FETCHER.

'Its all make believe, isn't it?'

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My Journal.
Last.Fm if your interested...

Guybrush

Irreducible Complexity is a sad, sad argument which is tiring to all biologists who study evolution. Not a single convincing argument has ever been put forth by the people who defend it. The page Il Duce refers to uses the human eye as an example. Today, anyone who doubt such things luckily don't have to look further than good old Wikipedia to read up on how eyes have evolved, from a simple organ to one more complex.

>> Evolution of the eye - Wikipedia, the free encyclopedia

Don't believe in creationist nonsense. They use every dirty trick in the book, such as deliberately misquoting Charles Darwin and other famous scientists in order to warp their original intentions/writings. Creationist writers on the internet are fanatical, manipulative wankers of the worst sort.

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Salami

Don't get me started on that!

Although I think the current line they are attempting seems to relate more to the flagellum in eukaryotic cells, as is Michael Behe's argument in his book "Darwin's Black Box".

They've realized that the eye isn't a good example of "Irreducible complexity".

The main problem with it is that according to Richard Dawkins, "half an eye is better than no eye at all". Because an eye without the lens or suspensory ligaments is still an eye, even if less evolved than our current ones, and will still be able to sense light.

The idea is that certain cells are photosensitive, and organisms with large clusters of these cells will be able to detect light, and will find this beneficial for survival, as they will be able to negotiate tricky objects more easily.

Thus, they will have a greater chance of surviving and passing on the allele which codes for "photosensitive cell patch" in their DNA.

And when evolution continues, positive mutation after positive mutation will eventually lead to a sclera, cornea, lanse, etc. and finally a fully developed eye.



I think I have successfully deflated that argument. Let no one else speak of irreducible complexity on this forum!

Guybrush

Your knowledge of evolution is refreshing, Mighty Salami

Although I don't want to get into specifics, the "irreducible" bacterial flagellum has also been shown to be reducible by biologists

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The Batlord

Yeah, wasn't it shown in some court case about evolution vs intelligent design, that the bacterial flagellum in a simpler state was like a needle that allowed the bubonic plague to inject it's genetic code into a cell?

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Salami

I started getting really interested in the subject whilst doing GCSE biology, and I really can't drag myself away! It's just so fascinating! I'm also aided by the fact that my mum is a professor in embryology and my dad is a geologist.
I'm assuming you are referring to the Type three secretory system? TTSS?

Sadly when I put forward that idea to some ID proponents I was told to show them the evidence in the fossil record, which I couldn't do anything about! And dad was up in Norway!

The Batlord

Wait, so were you just shootin' the ****, discussing intelligent design on the steps of the local pizza place type of situation, and they up and made you gather research data?! Classy.

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Guybrush

Yes, I was thinking of the Type Three Secretion System which is basically a needle-like adaptation for detecting other organisms and secreting proteins. It is made up of a smaller subset of the same proteins which make up the eubacterial flagellum and the two are homologous, meaning they have shared evolutionary ancestry.

I hadn't heard about the bubonic plague before, but since it's caused by gram-negative bacterias of which many are known to possess TTSS, that sounds likely.

I think that by logically presenting a case that shows the flagellum is not irreducibly complex, you've already won the argument. After all, had the flagellum really been irreducibly complex, then you shouldn't have an argument to counter that statement with.

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Salami

Well, they said something to the extent of "if this is true, then why don't we see any evidence for it in the fossil record?"
I said that I thought that if we looked in precambrian strata, we'd probably find some rudimentary motor far less complex than this, but they accused me of making a remark like that without evidence and therefore "begging the question".
I felt like asking them to explain samites and pelites found in Dalradian folds if they were so knowledgeable about geology, but I thought better of it.

I'd like to elaborate on this slightly: The TTSS is not used in the rotary motor, but is found in parasitic bacteria who use it as a pump for poisoning the host cell. It is shaped according to the shape of the protein it pumps through, or if I wanted to be technical I'd say it corresponds to the tertiary structure of the protein.
What is very interesting is that you will find these systems in bacteria that are not closely related. The point is that these protein structures in the TTSS are very similar to the flagella motor.
What can we deduce from this?
Steveeden would probably start trying to "open my eyes" at this point, but to the rest of us it is clear that the TTSS was taken from these bacteria and used in the flagella for a DIFFERENT PURPOSE.

So what I'm trying to say is that although it might not work if not all the components are present, the components themselves can be taken from other cells and used for a different purpose. Isn't it incredible that the TTSS can do two completely different things?

I hope you found this interesting, I certainly did!
^^^See above!
Well, they wanted "fossil evidence", and the fact that I don't carry any around with me was apparently enough for them to start laughing at me.

Guybrush

That's a tricky way of getting to the main point, I think.

Put simply, the TTSS represents a reduced version of the flagellum which, as you write, is useful for pumping/secreting proteins. Had the flagellum been irreducibly complex, then any "reduced" part of it (like the TTSS) would be useless. The TTSS shows that it is possible for bacteria to evolve a TTSS first and then evolve that structure into something more complex (made up of more proteins) like a flagellum.

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