Why?

[Caitlin]

Aincha glad ya ast?

 

[SteveM]

On the other hand, cephalopods display and see colors, which indicate an evolutionary process.

Unique among Cephalopods, Nautilus retains an unevolved lensless eye, and can only perceive shadows and movement. I guess at 1800 feet much else would be a waste.

 

[pearlescence]

I've marked enough exams to know when a question isn't being answered.

 

[Mikeyy]

I doubt if the animal knows or cares that we are impressed with it's beauty. I think as Dave says it is simply a product produced for the comfort of the animal inside. I am sure the beauty of this nacre is probably only evident to us and has no other purpose then stated.

 

[Lagoon Island Pearls]

Unique among Cephalopods, Nautilus retains an unevolved lensless eye, and can only perceive shadows and movement. I guess at 1800 feet much else would be a waste.

Scallops have primitive eyes too. They don't necessarily create an image from them, insomuch as use them as a binary control. (ie) light, no light and process the combinations thereof.

Octopus and squid though, use light and color for breeding, emotion, camouflage etc. because they developed complexed retinas and chromatophors.

Somewhere along the line, molluscs evolved to use color to their advantage. It seems to coincide with losing the shell or in the case of nautilus, the precursor to it.

The missing link perhaps?

 

[SteveM]

Somewhere along the line, molluscs evolved to use color to their advantage.

Need to be specific, keeping in mind the multiple statements today to the effect that the color of nacre is irrelevant to the evolutionary process.

 

[Lagoon Island Pearls]

Need to be specific, keeping in mind the multiple statements today to the effect that the color of nacre is irrelevant to the evolutionary process.

Exactly. Nacre is a process in shell structure and little else. Due to the fact cephalopods developed these traits later in the evolutionary chain, suggest there was no dependence on color previously.

 

[pearlescence]

Mikeyy, there has to be a sound evolutionary reason why shells go to the trouble of being multicoloured. They could be dull or single coloured, but some at aleast are not just coloured but multicoloured. Darwin would insist that you don't make all that effort without some good species promoting reason. Especially when the molluscs have been doing it for so long - I mean blind cave tetras can lose their eyes within a relatively short time because they are in total darkness and don't need them (but now I hear they are evolving them back in aquaria!)
If colourful skins were a sure fire evolution promoter then we would have plaid and stripey skin. But we don't. It might work though!

 

[CortezPearls]

Color means nothing to a color blind animal. I would dare to state a most anti-Darwinian solution to Wendy's question of "Why???"... because our Maker wanted to make something beautiful and shinny for his little, color-loving, creations (us)

I truly don't think there is any other "real" answer... I don't believe our lowly pearl invertebrates could have expected for us to evolve and appreciate their iridescent shells...after all: this is a real risk for them! We (humans) have been able to wipe many of their populations because of our insatiable desire for their nacreous orbs and colorful shells. Thus, this just another unanswerable question from the Evolutionary standpoint...in my opinion.

 

[Lagoon Island Pearls]

If colourful skins were a sure fire evolution promoter then we would have plaid and stripey skin. But we don't.

That's why we have boobs, butts and wear pearls. In the absence of visual stimuli, pheromones fill that niche.

Color means nothing to a color blind animal. I don't believe our lowly pearl invertebrates could have expected for us to evolve and appreciate their iridescent shells...after all: this is a real risk for them!

Precisely. They make every effort to blend in to the environment. There is no display in feeding, breeding or hierarchy.

 

[Mikeyy]

You could be right but I am not sure that just because something is colorful and beautiful to us that there necessarily has to be any particular reason. Sunsets are beautiful and colorful. The reason for this is explainable scientifically but is there a purpose to the beauty or color? I think some things are just not explainable. But I will keep watching to see what you all come up with.

 

[AMc]

Lol- Douglas, I didn't have enough courage to say it myself: Just Because. Although I did appreciate Dave's eloquent analogy to satin sheets- comfy, protective and slick, the texture is the the most important function for the animal, the refractive (and gorgeous!) results simply unintentional and inconsequential to the animal within, a by-product of the quest for a comfortable home.

 

[pearlescence]

Cute, but evolution doesn't work like that.

 

[Lagoon Island Pearls]

Nature plays all kinds of tricks on us.

I have feathers from a Stellar's jay, that I use to demonstrate color shift. I give them to a person to hold before their eyes. I then have them rotate in a circle. The feathers change color from brilliant blue, to dark brown depending on the angle of the light.

When we look at the water of a lake or ocean it's blue, but we all know water is not blue. It only appears that way because of how light is reflected to our eyes, and how our brains are able to discriminate color temperature and frequency.

 

[Nora]

Dedicated to Mikeyy and Douglas.
This is from Nora's Eli:

The discussion sort of reminds me of the song we used to sing at summer camp around the camp fire. The one that went:
Tell me why the stars do shine,
Tell me why the ivy climbs,
Tell me why the sky is blue,
And I will tell you just why I love you.
The official answer, if you remember, was:
Because God made the stars to shine,
Because God made the ivy climb,
Because God made the sky so blue,
Because God made you, that's why I love you.
Of course, I sort of prefer the subversive response:
Nuclear fusion is why the stars do shine,
Geotropisms are why the ivy climbs,
Scattering of light rays is why the sky is blue,
And endocrine imbalance is why I love you.

As far as I'm concerned, pearls are a glorious natural accident and let's just relish them.

 

[AMc]

That's adorable!

 

[lisa c]

Cute, but evolution doesn't work like that.

Well, doesn't it? work that way? It exists, we just don't get it


maybe it's not lack of courage so much as being considerate or politically correct, and not having the graceful words that Douglas and Mikeyy had to express what's close to our hearts.

Ah, shoot. Not that Douglas and Mikeyy aren't considerate and politically correct. Sheesh. I'll stop now.

I love that poem, Nora's Eli.

 

[Caitlin]

Maybe the answer is in [FONT=&quot]Dobzhansky's Genetics of Natural Populations?
let's say that the color of the nacre is an unintentional side effect of its form and function, the question could become,"What is it about us that we evolved to appreciate these qualities, seek them out and ponder them so?" and further, "Is this really a sustainable trait?"
[/FONT]

 

[AMc]

"Is this really a sustainable trait?"

I sure freaking hope so! If not, then I'd say humanity is Doomed.

 

[SteveM]

So have we provided an answer, or does the question require rephrasing?