tgamble

This may have been answered already (probably has) but I missed it. Is there any resource on the web that goes into the evolution of the eye in detail? I know that every stage that is needed is present in living organisims (and the evolution of these organisims appeared in the expected order?) but how many stages are there and what organisims exactly represent each stage? Is there any page that goes into the biochemical detail of how each stage can evolve into the next?

Thanks for the help.

Also, is the idea that different eyes evolved independently going out or is it to soon to tell?

<a href="http://www.sciencenews.org/sn_arc97/5_10_97/bob1.htm" target="_blank">http://www.sciencenews.org/sn_arc97/5_10_97/bob1.htm</a>

<a href="http://www.pbs.org/wgbh/evolution/library/04/4/l_044_01.html" target="_blank">http://www.pbs.org/wgbh/evolution/library/04/4/l_044_01.html</a>

[ January 12, 2002: Message edited by: tgamble ]</p>

Cthulhu (2)

Everything that has an eye seems to have evolved from something that could sense light, but that does not contradict the independent evolution of eyes.

theyeti

Well this is what I get for being a sleepy-head. I wrote out a whole rant about Denton's eye argument for another group and didn't even know that my favorite gang was discussing it too. So I may as well re-excrete it.

(Please note that I don't even deal with his "optimality" argument here, just the logical consequences of his argument. I seriously doubt that his optimality argument is valid at all, after even a cursory glance, but even if it is, his conclusions are absurd.)

What I find extremely odd is his justification of "pre-adaptation". The fact that this inverted retina is found in fish would seem to destroy the design argument, and Denton even concedes that the "design" is useless for the fish:

Okay, so it *wasn't* pre-adapted for the sake of the fish. Denton's reasoning that then follows this admission requires us to assume that the fish got screwed over for the sake of mammals and birds, as if we endotherms are the favorite pets of the designer. But there's no need for this. If the designer made the inverted retina to begin with, presumabably some time after the origin of life, then there's no reason that s/he/it couldn't have done it at a later date to give mammals and birds their own retinal design, and to leave that of the fish non-inverted. Or s/he/it could have reverted that of fish to one identical to that of the cephlapods. Claiming that the designer has some animosity towards the fish pretty much negates any reasoning that we should expect s/he/it to care about making useful designs (not to mention making us wonder why 2/3 of the Earth is convered with water). He continues:

This is begging the question. Even if we accept that the vertebrate retina is more useful for endotherms, this doesn't mean that it was intended ahead of time. It is precisely because evolution is *not* directed that awkward arangements occur that can later be used adaptively; if evolution were directed, we would not expect awkward arangements in any organism, except possibly non-extant transitionals. His dismissal of undirected evolution is entirely unwarranted; even accepting the inverted retina's usefulness to endotherms, this doesn't mean that it was pre-adapted; it's simply that endotherms have evolved to make the most out of a bad situation. This is in fact a logical necessity if undirected evolution is true -- all de novo adaptations will have their origins as something that is either non-adaptive, or adapted for something else.

The real question is why the designer would pre-adapt something when the entire point of ID is that the designer steps in or guides things to add new adaptations. Did s/he/it suddenly lose the ability to guide evolution after the Devonian? If the point of the vertebrate retina is to help endotherms, why did it step in long
before the appearance of these groups when doing so created bad designs in ectothermic vetrebrates? The extreme illogic of this scenario makes the undirected one much more reasonable, even if we concede the usefulness of the inverted retina.

Bullshit. It is maladaptive, it's maladaptive for the fish! (And likely amphibians and reptiles too). Denton said so himself! How can he hold two contradictory notions like this, that the retina is both adaptive and maladaptive and therefore was designed?! I have a feeling that Denton hasn't learned much since his molecular phylogeny fiasco.

theyeti

[ January 15, 2002: Message edited by: theyeti ]</p>

davidH

ok, the moderator deleted my last post on this.

When people bring up the arguement of why we see some imperfections in our bodies and that a creator could never have made it with the imperfections. (Not saying an "inverted" eye is.)
This is the reason why;

Whenever Adam and Eve sinned, they brought sin into a perfect world. God had created everything perfectly and nothing was wrong.

"And God saw that it was good."

But whenever sin entered the world it "distorted"
the perfect creation that God had made and things that God had created perfectly were now imperfect.
Like when God said to adam - the ground is cursed because of you - it will produce thorns..etc.
So that is why when looking at living things you can't argue that a creator could never have created something that's imperfect. The way things are now is not the way they would have been if there was no sin in the world.

I just thought I'd put that up again because a few of you were putting this suggestion forward.


Now, about the squid - it's retina is not "inverted" because it has a greater need for light in the depths of the sea. It feeds at night and so the fact that the nerves don't cover the retina enable it to see far more effectively than us. To me that shows design - the squid were made by God for the sea and so God made their eyes so that they could see down there.

You ask why our eyes aren't like that. Apart from the facts already stated at the beginning, maybe there's another reason.
I read on a post on the other topic I was doing that the nerves and all only allow 10% of photons through - not sure on this though.
But at a guess I would say that the optic nerves shade our retina from the sun. If we had no nerves "shading" the retina we would have up near the 90% of photons hitting the retina. Now how would that affect the vision?
Would light be 9 or 10 times as intense? If so then we would be blinded. As it's the intensity of light in a laser pen that damages the retina.
Again if this is the case then that suggests design. That the nerves would shade the light but still allow enough for perfectly good vision and the capillaries shade the light too but also remove dead cells. etc. I can see no better way for the eye to be formed - by putting the nerves behind the retina you would only cause more problems and the intensity of the light might be too great.

It might be interesting to see what would happen to the retina of a squid if it is exposed to daylight - does it cause blindness if exposed for too long? I reckon it would be worth investigating.

But either way nothing about the eye disproves the fact that God created it. Infact the complexity of it and all the tremors, saccades and drifts - make the odds of it occuring by mutations and natural selection vast. Infact I believe they are so vast that it's just not plausible to believe that they could have occurred like that.

On my other topic we debated the evolution of the eye but no one has explained a way in which it could have arisen that could be satisfactory. One person said that none of the theory's satisfied him - but I guess he believed it anyway.

Mageth

Whenever Adam and Eve sinned, they brought sin into a perfect world. God had created everything perfectly and nothing was wrong.

David, can you see what's wrong with this? How can you say god created everything perfectly with nothing wrong when he left in a major flaw that would allow the act of eating an apple to screw everything up? Sounds like a major flaw and an imperfect creation from the start, to me.

Mageth

As far as your (yuk yuk chuckle) eye theory goes, why would a designer not bring the nerves in from the back and use another, simpler mechanism (that would not create a blind spot) to block the (supposedly) excess photons, or otherwise design the eye so the excess photons wouldn't damage it (photons damaging an eye sounds like a design flaw in and of itself, to me...)?

BTW, there's lots of nocturnal terrestrial animals that could use a less-obstructed retina such as that found on the squid. I wouldn't mind being able to see a little better at night myself.

davidH

No, it wasn't a flaw. It was called freedom. God valued freedom more than anything else because if humans weren't free but HAD to love God that would bring him no happiness. As a robot programmed to say "I love you" to you, would bring you content.
But freedom meant complete freedom - that meant the possiblity of disobeying God - if they didn't have this choice they wouldn't be free, would they?
So that's why. I covered some of this in another debate.

Doh, it's been deleted or something - this new server is messing up a lot of stuff. When I find it I'll put it up, cause you can't start a new topic here =)

davidH

Mageth, maybe that's why God created us with 2 eyes, cause one eye sees everything the blind spot of the other doesn't.
And about the nerves and you seeing better in the night - that might be at the expense of you being blinded the following morning when you look out of the window and see the light of the sun.

theyeti

Yes, we've heard that argument before. Nothing could possibly be more ad hoc and contrived. It's rather contradictory too. If The Curse is resulting in things getting worse, then why are there things that work great? Is The Curse highly selective about what it curses? What about horrible devices, like toxin transporters used by pathogenic bacteria, that are highly complex and well adapted to what they do? Was that The Curse? If so, then it refutes the claim that only God could create complex adaptations.


Guess what. Fish live in the sea too, sometimes very deep, and they also have inverted retinas which are not optimal. Even Denton acknowledges this; he just imagines that the retina was "pre-adapted" for birds and mammals and screw the fish, amphibians, and reptiles. So if God created the squid eye so they could see down there, can we safely assume that He did not create the fish eye? Or are we going to blame that one on The Curse too?

The idea that the eye is designed to avoid light because it's also designed as too sensitive is circular. It could be designed without being too sensitive, and thus eliminate the need for a suboptimal compensatory design. It's not as if the eye un-inverts itself at night, and then re-iverts itself when the sun comes up -- it's always inverted and always taking in less light then it could. Besides, the real issue is the blind spot caused by the optic nerve.

Again, it makes no sense to design a tissue for sensing light that will get damaged under normal circumstances. It's like putting a setting on a radio that is loud enough to make you permanently deaf, and then putting a bar on the dial to keep you from using that setting.

Since many squid live in shallow waters, I would say no. Octopi are also known to come out of the water on occasion.

Nothing could disprove the idea that God created it; it's not a testable hypothesis and does not fit under the rubric of science. But we can show that if it were desgined by someone, then that designer is not consistent, benevolent, or omnipotent. If one of the eye designs is better than the other, then one group is getting screwed or has a bad designer. This makes it difficult to justify design, at least as advanced by creationist/IDist.

It's been so done to death, I don't want to get into it. Use the search engine to find lots of past discussions of eye evolution with plenty of highly detailed scenarios. There are lots of simple and intermediate eyes to be found in nature now, so the claim that it couldn't have evolved through functional intermediates is empirically false.

theyeti

theyeti

Everything from 2001 has been archived. Try checkhing there.

theyeti