CX

I just spent about 2 hours carefully reading through this entire thread. (One of the joys of Software Development is plenty of down time at work). I've learned more this afternoon than in 17 years of education (granted I've studied absolutely no biology at all). Thanks very much.

garraty

I'd also like to add a thankyou.

The evo/cre forum was the reason I started frequenting the II a few years ago, and I admit that for quite some time I haven't looked in here, all the arguments have been won, and I knew all I needed to know.

Now I know even more....

You guys are evolving yourselves you know, peez, DD, OC, MrDarwin et al, after all this time answering the same questions over and over you are getting far better at fielding the questions posed here.

What a marvelously informative post! This is one for the archives, not only do you cover the origin of the eye, but also sum up evolution in all it's different forms, from Genetic Drift to Natural Filtration You've blended hard core science with apt analogies, every rebuttel has been patiently dumbed down to a kindergarten lesson, and at the same time you amuse yourselves with the latest discoveries in a way that only "masters" could appreciate.

This thread makes my head hurt, not from the overflow of information, but how much time and effort has gone into every post.

The fact that you know evolution is true, infact the only reason you have food on the table is because it is so true you can make a living off the science of it, you spend your day at work with evolution and then come home and spend hours trying to defend it to people who don't even try to understand it. Your patience is astounding.

And you've been doing this for years.

So once again thankyou for the effort in educating so many of us who have learned something from this forum. It isn't all going to waste.

luvluv

All righty, I'm a bit confused after reading back over this.

It seems to me that Peez's view is that the evolution of something like the eye didn't really get a goin' until later in the evolutionary scheme of things. (Inasmuch as his example was emphatically not unicellular).

The example being put forth by Wizardry and MrDarwin seems to suggest that the precursors of the evolution of something like the eye (with rhodospins and whatnot) were present in some of the earliest unicellular organisms.

So it seems we have the unicellular track and the multicellular track. It seems to me that the unicellular track is more promising, or at least, it's more simplified and thus a more pragmatic model for getting to the issues at hand.

I thought Wizardry made an excellent point here:

From everything I've read, I think this makes the most believable case for how sight could have evolved. (I know Peez's opening statement said virtually the same thing, that a protein would go from reacting to salt to reacting to light, but I don't see how that would confer much of a survival advantage to a multicellular organism).

So, if everyone is agreed, lets just abandon the multicellular model and explore the unicellular model.

Now comes the part where I ask the aggravating questions:

1) Is this case that Wizardry has presented the "orthodox" position? Is there an "orthodox" position about the evolution of the eye? (I'm wondering if there is a FAQ somewhere or just a book or article about the issue that could facilitate this?)

I'm asking because in re-reading this it seems that most of you are offering somewhat speulative scenarios, which leads me to believe that there perhaps is no orthodox position on this subject. It reminds me of so many theodicies... sure these things would make sense if what they describe actually is the case. It is certainly a consistent and possible answer to all the objections. But how do you know that it DID take place? Does not evolutionary biology break down into theology at this point, where you attempt to establish what did happen through application of your axiomatic pressuppostions. But like theology, it is all rather unconvincing to one who does not have a prior acceptance of your axiomatic pressupostions.

I say all this to say that you are doing a good job of convincing me that it COULD have happened. (No small feat! Congratulations!) I'm now asking you to give me reason to move from the "could" to the "did". Is there evidence that can move me to that position?

My beef with biology is that it is the only physical science where "coulds" are AUTOMATICALLY translated into "dids" due to the (perceived) impossibility of an alternative. (If not evolution, then what?) But what if I believe there is an alternative? (God, intelligent designers who are more simple than that which they design, etc.)

2) What is involved in the protein responding to salinity? (I think somebody covered this earlier in the thread but for the life of me I can't find it. If I do find it after I post this I'll edit out this part, but if I can't would somebody do me a solid and paste it in response to this portion? Thanks.)

3) Can you identify a chain of organisms in which the evolution of the eye took place? It doesn't have to be accurate, just a description of the animals with one photocell, then the animal with the sheet of photo cells, then the animal with the concave photocell, etc. Just to get a picture of how this could have happened.

Also, could someone explain genetic drift for me? From context, that seems to mean the accidental propigation of certain features which have no evolutionary advantage at all from sheer luck of the draw. What factor does this play in evolution?

Finally, the notion promoted here, that small mutations produce large effects, does not (within my limited knowledge) reflect the reality of the fossil record, or of the evolutionary model with which I am generally presented. I was always of the opinion that evolution is the description of small advantages accumulating over time. This is the view that Dawkins defends in climbing mount improbable, if I'm not mistaken? What you folks seem to be defending is something closer to Gould's position of punctuated equilibrium (are the mutually exclusive, by the way?).

So, while I know there is controversy in this issue, which is it? Are the advantages incremental or not? If so, how do they confer an advantage? If not, why aren't they more blatant generally? More observed? If every human being is walking around with a dozen or so mutations, and small mutations can have large effects, where are the large effects?

This is a big part of my resistance to evolution as a theory. If it cannot produce big effects, why would any mutation confer any signifigant advantage? If it can produce big effects, why aren't they constantly visible?

ooh_child

Glad to see you're back, luvluv. I've been lurking this thread, and I was hoping you'd show back up

Looking forward to the response:notworthy

MHB

HRG

Not at all. Astronomers automatically translate "these photons could have come from Sirius (but they also could have been created inside our solar systems by powerful invisible djinns)" to
"these photons did come from Sirius". Geologists automatically translate "these recordings of a seismometer could indicate an earthquake (but also the rumbling of gremlins)" to "they do indicate an earthquake", etc.

If you are sufficiently creative, you can invent alternatives to any scientific theory.

In addition, I submit that an intelligent designer must be as least as complex as his designs - because he has to have a model of the design "inside" himself.

Regards,
HRG.

DMB

Luvluv:

I'm not a biologist and am very much open to correction from the experts, but on the philosophical status of evolution I think there are certain distinctions to be made.

Biologists are convinced that evolution has occurred on a massive scale because of physical evidence such as the fossil record and the genetic record. What is particularly remarkable is that although Darwin took many years to produce The Origin of Species because he was gathering the evidence for evolution, since the publication an enormous amount of evidence has come to light that is supportive of evolution. Evolutionary theory has shown itself to be good at predicting likely discoveries.

There is no branch of science which yet has all the answers. In fact, given the history of discovery and progress over the past 150 years in biology, there is no reason to suppose that many more important discoveries are not waiting for us in the future.

Prediction is an important part of scientific progress. It acts as a reality check. Inevitably, some predictions will turn out to be wrong, and will show where people are making incorrect assumptions. When critics of evolution come up with objections about the impossibility of the evolution of an eye or a wing, then of course biologists have to reply by showing how these things could have occurred. There is a lot of real evidence already, but there are gaps and so speculative predictions are made to demonstrate plausibility. The term "just-so stories" (from Kipling's wonderful stories for children on such topics as "How the elephant got its trunk") is often used in a contemptuous way to dismiss these efforts. But these just-so stories are valuable and can lead to real future discoveries. What is important is to be able to distinguish between facts and just-so stories, so that no-one is deceived.

With regard to the uselessness of small advantages, it is simply human nature to be more impressed by "with one bound he was free" than by " for thirty hours he rubbed the rope binding his wrist againt the piece of rock so that it weakened and finally broke". As someone with a mathematical background I am only too aware to most people's blindness to small increments and their affects. For a long time I was involved in the field of population. Most people could see that if a population were to increase by 10% per annum it would have a considerable effect. But surely 1% per annum was negligible. Nevertheless, such an increase will double a population within a normal life span. If you invest your money and receive compound interest on it, small increases in the rate of interest can have a big effect downstream.

Remember too that mutations don't necessarily have to confer a survival advantage on an individual; they simply have to help reproductive success. If a particular mutation were to confer a 1% reproductive advantage, it would spread pretty quickly. Even if it confers neither advantage nor disadvantage it can still be established if it happens to occur in individuals that for other reasons enjoy reproductive success.

Peez

No, that is not my view. I was not making an effort to tell you how our eye ("the eye" is a bit general, since there are a number of different "eyes") actually evolved, simply because I do not know how our eye actually evolved. I was trying to show how it could evolve, and specifically how each step would be advantageous over the last. There are many possible paths that could have been taken, my intention was only to show that such a path is not impossible.The evidence certainly supports that view.There is no doubt that the precursors to the eye were present in unicellular organisms. The specific path that evolution took to our eye is not known, though at least some of it may be inferred. The important point here is that our eye presents no obstacle to accepting the theory of evolution.I am not particularly attached to the "multicellular model," though it remains a possibility. I presented it because it seemed simpler to understand.There are a number of ideas about how our eyes evolved, but because eyes do not fossilize very well there is no "orthodox" position that I am aware of. Note that Wizardry opened the quoted text with:I believe that the point here is not that this scenario or that scenario describes how our eye actually evolved, rather the point is that such an eye can evolve through the mechanisms of the theory of evolution.It is really quite simple. You suggested that the theory of evolution is insufficient to explain how our eye could have evolved. In order to counter this suggestion we do not need to show that we know exactly how it did evolve, we only have to show that it could evolve by the mechanisms of the theory of evolution. If you suggested that air currents and gravity could not account for a snowflake coming to rest on a particular spot on a branch of a tree, we do not have to produce evidence of a specific path that the snowflake actually took, we have only to show that gravity and air currents could indeed result in the snowflake getting there.I am not sure if I understand you. We know that humans (including their eyes) evolved from unicellular organisms, and we know that the theory of evolution is sufficient to explain how this occurred. There is no other scientific explanation known. Of course it is possible that one or more supernatural entities have interfered, but that is beyond the realm of science and in any event an unnecessary assumption.Given your lack of knowledge of biology, does this not seem to be a, um, bold statement?I have never claimed that god or any other intelligent designer was not involved. I have merely explained that such interventions are superfluous and unscientific.Wizardry discussed it about 2/3 of the way down page 4 of this thread.This seems to be a good site (though I did not read it carefully).Your description is essentially correct. Because it is random, nobody expects it to produce adaptation. Also, it tends to be quite weak in large populations. However, it is no doubt important in non-adaptive evolution (e.g. changes in non-coding DNA), and it may be important in the evolution of adaptations in very small populations (in such populations, it may be more powerful than natural selection).It is not clear what you are getting at here. I am not, and I know of nobody who is, promoting the idea of saltational evolution (evolution in large and dramatic jumps). Of course, "large" and "small" are relative terms, but no evolutionary biologist is suggesting that useful complex organs appear from a single mutation. The changes that we have suggested in the eye evolution scenarios are very subtle, just a small alteration in the structure of a protein.

With regards to Dawkins vs Gould, they are not mutually exclusive. Both have made it clear that evolution has proceeded in small, incremental steps.If you are referring to Dawkins vs Gould, the controversy is over how important isolated small populations are in evolution, how evolutionarily stable large populations are, and perhaps how fast evolution proceeds under different conditions.[quote][b]Are the advantages incremental or not?[quote][b]If you mean does adaptive evolution proceed by increments, each of which is advantageous to the previous one under the conditions present, then the answer is yes (with a few possible exceptions).See the discussion of eye evolution.Sorry, I do not understand you here."Small mutations" can have "large effects," and such "large effects" are often fatal (did you know that most human eggs successfully fertilized die long before birth?). However, most mutations have little or no effect. In general it is mutations of small effect that contribute to evolution, as in the scenarios that we have offered for the evolution of the eye.I don't see why you cannot accept that a small change can be an advantage. It does not have to be a big advantage, a 1% better chance of survival could produce significant evolution.

Peez