Stephen Meyer had a piece published in the Daily Telegraph and this generated two surprisingly supportive letters.
The letter from Dr Wainwright at Sheffield is interesting as he is an agnostic. If my memory serves me correctly he believes in Panspermia - life from outer space.
13 comments:
Panspermia supports ID exactly how? In the classic, Sir Frederick Hoyle panspermia, the evolution merely occurred somewhere else.
I was slightly surprised to see such a strong emphasis on irreducible complexity as an indication of intelligent design, as that's probably the most thoroughly debunked of the ID claims (not to mention being a vestige of Creation Science). Heck, arches are irreducibly complex structures and they form in nature all the time. Biological irreducible complexity forms by much the same means (co-option and removal of scaffolding).
This is quite apart from the oft-discussed issue of whether the bacterial flagellum is actually irreducibly complex.
Lifewish,
You said:
"Biological irreducible complexity forms by much the same means (co-option and removal of scaffolding)."
Have you got a few good examples where we know this has actually happened?
[i]co-option and the notion of a support system -both would need to be having a seperate function all the time the flagellum,for instance was being built, or they would be selected against.[/i]
Until they got included into the protoflagellum, yes. That's not so much of an issue, though, since the flagellum isn't actually irreducibly complex.
Now, the Krebs cycle, that's irreducibly complex. TalkOrigins has a good post on it. The short version:
"In the evolution of the metabolism, the achievement of the fundamental steps of the Krebs cycle was not difficult at all. Almost all of its structure previously existed for very different purposes (anabolic), and cells had to add just one enzyme (succinyl-CoA synthetase for the transformation of succynol CoA into succinate) to convert a collection of different pathways into the central cyclic pathway of the metabolism. This is one of the most clear cases of opportunism we can find in evolution."
It's something that most computer programmers are probably familiar with - the program that, in breaking horrendously, actually manages to do something interesting. My favourite was when my attempt to write images to bitmap format ended up producing some extremely pretty patterns.
I'm trying to think what else would qualify as irreducibly complex that I could discuss. Any suggestions? Am I allowed to include "artificial life" examples? They evolve faster than the real-life versions so it's easier to watch irreducible complexity actually evolving rather than having to infer its evolution from the body of evidence (I can think of at least one example off the top of my head).
Just realised I didn't answer a few bits of Mike Godfrey's post. For a start, I should elaborate on my comment about the irreducible complexity of the flagellum - there are some variants of it that lack the L- and P-rings. Next question:
Also what use for instance is the hook (universla joint) outside of the flagellum,where else is its function found?
What is the function of the support system before the IC system turned up?
You mean the bend in the flagellum shaft? That'd tend to appear naturally, I'd have thought - IIRC, the shaft (which was originally just an excretion) is believed to have been coopted to help the bacterium cling to stuff, which wouldn't work so well if the bacterium looked like a pincushion. Hence, it would have been evolutionarily probable for the shaft to develop a bend in it.
Does that answer your question, or am I talking about something completely different?
What is the function of the support system before the IC system turned up?
I'm not sure quite what you mean by the "support system". Could you elaborate?
lifewish, I looked on the site and didn't see the evolvable pathway to the Krebs cycle. Maybe I just didnt see it?
"Almost all of its structure previously existed for very different purposes"
Would you mind telling me which cycles these structures existed in previously?
"This is one of the most clear cases of opportunism we can find in evolution."
Again is there a pathway here that I'm missing? How do we know it evolved?
Thanks
Nathan: just so you know, I'm currently trying to get hold of the paper that the quote I referenced comes from. (I'd have it already if the Springer site wasn't missing a few authorised IP ranges, including the one I'm in).
As with the Nilsson and Pelger paper, I will of course be unable to forward anyone a copy because that would possibly be in breach of Big Scary Copyright Laws. On a completely unrelated note, if anyone has an address they perfer to receive files at, get in touch with me at ajl59 at cam.ac.uk
[quote]The support system I am refering to is the 'scaffolding' you mentioned.[/quote]
I was using the word "scaffolding" in a slightly different context from how I think you're using it. What I meant was that irreducible complexity can be formed when a reducibly complex system is stripped down to the bare essentials. For example, lungs aren't something you'd really expect to be able to evolve, given that life began in the sea. How on earth does one get from a fish to a ferret, when the former will suffocate the moment it leaves the water?
IIUC, the current understanding is that the lungs started off as just a swim bladder, and only subsequently got coopted for breathing when the fish "realised" that here was a ruddy great bubble of oxygen they were carrying around with them. Of course, they'd still have gills. But then some fish realised that they could actually leave the water now that they weren't dependent on H2O flowing past their gills. So they gradually left the oceans and, coming across this new land practically bereft of large life forms, spread like there was no tomorrow.
In doing so, their gills were completely useless - the oceans were too cutthroat an environment for them to easily go back to. So they dwindled away, until the lungs of the critter formed part of its irreducibly complex anatomy - if you removed the lungs, the critter would croak.
And one of those fish was probably our great-great-great...
(2 hours later)
...great-great-grandfather. Kinda puts life in perspective.
Right, less lecturing, on with the discussion. Sorry for going on a bit.
The flagellum with L,P S,M & C rings- remove any part of this system and it stops functioning.
My understanding is that bacterial flagella exist that do not incorporate the L- and P-rings. Therefore, though specific variants of the flagellum may fall apart without them, the general concept of a flagellum without them is perfectly sound and there's no reason to believe it couldn't exist as an intermediate step.
My main questions are regarding the scaffold (secretory system) which allows the IC falgellum to be produced.
In this senario we have a protoflagellum and its support system-all of which is under selection pressure -pressure based on function.
As evolution is blind each change however small must be functional.
The protoflagellum is being built by the support system -what function do both currently meet in order to avoid selection?
I should note that at this stage it's a bit early to be calling it a protoflagellum. The secretory system will be performing its role of getting rid of gunk in the cell. Some of the gunk will turn out not to want to let go that easily, so it gets gradually shoved out, forming the shaft of what would later be the flagellum (I wonder if this is how hair evolved?). This shaft turns out to be useful for helping the cell stick to stuff, which ensures that it will generally stay near nutrition (rather than being swept off into the wide, foodless blue yonder).
A few nontillion bacteria later, one of them accidentally gets an ion pump stuck to its base. The whole thing starts to spin, which means that most of the nasty chemicals go away faster. Later this dispersal system gets coopted as an outboard motor.
For the record, I'm getting a lot of this from the TalkOrigins FAQ which, though brief, provides a good framework for further study.
Sorry for the long post oh just thought of one other thing -you said the hook tends to appear naturally -what evidence is there for that ?
You think you have problems with long posts??
I have no idea whether there's any supporting evidence for this. However, my observation is that putting a bend in the shaft would increase the amount of shaft that was pressed against a nearby object, thus making it better for sticking to things. Therefore, it seems fairly plausible that a bend would develop.
And one of those fish was probably our great-great-great...
(2 hours later)
...great-great-grandfather. Kinda puts life in perspective.
Oops...
The first fish moved onto land about 365MYA (according to wikipedia). Given that I can say about one "great" a second, and assuming a (very conservative) animal lifespan of 10 years, this means I should have kept saying "great" for about a year and a half (with no time off for good behaviour). Now that really puts life in perspective.
Sorry, did we ever get those pathways for the formation of IC structures? That we KNOW have evolved?
Also thanks for the fish story. I was wondering how they did that.
Sorry, did we ever get those pathways for the formation of IC structures? That we KNOW have evolved?
Technically there are no natural systems that we KNOW have evolved - for all we know, God is wandering the Earth modifying bacteria to eat nylon as we speak. So, two questions:
1) am I allowed to give pathways for IC structures that we are fairly sure evolved, or is that circular reasoning?
2) am I allowed to include examples taken artificial life (genetic algorithms et al)? We can probably be fairly sure that God isn't tampering with the computers (although the Devil might be, I'm never quite sure :P).
Slightly OT: I'm still trying to get at the paper on evolution of the Krebs cycle - hopefully I'll be able to grab it when I pass through the maths dept. in a few minutes.
I would like to see clear cut BIOLOGICAL pathways to irreducibly complex structures. The Krebs cycle would be interesting.
OK, I've roped a couple of biologists into getting at the article for me. Should have it by tomorrow (if not I'll beat them round the head til it shows up).
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