Can sense organs like the eye really evolve?

Hi Portillo, Well, for starters, there are many more examples than that. For instance, Pressie mention lab-based studies, and those have observed natural selection in action, creating new features. Such studies do not prove how an eye was formed, no, but they do demonstrate that it is, both in principle and in practise, possible for natural selection and random mutation to create new features. Having established this, the evolution of a complex organ like the eye has to be viewed as rather less unlikely than the OP would have it.But I am less interested in that argument and more interested in asking you a question; what evidence would you expect to see if the eye did evolve?Just consider the hypothetical for a moment. Imagine, for argument's sake, that the eye did evolve. What material evidence of this would expect to see?Mutate and Survive

Hi Portillo,I can't help but notice that you ignored my question in favour of a brief creationist soundbite. That's a shame, since I thought you might want to actually discuss the topic. Well for starters, adaptation and variation within a species is evolution. perhaps you meant to say "Macro-evolution". If so, then you are still wrong, since macro-evolution has been observed taking place in the lab. Further, the fossil record leaves little doubt that evolution has sculpted one species into another many, many times over. Despite the impression given by this quote, Grasse was a believer in evolution. He was a Lamarckian rather than a Darwinist, but still an evolutionist. And since he died in 1985, I'm guessing that his maverick views were voiced quite a long time ago.; the Forties perhaps. Even then he was in a minority. Believe it or not, quite a lot of work has gone on since that time and it makes mock of Grasse's silly nonsense.But enough of this. You ignored the most important part of my post. We are meant to be talking about the evolution of the eye after all. So please, answer the question; What evidence would you expect to see if the eye did evolve?

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Just consider the hypothetical for a moment. Imagine, for argument's sake, that the eye did evolve. What material evidence of this would expect to see?This is the most important part of this post. It is an important question. If you are unable to answer this question, how can we take you seriously on this topic? After all, if you can't define what evidence we ought to expect if eye evolution occurred, then you can't expect to be taken seriously when you claim that such evidence doesn't exist.So please, answer the question; what evidence would you expect to see if the eye did evolve?Mutate and Survive

Hi Portillo, thanks for your reply. That is an extremely vague statement. Perhaps you might clarify for me; what sort of "developmental process" do you have in mind? Given that fossilisation is an imperfect process (and fossil discovery is even more haphazard) it would be unreasonable to demand that a specific lineage be completely represented in the fossil record. The fossil record is simply not that complete. Instead it shows us snapshots of evolutionary change over time.Further, the terms "fully formed" or "half formed" are meaningless in biology. No biologist would expect to see a "half formed" creature in the fossil record. That makes no sense and is not a prediction of the ToE. Rather, all organisms are viewed as examples of their own species or clade. There are no partly formed species because there is no blueprint toward which the species is working; there is no goal. Ancestor species are not partly formed versions of their descendant species. They are fully functional examples of their own species.I would love to know what a half formed creature would look like.Meanwhile, if you're interested in what an early vertebrate eye might look like, I highly recommend this article, Early Evolution of the Vertebrate EyeFossil Evidence, by Gavin C. Young. It discusses and illustrates some amazing fossils of early chordates and vertebrates. Particularly interesting are the intricate fossils of 400 million year old placoderm fish, that show detail of cartilage around the eyes and brain case. These fossils preserve superb evidence of eye evolution, as they are intermediate between jawless and jawed vertebrates. In general, by evolution, that is by natural selection working upon random mutations.Specifically, in the case of vertebrate eyes, it is thought to have happened by the first photosensitive cells forming into clusters. These clusters gradually became concave, thus allowing limited directional vision. Then they progressed, to a stage of a mucous-filled cavity, then to a cavity covered with a lens. The same process of gradual development led to the various modern vertebrate eyes.Here is a video that goes into more detail on the stages of eye evolution; the most relevant material starts about two minutes in.For an even more detailed look at the structure and evolution of eyes, go here;https://www.youtube.com/watch?v=cnQGUQvtaPg That depends on what you're asking. Have we seen an eye evolve from scratch, from start to finish? No, of course not. Indeed if we had seen an eye form that rapidly, it would falsify many important aspects of the ToE. On the other hand, if you are asking whether the intermediate stages proposed for eye evolution are viable, then yes they are. All of them exist in modern species. We can also watch very primitive eyes gradually changing into more complex eyes during embryological development. Insofar as it provides strong evidence that natural selection can shape an organism over time, then yes. That's one of the observations that is required by the ToE and it's one that has been made. Similarly, the experiments that confirm the ability of random mutation to produce useful new features provide evidence for evolution in general. All of this provides a strong evidential backdrop for the the eye in particular. Well you are entitled to your belief. As it happens, the scientific consensus is not dependant on what you, or I, or anyone else believes. Evidence is all that matters and so far all observations from living species and from the fossil record are consistent with the eye having evolved. And in other respects, the eye is inferior to a camera. For a start, my camera can focus. My eyes can't and need corrective lenses. I can't easily change the lenses on my eyes as I might on a camera, or add a zoom (that last one is particularly annoying when I'm out birdwatching). Also, not wishing to state the obvious, I can't take snapshots with my eyes, print them out and bore my friends with them. My camera is attached to an "information processing system" though;it has a tiny computer inside it.So in actual fact, cameras and eyes are rather dissimilar, each with some strengths and some flaws. The alleged superiority that you are so impressed with is far from being as complete as you seem to think it is. Nor is it true that the superior design must necessarily be designed. Evolved antennae can work better than engineered ones, certainly well enough for NASA to use them. Yet they are not designed, their shapes are determined genetic algorithms, designed to mimic evolution.Mutate and SurviveEdited by Granny Magda, : No reason given.Edited by Granny Magda, : No reason given.Edited by Granny Magda, : No reason given.

Hi Big Al, Well yes, obviously my eyes can focus, but their range is still inferior to a camera. The camera is still superior, even without corrective lenses. You're getting caught up in the analogy. We're not talking about a specific camera here. A very different system. Memories are famously prone to error. If you remembered wearing a blue jacket at your last birthday party, but I show you a photo of you, at the party, wearing a black jacket, which would you trust? The photo or your memory? Also, good luck downloading your favourite memory onto your desktop.Do you have anything to say about eye evolution or would you prefer to squabble about an analogy?Mutate and SurviveEdited by Granny Magda, : No reason given.

Okay. I see. You have no coherent point to make about the evolution of the eye, so instead you're going to waste everyone's time and attack the analogy. Well if you're just going to be an idiot about it Al, I'm not going to waste any further time on you. Attack the analogy all you like; the whole "eye = camera" analogy wasn't mine in the first place, it was Portillo's. What exactly is your problem? Do you really think that being this childish is doing you any favours?Address the topic or please leave me alone.Mutate and Survive

Hi Parasomnium, But I don't have any horses... Well true, he could be a complete moron, I certainly wouldn't rule it out. I disagree. It's an analogy. It doesn't matter what damn colour jackets he actually has. For the purposes of the analogy he has a goddamn black jacket! I might as well reply that I can't have used photoshop because my computer is broken. It's just childish. Or very, very dumb.Also, I would just like to reiterate that I said this was a poor analogy from the start. What would be even more relevant would be to spend some of our time in the eye evolution thread talking about the evolution of the eye. Instead, Big Al would rather witter on about cameras. It's an avoidance tactic, a way of making look as though they're addressing the issue when in fact they're not. It's pathetic.Mutate and SurviveEdited by Granny Magda, : No reason given.Edited by Granny Magda, : No reason given.

Hi Portillo,This thread is the eye evolution thread, remember? It's not the "Random Whines About Evolution" thread or the "Let's Quote Mine Stephen Jay Gould!" thread. It's the eye evolution thread. For talking about eye evolution.Do you have anything to say about eye evolution? Like a reply to message 153 for example? It's the one entitled Eye Evolution.Or you might like to respond to this; As was shown in one of the videos I linked to earlier, all eyes share basic elements, like ciliary and rhabdomeric photoreceptors. The difference is what structures evolved from these basic building blocks. Further, the differences in structure fall into a clear evolutionary pattern, with closely related creatures having similar eyes. Genetic analysis shows the same pattern. You can read more about it here; How Many Genes Does it Take to Make a Squid Eye?So yeah. Eye evolution. Feel free to touch on that subject any time you like.Mutate and Survive

Hi Portillo, Planarian worms would disagree with you. They have simple eye spots. Showing one example of a complex eye does not render my example of a simple eye invalid. That it not a claim that I would make. "Primitive" is only meaningful in evolutionary terms when the creature in question left modern descendants. The trilobites didn't, they went extinct. And some had no eyes at all. Your point?Also, you are aware aren't you, that the three major groups of trilobite eyes fall into an nested hierarchy? And that they emerge in the fossil record only over great periods of time, just as we would expect had they evolved? This claim is straightforwardly false. Trilobites are far from the first things found in the fossil record. Ever heard of stromatolites? These fossils, left by cyanobacteria, go back at least 2 billion years, compared to the trilobites' 526 million years. Good question. Of course, I have already answered it.The commonality between eyes is obvious when you look at their construction. They are all made up of the same basic photoreceptors; ciliary and rhabdomeric. They share genes, even between distantly related groups like molluscs and planarians.What you need to understand is that the last common ancestor of all these groups would have had very primitive light-sensing abilities, likely without anything recognisable as a modern eye. After the various lineages split off, they independently took these building blocks and developed them, but each group took a slightly different path with them, leading to the diverse forms observable today. This is all entirely consistent with an evolutionary model. When we point to the eyes of a scallop and a squid and a human, and compare them, we are not suggesting that one evolved from the other. Rather, such comparisons are intended to show that each individual stage of the putative route of vertebrate eye evolution is, by itself, possible.One thing I can't help but notice is that you still haven't made it any clearer what you meant by this; I would be grateful if you could elaborate on this. What evidence exactly would you expect to see if evolution were true? What kind of "process" would you expect to see and over what kind of time-scale?I'm sorry to harp on at you, but this is an important question. How can you tell us that there's no evidence for evolution if you can't tell us what evidence we should expect evolution to leave?Mutate and SurviveEdited by Granny Magda, : No reason given.

Hi CS,I think I might make the question "What evidence exactly would you expect to see if evolution were true?" my go to question for creationist posters and I'll tell you for why. I reckon that you'll usually see three basic responses to that question. 1) Unreasonable Demands I want to see the fossils! All of them! I want to see fossils for every single generation, for every imaginable iteration of each and every evolutionary lineage going back to the dawn of time. And I want them all to have perfectly fossilised eyes demonstrating every tiny change that took place throughout their history. I would also like the moon on a stick, served to me by a flying pig.Essentially, the creationist will demand far more evidence than we might ever hope to find. Usually they will place much less stringent requirements upon their own arguments. 2) Strawman Intermediate forms? Well then, just show me a crocoduck! Or a half-man-half-monkey!! Show me a scallop turning into a squid!!!Show me life springing from my peanut butter jar!!!! Or any number of other crazy things!!!!!!!!!!Here, the creationist demands evidence for a version of evolution that no sane biologist would recognise. These kind of demands seem to spring from severe misconceptions about what the ToE actually says. Quite often, if we were to provide this kind of evidence, we would falsify the ToE, not prove it. 3) Reasonable Demands With this one the creationist asks for reasonable evidence, that is something that is both compatible with the real ToE and is something that we might reasonably expect to be able to observe.I can't think of any illustrative examples off hand, because we so rarely get asked this kind of question on these forums. In theory though, should this happen, you could just show them the evidence.I'm not saying that this will work any better than any other approach, but it's got to be worth a shot. And if that fails, I'll just call them dumbasses and say rude things about Jesus.Mutate and Survive