Freethought & Rationalism Archive

tgamble · 06-10-2002, 05:56 AM

I was talking to another creationist and I was pointing out examples of the DI's incompetance. One of the examples is their comments on the eye in response to Dr. Ken Miller.

<a href="http://www.ncseweb.org/resources/articles/954_Setting_the_Record_Straight_v4.pdf" target="_blank">http://www.ncseweb.org/resources/articles/954_Setting_the_Record_Straight_v4.pdf</a>

Brown University biologist Kenneth Miller asserts that the "imperfect" wiring of the vertebrate retina proves that natural selection, not an intelligent designer, produced the eye. God, in Miller's opinion, wouldn't have done it that way. To arrange the retina as Miller thinks best, however, would render it inoperative.
In the first show of the PBS series I pointed out that the light sensitive portions of the photoreceptor cells of the vertebrate retina are not positioned optimally to face the incoming light. Instead, they are placed beneath the neural wiring of the retina. This arrangement cannot be explained in terms of intelligent design, but is perfectly understandable in light of evolution. The vertebrate retina evolved as an outgrowth of the brain, and as a result its neural wiring retains its original arrangement, scattering the incoming light before can be sensed by the photoreceptor cells.
One can argue whether or not "God would have done it that way," but on one point there can be no dispute. The Discovery Institute is dead wrong when it says that the retina would be "inoperative" if it were arranged with the neural wiring beneath a layer of light sensing cells. How can we be so sure? Because that's exactly how the eyes of many mollusks are arranged. It will, no doubt, come as a great surprise to squid everywhere that, according to the Discovery Institute, their eyes don't work!

In response he said "One of my nonchristian Science textbooks state that the octupus eye and human eye are very similar almost exactly alike. But I guess that is wrong to or is it?"

How similar is the octopus eye to the human eye? I doubt this changes the fact (if it is a fact)that the octopus eye is wired in a way that the DI claims won't work. Thanks.

MrDarwin · 06-10-2002, 07:14 AM

The octopus eye is superficially similar to the vertebrate eye (not just the human eye). It has all the same basic parts: a fluid-filled chamber, a muscular iris with an adjustable pupil, a retina on which an image is projected, a lens that can sharpen that image. But I suspect that if they were compared in detail, there would turn out to be more differences than just the retina and how the nerves feed into it.

Edited to say that I was right about there being other differences; <a href="http://ebiomedia.com/gall/eyes/octopus-insect.html" target="_blank">here's</a> a link to an article about octopus eyes, that goes into a bit more detail about similarities and differences from those of vertebrates.

A bit more technical, comparing cephalopod vs. vertebrate rhodopsins (search on the keyword "cephalopod"): <a href="http://www.embl-heidelberg.de/~krebs/Rhodopsin.htm" target="_blank">http://www.embl-heidelberg.de/~krebs/Rhodopsin.htm</a>

[ June 10, 2002: Message edited by: MrDarwin ]

lpetrich · 06-10-2002, 07:45 AM

<a href="http://www.maayan.uk.com/evoeyes2.html" target="_blank">A nice page with different eye architectures</a>.

Vertebrate and cephalopod eyes have lots of similarities in overall architecture, but lots of differences in detail.

Which side of the retina the nerves are on:
V: Toward incoming light
C: Away from incoming light

Develops as a pocket in the
V: Optic nerve
C: Skin

Divided in two?
V: No
C: Yes, into outward and inward parts

Etc.

RufusAtticus · 06-10-2002, 08:18 AM

Simply put, the cephalopod eyes gets it right. I guess our designer (wink wink nudge nudge) paid more attention to them than us.

~~RvFvS~~

MrDarwin · 06-10-2002, 08:35 AM

One thing I found especially interesting was how the respective lenses focuse the image on the retina. In the vertebrate eye, the lens changes shape to change the focal length. In the cephalopod eye, the lens stays the same shape but moves to change the distance between the lens and the retina.

Skydancer · 06-10-2002, 10:54 AM

Quote:

Originally posted by MrDarwin:
One thing I found especially interesting was how the respective lenses focuse the image on the retina. In the vertebrate eye, the lens changes shape to change the focal length. In the cephalopod eye, the lens stays the same shape but moves to change the distance between the lens and the retina.

Another case of the cephalopod eye being better designed, too. Humans almost invariably need corrective lenses as they get older - because the lens loses flexibility. This wouldn't be a problem with a cephalopod version.

MrDarwin · 06-10-2002, 10:59 AM

Quote:

Originally posted by Skydancer:
Humans almost invariably need corrective lenses as they get older - because the lens loses flexibility.

Oh, but that happens because of The Fall.

06-10-2002, 05:56 AM	#1
tgamble Veteran Member Join Date: Sep 2000 Location: St. John's, Nfld. Canada Posts: 1,652	Octopus eye compared to the Human eye I was talking to another creationist and I was pointing out examples of the DI's incompetance. One of the examples is their comments on the eye in response to Dr. Ken Miller. <a href="http://www.ncseweb.org/resources/articles/954_Setting_the_Record_Straight_v4.pdf" target="_blank">http://www.ncseweb.org/resources/articles/954_Setting_the_Record_Straight_v4.pdf</a> Brown University biologist Kenneth Miller asserts that the "imperfect" wiring of the vertebrate retina proves that natural selection, not an intelligent designer, produced the eye. God, in Miller's opinion, wouldn't have done it that way. To arrange the retina as Miller thinks best, however, would render it inoperative. In the first show of the PBS series I pointed out that the light sensitive portions of the photoreceptor cells of the vertebrate retina are not positioned optimally to face the incoming light. Instead, they are placed beneath the neural wiring of the retina. This arrangement cannot be explained in terms of intelligent design, but is perfectly understandable in light of evolution. The vertebrate retina evolved as an outgrowth of the brain, and as a result its neural wiring retains its original arrangement, scattering the incoming light before can be sensed by the photoreceptor cells. One can argue whether or not "God would have done it that way," but on one point there can be no dispute. The Discovery Institute is dead wrong when it says that the retina would be "inoperative" if it were arranged with the neural wiring beneath a layer of light sensing cells. How can we be so sure? Because that's exactly how the eyes of many mollusks are arranged. It will, no doubt, come as a great surprise to squid everywhere that, according to the Discovery Institute, their eyes don't work! In response he said "One of my nonchristian Science textbooks state that the octupus eye and human eye are very similar almost exactly alike. But I guess that is wrong to or is it?" How similar is the octopus eye to the human eye? I doubt this changes the fact (if it is a fact)that the octopus eye is wired in a way that the DI claims won't work. Thanks.

06-10-2002, 07:14 AM	#2
MrDarwin Veteran Member Join Date: May 2001 Location: Washington, DC Posts: 4,140	The octopus eye is superficially similar to the vertebrate eye (not just the human eye). It has all the same basic parts: a fluid-filled chamber, a muscular iris with an adjustable pupil, a retina on which an image is projected, a lens that can sharpen that image. But I suspect that if they were compared in detail, there would turn out to be more differences than just the retina and how the nerves feed into it. Edited to say that I was right about there being other differences; <a href="http://ebiomedia.com/gall/eyes/octopus-insect.html" target="_blank">here's</a> a link to an article about octopus eyes, that goes into a bit more detail about similarities and differences from those of vertebrates. A bit more technical, comparing cephalopod vs. vertebrate rhodopsins (search on the keyword "cephalopod"): <a href="http://www.embl-heidelberg.de/~krebs/Rhodopsin.htm" target="_blank">http://www.embl-heidelberg.de/~krebs/Rhodopsin.htm</a> [ June 10, 2002: Message edited by: MrDarwin ]</p>

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06-10-2002, 07:45 AM	#3
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	<a href="http://www.maayan.uk.com/evoeyes2.html" target="_blank">A nice page with different eye architectures</a>. Vertebrate and cephalopod eyes have lots of similarities in overall architecture, but lots of differences in detail. Which side of the retina the nerves are on: V: Toward incoming light C: Away from incoming light Develops as a pocket in the V: Optic nerve C: Skin Divided in two? V: No C: Yes, into outward and inward parts Etc.

06-10-2002, 08:18 AM	#4
RufusAtticus Veteran Member Join Date: Nov 2001 Location: NCSU Posts: 5,853	Simply put, the cephalopod eyes gets it right. I guess our designer (wink wink nudge nudge) paid more attention to them than us. ~~RvFvS~~

06-10-2002, 08:35 AM	#5
MrDarwin Veteran Member Join Date: May 2001 Location: Washington, DC Posts: 4,140	One thing I found especially interesting was how the respective lenses focuse the image on the retina. In the vertebrate eye, the lens changes shape to change the focal length. In the cephalopod eye, the lens stays the same shape but moves to change the distance between the lens and the retina.

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