Part 3 of a 7-part series with Dr. Eugenie C. Scott: Intelligent Design, Irreducible Complexity, and the Eye. Dr. Scott criticizes claims by proponents of creation science that the vertebrate eye is too complex a mechanism to have evolved by natural selection :
The Eye and Irreducible Complexity - Creationism Debunked
The Eye and Irreducible Complexity - Creationism Debunked
John Connolly: So you spoke a little bit about flagella. The other argument that is always drawn up is the Mammalian Eye, so could you maybe dispel that a little bit for us, the idea that the eye is too complex of a system to have evolved, that it must have had some intelligence involved?
Eugenie Scott: You know if you read the creationist literature, and I don’t want to wish that on anyone, but if you do you’ll find that they are very fond of quoting a statement that Darwin made on the Origin of Species where, and I haven’t memorized it but it’s something like “It is really quite preposterous to imagine something like the vertebrate eye, it’s so snazzy (he didn’t say snazzy), it’s got all these parts that work together to bring light to the eye and form an image, and nobody would think it would be possible for my natural selection to produce this”, and the creationists all say “see, Darwin himself says that the eye can’t evolve”. But they’ve never really looked at the book because they just keep quoting each other, and if you actually go to the Origin of Species and you find that passage and you continue reading it, the very next sentence is “But I can assure you that that’s not the case, that I can do this” and then he goes on with this wonderful description of how it’s quite possible to take a very simple structure, and with very few modifications improve its ability to assist an organism, in other words in Darwin’s own terms it had adaptive value.
I just knew who this woman is, and the importance of her position a few days back , when i assisted the video : Expelled: No Intelligence Allowed:
from Wiki:
Eugenie Carol Scott (born October 24, 1945) is an American physical anthropologist, a former university professor and one of the strongest voices challenging the teaching of young earth creationism and intelligent design in schools. From 1987 to 2013,[1] Scott served as the Executive Director of the National Center for Science Education, Inc., a pro-evolution nonprofit science education organization with members in every state.
So then she goes on :
Eugenie Scott: And he then does this wonderful thing, which Darwin did all his life of course [as] he was a wonderful naturalist, he went out to nature and he looked at nature and said “there’s something that’s kind of like what I’m talking about”, and if you look at the eye of a snail it’s hardly more than just a slight pigmented spot on the surface of the skin there, but having a pigmented spot does allow you to tell light from dark, so that’s adaptive to a snail; that would actually help a snail get along better, so any ancestral primitive snail or creature that had this light sensitive spot would be at an advantage and so it would live longer and as we say today would pass on its genes more than a creature of the same species that didn’t have that.
Now thats a pretty nice example of a superficial pseudoscientific claim.
In regard of the eye spot, from my personal virtual library:
The eyespot apparatus is irreducibly complex
Eyespots are the simplest and most common "eyes" found in nature, composed of photoreceptors and areas of bright orange-red pigment granules.
Euglena possess a red eyespot, an organelle composed of carotenoid pigment granules. The red spot itself is not thought to be photosensitive. Rather, it filters the sunlight that falls on a light-detecting structure at the base of the flagellum (a swelling, known as the paraflagellar body), allowing only certain wavelengths of light to reach it. As the cell rotates with respect to the light source, the eyespot partially blocks the source, permitting the Euglena to find the light and move toward it (a process known as phototaxis
Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from stimulus of light.[1] This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for photosynthesis. Phototaxis is called positive if the movement is in the direction of increasing light intensity and negative if the direction is opposite.
so their light sensitiveness has actually nothing to do with seeing. It has a entirely different purpose, namely moves towards or away from stimulus of light . It does not need a brain for doing so.
in order to function, the euglena needs a red eyespot, and a phototaxis receptor. Thats already a interdependent and irreducible complex system system.
the photoreceptors in euglena have the goal to trigger movement in the flagella in order the bacterias to move closer to the light source for photsynthesis. Several parts in the cell are required to accomplish this task, namely : Excitation of this receptor protein results in the formation of cyclic adenosine monophosphate (cAMP) as a second messenger. Chemical signal transduction ultimately triggers changes in flagellar beat patterns and cell movement. No messenger, no movement, no task accomplished...
euglena need 1. a eye spot, 2 receptor proteins, and their exitations results in cyclic adenosine monophosphate (cAMP) . that will result in flagella beat patterns and cell movement. That IS already a irreducible complex system.
At its simplest, the eye incorporates three functions:
Light detection
Shading, in the form of dark pigment, for sensing the direction light is coming from
Connection to motor structures, for movement in response to light
In some organisms, all three of these functions are carried out by just one cell—the single-celled euglena is one example. It has a light-sensitive spot, pigment granules for shading, and motor cilia. This structure, however, isn't considered a true eye.
The most-basic structure that is widely accepted as an eye has just two cells: a photoreceptor that detects light, and a pigment cell that provides shading. The photoreceptor connects to ciliated cells, which engage to move the animal in response to light. The marine ragworm embryo (right) has a two-celled eye.
What is required for this visual system ?
Photoreceptor cells
Pigment cells
the optic nerve
if they are not there all at ones right from the beginning, even the simplest eye will not work. That is already a irreducible complex system.
Eugenie Scott: “Well you know here’s another kind of creature, another little invertebrate creature the limpet that has that pigmented spot, but it also has kind of a little bit of an indentation on the skin where that pigmented spot occurs and that’s an advantage; that’s actually better than that snail eye because having an indentation as well as that pigmented spot allows you to get an idea of what direction the light is coming from, so that’s even better than being able to tell light from dark.
More pseudoscientific nonsense.
http://www.detectingdesign.com/humaneye.html
Another interesting problem with the argument for a selective advantage for a dimpled eye over a flat eyespot is the fact that determining the general direction of a light source can be achieved with a flat eyespot. Dimpling is not needed to determine the relative direction from which a beam of light is coming. All that is needed is an ability to rotate the eyespot relative to the source of light combined with the brain's ability to associate differences in the intensity of light with the change in orientation of the eyespot relative to the source of light. This sort of associative ability could produce essentially the same effect of being able to localize and even follow or move toward a source of light without the need for producing a dimpled or cup-shaped eye. In fact, the species Euglena, with just a flat patch of light-sensitive cells, can swim toward a source of light - - no dimpling needed ( Link ). In fact, some creatures, like starfish and sea urchin have no eyespots at all yet are still sensitive to light to the degree that they can move toward sources of greater light intensity
Eugenie Scott:And by the way, if you look at the physiology of this, being able to tell light from dark is useful for many creatures, I mean lots and lots and lots of organisms, for setting the biological clock for certain physiological reactions that happen. Being able to tell what direction the light is coming from is very useful because that might help you navigate toward food or away from heat or away from other kinds of phenomenon that you might want to avoid or be attracted to, and then Darwin goes on and find another animal, and he points to it as having not only some wiring down here at the bottom and this cup shaped thing, but actually the cup is formed almost to a pinhole, and it’s kind of the equivalent of the old fashioned pinhole cameras that I know people had in the early 20th century. Nobody has them now of course because we’ve all gone far beyond that, but a pinhole camera is a big advantage over just having a cup because a pinhole camera actually can allow an image to focus on the back of the eye. So anyway, he [Darwin] builds up this system step by step by step by step and actually on NCSE’s website we’ve got a little video talking about the evolution of the eye in the same fashion.
Another problem is, that this story telling has no empirical evidence to back up the claims. Its just fantasy.
And then you add a lens and that’s an improvement as well,
As if that is a easy task. Just add a lense. Not think about it. How the sake is that not rather a Kindergarden story, rather than science !!!
And there are tons of people which blindly believe that nonsense......
Eugenie Scott: so what Darwin does is look at the eye, the final product of the vertebrate eye which is a very snazzy kind of organ, it’s really good about getting images to the eye and getting that information to the brain, but he shows you how from very, very simple beginnings there is an adaptive value to each step until you finally build up to the final product.
As if to bring the information to the brain is a easy task.....
The visual system is made of three major parts: the eyeballs with retina, the optic nerve, and the visual cortex. The eye ball has at least individual 16 parts, while the visual system, consisting in the optic nerve and visual cortex, en-globes total at least another individual 14 parts. These items are minimal requirements for vision of humans. The question is, which evolved first: the retina (eyeball), the optic nerve, or the visual cortex ? Since all of these are interdependent, they would have had to arise and evolve at the same time, either interconnect since the beginning, or at the right time all togheter, once fully evolved. Not one of the three items could have preceded the others, as they would be useless. It is unimaginable to think of a different use that could be assigned to each part individually, and how each could individually have function and advantage of survival. If any one to three of these items were partially evolved, no vision would be achieved. There would be no possible advantage, and evolution could not continue.
The thalamus relies on electrochemical codes to the visual cortex. The visual cortex then interprets the signals and converts the signals into light, color, and visual images. Light, color, and visual images do not exist at all outside of a receptive brain. In fact they don’t exist at all inside of our visual cortex. Our visual images are pure perception. Tehy don’t exist in reality. The brain “manufactures” the light that we see, as well as the odors that we smell, sound we hear, taste, and texture. Without a brain’s visual cortex to interpret the signals it gets from the retina, the electromagnetic waves from the sun would only be useful in warming and energizing the planet earth. How would evolution “know” that if it evolved this incredibly complex vision system, light, color, and incredible images would be at the finish line.
Eugenie Scott: Now what the intelligent design folks want to do is they want us to start there, they want us to start at that final complex snazzy multi-component form and say “[it] couldn’t possibly form by natural causes”, but actually it’s very possible for it to form.
Assertion based on blind faith, and unsupported pseudoscience, as shown.
Eugenie Scott: And what’s kind of interesting about the eye story is that there were some Swedish scientists (and I am sorry I am having a senior moment, I don’t remember the exact reference) who did some computer modeling for how long would it take, given such and such a mutation rate for changing the surface of the skin and causing the cup forming and the pinhole eye and the formation of the lens from crystalline structures that are already there, and how long would it take to evolve an eye from something like Darwin’s original pigmented patch and it found that it could be done in something like 100 million years or something which, geologically speaking, is a drop in the bucket.
Yep. More nonsense.
Since Nilsson and Pelger's article was published, it has been widely--but erroneously--reported that their conclusions were based on a computer model. Berlinski calls this claim "an urban myth." At a minimum, PBS should make clear to viewers that Nilsson's conclusions are not based on computer models at all, and it should acknowledge that his work is highly speculative."
"What is one to make of all this? First, comparing the evolution of the eye to shape changes on a computer screen seems rather far-fetched. The entire project seems closer to an exercise in geometry than in biology. Second, the exercise assumes a functional starting point. Thus it has nothing to do with the origin of the biochemical systems of vision or the requisite neural network. Third, Nilsson and Pelger's computer exercise operates as if each 1% change in morphology can be accounted for by a single gene mutation. They do not consider the effects of pleiotropy, genetic background, or developmental processes. Fourth, an important part of the model relies on the special circumstance of a layer of clear cells covering the "retina." This layer somehow assumes the proper shape of a lens. Fifth, as noted by the authors, several features of the eye remain unaccounted for, such as the iris. Basically, the only result achieved was to show that two light-sensitive surfaces that differ in shape by 1% will have different efficiencies in photoreception, and that an uninterrupted series of 1% improvements is possible. The failure of scientists to produce new structures in selection experiments illustrates the implausibility of Nilsson and Pelger's "just so" story."
more at my personal virtual library:
Eye / brain is a interdependent and irreducible complex system
The human eye, intelligent designed
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