Dover, PA - Science and Intelligent Design.

[Lephi]

Intelligent design and creationism deserves to be in our classrooms.  They are no less theories than evolution.

In science, the word "theory" implies that there is evidence to support it. Theories are not wild guesses. Creationism and intelligent design (scientifically speaking) are as much theories as the view that humans oozed out of the ground spontaneously, or that the Flying Spaghetti Monster dropped them from the skies.

The complexity of life is a good support for the possiblity of heavenly creation, as is millions of years of religious practice, the Bible, etc.

[angus]

Nice quote.  I'm a tad busy at the moment, and I'll have to think about what you're asking.  My short answer is that being able to visually detect food and partners for reproduction gives it an advantage.  Remember, the theory is that accidental mutation gives the individual a difference.  If it turns out to be an advantage, the individual passes it on to others of its species.  Eventually, the ones without the advantage die off.  Or remain behind as the newly-equipped becomes a different species with a different specialty. 

Well, if they are in a dark sea, why do they need to see visible light?  A prehistoric sea was not clear distilled water.

maybe not, but it wasn't clouded with humus and other organic debris either.  most of the flocculant stuff comes from the decaying bodies of multicellular organisms, or from the bodies of single-celled organisms, and not from simple monatomic and polyatomic ions from sea salts.  So it's likely that back in the day, back when, say, the rhodopsin protein was evolving, the visibility was much greater, on average, than it is now.

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This may be useful to that organism in some way.  after all, photons are little packets of energy, and chloroplasts in green plants, which photosynthesize cellulose and other starches, are thought to be of endosymbiotic origin.  maybe that ability to detect the presence of photons, in a photochemical reaction, or a photoinitiated chain reaction sequence, gave that individual an advantage so great that it passed on its genes in such abundance that it became the dominant strain within the species, displacing other strains in time.  Or maybe its new ability allowed to evolve in a way that allowed it to fill a niche.  The sea surface may have been too harsh for most organisms, due to UV light and some unabsorbed IR light penetrating the upper reaches of the water, but this organism would be able to tell night from day, increasing its chances of survival.  or maybe it simply exploited this new ability to synthesize the chemicals it needed, allowing it to find alternative sources of food.  after all, you don't need to see UV light to know it's there, you just need to know that it's daytime.

My problem here is that the Sun produces heat.  I could understand something sensing heat, or even UVL.  Why that range?

Once developed, I can see why it stayed, but my question is, why did it develop?

Think about it.  A creature, Glub by name, is in the ocean.  Detecting heat makes sense.  Glub doesn't want to go to the harsh surface, where it's a lot warmer.  He wants to follow currents of different temperatures; Glub doesn't want to swim into waters superheated by volcanoes.  The ability to sense heat, I can understand, but why light?  Further, because vertebrates, and squids, et al., have eyes, the must have been developed at an early stage.  Why does Glub need to see in the visual light range?

I found an interesting quote on Wikipedia:

You must be logged in to read this quote.

It's from Charles Darwin.

Yeah, well Intelligent Design might have had more of a case in the 1800s before we had the massive experimental evidence that we have today.

[John Dibble]

Intelligent design and creationism deserves to be in our classrooms.  They are no less theories than evolution.

In science, the word "theory" implies that there is evidence to support it. Theories are not wild guesses. Creationism and intelligent design (scientifically speaking) are as much theories as the view that humans oozed out of the ground spontaneously, or that the Flying Spaghetti Monster dropped them from the skies.

The complexity of life is a good support for the possiblity of heavenly creation, as is millions of years of religious practice, the Bible, etc.

None of those can be considered scientific evidence of creationism.

[J. J.]

Nice quote.  I'm a tad busy at the moment, and I'll have to think about what you're asking.  My short answer is that being able to visually detect food and partners for reproduction gives it an advantage.  Remember, the theory is that accidental mutation gives the individual a difference.  If it turns out to be an advantage, the individual passes it on to others of its species.  Eventually, the ones without the advantage die off.  Or remain behind as the newly-equipped becomes a different species with a different specialty. 

Well, if they are in a dark sea, why do they need to see visible light?  A prehistoric sea was not clear distilled water.

maybe not, but it wasn't clouded with humus and other organic debris either.  most of the flocculant stuff comes from the decaying bodies of multicellular organisms, or from the bodies of single-celled organisms, and not from simple monatomic and polyatomic ions from sea salts.  So it's likely that back in the day, back when, say, the rhodopsin protein was evolving, the visibility was much greater, on average, than it is now.

The atmosphere was thicker, from what I've read.  There was also discussion of much more carbon in the atmosphere causing a greenhouse effect.  It seems like a less sunny planet.

[angus]

good point, from what I've read the atmosphere contained less oxygen and nitrogen, and more reduced forms such as methane and nitrogen.  also lots of carbon dioxide.  but all those are colorless anyway, and don't absorb visible light.  And, in fact, all absorb a great deal of infrared light, especially CO2, the mother of all greenhouse gases, so the earth was warmer, but not less visible.  None have any appreciable absorption in the UV spectrum.

[J. J.]

This may be useful to that organism in some way.  after all, photons are little packets of energy, and chloroplasts in green plants, which photosynthesize cellulose and other starches, are thought to be of endosymbiotic origin.  maybe that ability to detect the presence of photons, in a photochemical reaction, or a photoinitiated chain reaction sequence, gave that individual an advantage so great that it passed on its genes in such abundance that it became the dominant strain within the species, displacing other strains in time.  Or maybe its new ability allowed to evolve in a way that allowed it to fill a niche.  The sea surface may have been too harsh for most organisms, due to UV light and some unabsorbed IR light penetrating the upper reaches of the water, but this organism would be able to tell night from day, increasing its chances of survival.  or maybe it simply exploited this new ability to synthesize the chemicals it needed, allowing it to find alternative sources of food.  after all, you don't need to see UV light to know it's there, you just need to know that it's daytime.

My problem here is that the Sun produces heat.  I could understand something sensing heat, or even UVL.  Why that range?

Once developed, I can see why it stayed, but my question is, why did it develop?

Think about it.  A creature, Glub by name, is in the ocean.  Detecting heat makes sense.  Glub doesn't want to go to the harsh surface, where it's a lot warmer.  He wants to follow currents of different temperatures; Glub doesn't want to swim into waters superheated by volcanoes.  The ability to sense heat, I can understand, but why light?  Further, because vertebrates, and squids, et al., have eyes, the must have been developed at an early stage.  Why does Glub need to see in the visual light range?

I found an interesting quote on Wikipedia:

You must be logged in to read this quote.

It's from Charles Darwin.

Yeah, well Intelligent Design might have had more of a case in the 1800s before we had the massive experimental evidence that we have today.

Well, we have very little experimental evidence in relating to this.  Most evidence of evolution is empirical (as it is in meteorology, geology, astronomy).  There is some experimental research done, but not a lot.

[J. J.]

good point, from what I've read the atmosphere contained less oxygen and nitrogen, and more reduced forms such as methane and nitrogen.  also lots of carbon dioxide.  but all those are colorless anyway, and don't absorb visible light.  And, in fact, all absorb a great deal of infrared light, especially CO2, the mother of all greenhouse gases, so the earth was warmer, but not less visible.  None have any appreciable absorption in the UV spectrum.

And a lot of water vapor, clouds.  The hotter climate evaporates more water.  I'll check the salt amounts.

[J. J.]

Here is another problem.  Possibly the first creatures to develop eyes, some species, were trilobites.  The were not preditors; they scavaged on the sea floor.  Eyes didn't see through the bottom silt that they were sifting, but they had them.

Okay, why eyes? 

[John Dibble]

Here is another problem.  Possibly the first creatures to develop eyes, some species, were trilobites.  The were not[/i preditors; they scavaged on the sea floor.  Eyes didn't see through the bottom silt that they were sifting, but they had them.

Okay, why eyes? 

Perhaps to see predators coming.

[J. J.]

Here is another problem.  Possibly the first creatures to develop eyes, some species, were trilobites.  The were not[/i preditors; they scavaged on the sea floor.  Eyes didn't see through the bottom silt that they were sifting, but they had them.

Okay, why eyes? 

Perhaps to see predators coming.

What predators or, more appropriately, what eyeless predators.  And where did the predators get their eyes?

Edit:
Or better yet, why don't the predetors have eyes, yet.  The major predator was the jellyfish. 

[John Dibble]

Here is another problem.  Possibly the first creatures to develop eyes, some species, were trilobites.  The were not[/i preditors; they scavaged on the sea floor.  Eyes didn't see through the bottom silt that they were sifting, but they had them.

Okay, why eyes? 

Perhaps to see predators coming.

What predators or, more appropriately, what eyeless predators.  And where did the predators get their eyes?

Edit:
Or better yet, why don't the predetors have eyes, yet.  The major predator was the jellyfish. 

Well if the predators were eyeless, having eyes would give them an even bigger advantage, wouldn't you think? Also, it is important to note that some species of trilobites were eyeless, so they all didn't have the advantage.

As for which eyeless predators, I had to look up some info(I'm not an expert on the subject of trilobites), and here's something I found - http://www.trilobites.info/triloecology.htm

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And, need I remind you that even today jellyfish exist(as predators and prey) and still don't have eyes.

Anyways, the main point is that trilobytes weren't high up on the food chain, so evolving something like vision would definitely be usesful to them as a defense mechanism. Why didn't the predators also gain vision at the same time? Who knows - maybe the trilobytes were simply lucky and got the proper mutations to develop it before the predators did. Vision is a useful tool for all creatures, not just predators.

[J. J.]

Here is another problem.  Possibly the first creatures to develop eyes, some species, were trilobites.  The were not[/i preditors; they scavaged on the sea floor.  Eyes didn't see through the bottom silt that they were sifting, but they had them.

Okay, why eyes? 

Perhaps to see predators coming.

What predators or, more appropriately, what eyeless predators.  And where did the predators get their eyes?

Edit:
Or better yet, why don't the predetors have eyes, yet.  The major predator was the jellyfish. 

Well if the predators were eyeless, having eyes would give them an even bigger advantage, wouldn't you think? Also, it is important to note that some species of trilobites were eyeless, so they all didn't have the advantage.

As for which eyeless predators, I had to look up some info(I'm not an expert on the subject of trilobites), and here's something I found - http://www.trilobites.info/triloecology.htm

You must be logged in to read this quote.

And, need I remind you that even today jellyfish exist(as predators and prey) and still don't have eyes.

Anyways, the main point is that trilobytes weren't high up on the food chain, so evolving something like vision would definitely be usesful to them as a defense mechanism. Why didn't the predators also gain vision at the same time? Who knows - maybe the trilobytes were simply lucky and got the proper mutations to develop it before the predators did. Vision is a useful tool for all creatures, not just predators.

Okay, let's assume that the trilobites developed eyes to see and run away from predators.  Where did the predators get them?  We are predators; or ancestors crawled out of the sea and gradually developed into humans.  I buy that.  But the trilobites were not in our line; they were not in the lines of the predators.  Further, jellyfish were successful predators; their descendants are around today.  They never developed eyes, but they were successful.

Now, I can see a mutation in the genetics of the trilobite that eventually gives them eyes.  I can understand how this is a survival trait.  I can't understand how a species that was not a descendant of the trilobites got them.  You'd have to have the same mutation is different species, at about the same time (give or take 20,000,000 years).

[John Dibble]

Here is another problem.  Possibly the first creatures to develop eyes, some species, were trilobites.  The were not[/i preditors; they scavaged on the sea floor.  Eyes didn't see through the bottom silt that they were sifting, but they had them.

Okay, why eyes? 

Perhaps to see predators coming.

What predators or, more appropriately, what eyeless predators.  And where did the predators get their eyes?

Edit:
Or better yet, why don't the predetors have eyes, yet.  The major predator was the jellyfish. 

Well if the predators were eyeless, having eyes would give them an even bigger advantage, wouldn't you think? Also, it is important to note that some species of trilobites were eyeless, so they all didn't have the advantage.

As for which eyeless predators, I had to look up some info(I'm not an expert on the subject of trilobites), and here's something I found - http://www.trilobites.info/triloecology.htm

You must be logged in to read this quote.

And, need I remind you that even today jellyfish exist(as predators and prey) and still don't have eyes.

Anyways, the main point is that trilobytes weren't high up on the food chain, so evolving something like vision would definitely be usesful to them as a defense mechanism. Why didn't the predators also gain vision at the same time? Who knows - maybe the trilobytes were simply lucky and got the proper mutations to develop it before the predators did. Vision is a useful tool for all creatures, not just predators.

Okay, let's assume that the trilobites developed eyes to see and run away from predators.  Where did the predators get them?  We are predators; or ancestors crawled out of the sea and gradually developed into humans.  I buy that.  But the trilobites were not in our line; they were not in the lines of the predators.  Further, jellyfish were successful predators; their descendants are around today.  They never developed eyes, but they were successful.

Now, I can see a mutation in the genetics of the trilobite that eventually gives them eyes.  I can understand how this is a survival trait.  I can't understand how a species that was not a descendant of the trilobites got them.  You'd have to have the same mutation is different species, at about the same time (give or take 20,000,000 years).

Well, I don't think I can come up with an answer that will satisfy you(you might try asking an expert in the subject) - it's wholly possible that other species also gained the right mutations to get eyes. One of the reasons trilobites might have gone extinct was because of newly evolved predators like fish and sharks, which had eyes. Also, just consider that trilobites were the ones to first evolve 'true' eyes(at least that's what I've been reading) - that implies other creatures probably had some sort of sensory organs for vision, but they were not as developed or useful as eyes as we know them now. But quite frankly, don't look to me for all the answers - I don't know. Evolution is a theory, not a law - that implies it is incomplete, and scientists are trying to fill the gaps, but it's hard considering we have to work on the luck of finding fossils that do fill in gaps.


Also, just a clarification - though we are predators as we are now, our ancestors may not have been. Our having an appendix implies this, as it is pretty useless to us, but other animals that have them and actually need them use it to digest plants. A predator can evolve from a non-predator.

[angus]

I think you need to take a step back from actual organs (eyes) to the development of vision.  Baby steps.  Look at whatever organism first synthesized the protein Rhodopsin, for example.  Or opsin.  Or any of those whose allosteric changes are initiated, or stimulated, by photons.  Rhodopsin is a nice one, though, since it's absorption spectrum just happens, because of its chemical structure, to peak at about 500 nm (greenish).  So it appears to have the complement color, purplish.  Sort of.  Anyway, look at the purple bacteria, the ones that first evolved the proton pump.  Figure out why that protein evolved in that bacteria and you might be able to extrapolate on that.  It may very well be entirely accidental that "visual" light happens to be in the 400-700 nm range.  In fact, the only reason that "light" got to be associated with that particular region of the electromagnetic spectrum is because that just happens to be that part of the spectrum most useful to the species that first evolved the ability to write books, give names to stuff, and have arguments about the origins of stuff.  If cockroaches had developed language first, then "visual light" may have referred to, say, 500 - 1100 nm or something like that.  In this case there would certainly be overlap between heat (infrared) and light (visible) regions of the spectrum.  But the answer to all this probably lies much further back in prehistory.  Before "organs" evolved.  Maybe even before organelles evolved.

[J. J.]

Well, I don't think I can come up with an answer that will satisfy you(you might try asking an expert in the subject) - it's wholly possible that other species also gained the right mutations to get eyes. One of the reasons trilobites might have gone extinct was because of newly evolved predators like fish and sharks, which had eyes. Also, just consider that trilobites were the ones to first evolve 'true' eyes(at least that's what I've been reading) - that implies other creatures probably had some sort of sensory organs for vision, but they were not as developed or useful as eyes as we know them now. But quite frankly, don't look to me for all the answers - I don't know. Evolution is a theory, not a law - that implies it is incomplete, and scientists are trying to fill the gaps, but it's hard considering we have to work on the luck of finding fossils that do fill in gaps.

No, the problem is that the experts cannot come up with an explanation.  The "theory," your term, does explain some things very well, but there are these other questions that it does not explain.  Mutation might explain a shift in a characteristics in one species and its descendents, but not another species.  Environment might explain why a trait suddenly becomes useful, but it does not explain how the trait got there.

We are clearly missing something.  What causes some species, not directly related, to develop in the same way, while others don't develop (and survive)?

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Yes, as did some trilobites.  I'm not trying to imply any differently.  That seems to be more greatly related to environment.

[John Dibble]

Well, I don't think I can come up with an answer that will satisfy you(you might try asking an expert in the subject) - it's wholly possible that other species also gained the right mutations to get eyes. One of the reasons trilobites might have gone extinct was because of newly evolved predators like fish and sharks, which had eyes. Also, just consider that trilobites were the ones to first evolve 'true' eyes(at least that's what I've been reading) - that implies other creatures probably had some sort of sensory organs for vision, but they were not as developed or useful as eyes as we know them now. But quite frankly, don't look to me for all the answers - I don't know. Evolution is a theory, not a law - that implies it is incomplete, and scientists are trying to fill the gaps, but it's hard considering we have to work on the luck of finding fossils that do fill in gaps.

No, the problem is that the experts cannot come up with an explanation.  The "theory," your term, does explain some things very well, but there are these other questions that it does not explain.  Mutation might explain a shift in a characteristics in one species and its descendents, but not another species.  Environment might explain why a trait suddenly becomes useful, but it does not explain how the trait got there.

We are clearly missing something.  What causes some species, not directly related, to develop in the same way, while others don't develop (and survive)?

See the bolded again. We don't know - we're still figuring this stuff out. As I said, it is a theory and not law simply because we have enough evidence to support it in general but we don't know everything there is to know about the process, ie there are gaps waiting to be filled. It's also why gravity was bumped down from law to theory - turns out that under certain conditions, gravity behaves a bit differently so we need to figure out those behaviors before we can call it law. Science is a work in progress, and it doesn't claim to have all the answers. Quite frankly, you should be wary of anyone that does.

Also, just advise you to do some reading into mutation if you are interested in the subject.