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THE EXTRAORDINARY DESIGN IN THE EYE
THE EXTRAORDINARY DESIGN IN THE EYE
When you look around you out in open air and in a broad field, you can readily see all objects farthest and closest to you in all their colors, shape, and size. This view, which you have obtained without making any effort, is produced as a result of numerous complex reactions and interactions in your body. Now let us look at these complicated operations closer.
The human eye has a fully automatic mechanism that works perfectly. It is made up of the combination of 40 different basic parts and all these parts have critical functions in the process of seeing. Any defect or disability in even one of these parts would make seeing impossi
The human eye has a fully automatic mechanism that works perfectly. It is made up of the combination of 40 different basic parts and all these parts have critical functions in the process of seeing. Any defect or disability in even one of these parts would make seeing impossible.
The transparent layer in the front part of the eye is cornea. Right behind lies the iris. Giving the eye its color, the iris adjusts its size automatically according to the sharpness of light thanks to the muscles attached to it. For example, if we are in a dark place, the iris widens to take in as much light as possible. When light increases, it shrinks to decrease the amount of light coming into the eye.
The automatic adjustment system in the iris works like this: The moment light comes to the eye, a nerve impulse travels to the brain and gives message about the existence and brightness of the light. The brain immediately sends back a signal and orders how much the muscles around the iris will contract.
Another eye mechanism working parallel to this structure is the lens. The duty of the lens is to focus the light coming to the eye onto the retina layer at the back of the eye. Thanks to the movement of the muscles around the lens, light rays coming to the eye from different angles and distances can always be focused on the retina.
All the systems we have mentioned are far smaller yet far more superior to the mechanical devices designed by the use of the latest technology in order to imitate the eye. Even the most advance artificial imaging system in the world remains extremely simple and primitive compared to the eye.
When we think of the effort and knowledge that has been put into developing these artificial imaging systems, we can understand with what a superior creation the eye is made.
The eye and brain break up the visual world into various aspects, such as color, form, motion, and depth. These pieces of the picture are interpreted in a complex network of processing centers. To form a coherent picture of the world, the eye-brain takes signals from the retinas, relays them through the lateral geniculate bodies, and then passes them on to areas Vl and V2 (revealed in the inset, which shows the brain from beneath). These areas engage in a dialogue with centers farther along the pathway-some of which are still unidentified. Sensory Filtering: The Visible Spectrum As you'll learn when we discuss light, our eyes have evolved to process electromagnetic radiation. However, the range of electromagnetic radiation that falls within the visible spectrum is only a small part of all electromagnetic radiation. So we can see wavelengths between about 400 and 700 nanometers (all the colors of a rainbow), but we can't see Infrared or Ultraviolet. Not all creatures evolved with the same visual systems though. Depending on what cues would be most useful for a particular animal, it may evolve different capabilities. For example, although we cannot see Infrared light, some animals can. This picture shows a face photographed with film that is sensitive to infrared light. Looking at the picture, you can imagine how different your world would look if our visual system processed different sorts of information. 1
If we examine a single cell in the eye at the microscopic level, the superiority of this creation will be further revealed.
Let us suppose that we look at a crystal bowl full of fruit. The light rays coming from this bowl to our eye pass through the cornea and iris and are focused on the retina by the lens.
So, what happens in the retina so that the retinal cells can perceive light?
When light particles, also called, photons, strike the cells in the retina, they produce a cascading effect like a row of dominoes carefully arranged one after the other. The first of these dominoes in the retinal cells is a molecule called 11-cis-retinal. When a photon of light interacts with it, this molecule changes shape. This forces a change in the shape of another protein, rhodopsin, to which it is tightly bound. Now, rhodopsin takes such a form that it can stick to another protein, called transducin, which was already present in the cell, but with which it could not interact before due to its shape's incompatibility. After this union, another molecule called GDP also joins in this group.
Now, two proteins-rhodopsin and transducin-and a chemical molecule called GDP have bound together.
However the process has just begun. The compound called GDP now has the proper form to bind to another protein called phosphodiesterase, which always exists in the cell. After this bonding, the shape of the molecule that is produced will trigger a mechanism that will start a series of chemical reactions in the cell.
This is a flowchart outlining the major steps in the vision signal transduction cascade which occurs between the isomerization of retinal (which leads to the formation of metarhodopsin II, the first reactant in the process outlined in this figure) and the interpretation of a visual image by the brain. 2
11 Cis Retinal
All Trans Retinal
Upon absorption of a photon in the visible range, 11-cis-retinal can isomerize to all-trans-retinal. In the 11-cis isomer, the hydrogens (red in the 2-D ChemDraw representation) are on the same side of the double bond (red in the 2-D ChemDraw representation) between carbon atom 11 and carbon atom 12. In the all-trans isomer, the hydrogens are on opposite sides of the double bond. In fact, all of the double bonds are in the trans-configuration in this isomer: the hydrogens, or hydrogen and -CH3, are always on opposite sides of the double bonds (hence, the name "all-trans-retinal"). Note how the size and shape of the molecule change as a result of this isomerization. 3
This mechanism changes the ion concentration in the cell and produces electrical energy. This energy stimulates the nerves lying right at the back of the retinal cell. Consequently, the image that came to the eye as a photon of light sets on its journey in the form of an electrical signal. This signal contains visual information about the object outside.
In order for seeing to take place, the electrical signals produced in the retinal cell have to be transmitted to the center of vision in the brain. Nerve cells however are not directly connected to one another: there is a tiny gap between their junction points. How then does the electrical stimulus continue on its way?
At this point, another set of complex operations takes place. The electrical energy is transformed into chemical energy without any loss of the information being carried and in this way the information is transmitted from one nerve to the next. The chemical carriers located at the junction points of nerve cells successfully convey the information contained in the stimulus coming from the eye from one nerve to another. When transferred to the next nerve, the stimulus is again converted into electrical signal and continues its way until it reaches another junction point.
Making its way to the center of vision in the brain in this way, the signal is compared to the information in the center of memory and the image is interpreted.
Finally, we see the bowl full of fruit, which we viewed before, by virtue of this perfect system made up of hundreds of small details. And all these amazing operations take place in a fraction of a second.
Moreover, since the act of seeing takes place continuously, the system repeats these steps over and over. For example, the molecules playing a part in the chain reaction in the eye are restored to their original state every time and the reaction starts all over again.
Of course at the same time many other equally complex operations are taking place in other parts of the body. We may simultaneously hear the sound of the image we are viewing, and depending on circumstances we may sense its odor and taste and feel its touch. Meanwhile, millions of other operations and reactions have to continue without interruption in our body if we are to go on living.
The primitive science of Darwin's day knew about none of this. Despite that however, even Darwin realized the extraordinary design in the eye and confessed his despair in a letter he wrote to Asa Grey on April 3rd 1860 in which he said:
This is a schematic diagram of a rod cell. The stacked disks contain rhodopsin, the complex of opsin protein and 11-cis-retinal. At the synaptic body, the potential difference generated as the ultimate result of the retinal isomerization is passed along to a connecting nerve cell, creating an electrical impulse that will be transmitted to the brain and interpreted as visual information. 4
I remember well the time when the thought of the eye made me cold all over.5
The biochemical properties of the eye that have been discovered by modern science dealt a greater blow to Darwinism than Darwin could ever have imagined.
The complete process of seeing that we have summarized in barest outline here is even more complex in its details. However even this summary is enough to show what a glorious system has been created in our body. The reactions taking place in the eye are so complex and so finely tuned that it is quite unreasonable to think that these are a product of chance occurrences as the theory of evolution claims.
Michael Behe, a recognized professor of biochemistry, makes this comment on the chemistry of the eye and the theory of evolution in his book Darwin's Black Box:
Now that the black box of vision has been opened, it is longer enough for an evolutionary explanation of that power to consider only the anatomical structures of whole eyes, as Darwin did in the nineteenth century. Each of the anatomical steps and structures that Darwin thought were so simple actually involves staggeringly complicated biochemical processes that cannot be papered over with rhetoric. 6
But as we have seen, the theory of evolution is unable to account for a single system in a single living cell, much less explain life as a whole.
Having utterly demolished the hypothesis that life is 'simple', science demonstrated to humanity a very important fact. Life is not the product of unplanned happenings. It is the result of a perfect creation. The perfect creation of a superior Creator, Who brought life into being, Who is God, the Lord of the Universe.
It is He who created both humans and all other living beings. It is only logical that we, humans, worship GOD alone.
[Quran 17:36] You shall not accept any information, unless you verify it for yourself. I have given you the hearing, the eyesight, and the brain, and you are responsible for using them.
[Quran 67:2] The One who created death and life for the purpose of distinguishing those among you who would do better.* He is the Almighty, the Forgiving.
Article courtesy of www.DesignandUniverse.com
References:
1. http://www.starsandseas.com/SAS%20Physiology/Neurology/Sight.htm
2. http://www.chemistry.wustl.edu/~edudev/LabTutorials/Vision/Vision.html
3.Ibid. 4.Ibid 5. Ibid
5. Norman Macbeth, Darwin Retried: An Appeal to Reason, Harvard Common Press, 1971, p. 131. 6. Michael J. Behe, Darwin's Black Box, p. 22
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