ID, Irreducable Complexity, and the Eye

Beady

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Beady
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Been thinking about something, and want to try it out, here.

I understand that one major argument for ID is Irreducable Complexity, the supposed principle that something is too complicated to have evolved, because it can't possibly function except as a single, mature, assembled entity. The favored example is the eye (and I remember, some 45 years ago, my confirmation instructor slicing open a cow's eye in class, trying to demonstrate IC as evidence of Creation).

Seems to me that the eye as an example of IC is demonstrably wrong in two ways:

1) There are animals in existence that have fully-developed visual organs that demonstrate the various probable stages of evolution to the modern eye. First, there are fish that have no eyes at all, Then, there are microscopic animals that are able to "visually" sense motion, but nothing else. There are other animals who can sense just motion and shapes. Others can sense motion, shapes and contrast. Then comes black-and-white images (dogs), then color (cats), and finally better visual acuity (humans).

Problem, I don't really have examples of the more primitive stages.

As an extension of this argument, it occurs that there are two possible stages of development that may lie further down the road. One is telescopic/telephoto vision, where a second lens is located in front of or behind the first, and there are muscles to move them back and forth in relation to each other (or would that be a single lens, but with muscles to increase or decrease the curve?). The second would be to develop cones and rod or whatever that can see further into one or both ends of the spectrum.

2) Is there a functional difference between an evolving eye and a defective eye? At what point is a fetus' eyes functional? Is there a point at which the fetus' eyes just "switch on" and they work perfectly? What about the partially blind? Don't they have eyes which simply didn't fully develop? What is the difference between growth, development and evolution?

Mind, I'm not married to any of this; I just want to see how it all stands up.
 
Flatworms have 'eyespots' which generally sense light and dark.

There was a post around hwere someone deconstructed the evolution of the eye. I'll try to look around and see if I can find it again.
 
A range of eye complexity among molusks

(a) The limpet Patella has a simple patch of pigmented cells (photoreceptors)
(b) The slit shell molusk Pleutomaria has an eye-cup.
(c) The Nautillus eye functions like a pinhole camera (an early type of camera lacking a lens). A thick fluid in the cavity helps focus light onto the retina, a layer of photoreceptors.
(d) The eye of Murex, a marine snail, has a primitive lens consisting of a mass of crystal-like cells. The cornea is a transparent region of epithelium (outer skin) that protects the eye and helps focus light.
(e) The squid Loligo has a complex camera-type eye with a cornea, lens, and retina.

From Campbell & Reece's Biology.
 
Dr Adequate said:
A range of eye complexity among molusks

(a) The limpet Patella has a simple patch of pigmented cells (photoreceptors)
(b) The slit shell molusk Pleutomaria has an eye-cup.
(c) The Nautillus eye functions like a pinhole camera (an early type of camera lacking a lens). A thick fluid in the cavity helps focus light onto the retina, a layer of photoreceptors.
(d) The eye of Murex, a marine snail, has a primitive lens consisting of a mass of crystal-like cells. The cornea is a transparent region of epithelium (outer skin) that protects the eye and helps focus light.
(e) The squid Loligo has a complex camera-type eye with a cornea, lens, and retina.

From Campbell & Reece's Biology.
Click to expand...

What can each of these different organs sense?
 
Some animals have crappy eyes, such as the mole. Its eyes have probably de-evolved since they live in the dark anyway. Other animals have eyes that are much more sensitive and precise than ours, such as eagles. The bottom line is living organisms will evolve whatever organ they need in due time, after a series of accidental mutations that happen to be successful.
 
Beady said:
As an extension of this argument, it occurs that there are two possible stages of development that may lie further down the road. One is telescopic/telephoto vision, where a second lens is located in front of or behind the first, and there are muscles to move them back and forth in relation to each other (or would that be a single lens, but with muscles to increase or decrease the curve?). The second would be to develop cones and rod or whatever that can see further into one or both ends of the spectrum.
Click to expand...

Just a quick note, evolution doesn't suppose a more advanced organism as time goes on, simply one that's better suited to its environment.
 
-=Vagrant=- said:
Note that Michael Behe intented to use IC only in biochemical systems, not organs.
Click to expand...

Behe only applies his theory to biochemical systems because he is a biochemist. He sticks with what he knows.

Behe claims that well matched parts can't evolve naturally. If IC had real teeth, I can't think of a reason why you couldn't apply it to larger systems.

Anyway isn't the bacterial flagellum essentially an organ?
 
Beady said:
What can each of these different organs sense?
Click to expand...
Light...

To be more precise:

(a) The simple eyepatch allows detection of motion as evidenced by sudden changes of illumination, may be used to set the body clock; allows simple phototropism.
(b) The eye-cup allows directional motion detection: if you can see change with the left hand side of the cup, but not the right, then the change is to your left.
(c) The pinhole camera, by reducing the size of the aperture, makes this very precise. If we imagine an ideal pinhole of infinitessimal size, then each direction in the real world would corresponds to just one spot on the retina. Now this leads to a trade-off: the smaller the aperture, the better the focus --- but the less actual light gets in. This is partially solved by:
(d) The primitive lens. By doing part of the focussing work, this allows the pinhole to become bigger --- to become a pupil, letting in more light for the same amount of focus.
(e) The complex camera-type eye, in squid, can change the focus by shifting the lens back and forwards in the eye like a camera, with the obvious advantages that come with varying focal depth.

(You will recall that our own eyes change focus by the lens being stretched into different shapes, rather than moved back and forth. It's almost as though two completely separate design teams had set to work independently on the same problem.)
 
If I recall, a squid's eye also has all the blood vessels and nerves on the opposite side of the retina from ours. That is to say, the side you would have put them on had you built an eyeball.
 
clarsct said:
If I recall, a squid's eye also has all the blood vessels and nerves on the opposite side of the retina from ours. That is to say, the side you would have put them on had you built an eyeball.
Click to expand...
Yes, well, hindsight is easy.
 
Dr. A. said:
(You will recall that our own eyes change focus by the lens being stretched into different shapes, rather than moved back and forth. It's almost as though two completely separate design teams had set to work independently on the same problem.)
Click to expand...
Well, as we know, ID doesn't specify how many designers there are. I had assumed one per galaxy, but it might be a bigger team. Perhaps the designer who handled the human eye was on apprenticeship to the one who did the squid eye. Or perhaps he simply didn't do a thorough literature search.

~~ Paul
 
Oh hell

YES! That's IT! Each item had it OWN designer. It isn't Intelligent Design, it's the Intelligent Design Team. Polytheism, or better yet Aminism!

Hmmmmmmm.

It'll need some work, but it ought to throw a monkey wrench in there somewhere...
 
ID is odd. It claims it can look at nature and find the difference between creation and happenstance. ID supporters claim that life is designed. Doesn't that imply that the rest of the universe is the result of chance?
 
This is an older article on circadian rhythm research. IMHO recent research pretty well refutes the notion that the eye could not have evolved out of more primitive functions.

http://www.sciencenews.org/pages/sn_arc98/7_11_98/bob1.htm

I used to hear about the eye being an example of 'creation' quite a lot, but not so much recently. Maybe they have retreated from the claims.

(My view would be that ID is just an elaborate rendering of 'god of the gaps').

You cut open a cow's eye in Sunday school? Kewl.

There seems to have been a danger in sparking an unhealthy scientific interest in how things work...
 
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