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Author
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Topic: Investigating design
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Evan
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Member # 164
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posted 24. February 2004 11:02
The moderator just moved the thread on "Evolution caught in the act" to the Literature section on the grounds that the opening post was not really a brainstorm. However, I believe that Paul Nelson's and my responses were moving the thread in a positive direction.
So I would like to reframe the question.
A central point of ID theory, and of Dr. Behe’s ideas about irreducible complexity, is that there are limits to what natural processes can do in building biological processes at the cellular level. The place to start in investigating this question of what natural processes can not do is to investigate what natural processes can do.
Therefore, I ask the same question Micah asked in a thread last week - what experimental research can be undertaken by the ID theorists to empirically distinguish between what natural process can and cannot do? Focusing on the minute details of a study such as this seems to me like a good place to start . I think it would be good for the ID movement for people such as Dr. Behe or Paul Nelson to address this question.
In particular, I offer the following about the “Evolution Caught in the Act” paper. It would seem like a good next step would be to try to reproduce the results in an effort to start to find some way to measure probabilities of the detailed steps in the changes outlines in the paper. If, under the same circumstances, the bacteria generated the same solution, we might be justified in saying the probability for this change is quite high. But suppose in a repeat of the experiment, the bacteria failed to find a solution, or found a different one, or found one more quickly or slowly? That would seem to perhaps tells us something different about what happens.
Secondly, it would be interesting to sample the populations at different times other than at the end - was the solution created by just one bacteria and then spread because that bacteria was by far the most successful in the environment, or was this a solution that was found by multiple bacteria (or even lots of bacteria?) These are all questions that need to be asked.
Again, the issue is to test ID concepts. Another way of describing the situation is to say that ID posits, at some level, isolated “fitness peaks” with no plausible pathways between them, but evolutionary theory says those pathways are there. Studies such as this one start us on the path of investigating what forms these evolutionary pathways from one peak to another might take - are they disconnected by unbridgeable canyons or not? This is an issue that needs research.
[ 24. February 2004, 11:05: Message edited by: Evan ]
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The Deuce
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Member # 992
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posted 24. February 2004 12:42
Hey, Evan, I don't have access to the paper, but the impression I got from reading Behe and Pim's description was that it wasn't the bacteria that generated the new thioredoxin per se, but rather that the workers used lab techniques to generate a bunch of variations in only the four relevant amino acids of the protein until they got a couple that did what they wanted.
It seems kind of difficult to me to talk about adaptive peaks in this instance, since the workers had already put an appropriate protein in place, identified the few sites that needed to be modified on the protein to make it work, and then generated the mutants themselves until they got the right combination. I'm not trying to knock your idea here, but I don't see how the experiment could have not worked, unless they had identified the wrong mutation sites. I'm sure more experiments like these could be used to help pin down more exact probabilities and whatnot, I just don't see it working quite like that. In particular, I'd be interested in seeing how many combinations of those four amino acids are capable of allowing the protein to do the job, or if it's just the one.
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Pim van Meurs
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Member # 541
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posted 24. February 2004 12:49
Deuce: Hey, Evan, I don't have access to the paper, but the impression I got from reading Behe and Pim's description was that it wasn't the bacteria that generated the new thioredoxin per se, but rather that the workers used lab techniques to generate a bunch of variations in only the four relevant amino acids of the protein until they got a couple that did what they wanted.
Correct, they created a random set of mutations in a specific range rather than have 'normal evolutionary processes' take place. This may be a reasonable step since given actual mutation rates, the process may just have taken too long for any reasonable experiment. Nevertheless, they generated random mutations and used strong selection, two components of evolutionary (Darwinian) theory.
What is fascinating to me is how it required only minor changes (2 point mutations if I recall correctly) for a novelty to arise out of pre-existing components.
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Evan
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Member # 164
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posted 24. February 2004 12:53
My understanding is this (and I am not a biologist, although I do have a reasonably good laymen's education) is that two things happened:
1) The experimenters narrowly constrained the situation, and then
2) the bacteria evolved an unexpected solution to the problem.
Exploring the ways that 2) happened - both the sub-steps in terms of both individual bacteria and the overall population with the intention of attaching probabilities to these factors should be the goal of ID research.
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The Deuce
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Member # 992
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posted 24. February 2004 13:57
2) the bacteria evolved an unexpected solution to the problem.
I'm pretty sure the workers generated the mutations themselves in this case, in the four amino acids that were relevant (or maybe two as it turned out), so adaptive peaks and intermediates didn't really come into play here. It sounds like it was more of a constrained random search of the different combinations of those four acids.
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