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Date: 2005/04/18 15:34:31, Link
Author: AndyG
Charlie neatly sums up one of the arguments for intelligent design, which is argument from ignorance. He has used this argument almost exclusively in his discussions on talk.origins and at the Panda's Thumb. The bottom line is that Charlie cannot possibly see how microglia could have arisen to respond to brain injury, and thus invokes an intelligent agent.

There are over a thousand papers on the activation of microglia after injury, and theri behaviour is well-characterized. They respond to cytokines released by damaged brain tissue (such as the interleukins), which causes them to change their behaviour. This is no different in prinicple from the activation of a variety of blood cells after injury.

We do not know every detail about how inflammatory responses evolved, although there are plenty of clues out there. In fact, if Charlie took the time to read the literature on neuroinflammation, he might come up with some ideas himself. But that's too much like hard work, right? FAr easier just to sit back and say it was designed.

As a final thought, I challenge Charlie to write to the authors of the paper he cites and ask them whether they agree with his thesis. I will be interested to see their reply.

Date: 2005/04/18 20:52:30, Link
Author: AndyG
Quote
   The burden of proof lies with the person making the claim.


Exactly. You are claiming the microglial system is the result of intelligent forces. So go ahead, show us the evidence. Saying you can't imagine how it could have evolved is not evidence for intelligent design.

Meanwhile, do some reading on teh relationship between microglia and macrophages.

Date: 2005/04/19 13:41:37, Link
Author: AndyG
Quote
One must wonder where the insight came from that allows these cells to transform from the "resting state" to the activated state in the presence of a threat.


I think it came from Interleukin 1.

Date: 2005/04/20 11:52:52, Link
Author: AndyG
Quote
Professor: Scientists say that evolution is true.
Student: How do they know this?
Professor: It's explained in any textbook on evolution.
Student: Well, who writes the textbooks?
Professor: The scientists.


Actually, the exchange goes like this:

Professor: Scientists say that evolution is the best current explanation for life's diversity
Student: How do they know this?
Professor: Because the data that we have is best explained by modern evolutionary theory
Student: Does this mean we know how every organism and every biochemical system evolved?
Professor: No. But it's a start.

Date: 2005/04/20 13:06:20, Link
Author: AndyG
Quote
I would really prefer to discuss the question that I started with, which referred to the evolutionary mechanism by which microglial cells might have evolved.


What's the point? If we delve into the literature and piece together a scenario for you, you will reply that it is insufficiently detailed and therefore, in your opinion, microglia are the products of intelligent design. Been there, done that.

Quote
Student: I would be interested in knowing what you mean when you use the term evolution. Do you simply mean "change over time" or do you mean "change in gene frequency as a result of natural selection" or do you mean "the accumulation of fortuitous mutations over time as a result of natural selection leading to new adaptations, structures and processes".
Professor: Next question.


Evolution is change over time. Things change because their genetic material changes. So evolution is a change in allele (not gene) frequency. This can happen by natural selection, or by other mechanisms such as genetic drift. Over time this will lead to new adaptations, structures and processes.

Quote

Student: OK, I'll move on. Perhaps you would care to describe some of this data that you refer to? Is it empirical data, in the form of observations or experiments and how does it support whatever it is that you call evolution?
Professor: <<sound of crickets chirping>>


It is empirical data in the form of observations. If that data does not satisfy you, Charlie, that's too bad. There's no pleasing some people.

1. By the by, what data *would* satisfy you?
2. Have you contacted the authors of that paper yet to ask if they think microglia are the result of intelligent design?

Andy Groves

Date: 2005/04/20 17:38:46, Link
Author: AndyG
Quote
Cite one piece, just one piece, of empirical data that links the changes in allele frequency that occurs under selection and the appearance of new structures, processes or adaptations.


Minor quibble: Remember I said that these changes do not need to occur by selection - drift is also a mechanism of evolution.

But anyway, your example of the evolution of a new structure, adaptation or process is the evolution of nylonases in bacteria.

Negoro, S., Biodegradation of nylon oligomers (2000), Appl. Microbiol.
Biotechnol.54, 461-466.


Kato K, Ohtsuki K, Koda Y, Maekawa T, Yomo T, Negoro S, and Urabe I.
(1995 Oct). A plasmid encoding enzymes for nylon oligomer degradation:
nucleotide sequence and analysis of pOAD2. Microbiology , 141 ( Pt
10),  2585-90.


Prijambada ID, Negoro S, Yomo T, and Urabe I.  (1995 May). Emergence
of nylon oligomer degradation enzymes in Pseudomonas aeruginosa PAO
through experimental evolution. Appl Environ Microbiol , 61,  2020-2.


Yomo, T., Urabe, I. and Okada, H., (1992) No stop codons in the
antisense strands of the genes for nylon oligomer degradation,
Proceedings of the National Academy of Sciences USA 89, 3780-3784.


Kato K, Fujiyama K, Hatanaka HS, Priyambada ID, Negoro S, Urabe I, and
Okada H.  (1991 Aug 15). Amino acid alterations essential for
increasing the catalytic activity of the nylon-oligomer-degradation
enzyme of Flavobacterium sp. Eur J Biochem , 200,  165-9.


Ohno S.  (1984 Apr). Birth of a unique enzyme from an alternative
reading frame of the preexisted, internally repetitious coding
sequence. Proc Natl Acad Sci U S A , 81,  2421-5

Date: 2005/04/20 21:25:13, Link
Author: AndyG
See what I mean, Charlie? There's no pleasing some people.

You did ask for one example, didn't you? Do you want another one? How about the selective reduction of pelvic fins and body armor in sticklebacks?

Date: 2005/04/21 13:22:13, Link
Author: AndyG
Quote
You also cannot demonstrate (as described above) that this was a random or accidental mutation and not the result of directed guidance from a dynamic and responsive genome to changes in environmental conditions.


You mean Lamarckism?

Date: 2005/04/21 16:46:31, Link
Author: AndyG
Quote
We simply don't know enough yet about reverse transcription, retrogenes, retropseudogenes, retrosequences and retrotransposons to say that acquired characteristics can never be inherited.


No, we can't say that. However, at present the only evidence that they can is some extremely controversial work from Ted Steele and colleagues in the only system in the body that undergoes significant genetic rearrangement during development.

Date: 2005/04/25 15:24:49, Link
Author: AndyG
Quote
416 people have viewed this thread but I've not gotten one single answer to my query. I wonder what that means?


It means We Don't Know.

Date: 2005/05/17 13:28:02, Link
Author: AndyG
John Walker, who you cite, was one of my undergraduate supervisors at Cambridge. His current web page is here.

Please write to him and ask him if he thinks these motors are the product of intelligent design, and report back here. Thanks.

Date: 2005/05/19 15:12:49, Link
Author: AndyG
Dr Walker displays exactly the sort of closed minded naturalistic viewpoint that....errrrr..... won him a Nobel Prize   :0

 

 

 

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