Freethought & Rationalism Archive

Jesus Tap-Dancin' Christ · 11-01-2002, 09:34 AM

Quote:

Originally posted by Vanderzyden
[from your own source:]
Salmonids depend mainly on vision to detect danger, but they also have an excellent sense of smell and a well-developed lateral-line sense.

Note that while vision is a primary sense, they still have a great sense of smell. Thus, in a situation where SIGHT HAS NO MEANING, they still are not blind, so to speak. Thus it is highly possible, and even likely that a fish transplanted to a dark environment will survive PROVIDED that there are food sources. If there simply are not any, then naturally, they will not survive. But that is true of ANY animal. This renders the ENTIRETY of your objection moot.

Shut up, get over it, and stop wasting our time.

Coragyps · 11-01-2002, 09:53 AM

Quote:

All things considered, it seems like we have a case of poor conditions and insufficient time for a sighted fish to become eyeless.

So how did all those little eyeless fishies get into all those caves? Went there for a picnic during Noah's flood, perhaps? You are far beyond obtuse, VZ - I don't even know what to call it.

Baloo · 11-01-2002, 10:10 AM

John,

Glad to see you back.

Quote:

I do not agree with your assertion, since you are loosely employing the term "eye tissue". Previously, I have argued that the tissue in the optic cup of the the sightless cave fish is not properly eye tissue. Certainly it is not a complete vestigal or malfunctional organ. The tissue in the optic cup is the remnants of early embryonic development. The eye never develops. In fact, the entire region remains empty and "flat" throughout development.

Let me refine my contention.

1) As the embryonic development takes place, we see structures that resemble early forms of eyes in sightless fish. (as per your earlier quote)
2) The formation of embryonic structures takes place after cell specialization has occured. (basic biology)
3) These eye-like embryonic structures, being identical in form and function to the same embryonic structures in sighted fish, are the result of the same kinds of specialized cells as those in the sighted fish.
4) These specialized cells, which go on to form fully functional eyes in sighted fish, are eye cells by definition.
5) Also by definition, groups of cells with of the same type are tissues; thus, any cluster of these eye cells are correctly refered to as eye tissue.
6) Thus, sightless fish, which have groups of cells which, in sighted fish, go on to form eye organs, do in fact have eye tissue.

Quote:

Secondly, you are implying that some other tissue would fill the the orbit better, since the "eye tissue" is useless. OK, what tissue would that be? And from an economic standpoint, why would the designer need to use other tissue when an extension of the developmental tissue is sufficient? As I explained to Doubting Didymus, the fish is no more vulnerable to attack or disease as it is now. Smoothing the empty eye orbit with bone or lining the orbit with different (non-eye) fleshy tissue would have afford no advantage.

The DNA of the fertilized egg of a sightless fish contains all of the information necessary for that egg to grow into a functional adult fish. Specifically, the information needed to form specialized cells is packed into this DNA. More specifically, the information needed to tell a non-specialized cell how to become a "non-eye fleshy tissue" cell is packed into this DNA. If the fish has the information necessary to form such tissue, and that tissue can fill in the (aesthetically pleasing?) holes in the fish's skull, then it would clearly be a disadvantage to pack the unnecessary information needed for the fish to be able to form eye tissue.

Rephrased, the information needed for eye cell formation in the sightless fish is unnecessary DNA baggage, lacking the positive claim that the eye tissue is better suited to fill in the cavities than any other fleshy tissue in the fish.

Blinn · 11-01-2002, 12:28 PM

Quote:

Originally posted by Vanderzyden:
Scigirl,

That was discussed earlier in the discussion. If you really doubt that an animal that has suddenly become blind will not go extinct, then please go back and read (somewhere in the middle of the thread).

Thanks,

John

Vanderzyden � you would do well to follow your own advice.

Quote:

Originally posted by Vanderzyden:


DD,

As before, I will ask:

What should lead us to believe that sighted fish, who are forced into caves, could survive at all?

Living in the dark is equivalent to being blind. Being forced into darkness for life is equivalent to having the eyes removed. Surely you agree that sight is the primary sense. Without it, the fish could not find food, especially in a new environment. Without food, the first generation will die, immediately. Any progeny that survive in the dark cave will die, immediately. This hypothetical new species never gets the chance to "evolve".

You already said this once, <a href="http://iidb.org/ubb/ultimatebb.php?ubb=get_topic&f=58&t=001516&p=5" target="_blank">here</a>:

Quote:

Quite an amazing thing, I think: the creature functions without an eye. If it had "evolved" this way, we would not observe this fish. It would not exist. There would be no living specimens, since the first "eyeless" surface fish would die immediately. In the wild, an animal that requires sight in order to obtain food would die shortly after its vision degraded. If blind offspring are born to seeing parents, they will notsurvive long after birth. So, I find the suggestion of evolving blind fish to be wholly nonsensical. The Darwinist would do well to think through the likely scenarios before postulating such far-fetched schemes.

To which I replied:

Quote:

An unsighted fish above ground may be at a selective disadvantage relative to a sighted fish, but that is not the scenario that we have here. Surface dwelling (sighted) fish moved into caves. Only after they're already living in total darkness (where there is no selective advantage to being sighted) is sight lost.
Vision is important for most fishes, but its usefulness is often constrained by factors such as water clarity, water depth, or temporal activity. I think I'm safe in stating that many, if not most fishes, rely on sight only partially, if it all, in locating food. Olfaction is a much more important sense in that endeavor. And then let's not forget about lateral lines. Fishes and some amphibians have a sensory pores along their head and body which can detect movement in the water around them. Moving from the surface into caves wouldn't be a problem for these fish.

And since you apparently didn�t notice it there, I reiterated it on page 7.

Quote:

Originally posted by Vanderzyden:
 We must consider land predators and water predators. Land predators may be avoided just as easily by avoiding the shoreline as they can by hiding in caves. Water predators would follow the fish into the caves. Each would be unable to see. The water predator threat is greatly diminished, but still remains. If the water predators could somehow accidentally eat a few fish, they would find that their food supply would eventually diminish to zero and the predators would go extinct (locally). Furthermore, the predator would be unlikely to be able to eat enough food to sustain itself properly.

What predators do Mexican blind cavefish have?

Quote:

Meanwhile, the fish population would rapidly decrease because it could not see to find food, if there is any food to find. All of this seems to contribute to the rapid extinction of the fish and the water predators.

Um, the one important point that you seem to be missing here is that Mexican blind cavefish do find food!

Quote:

I have also raised the issue of progeny.

Yes, you did so <a href="http://iidb.org/ubb/ultimatebb.php?ubb=get_topic&f=58&t=001516&p=5" target="_blank">here</a>

Quote:

Note: additional complications arise when we consider reproduction.

At the time, I replied as follows:

Quote:

Are you implying that blind animals are unable to reproduce? Well, they do, otherwise there wouldn't be any, would there?
I've watched Mexican blind cave fish, Astyanax mexicanus spawn, and they do it quite well without being able to see one another. You may want to read about <a href="http://www.lookd.com/fish/laterallinesystem.html" target="_blank">lateral lines</a>. I've also watched two males of another species of blind cave fish intensly fight with one another. I'd speculate that blind recognition of a conspecfic and its sex would be through olfactory or pheromonal cues.

Quote:

First, there is the difficulty for the female in finding a proper place to lay the eggs.

<a href="http://www.aquariacentral.com/fishinfo/fresh/characins.htm" target="_blank">Characins</a> don�t lay eggs; they�re egg scatterers.

Quote:

Second, there is an additional complication in the male being able to fertilize the eggs.

See above.

Quote:

Remember, we are dealing with fish that until just recently were heavily dependent upon their sight!

You�ve yet to demonstrate that this statement is true.

Quote:

Will they "smell" their way to a suitable location in this strange, dark environment?

A suitable location for what?

Quote:

For the sake of argument, let's say that somehow that new fish are able to hatch.

Oh, wow! Imagine that! Tetra fry somehow managing to develop from tetra eggs! Wait �til I tell the guys in the local aquarium club!

Quote:

Here is yet another problem: How will these young fish survive in the dark? How will they find food?

Characin fry feed on particulate matter suspended in the water column. I don�t see how finding food is a problem.

[ November 01, 2002: Message edited by: Zetek ]

Vanderzyden · 11-01-2002, 02:05 PM

And your main point is what, precisely?

scigirl · 11-01-2002, 02:33 PM

The point, exactly, was to refute one of your main arguments against this fish evolution, which you stated here:

Quote:

Originally posted by Vanderzyden:
That was discussed earlier in the discussion. If you really doubt that an animal that has suddenly become blind will not go extinct, then please go back and read (somewhere in the middle of the thread).

Yes I do doubt that an animal that has suddenly become blind (suddenly being a relative term) will automatically go extinct. So - either try another argument, or offer proof or evidence (besides your own incredulity) that blind fish necessarily go extinct.

scigirl

Blinn · 11-01-2002, 06:45 PM

Quote:

Originally posted by Vanderzyden:
And your main point is what, precisely?

In addition to scigirls comments, that you don't know your ass from a hole in the ground.

Zetek

Vanderzyden · 11-01-2002, 07:58 PM

Quote:

Originally posted by Baloo:

Glad to see you back.

(snipped points 1-6)

The DNA of the fertilized egg of a sightless fish contains all of the information necessary for that egg to grow into a functional adult fish. Specifically, the information needed to form specialized cells is packed into this DNA. More specifically, the information needed to tell a non-specialized cell how to become a "non-eye fleshy tissue" cell is packed into this DNA. If the fish has the information necessary to form such tissue, and that tissue can fill in the (aesthetically pleasing?) holes in the fish's skull, then it would clearly be a disadvantage to pack the unnecessary information needed for the fish to be able to form eye tissue.

Rephrased, the information needed for eye cell formation in the sightless fish is unnecessary DNA baggage, lacking the positive claim that the eye tissue is better suited to fill in the cavities than any other fleshy tissue in the fish.

Hi Baloo,

I could address each point you made in the first part of your post, but I think it would be sufficient to address the main argument you are making at the end. If, after reading this reply, please tell me if you would like me to respond in detail to each of those points.

First, I would like to say that I am pleased that you recognize that the genetic code is indeed information. Perhaps you have thought about where that information originates.

It is my understanding that, when the an allele of the eye-tissue gene(s) is expressed, it produces effects which are more basic than other eye-tissue genes. Perhaps there is a terminal codon at some point further along in the gene, and it "programs" the embryonic eye-tissure components to develop to a particular point and then stop. If the DNA had been copied from a prototype at the time the sightless fish was instantiated, the particular gene in question could have been modified (truncated?, nullified?) Of course, I am sure that others here could articulate this more eloquently and precisely.

Now, I think we agree that the tissue is not wasted, since it seals and protects the orbit of the eye. So, why should we think of information as wasted? In the first place, information costs nothing in the case we are studying. In fact, there are great benefits to information modification and extension. Again, I think of software, which is directly analogous.

If I am writing software code that I will use as a template for many functions (e.g. object-oriented programming), then I will write the "framework" code (e.g. parent classes) first. This framework code will contain the basics for all of the variant uses I envision. With each particular use of the template (e.g. child class), I will "turn off" or "turn on" certain features that are found in the template. In fact, I may take a particular use of the template and extend it with additional features not found in the original template. As you can see, much of the code is written once, and simply copied into another usage scenario, where it is modified or extended.

Note: I realize that some of those who might read this are software engineers, so please understand that I am intentionally avoiding the use of highly technical language and concepts, as a courtesy.

Coming back to the eyeless fish, we can see that the information is not "wasted", and that the design is quite elegant. In the eyeless fish, we see that the orbit is well-lined and well-protected, leaving the fish no more vulnerable to attack or disease than it surface counterpart. The glory of the Creator is seen in his flexibility to bring about two similar species, one with sight, one without. Both function well in their respective environments.

John

[ November 01, 2002: Message edited by: Vanderzyden ]

scigirl · 11-02-2002, 09:06 AM

Vanderzyden,

After reading this last post of yours, and some of your more recent ones in regards to genetics, it appears to me that you are a theistic evolutionist, and not a creationist. You just don't realize it yet.

Quote:

Vanderzyden:
It is my understanding that, when the an allele of the eye-tissue gene(s) is expressed, it produces effects which are more basic than other eye-tissue genes.

Structures such as organs are not usually encoded by one gene. They are encoded by a multitude of genes, which get turned on and off at appropriate times during development.

How do we know this? Well, look at pictures of embryos. Tissues elongate, fold around each other, regress, etc, and at some point, structures start to emerge which look like eyes and kidneys. They aren't built the same way we build stuff, which is usually piece by piece.

Quote:

Now, I think we agree that the tissue is not wasted, since it seals and protects the orbit of the eye. So, why should we think of information as wasted? In the first place, information costs nothing in the case we are studying.

Actually it does. DNA that is not expressed or used still has to be replicated, which costs ATP. And tissues that are made, then regress, also cost ATP (ATP is energy currency).

Quote:

In fact, there are great benefits to information modification and extension. Again, I think of software, which is directly analogous.

If I am writing software code that I will use as a template for many functions (e.g. object-oriented programming), then I will write the "framework" code (e.g. parent classes) first. This framework code will contain the basics for all of the variant uses I envision. With each particular use of the template (e.g. child class), I will "turn off" or "turn on" certain features that are found in the template. In fact, I may take a particular use of the template and extend it with additional features not found in the original template. As you can see, much of the code is written once, and simply copied into another usage scenario, where it is modified or extended.

EXACTLY! That IS a good analogy for gene control in development.

That is what biologists believe. Evolution often acts on the modification genes, not the actual "template" (to use your analogy). Have you heard of those experiments they did with fruit flies, where they made tiny tiny modifications to certain genes and they got legs growing out of eye holes? What do these studies tell us? Certain changes in the DNA do allow drastic modifications to body plans. What is this-a mechanism of evolution.

You can believe that a higher being made us using your analogy - but then you must call yourself a theistic evolutionist.

Quote:

Coming back to the eyeless fish, we can see that the information is not "wasted", and that the design is quite elegant.

One thing to remember - natural selection usually only publishes the success stories. There were probably plenty of fish that lost their eyes and did not have protection - and those ones did not produce offspring, and they died. You might think, "well that's convenient, the biggest evidence for evolution aren't even around!" But - if evolution is true, than you will expect to see some offspring of all different animals that do have harmful mutations, and they do not survive as readily.

We learn more about evolution from the "mutants" than we do the "normal" animals. What are these mutants telling us: that yes, indeed, the mechanisms for evolution are at work every second of every day.

Quote:

In the eyeless fish, we see that the orbit is well-lined and well-protected, leaving the fish no more vulnerable to attack or disease than it surface counterpart.

But why is the embryological development of this non-eye so eerily similar to the fish with eyes?

If you agree that the turning on and turning off of genes is what creates the eye (or non-eye), and both the DNA sequences for those genes, and the embryological expression of those genes, are similar in two organisms, you can conclude the following:
1) they got the genes from the same place (descent, i.e. evolution)
2) they got the genes from two different places (creationism)

If #2 is correct, which is what a creationist proposes, than it still doesn't explain why the genes and the embryological patterns are the same. Either the creator wanted it to look like #1, or.... the creator used evolution to diversify life.

scigirl

scigirl · 11-02-2002, 09:15 AM

Incidentally, a few of your claims or questions have been addressed at length, if you are interested:

<a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=58&t=001622" target="_blank">sub-optimal debate</a> - where I propose two "sub-optimal" structures and ask what the ID explanation for those structures is,

<a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=58&t=001596" target="_blank">Good mutations anyone?</a> , started by you of course, and the thread is filled with examples, as well as lengthy dialogues as to why the word "mutation" is a complex issue

and

<a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=58&t=001631" target="_blank">Evolution of the placenta </a>, where I give examples of several 'precious'

mechanisms for macroevolution.

scigirl

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search

11-01-2002, 02:05 PM	#275
Vanderzyden Senior Member Join Date: Jul 2002 Location: California Posts: 694	And your main point is what, precisely?

11-02-2002, 09:15 AM	#280
scigirl Veteran Member Join Date: Jul 2001 Location: Seattle Posts: 4,261	Incidentally, a few of your claims or questions have been addressed at length, if you are interested: <a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=58&t=001622" target="_blank">sub-optimal debate</a> - where I propose two "sub-optimal" structures and ask what the ID explanation for those structures is, <a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=58&t=001596" target="_blank">Good mutations anyone?</a> , started by you of course, and the thread is filled with examples, as well as lengthy dialogues as to why the word "mutation" is a complex issue and <a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=58&t=001631" target="_blank">Evolution of the placenta </a>, where I give examples of several 'precious' mechanisms for macroevolution. scigirl

Freethought & Rationalism Archive

The archives are read only.