "the" driving force behind evolution. It is one of many. It just happens to be a powerfull one. There is always some debate concerning the specifics of the mechanisms among the experts, but very few would agree with a marginalization of natural selection.
quote:
Now all of this has been building up to the idea that Natural Selection may not be vindicated as the driving force behind Evolution by the fossil record when properly interpreted.
Scroll up. And then up once more. Again, no one (to my knowledge) claims that natural selection is "the" driving force. Just a powerfull one.
quote:
Now, I will, (for now *mwhahahhaha*) assume common descent.
Ok... but did you look at the summary of the molecular evidences for common descent over at the Talk Origins archive?
quote:
Objections are often raised to the blindness, the randomness, of evolution that focuses only on the biological fitness of the end organism, and is obtained only through a hecatomb of the slightly less fit.
I am unaware of any aspect of the ToE that would describe anything like an "end organism".
quote:
Several features of the fossil record, might attack a traditional N.S. based evolution effectively:
If it was found that there was no correlation between generation times and evolutionary rates.
Good thing for us that we can observe rapid mutation and adaptation to environmental changes in organism with short generation times.
quote:
Why? Because logically the frequency of the selection/mutation cycle has changed, and the maximal rate of evolution is dictated by this cycle. A contention can be made that this signal could be over ridden by environmental considerations, but this will pose significant problems further down the line, I think.
(emphasis added)
What data are you basing this claim on? Actually, I'm not sure exactly what you mean by "frequency of the selection/mutation cycle". What cycle?
quote:
If it was found that life did not approach a point of fitness asymptotically.
Why? Because the strength of selection should diminish as well as the availability of new mutation, acting together to slow evolutionary change as organism become more fit.
It is well established that organisms who are well suited to their environment change little, especially over short time periods. See the platypus as a fine example, but even this beastie has undergone some changes in the last several million years.
quote:
Now, all three of these observations are evidence against Natural Selection as the driving force of Macro-Evolution because of it is observed in the fossil record that there is little or no correlation between the rapidity of morphological change and generation times.
If there were a way to actually measure generation times from the fossil record, you might be able to make that statement.
quote:
Not only is there not an asymptotic approach of complexity in organism, but if anything it appears to be exponential, organisms appearing to evolve faster when there is less material available to evolve from, |
Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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larry_boy
New Member
14 Posts |
Posted - 07/20/2005 : 09:28:44 [Permalink]
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Clarifications, refutations, and other tions.
quote:
Originally posted by Dude
quote:
So ToE cannot be tested by manipulating experimental vatiables.
Some aspects of it surely can, especially in organism with short generation times. Many of our prokaryotes have generation times measured in minutes, under ideal conditions.
quote:
let me clarify by saying that the history of the world could never be recreated and that creation observed.
No one has ever (to my knowledge) said that it could. But how is that relevent?
Some of this confusion is no doubt my fault because of my various purposes. One of the things I am attempting to discuss is the logical structure behind theories and the kinds of evidence which have barring on their acceptance.
Refer to the context of the original statement under discussion and I think you will have your answer about how it is relevant.
quote:
Originally posted by Larry Boy
If we follow the internal logic of a theory, people (empirically) follow it in different ways and make different, sometime opposite predictions (from the same theory). Clearly the claim that a theory predicts both a set of observation or their opposite is non-senses, and these observations cannot be used to support the theory itself, unless one set of predictions can be rigorously demonstrated not to follow from the central logic of a theory.
To worsen problems, many times the most important predictions of a theory are experimentally untestable. For instance, no practical experiment could test the theory of common descent, because it is an historic claim, in the same way as I cannot conduct an experiment to discover if Roosevelt met with Church hill on august 12, 1939. (I am not making the contention that common descent incorect (yet) or unknowable.)
Clarification:
Defining experiment: A test under controlled conditions that is made to demonstrate a known truth, examine the validity of a hypothesis, or determine the efficacy of something previously untried. -> Now the stuff on molecular evolution is great, grand and glorious, but cannot properly be said to be experimental results, because the data were not generated under controlled conditions.
In the same fashion observation of the cosmic background radiation is not experimental, because there are uncontrolled variables that might affect our conclusions, and the only way to demonstrate that the observations support our hypothesis is to bring to bear a massive amount of theoretical knowledge which will allow us to interpret the data correctly. To know that newtons quantization of the laws of motion or gravity are correct, no theoretic knowledge is needed at all, only experimental evidence and then it is plug and chug my friend.
So, my contention simply is that because it is not experimental data, the underlying theories used to interpret the data must be correct for the conclusions to be correct, because our data are being interpreted through those theories. (remembering this is not the case with experimental physics because the claims are essentially different. Physics caim 'when I dropped a ball, it fell, and factors a-c are sufficient conditions to produce this effect.' This is an experimental observation, and no theory is necessary to reach this conclusion, though the results of the experiment have a barring on theory. The claim that the DNA sequences of modern organisms are different in specific ways is a 'simple' observation (though one much much harder to make then the experimental observation of a falling object.) and, as such, Fushers statement that “Facts alone are the only thing that leads to the adoption of a theory. Science starts with a hypothesis based on some set of observations. Successful experimentation, observations that support the hypothesis and successful predictions based on the hypothesis lead to the adoption of the theory from the original hypothesis.”
is incorrect, because if and only if the hypothesis or theory being established is a claim of the experimental kind, and not of the observational, or historical kind, is theory irrelevant. For historic truths to be established the logical validity of the theory itself must be established independent of the data through rational debate, closer in appearance to philosophical discussions than strictly experimental interpretation. This is an oft made claim I hear of science, and I felt it needed correction, science is not just experimentation, the collection of data, and predictions, it is a rational endeavor in the same way as mathematics or philosophy (though less rule-bound than the former, and more than the latter.).
So Nyeh.
quote:
quote:
What I was getting at is that the fossil evidence for gradual anagenic change of species, aside from being nearly absent, cannot be taken as a validation of Evolution by Natural Selection
If you only examine fossils, this would be correct. All the fossil record would show is change over time, and it would not be evidence for natural selection as the driving force of evolution.
However, when you incorporate geology and include the record of various catastrophic events and drastic changes in climate, you can see a direct correlation to extincion and the appearance of new species in conjunction with these events. That is evidence, in the fossil record, for natural selection. Species adapt and change, or die out, due to environmental changes.
Unfortunately for you... no.
The problem with using catastrophic events to validate natural selection is that the traits which are selected for in the catastrophe could have in no way been built up brick by brick by natural select. To demonstrate the problem let us look at a modern study on anti-biotic resistance. At the moment the bacteria are exposed to the anti-biotic they either a) die or b) survive. The trait of the bacteria that allows them to survive cannot have originated through natural selection for anti-biotic resistance because there was no anti-biotic to be resistant to until they were first exposed. Similarly the ability of an organism to survive catastrophe X could not have been created over thousands of generations of selection for organisms to survive catastrophe X, because catastrophe X occurs in the future of the organism, not the past. I think that is sufficiently clear.
No one would argue that I can't kill off A whole bunch a organisms with a disaster. Death of organisms which do not have the ability to survive is not particularly interesting. Now, after the catastrophic event, there is a radiation of species, |
| Edited by - larry_boy on 07/20/2005 09:34:08 |
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HYBRID
BANNED
USA
344 Posts |
Posted - 07/20/2005 : 09:58:59 [Permalink]
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| You all find me funny, that's quite alright, because I myself, and friends of mine find your way or thinking funny as well. It works both ways. Its too bad that the theory of evolution is just a way of thinking, and not a fact. |
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Valiant Dancer
Forum Goalie
USA
4826 Posts |
Posted - 07/20/2005 : 10:38:38 [Permalink]
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quote:
Originally posted by HYBRID
You all find me funny, that's quite alright, because I myself, and friends of mine find your way or thinking funny as well. It works both ways. Its too bad that the theory of evolution is just a way of thinking, and not a fact.
http://redwing.hutman.net/%7Emreed/warriorshtm/troller.htm |
Cthulhu/Asmodeus when you're tired of voting for the lesser of two evils
Brother Cutlass of Reasoned Discussion |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 07/20/2005 : 11:02:39 [Permalink]
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quote:
Originally posted by larry_boy
It seems to me that an equally good case (OK, better) could be made on the basis of the evidence that you just asserted that new species simply appear, and are then either preserved or destroyed on the basis of their fitness.
Do you know of any creature which is not born of at least one parent? I was, I'd bet you were, and so on, suggesting that the first creatures classifiable as Homo sapiens sapiens were also born, not "poofed" into existence. We've never, ever seen a single creature suddenly appear. The idea that species "simply appear" is magical, and based upon no scientific evidence.quote:
To all of this, bear in mind the additional havoc caused by the fact that, while it is well established that organismal mutations are random and undirected, no such knowledge exist for the process of speciation.
There is no single "process of speciation."quote:
If you are aware of any other explanation for adaptation, I would love to hear it.
Considering that "adaptation" is the end result of the combination of effects of not only natural and sexual selection, genetic drift, and all other mechanisms of evolution, the above seems a strange challenge to offer.quote:
And while “very few would agree with a marginalization of natural selection” I feel 'very many would agree with a marginalization of everything else.' And yes, btw, people do make such claims. “Every local population is very precisely adjusted in its phenotype to the exacting requirements of the local environment. This adjustment is the result of selection of genes producing an optimal phenotype.” (Mayr's “Systematics and the Origin of Species”.)
That's a marginalization of natural selection? Or of everything else?quote:
I think most people these days will grant a role for drift and neutral mutations in altering phenotypes, but the general emphasis still seems to be that all or almost all phenotypic features originate and are elaborated for adaptive reasons. (unless you are a filthy neutralist.)
Much more than "granting a role." For many years, there has been an active debate over whether genetic drift or natural selection has played more of a role in generating the diversity we see today. And if I've been correctly reading the current news coming from evolutionary biologists, genetic drift seems to be on the top of the heap these days.quote:
If you think that something other than Natural Selection is THE driving force behind evolution, please, step up to the plate.
Genetic drift, apparently.quote:
By it I was trying to show that to obtain one part of evolutionary advancement (my poorly phrased 'end organism'), thousands of individuals had to die.
So what? Arguments from negative consequences don't hold much weight, for one thing. Second, nobody has claimed that evolution is necessarily "efficient." Third, even without environmental change prompting a need to adapt, thousands of individuals die.quote:
Right, exactly my point, in experiments where natural selection is the evolutionary force, then short generation times, poor adaptation to the current environment, and high mutation rates all increase the rate of evolutionary change.
Thus, you're making the case for punk-eek.quote:
Luckily, there is! Recent studies estimate many dinosaur's generation times based on bone growth patterns, and logically any large complex organism will tend to have longer generation times then small, simple, organisms. So the fact that we spend 2/3 of the earths history fine tuning small simple organisms (when evolution is fast, and there is little to be done), and only 1/3 generating the much greater amount of genetic information contained in all multicellular life on the planet earth (when it is slow, and there is lots to be done) seems preposterous.
Do you have any evidence that selection pressures have been equal amongst all organisms for the last four billion years? Because it is only under such conditions that what you've said seems "preposterous."
Besides, of course, Special Relativity and quantum electrodynamics also seem preposterous, but they're perfectly good theories.quote:
I was not speaking of evolution proceeding more quickly when organisms are poorly adapted, but instated about it proceeding more quickly when organisms are more complex, and, presumably, under a) less pressure, less mutation, longer generation times, and harder adaptations to craft (owing to their higher level of complexity). Which is all, as I claim, very strictly against natural selection as the driving force.
I'd really enjoy seeing evidence that more-complex organisms are under less pressure. "Presumably" doesn't really cut the mustard in a discussion such as this. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 07/20/2005 : 11:45:20 [Permalink]
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Now the stuff on molecular evolution is great, grand and glorious, but cannot properly be said to be experimental results, because the data were not generated under controlled conditions.
Which has what to do with the observations supporting common descent?
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Unfortunately for you... no.
The problem with using catastrophic events to validate natural selection is that the traits which are selected for in the catastrophe could have in no way been built up brick by brick by natural select. To demonstrate the problem let us look at a modern study on anti-biotic resistance. At the moment the bacteria are exposed to the anti-biotic they either a) die or b) survive. The trait of the bacteria that allows them to survive cannot have originated through natural selection for anti-biotic resistance because there was no anti-biotic to be resistant to until they were first exposed. Similarly the ability of an organism to survive catastrophe X could not have been created over thousands of generations of selection for organisms to survive catastrophe X, because catastrophe X occurs in the future of the organism, not the past. I think that is sufficiently clear.
Do you not grasp the concept, or are you deliberately creating a strawman?
The idea that a catastrophic event can drive natural selection is really quite an obvious one. You have event X, it changes environmental conditions drastically, a bunch of organism CAN'T survive so they go extinct. Organism Y, however, survives the catastrophe. The traits that have allowed Y to survive continue to get passed on. THEN, due to the altered environmental conditions, Y adapts and changes to be better suited to the new environment, resulting in the developement of new species.
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No one would argue that I can't kill off A whole bunch a organisms with a disaster. Death of organisms which do not have the ability to survive is not particularly interesting. Now, after the catastrophic event, there is a radiation of species, however, what evidence is there that natural selection is the force that has been crafting these new organisms to fill up the empty space?
What evidence is there that species are even changing in this scenario?
The evidence of new species radiating after extinction events is clearly documented in the fossil record. If you reject the idea of natural selection as one of the driving mechanism behind the appearance and radiation of these new species, what then do you propose?
I'll have to add that the idea of species "suddenly appearing" is a false assertion.
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To all of this, bear in mind the additional havoc caused by the fact that, while it is well established that organismal mutations are random and undirected, no such knowledge exist for the process of speciation. For Natural Selection to be an important process, it must be involved in the generation of these new species that appear during the adaptive radiation, but what evidence is there that Natural Select is important in this instance?
Mutation may be random and undirected, but the result is not. If the mutation is beneficial or neutral, the organism survives. Otherwise it fails to survive.
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Dude? Are you seriously telling me that you think that a scientist said that speciation doesn't have to cause morphological change? If two species are identical, how exactly do you think they are different? In all fairness you may have been confused by my use of morhpological when phynotypic was more apropriate.
Just reiterating what you said. The statements you claimed these scientists made, as you presented them, were not mutually exclusive.
Also, there are multiple phenotypic and morphological differences among members of the same species. Just look at dogs, for an example. Or humans for that matter. And then there are some different species that have remarkably similar morphology and appearance.
Speciation occurs when genetic information changes enough to prevent the production of fertile offspring.
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Again poor phrasing, I was simply trying to explain why short generation times (the selective part of the cycle) and high mutation rates (only germ-line mutations affect evolution, so only the mutation that an organism inherits at birth are evolutionarily relevant.) should increase the rate of evolution if natural selection is the evolutionary force. No data, just a logical claim, though I'm sure data back it up.
Short generation times and high mutation rates do effect the rate of evolution. Natural selection takes effect after the mutation occurs.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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