The human eye is enormously complicated - a perfect and interrelated system of about 40 individual subsystems, including the retina, pupil, iris, cornea, lens and optic nerve. For instance, the retina has approximately 137 million special cells that respond to light and send messages to the brain. About 130 million of these cells look like rods and handle the black and white vision. The other seven million are cone shaped and allow us to see in color. The retina cells receive light impressions, which are translated to electric pulses and sent to the brain via the optic nerve. A special section of the brain called the visual cortex interprets the pulses to color, contrast, depth, etc., which allows us to see "pictures" of our world. Incredibly, the eye, optic nerve and visual cortex are totally separate and distinct subsystems. Yet, together, they capture, deliver and interpret up to 1.5 million pulse messages a milli-second! It would take dozens of Cray supercomputers programmed perfectly and operating together flawlessly to even get close to performing this task.1
That's so powerful to me! Obviously, if all the separate subsystems aren't present and performing perfectly at the same instant, the eye won't work and has no purpose. Logically, it would be impossible for random processes, operating through gradual mechanisms of natural selection and genetic mutation, to create 40 separate subsystems when they provide no advantage to the whole until the very last state of development and interrelation.
How did the lens, retina, optic nerve, and all the other parts in vertebrates that play a role in seeing suddenly come about? Because natural selection cannot choose separately between the visual nerve and the retina. The emergence of the lens has no meaning in the absence of a retina. The simultaneous development of all the structures for sight is unavoidable. Since parts that develop separately cannot be used, they will both be meaningless, and also perhaps disappear with time. At the same time, their development all together requires the coming together of unimaginably small probabilities. 2
The foregoing represents the core of "irreducible complexity." Complex organs made up of separate but necessary subsystems cannot be the result of random chance. Or, using the above language, such development could only result from "unimaginably small probabilities." For me, this means "statistical impossibility."
Come to think of it, I remember Darwin specifically discussing the incredible complexity of the eye in Origin of Species
To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have formed by natural selection, seems, I freely confess, absurd in the highest degree possible. 3
So, how did Darwin deal with the staggering realities of the eye in the 1850's? As "absurdly" improbable as it was, he followed through with his theory and pointed to the simpler eye structures found in simpler creatures. He reasoned that more complex eyes gradually evolved from the simpler ones.
However, this hypothesis no longer passes muster. Short of the micro-biological and genetic information issues, paleontology now shows that "simple creatures" emerged in the world with complex structures already intact. Even the simple trilobite has an eye (complete with its double lens system) that's considered an optical miracle by today's standards.
Wait. The trilobite reminds me of something… Before I continue with the marvel of irreducible complexity and design, I have one more thought about Darwin and his original claims…
1 Lawrence O. Richards, It Couldn't Just Happen, Thomas Nelson, Inc., 1989, 139-140.
2 Dr. Ali Demirsoy, Inheritance and Evolution, Meteksan Publications, Ankara, 475.
3 Darwin, Origin of Species, 155.