Talk:Eye

From EvoWiki

Para 2 re the blind spot is utter bilge. See 'Consciousness Explained' by Daniel C. Dennett, for example. I'll update it with something more logical when I get around to it. Noisy 14:24, 9 Jul 2004 (BST)

Contents 1 re: para2 blind spot 2 Thank God evolutionists don't design eyes. 3 The eye is composed of spare parts 4 Mind-boggling 5 On the sub-optimal design of THIS PAGE 5.1 Protective power of a Kleenex

re: para2 blind spot

Regardless of factual objections to the remarks about extra cognitive processing being required to compensate for flawed design (this may or may not be true -- I don't know), I could see how this argument might be unsatisfactory to a proponent of ID, who may not believe that God had any reason to design perfect eyes, per se, especially considering that the sum of all those putatively perfect parts (ie. man) is doctrinally described as "imperfect."

I don't think it's terribly crippling to the arguments of ID merely to show that a natural design is suboptimal, because the concept of "optimum" introduces a certain goal-oriented value that, in the case of intelligent design theory, can never be ascertained.

Of course it doesn't falsify the ID arguments. Rather, it forces ID proponents to decide whether they want ID falsified or unfalsifiable. If they answer, "oh, that's OK; the designer can do anything, so anything we find is reconcilable with design", their standpoint is unfalsifiable and firmly outside of science. --tk 08:55, 28 Feb 2005 (UTC)

Part of the problem with ID is they want it both ways. Things that seem like good design become marvelous evidence for ID, but things that seem like utterly stupid design are not to be taken as evidence against ID. That's not how the game works. Some of the design elements we see are BLUNTLY unintelligent. There is no sane reason why we should have our testes form in our abdomen and then descend, leaving a badly patched hole behind if we were designed. If things that work well evidence intelligence, then things that are obviously inferior must be seen as evidencing a lack of design.

--Suttkus 17:25, 17 June 2006 (BST)

Here's a challenge: what would it take to falsify neo-Darwinism? J.B.S. Haldane once said: "I will give up my belief in evolution if someone finds a fossil rabbit in the Precambrian." But I'll bet if one was found, it would be explained as the result of convergent evolution. ID is at least theoretically falsifiable, by finding plausible, detailed biochemical pathways of development of complex structures. The lack of any at present is of course not reason to doubt that ones could be found. But falsifiability is over-rated, especially when dealing with historical data. It is explanatory power which is more important to a theory's success. ID, which says design requires intelligence, is a perfect foil to random mutation and natural selection, which says that the "design" we see is only apparent and can be explained entirely through natural processes. Neo-Darwinists should strive to buttress their side by coming up with some reasonable pathways, or they risk losing out to ID, which is using mathematics and biochemistry to put limits on the same. [S. Cheesman 20 Nov 2005]

"Convergent evolution?" That describes similar, not identical, creatures. There is a difference between a rabbit-like creature and a literal rabbit in the Precambrian. Anyway, the only creatures that existed in the Precambrian were single-celled and a few soft non-vertebraic multi-celled creatures. Vertebrates didn't exist at all until the Cambrian, and mammals didn't exist until the Triassic (the latter being about 300 million years after the end of the Precambrian.) So even that rabbit-like creature isn't too terribly likely to be found. So, yes, a rabbit (or even rabbit-like) fossil from the Precambrian era would devalue evolution as we know it (note, however, that evolution being false wouldn't make ID or Creation necessarily true.) And falsifiability is the cornerstone of science; to say otherwise shows an ignorance of it. The entire scientific method, in a nutshell, is "Here's a hypothesis. Let's try our hardest to prove it false! We failed? Hey, the hypothesis is stronger! Let's try harder!" Yes, really. It's not trying to prove everything else false while picking out little bits and pieces of evidence that seem to support your own so-called theory (as is usually done with ID); it's making a useful, predictive hypothesis and then trying to disprove it. The problem (for ID) here is that all efforts to prove evolution false have, so far, either been flawed or failed to actually prove evolution false — and for such an unloved theory that was created about 200 years ago, there have been a lot of attempts to prove it false, making evolution one of the most well-supported theories in science (which still doesn't necessarily mean it's 100% true, mind you, but you've got your work cut out for you if you want to prove it false for real, or come up with a better theory that is falsifiable and continues to explain all the evidence and isn't flawed in some major way. Cutting and pasting from Creation/ID websites won't cut it; most, if not all, of their arguments have already been showed to be flawed.) And I have yet to see a single ID argument that properly applies mathematics or biochemistry in any meaningful way, though feel free to enlighten me. And, oh yes, before I forget, the explanatory power of "A higher intelligence did it" is moot, because a higher intelligence could (in theory) be responsible for any number of things that we see on a daily basis. (I'm reminded of a satirical comic that made reference to "Intelligent Falling," that is, that "God- er, I mean an Intelligent Faller" makes things go down instead of gravitational forces.) But unless you can provide evidence of your Intelligent Whatever, or even come up with tests concerning such an entity, why should scientists take such an idea seriously? --HeroicJay 08:29, 21 Nov 2005 (GMT)

Another comment: "But I'll bet if [a fossil rabbit in the Precambrian] was found, it would be explained as the result of convergent evolution." - That's a pretty safe bet for you insofar as you won't ever lose it. The reason is that a fossil rabbit won't be found in the Precambrian in the first place. That's my bet. --tk (t) 10:59, 21 Nov 2005 (GMT)

Thank God evolutionists don't design eyes.

There are numerous reasons why the eye is designed as it is; without enumerating them all here, do a simple web search using "eye design backwards" and look at a few of the pages set up to counter this simplistic argument.

In short, the eye's design optimizes oxygen and nutrition delivery to the photoreceptors, as well as cooling processes and healing/repair.

Do you have a theory as to why this optimization was needed for all aquatic vertebrates, but not for squids or octopuses? - RRH

Were we really put together as Richard Dawkins suggests, we'd likely be blind (permanently) in a rather short period because of the extensive damage caused by the light, and we likely wouldn't see that well to begin with.

In fact, because of the transparency of the intervening tissues, the wavelength of light, and the design (yes) of the cones in the part of the eye most critical for acute vision, there is virtually no degradation in the quality of vision due to having the receptors at the back.

Taken as a whole, there is no optical system yet designed by man that even approaches the eye in terms of the range of its sensitivity, resolution and function, yet you still believe that blind chance can produce something like the eye, or quibble about a blind spot (which takes a pretty sensitive test to detect)?

Still, discussions about the eye don't even address the issues raised by ID. ID is about biochemistry, not anatomy. The eye contains dozens of systems, each of them involving the sophisticated interaction of specific proteins and other biological agents. Is there a single detailed Darwinian explanation for the origin of even one of these systems? Let's see even one plausible pathway that names specific proteins and how they a) came to exist, or b) play their current roles.

Actually, understood at this level, ID is falsifiable. If Darwinian evolution can answer even a tiny fraction of the biochemical challenges presented by ID proponents, then the central proposition of ID has been disproved. Create a light-sensitive cell from a non-light sensitive one. Show *how* a flagellum evolved from anything simpler (don't just give an example and wave your hands).

Your argument from lack of imagination doesn't convince scientists. And your assumption that ID proponents will give up when their "challenges" are met is naive and has been disproved already - for example irreducible complexity is logically dead and ID proponents still exist.

Science does not work as you think it does. "Show me what exactly happened to whatever entity I choose, with as great detail as I want, and prove it beyond any unreasonable doubt, or else I will replace your theories by some god" is an impatient, unscientific attitude. --tk (t) 16:01, 14 Oct 2005 (BST)

I've updated the page to strengthen it a bit and rebuke some of his arguments that weren't really addressed before. --Suttkus 17:25, 17 June 2006 (BST)

The eye is composed of spare parts

The eye develops as an offshoot of the central nervous system. Not surprisingly, the majority of the cells in the eye are nerves and glia, same as the rest of the CNS. Proteins in the lens differ between species, but are generally versions of proteins used elsewhere, including in some basic biochemical processes like sugar metabolism. Proteins involved in light reception are based on 7-pass transmembrane proteins, which predate the splits among the 3 kingdoms. Archea, in fact, have a 7-pass, light harvesting protein that includes retinal (called bacteriorhodopsin) - they use it to generate energy. From the receptor on down, it's trimeric G-proteins, relatives of which also happen to transduce most forms of synaptic signaling in the nervous system. Key developmental regulators involved in producing the eye, such as the Pax proteins, have a conserved function all the way back to Drosophila, where the eye shares little structural similarity with the vertebrate eye. This indicates that, much like rhodopsin, the developmental regulators that produce a light sensing organ are ancient.

So, what part of that needs divine intervention? User:Dr._Jay

Mind-boggling

Fact: there is a very small part of the electromagnetic spectrum we call visible light. Notice that 'visible light' only applies to certain frequencies that can be detected by our eyes through tiny rods and cones which are situated in the retina. If we didn't have that ability, so much for the visible nature of that part of the electromagnetic spectrum. Isn't it strange that our physical world only shows its beauty within the confines of these frequencies (colours ranging from violet to red) in that part of the electromagnetic spectrum? Gamma rays, X-rays, Ultraviolet, Infrared, Microwaves, Radiowaves, they all have their use but don't contribute to our way of visual experiencing our material universe. How was it possible for evolution to evoke such abilities? How did a random process come up with an organ that can detect 'visible' light if this cannot be detected otherwise. Food for thought. Adelphos 12.43 24 July 2006 (GMT)

Thought is not the best procedure here. Reading is. Read Darwin (Darwin on evolution of the eye). He can tell you how it was possible. But you can forget that "random process" rhetorics. Evolution has a non-random component, a fact that creationists will often "forget" to tell you, so it is not a random process.

As for visible light: on the surface of the earth, visible light is one of the few parts of the electromagnetic spectrum that exist and give you useful information. It's only natural that an organ that detects it has evolved. --tk (t) 12:28, 24 July 2006 (BST)

As many others I read Darwin but it explains nothing. 'Visible' light is only visible because we have an organ that inhibits the possibility to make it visible. If not this part of the electromagnetic spectrum would be useless to us. Ultraviolet and Infrared can be detected and reacted upon by our skin. 'Visible' light doesn't have that effect. So the questions remains: How could evolution (not a random process? I beg to differ) come up with an organ that can detect an otherwise undetectable small range of electromagnetic frequencies, thus making our universe visible to us as we are able to perceive form and colour. Adelphos 9.22 P.M. 24 July 2006 (GMT)

Show me a natural source of light that 'only' puts out visible light. Nowimnthing 20:52, 24 July 2006 (BST)

Bioluminescent fungi and animals?--Mr A. 00:08, 25 July 2006 (BST)

According to this [1] Bioluminescence is produced in some way by all cells but a very few have it in the visible spectrum. Of course my statement was a bit hasty since any evolved natural light like bioluminescence would develop in response to already existing eyes and not been able to play a part in their initial evolution. Nowimnthing 14:31, 26 July 2006 (BST)

You fail to realize that most of the electromagnetic spectrum is undetectable by the vast majority of living organisms primarily because the vast majority of living organisms are either not exposed to heavy X-ray or Gamma radiation, or they are incapable of perceiving the vast majority of the electromagnetic spectrum, in that, there are no organisms known to man that can naturally emit radio wave or microwave frequencies.

The reason why organisms are capable of perceiving visible and ultraviolet light, as well as infrared radiation is because those three forms of radiation are the most abundant forms of radiant energy on Earth, so much so that virtually all organisms have developed ways of perceiving them in one way or another.--Mr A. 23:31, 24 July 2006 (BST)

I had to change the format of Mr. A's response, otherwise I'll create confusion with my answer.

"Not a random process? I beg to differ" - well, if you understand so little of the theory of evolution, I guess you should try to understand its mechanism first before you try to understand the evolution of the eye. After all, the second is based on the first.

But if you don't want that, you'll have to accept for the time being that an organism will adapt to its surroundings because of natural selection, a process you don't understand yet but may understand some time in the future. Given that fact, what is so special about evolving an organ that responds to some of the radiation that is there, and not to the radiation that is not there? --tk (t) 08:54, 25 July 2006 (BST)

How can an organism by natural selection adapt to something that isn't detectable without the proper tools. That's my point, you see? Adelphos 12:54, 28 July 2006 (GMT)

Any light-sensitive chemical is a proper tool for detecting light. And there are many of those. After all, visible light has the right wavelength range for interacting with outer electrons. --tk (t) 12:19, 28 July 2006 (BST)

Other wavelengths either have too violent an interaction with an organism's electrons, like the way gamma radiation will strip electrons from their atoms, and the way ultraviolet light induces the formation of thymine dymers, or they don't interact at all, like radio waves.--Mr A. 14:04, 28 July 2006 (BST)

Do also realize that you want us to embrace our faith by appealing to our ignorance. Personally, I find it a little insulting whenever someone says something along the lines of "I can't comprehend how this (insert biological process here) could have occured, so that's proof of God!" --Mr A. 14:10, 28 July 2006 (BST)

On the sub-optimal design of THIS PAGE

As an anonymous contributor said (then removed), I would rather this page focussed on the morphology of the eye, and contrasted it with the eyes of molluscs. In my opinion, the creationist claims about the intelligent design of the eye should be given their own claims page, complete with source. After all, if someone comes here looking for a response to a claim like "The inverted photoreceptors are needed to protect against UV light", then they won't look here, but on the claims page. In fact, I think that both vertebrate and invertebrate eyes should be covered on a single page: Eye.--Doddy 07:00, 28 May 2007 (BST)

Sounds good. --12:23, 6 June 2007 (BST)

Protective power of a Kleenex

I know Suttkus wrote this last year, but it's just wrong. It is certainly true, from what research I did today, that the pigmentation of the cells above the photoreceptors [i]do[/i] protect against UV light. Up to 40% in normal people. That's better than a tissue--Doddy 13:23, 28 August 2007 (BST)