the eye thread.

[Biblewriter]

I have been examining the alleged evolution of the eye. For the purpose of this discussion I have been using the presentation in Wickipedia. This presentation is typicial of the gross oversimplification typically found in evolutionary explanations.

As this is a very complex subject, I propose to begin with only the alleged first step. The development of a light sensitive patch.

If this new type of sensory cell and its associated nerves and interpretative area did not come about by a series of gradual steps, then they must have all developed at the same time. Such a remarkable genetic accident is essentially unthinkable. But if all the parts of this remarkable new system did not develop at the same time, then they had to have come about through a series of gradual steps.

So now I ask the evolutionists in this forum to propose a series of steps by which a cell designed to sense pressure, pain, or temperature could mutate into a cell designed to sense light, along with appropriately modified nerve cells and an appropriate interpretative area in the brain.

In defining such a series of steps, we need to remember that light sensing cells are not only shaped differently from nerves such as those used to sense presure or pain, they work in an entirely different way, using a different set of chemical reactions.

In addition, the nerves that carry light information to the brain are different from the nerves that carry touch information to the brain.

So how does this vastly different type of sensory system come about by a series of minor steps? We must remember that each sequential step must of necessity give individuals that posess that variation a distinct selective advantage.

 

[birdan]

I have been examining the alleged evolution of the eye. For the purpose of this discussion I have been using the presentation in Wickipedia. This presentation is typicial of the gross oversimplification typically found in evolutionary explanations.

As this is a very complex subject, I propose to begin with only the alleged first step. The development of a light sensitive patch.

If you wish to have a discussion with 'evolutionists', it is probably a good idea to post this in the general Origins Theology forum, and not here in the creationism forum. But since you asked ....

I hope you realize that the Wikipedia article only provides a very high level summary of the topic, and shouldn't be used to draw conclusions such as 'gross oversimplification typically found in evolutionary explanations'. In fact, I'm sure you could read relevant material full time for several years.

If this new type of sensory cell and its associated nerves and interpretative area did not come about by a series of gradual steps, then they must have all developed at the same time. Such a remarkable genetic accident is essentially unthinkable. But if all the parts of this remarkable new system did not develop at the same time, then they had to have come about through a series of gradual steps.

So now I ask the evolutionists in this forum to propose a series of steps by which a cell designed to sense pressure, pain, or temperature could mutate into a cell designed to sense light, along with appropriately modified nerve cells and an appropriate interpretative area in the brain.

In defining such a series of steps, we need to remember that light sensing cells are not only shaped differently from nerves such as those used to sense presure or pain, they work in an entirely different way, using a different set of chemical reactions.

In addition, the nerves that carry light information to the brain are different from the nerves that carry touch information to the brain.

So how does this vastly different type of sensory system come about by a series of minor steps? We must remember that each sequential step must of necessity give individuals that posess that variation a distinct selective advantage.

I think the problem here is that you are starting too far into the evolutionary process. It's sort of like your asking how step 20 could have happened all at once, when in fact there are many steps leading up to step 20. So let's go back a bit and start closer to step 1.

Eye spots do not have to be unique cells. In fact many single cell critters have eye spots (stigma) which help that single cell detect light. A good example would be the euglena, which is a single cell protist that is part animal (it digests outside nutrients like an amoeba) and part plant (it contains chloroplasts which convert light into energy via photsynthesis).

It has a flagellum which it uses to move about. At the base of the flagellum is its stigma, which interferes with light that falls on light sensitive crystals at the base of the flagellum. Since the euglena is always rotating on its long axis, the eyespot 'detects' light and this in turn causes the flagellum to rotate stronger in the direction towards the light. Note there is no need for nerves or neural processing - it is a simple photo-chemical reaction which causes the steering towards the light. The euglena has no 'choice' on where to go, it's chemical reactions make it go towards the light.

You may ask where did the flagellum, photo-sensitive crystals, stigma, etc. come from, but each of those topics can evoke lengthy replies (evolutionary explanations are far from 'oversimplified'!), and you seem to want to concentrate on eye evolution.

So, we have a very basic light detecting mechanism in a single cell protist. That would be much closer to step 1 than your example. In the euglena, as in all single cell light-sensitive organisms, the 'light detection mechanism' is simply a reaction between a small set of molecules.

For a second step, I'd suggest you read up on volvox - a colony of cells (but not a true multi-cellular organism) which form a hollow sphere with an opening at one end. The 'eye spot' in this group of cells is located inside the sphere opposite the opening (all the cells have stigma, but the cells mentioned have more pronounced stigma), and thus provides a better way than the euglena to detect the direction of the light. So now we have a basic step 2 - a group of cells acting as a unit and which are able (better than single cells) to detect and respond to light.

But it probably would be a good idea to move this question out of the creationism forum ....

Hope some of this helps. What I wrote is still a very simplified version. I checked PubMed and Google Scholar for articles only on 'Euglena stigma', and there were over 800!

 

[Biblewriter]

If you wish to have a discussion with 'evolutionists', it is probably a good idea to post this in the general Origins Theology forum, and not here in the creationism forum. But since you asked ....

I thought that was where I was when I posted this. I asked for it to be moved, but it hasn't happened yet.

I hope you realize that the Wikipedia article only provides a very high level summary of the topic, and shouldn't be used to draw conclusions such as 'gross oversimplification typically found in evolutionary explanations'. In fact, I'm sure you could read relevant material full time for several years.

I think the problem here is that you are starting too far into the evolutionary process. It's sort of like your asking how step 20 could have happened all at once, when in fact there are many steps leading up to step 20. So let's go back a bit and start closer to step 1.

Eye spots do not have to be unique cells. In fact many single cell critters have eye spots (stigma) which help that single cell detect light. A good example would be the euglena, which is a single cell protist that is part animal (it digests outside nutrients like an amoeba) and part plant (it contains chloroplasts which convert light into energy via photsynthesis).

It has a flagellum which it uses to move about. At the base of the flagellum is its stigma, which interferes with light that falls on light sensitive crystals at the base of the flagellum. Since the euglena is always rotating on its long axis, the eyespot 'detects' light and this in turn causes the flagellum to rotate stronger in the direction towards the light. Note there is no need for nerves or neural processing - it is a simple photo-chemical reaction which causes the steering towards the light. The euglena has no 'choice' on where to go, it's chemical reactions make it go towards the light.

You may ask where did the flagellum, photo-sensitive crystals, stigma, etc. come from, but each of those topics can evoke lengthy replies (evolutionary explanations are far from 'oversimplified'!), and you seem to want to concentrate on eye evolution.

So, we have a very basic light detecting mechanism in a single cell protist. That would be much closer to step 1 than your example. In the euglena, as in all single cell light-sensitive organisms, the 'light detection mechanism' is simply a reaction between a small set of molecules.

For a second step, I'd suggest you read up on volvox - a colony of cells (but not a true multi-cellular organism) which form a hollow sphere with an opening at one end. The 'eye spot' in this group of cells is located inside the sphere opposite the opening (all the cells have stigma, but the cells mentioned have more pronounced stigma), and thus provides a better way than the euglena to detect the direction of the light. So now we have a basic step 2 - a group of cells acting as a unit and which are able (better than single cells) to detect and respond to light.

But it probably would be a good idea to move this question out of the creationism forum ....

Hope some of this helps. What I wrote is still a very simplified version. I checked PubMed and Google Scholar for articles only on 'Euglena stigma', and there were over 800!

I am not asking for step 20, or for step 500, to happen "all at once."

I am asking someone to explain a sequence by which a light sensitive spot (complete with nerves to carry the signal to the brain and a center in the brain to interpret that signal,) could evolve in gradual steps, every one of which would give its posessor a distinct reproductive advantage.

Without such a sequence, the light sensitive spot would have to have appeared suddenly, complete with the necessary nerves and brain cells. As this is unthinkable, inabitlty to demonstrate the possibility of such a sequence is inabilty to explain how this organ could have evolved.

You have not even begun to answer the question .

 

[Biblewriter]

After overcoming the problem of developing a light sensitive spot by gradual changes, we come to the next impassable point.

It is indeed possible for a light sensitive spot to "happen" to be located in a low spot on the head, and for this low spot to gradually grow deeper, even to the point of a pinhole opening. Natural selection could indeed accomplish these.

But how to close this opening? The minimum requirement would be for some form of a transparent cornea, combined with some kind of a transparent retinal fluid. Both would of necessity have to appear at the same time.

Again, how could an iris develop by gradual steps? To be successful, it would have to have a movable membrane, an apparatus to move that membrane, the nerves to direct that apparatus, and a section of the brain to control it.

The same applies to the origin of a lens.

But the biggest problem of all is the development of an eyeball. Now this light sensitive cavity must move into a socket along with the mussels to move it, the nerves to control the mussels, and a brain section to direct the nerves.

Even the possibility of an eye evolving, much less an account of its evolution, cannot be demonstrated until someone can demonstrate a logical process whereby each of these transitions could have developed gradually, with each stage giving its possessors a distinct reproductive advantage.

Such is the case with most of the organs of most of the organisms. They cannot have developed gradually, for natural selection would reject them as they began to develop. They had to appear suddenly in a more or less complete form. Assuming that such a thing happened even once is preposterous. But assuming that such changes took place regularly takes far more faith than believing in creation.

 

[shernren]

I have been examining the alleged evolution of the eye. For the purpose of this discussion I have been using the presentation in Wickipedia. This presentation is typicial of the gross oversimplification typically found in evolutionary explanations.

I'll just say that of course it's grossly oversimplified. The entire content of Wikipedia is nothing but grossly oversimplified summaries of expert knowledge on certain topics. One might as well try to do theology with a My First Picture Bible.

Since this is the Creationist subforum I won't say much more. You'll have to stick your neck out and put this in the Origins forum if you really want substantive input. (Although there seems to be a new breed of TEs who really wouldn't care one way or another ... )

 

[vossler]

Since this is the Creationist subforum I won't say much more. You'll have to stick your neck out and put this in the Origins forum if you really want substantive input. (Although there seems to be a new breed of TEs who really wouldn't care one way or another ... )

New breed?!?!?

 

[mark kennedy]

So now I ask the evolutionists in this forum to propose a series of steps by which a cell designed to sense pressure, pain, or temperature could mutate into a cell designed to sense light, along with appropriately modified nerve cells and an appropriate interpretative area in the brain ...

....necessity give individuals that posess that variation a distinct selective advantage.

I don't think you are going to get an intelligent response, let alone an answer, they simply don't have one. Major adaptive changes are a given in in TOE not something that has to be substantiated. I have argued for years that the three fold expansion of the human brain from that of apes is simply impossible. To date I have not heard a single argument that makes sense of such a rapid expansion which is typical of TOE. You are never allowed to question it,

It's not just the eye and by the way Darwin honestly admited that it was a null hypothesis if it could not be proven that precursors are possible.

“If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.” (Darwin, On the Origin of Species)​

With a cranial capacity nearly three times that of the chimpanzee the molecular basis for this giant leap in evolutionary history is still almost, completely unknown. Changes in brain related genes are characterized by debilitating disease and disorder and yet our decent from a common ancestor with the chimpanzee would have had to be marked by a massive overhaul of brain related genes. I have proposed that a critical examination of common descent in the light of modern insights into molecular mechanisms of inheritance is the single strongest argument against human/ape common ancestry. The actual arguments that should exist against such a proposal is nonexistant because they don't have one and they don't need one.

Theistic Evolutionists have the deluded notion that they can accept evolution and God, nothing could be further from the truth. This is not about science or evidence it's about religion and atheists believe they can do religion better then Christians. They need not prove anything, you just have to assume everything. It's as simple as that.

Grace and peace,
Mark

 

[Biblewriter]

I don't think you are going to get an intelligent response, let alone an answer, they simply don't have one. Major adaptive changes are a given in in TOE not something that has to be substantiated....This is not about science or evidence it's about religion and atheists believe they can do religion better then Christians. They need not prove anything, you just have to assume everything. It's as simple as that.

Grace and peace,
Mark

I have so far received no answer to this challenge. (Except the absurd answer about euglena, which do not have anything even resembling nerves, and by the poster's own admission cannot make choices based on their purported light detection ability.)

It is simply impossible for a light sensitive spot on the surface of an organism to gradually develop into a light sensitive recess with a pinhole opening. It is true that once the recess became deep enough that its opening began to act like a pinhole, that would give its owners a distinct reproductive advantage. But until the opening got that deep, such a recess would actually be a disadvantage, rather than an advantage.

There are two distinct evolutionary impossibilities in this supposed process. First, as the recess began to develop, it would only be a place to catch dirt, thus rendering it a detrimental mutation that would be rejected by natural selection. Then, as the recess became deeper, it would restrict the organism's field of vision for eons before it became deep enough to act as a pinhole lens. This would be a very strong disadvantage, and would thus be rejected by natural selection.

Nothing in this line of reasoning is based on any religious assumption of any kind. It is based entirely on standard evolutionary theory. But here we see two places where evolutionary theory totally breaks down in this first step of the supposed evolution of the eye.

The same is true in every step of this supposed evolutionary sequence.

Until someone can demonstrate a series of small steps by which each of these major changes could have taken place, with each step conferring a distinct reproductive advantage over the previous step, no one can demonstrate that such an evolutionary sequence is even possible, much less probable.

 

[Mallon]

But until the opening got that deep, such a recess would actually be a disadvantage, rather than an advantage.

Tell that to the planaria.

 

[Willtor]

Eye Video

You might look up some of Dan-E. Nilsson's research if you're near a university and can get on their network.

 

[MattLangley]

A netbook is such an amazingly complex piece of technology that serves such a specific purpose that there is no way it could have been developed in steps, it must have only come together in a single act of creation...

 

[Biblewriter]

Tell that to the planaria.

Are you denying the accuracy of what I said?


I pointed out a distinct disadvantage to having an eye spot located in a recess as opposed to having such a spot located on a flat surface.

Now we have Dan-E Nilsson's comments to deal with. He claims that a restricted field of vision is actually an advantage!

Even if he were correct about this, the rest of what he says in his video is garbage. To imagine that such a development could take place in a few hundred thousand generations is pure nonsense. And he glibly talks about lenses "developed," without the slightest explanation of how they appeared in the first place!

Nilsson glibly speaks of a lens developing at the opening the opening, without the slightest explanation of the order in which the elements he posits appeared. For his theory to work, a transparent, or at least transulcent, covering over the opening had to have suddenly appeared by a single mutation. At the same time a transparent, or at least a translucent, fluid would have
appeared inside the cavity. Unless both of these were at least translucent, the sudden appearance of such a combination would be a crippling mutation.

But he passes over this stage, and posits a second membrane with a fluid between them. The fluid between these membranes would have to have a refractive index different from the fluid in the rest of the cavity, otherwise it could not focus light. So now we have to have a mutation producing a second membrane, a second mutation producing a second fluid materially different from the first fluid, and a third mutation confering an increased pressure in this fluid. Any of these would be useless without both of the others. The probability of all these mutations happening in the same species, and close enough together to act in combination is impossibly small. But unless this happened, the rest of his theory is nonsense.

 

[Mallon]

Are you denying the accuracy of what I said?

Yes, because of existence of planarians shows that dirt trapped in cupped eyespots is not a problem.
Perhaps you could test your idea by building a functional model to show that cupped eyespots do trap dirt to detrimental levels. Don't forget to account for the fact that these eyes would have evolved underwater.
In fact, I suspect a sufficiently-cupped eyespot would create eddies that would help keep the primitive eye clean. Rudwick (1964) showed this to be the case in the openings of richthofenid brachiopods.
I should also point out that a deepening eye cup would also produce sharper images as a result of the narrowing of proto-pupil relative to the light-sensitive retina. This would have a strong selective advantage, particularly in predators that do not need peripheral vision.

 

[Willtor]

...

Now we have Dan-E Nilsson's comments to deal with. He claims that a restricted field of vision is actually an advantage!

This is not quite what he said. You should watch the video again. He said it was an advantage over what came before. He also demonstrated this with his little apparatus.

Even if he were correct about this, the rest of what he says in his video is garbage. To imagine that such a development could take place in a few hundred thousand generations is pure nonsense. And he glibly talks about lenses "developed," without the slightest explanation of how they appeared in the first place!

Nilsson glibly speaks of a lens developing at the opening the opening, without the slightest explanation of the order in which the elements he posits appeared. For his theory to work, a transparent, or at least transulcent, covering over the opening had to have suddenly appeared by a single mutation. At the same time a transparent, or at least a translucent, fluid would have
appeared inside the cavity. Unless both of these were at least translucent, the sudden appearance of such a combination would be a crippling mutation.

But he passes over this stage, and posits a second membrane with a fluid between them. The fluid between these membranes would have to have a refractive index different from the fluid in the rest of the cavity, otherwise it could not focus light. So now we have to have a mutation producing a second membrane, a second mutation producing a second fluid materially different from the first fluid, and a third mutation confering an increased pressure in this fluid. Any of these would be useless without both of the others. The probability of all these mutations happening in the same species, and close enough together to act in combination is impossibly small. But unless this happened, the rest of his theory is nonsense.

Ah, I think I see the problem. You appear to believe that the video contains the entire content of his research. This is not correct. As I suggested earlier, you can access the content of his research if you live near a university with a subscription to the requisite publications.

That aside, even I could posit a sequence of positive stages that would allow for the lens to appear. Now, I haven't researched the matter so I don't know if what I might posit would have any correspondence to what actually occurred. But surely if I can hypothesize so can you.

 

[Biblewriter]

Yes, because of existence of planarians shows that dirt trapped in cupped eyespots is not a problem.

I take it you have never had a blackhead!

Indeed, dirt would not be a serious problem to a very shallow recess, but as it grew deeper, it would.

Perhaps you could test your idea by building a functional model to show that cupped eyespots do trap dirt to detrimental levels. Don't forget to account for the fact that these eyes would have evolved underwater.
In fact, I suspect a sufficiently-cupped eyespot would create eddies that would help keep the primitive eye clean. Rudwick (1964) showed this to be the case in the openings of richthofenid brachiopods.
I should also point out that a deepening eye cup would also produce sharper images as a result of the narrowing of proto-pupil relative to the light-sensitive retina. This would have a strong selective advantage, particularly in predators that do not need peripheral vision.

Here the key word is "sufficiently-cupped." I recognized this in my initial post on this subject. I used the trigger point of deep enough to act as a pin-hole lens, but the video demonstrates that the trigger point may be more shallow than that. But the point is that until the recess is deep enough to confer a distinct advantage, natural selection would reject it as vestigial.

My approach to this question is that of a mechanical engineer, as that was the field in which I practiced as an applied scientist. I analyze the theory on the basis of the mechanics of how it works.

We have before us a basic theory of how evolution operates. This theory is that random changes in the genetic structure of a species occur through mutations. When one of these random changes produces a distinct reproductive advantage over the previous condition, natural selection will favor that change, and the previous condition will gradually be phased out.

But for this process to operate, each and every stage in the development process must of necessity confer a distinct reproductive advantage over the previous condition. If even one stage fails to confer such an advantage, the process cannot go forward.

The whole point of all this is that for evolution to have occurred, one of two things absolutely must have occurred. Either the process described above must have taken place, or the "new" organ must have suddenly appeared as a result of a single mutation. There is no third choice available.

Since this alternative suggests Intelligent Design, it is considered unacceptable. But this is the only choice available unless it is possible to demonstrate an unbroken series of small advantageous steps by which the organ could have developed.

 

[Biblewriter]

This is not quite what he said. You should watch the video again. He said it was an advantage over what came before. He also demonstrated this with his little apparatus.

Yes, he said it was an advantage over what came before, but that is saying it is advantageous. His little demonstration indeed demonstrates that a reduced field of vision will allow greater discrimination in the location of a light or a shadow. But it neglects the fact that a reduced field of vision also reduces what is seen.

It is common knowledge that enhanced peripheral vision is a distinct advantage in sports, and this would obviously apply also in warfare. The "eat or be eaten" jungle of evolution can only be compared to warfare. There is clearly a point at which improved discrimination will trump a wider field of vision, but I do not think that would apply in the early states of this development.

Ah, I think I see the problem. You appear to believe that the video contains the entire content of his research. This is not correct. As I suggested earlier, you can access the content of his research if you live near a university with a subscription to the requisite publications.

I understood that, but my point was, and remains, that too many things would have to appear simultaneously.

That aside, even I could posit a sequence of positive stages that would allow for the lens to appear. Now, I haven't researched the matter so I don't know if what I might posit would have any correspondence to what actually occurred. But surely if I can hypothesize so can you.

I do not believe that such a series can be hypothesized such, for I do not believe this could have happened. (And I do not mean that my faith would not allow this. I mean that basic evolutionary theory would not allow it.)

Any attempting to do this must demonstrate that every change is small, and that every change confers a distinct advantage over the previous condition.

I checked out Dan-e Nilsson, and see that he and Suzanne Plegar have attempted this, and am going to suspend my participation in this discussion until I can obtain their paper.

 

[Willtor]

Yes, he said it was an advantage over what came before, but that is saying it is advantageous. His little demonstration indeed demonstrates that a reduced field of vision will allow greater discrimination in the location of a light or a shadow. But it neglects the fact that a reduced field of vision also reduces what is seen.

It is common knowledge that enhanced peripheral vision is a distinct advantage in sports, and this would obviously apply also in warfare. The "eat or be eaten" jungle of evolution can only be compared to warfare. There is clearly a point at which improved discrimination will trump a wider field of vision, but I do not think that would apply in the early states of this development.

Pinhole vision works pretty well for the nautilus. Are you saying that it thrives in spite of what is a disadvantage over what scientists are saying came before?

I understood that, but my point was, and remains, that too many things would have to appear simultaneously.

I do not believe that such a series can be hypothesized such, for I do not believe this could have happened. (And I do not mean that my faith would not allow this. I mean that basic evolutionary theory would not allow it.)

Any attempting to do this must demonstrate that every change is small, and that every change confers a distinct advantage over the previous condition.

I think a lens would develop quite simply, especially if it develops in an aquatic population. But --

I checked out Dan-e Nilsson, and see that he and Suzanne Plegar have attempted this, and am going to suspend my participation in this discussion until I can obtain their paper.

No problem. I'd be interested to hear what they say (or what their sources say) on the matter.

 

[Mallon]

I take it you have never had a blackhead!

Indeed, dirt would not be a serious problem to a very shallow recess, but as it grew deeper, it would.

Please demonstrate it. If the eye evolved underwater, as it is believed, would it not be constantly flushed out? Particularly when the animal is moving?
How do you suppose Nautilus deals with this problem? It has a "pinhole" eye, but the opening is quite large. Certainly large enough for silt to get in there:

But for this process to operate, each and every stage in the development process must of necessity confer a distinct reproductive advantage over the previous condition. If even one stage fails to confer such an advantage, the process cannot go forward.

Not all evolutionary changes are necessarily adaptive. Consider that pleiotropy allows several non-adaptive traits to 'piggyback' on an adaptive one. Also be sure to check out Gould's famous essay on evolutionary 'spandrels':

The Spandrels of San Marco and the Panglossian Paradigm:

That said, I still don't see (ha!) where in the evolution from flat eyespots to pinhole eyes the selective advantage fails. I certainly don't think you've demonstrated that trapped dirt/sand/silt would be a significant problem.