Quetzal

I'm not entirely clear what you are looking for. Are you trying to find out whether squid eyes are additional evidence for sloppy design? I have no idea. I'm not sure anyone's done any detailed work on that issue. I'd be interested to read it if you can point some out.

I don't think it's very important one way or the other. [shrugs] Squid eyes developed over time via the same natural evolutionary processes as vertebrate eyes, snail eyes, annelid eyes, various insect compound eyes, etc. It stands to reason (and could probably be predicted) that there will be flaws in any naturally evolved design. After all, it merely has to be "good enough" for its environment. Bottom line, only ID/Creationism requires that structures/organisms be perfect - if they aren't, then the supposed designer/creator is incompetent and we have no reason to pay any attention to him/her/it. That follows whatever critter we're talking about.

LiveFreeOrDie

All I'm trying to do is shed some light on the "suboptimality" argument that we evolutionists use to refute the "perfect designer" claim. Many times I've seen the vertebrate eye put forth as an example of suboptimal design and almost as many times I've seen the cephalopod eye proposed as an example of a "better" design. I think the ARN paper I originally referenced shows, however, is that there are many tradeoffs in any design. Just because squid have there retinas arranged "properly" doesn't guarantee that they actually see any better. This in my mind invalidates the whole argument whereby the squid eye is used as a counterpoint to show how suboptimal the vertebrate eye is. Without any facts regarding the subjective quality of vision each eye provides its owner, any claim that one eye is more optimal than the other is without merit IMO.

I think the broader conclusion is that playing one species off another to demonstrate suboptimality is a tricky business. It is very difficult to know the full range of costs and benefits of competing designs in enough detail for one to soundly conclude that one design is better than another. This means we can really only make suboptimality arguments by comparing to hypothetical designs, which is still valid by rhetorically weaker.

The better approach when confronted by an IDer who claims that the human eye is "perfect" is to simply force them to prove it. We can point out how birds have better visual acuity, cats have slit irises for better light sensitivity, squid have right-way retinas, etc. There is no need to prove the human eye to be imperfect -- only to raise enough questions to put into doubt the claim that it is.

A subtle distinction, I suppose, but one position is much easier to defend than the other.

Morat

I've always felt an excellent argument for suboptimum design in humans is the large number of people who choke to death on their food each year.

Synaesthesia

I think the case of the retina’s relation to the layer of vessels is itself a microdomain, though not as easy and clear as a hypothetical situation, it does make a good case.

There is indeed no guarantee that the squid will see better then another species just because of this feature. However, this variant is clearly better than the other one, making little difference but the sensitivity to photons. The crux of the argument is that designers are able to transfer skills from one place to another. In the blind, meandering search through genetic space, it is only expected that stupid disadvantages will develop in some creatures that are overcome in others.

elwoodblues

"I've always felt an excellent argument for suboptimum design in humans is the large number of people who choke to death on their food each year."

Curiously, no. It's just another side-effect of Darwinian evolution.

Check it: The reason we choke is (usually) because of our larynx and vocal cords. Without those, we'd have a lot more room down there, and wouldn't choke nearly so often. Lives would be saved every year.

However, it's a tradeoff. We have vocal cords so we can speak, communicate with a wide range of inflections and sounds. We can transmit information from one to another.

In the scheme of things, this is a very profitable trade-off.

Peez

Just a few quick comments: According to Human Physiology (Lauralee Sherwood, 1989, West Publishing Company, p. 168): So, no, it is not the "vast numbers of red blood cells" that make the choroid "virtually opaque." A minor point, I suppose, but one that makes me doubt the author's knowledge of the eye. Only if the rods and cones function exactly as they do in the vertebrate eye. Obviously, they do not work that way in the cephalopod eye. You mean like knowing that the choroid is pigmented, and is not opaque just because of the blood?

Peez

Peez

Not necessarily. We still need a passage for air, it still needs to be stiff so that it will stay open as we breath, and we still need a mechanism to prevent food from blocking it. It is not clear that the vocal chords are responsible, nor that the larynx is. Note that moving the larynx up causes the epiglottis to close, helping to prevent food from entering the trachea. Also note that the vocal chords may close to keep food from moving any farther down the trachea if it does get by the epiglottis. As long as there is a pharynx, carrying food or air, there is a chance of choking. This is, indeed, the important consideration. If the net result is an increase in fitness, that's where evolution will take you.

Peez

Morat

I'd imagine any half-way competant engineer could manage a way to get food into your stomach without having to worry about it getting stuck in your airway.

elwoodblues

"I'd imagine any half-way competant engineer could manage a way to get food into your stomach without having to worry about it getting stuck in your airway."

Certainly. Which is a huge point for evolutionary theory.

Of course you can imagine (and even construct) such a system, that works more safely and efficiently. But you don't have to worry about making each intermediary 'step' a progressive step 'forward' or 'up' in usefulness. Evolution does. It can't just scrap a whole system and start fresh. Look at how bird wings incorporate vestigial arms and fingers. Sure, there might be better designs that DON'T use those things. But that would mean evolving a wing out of NOTHING, and that's a lot tougher than evolving a wing out of something that's already there.

I only dabble in evolutionary theory; I'm sure that's apparent. I'm sure someone else here can explain it better.

Dr Rick

Your last post on the thread can be found on this <a href="http://ii-f.ws/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=58&t=000011&p=6" target="_blank">page</a>. Your post here was deleted because the other thread contains responses to your questions and arguments which you have not answered and yet tried reposting here.

[ January 11, 2002: Message edited by: rbochnermd ]</p>