A Possible Origin of the Eye
Letís consider how the eye might have evolved through a series of small evolutionary steps. Letís start with a simple, single-celled organism that can swim about, using its tail as propulsion. We will assume that this simple organism has a clear, jellyfish-like body. This creature is competing with similar organisms to feed on algae-like material found in warm tide pools near the sea coast. Our creature finds its way around by sensing objects that it has bumped into. Our creature is shown below. Letís assume that one of our creatures has undergone a mutation resulting in a dark mole or freckle on its body. As our mutated creature swims near the surface of the sea, the sunlight heats the freckle more than the rest of the creatureís body, because the darker material absorbs more heat. Swimming in shallow tide pools close to land, the creature senses the strong solar heat. Our creature realizes that when the heat is more intense, it is easier to find food. This provides a big advantage over its competitors and our creature grows and reproduces many times, passing on the dark spot to its descendants. The descendants soon edge out the creatures without the spot.
Some of the creatures have darker spots that receive more solar heat, making the richer food sources easier to find. These creatures will out-feed the ones with lighter spots and pass on the darker spots to the next generation. This spot will eventually become black, like the cavity inside the human eye.
After many generations, a second mutation occurs. This mutation causes a small pocket of clear, jelly-like material to form on the top of the black spot. This new material could be genetically identical to the clear jelly material of the rest of the body. It acts like a lens and helps to focus the light, generating a more intense heat. This creature now has an even easier time finding the warm, shallow tide pools where the food is plentiful. Over many generations of evolution, this crude mechanism develops more nerve connections and the lens becomes more refined. Small muscles develop that can change the shape of the lens and allow controlled focusing of the light. At each stage, the new generation has an advantage in finding food and is able to survive and reproduce. A third important mutation occurs that causes the genetic code to produce a second similar eye. This offers better vision and a backup eye. Ultimately, a human-like eye evolves.
Evidence that the eye evolved and was not designed lies in the fact that the human eye is a rather poor design. Besides allowing macular degeneration, cataracts, retinal detachment, astigmatism, presbyopia and glaucoma, the eye has some design features that would make anyone cringe. For example, the blood vessels are actually between the light sensors and the eye lens, causing vision distortion. A sensible design would have put the blood vessels at the bottom of the sensors, away from the light source.
Humans have been able to develop electronic eyes, based on the silicon atom, that are far superior to the human eye. For example, the electronic eye on a space satellite can spot an object much smaller than a golf ball on the earthís surface. The human eye is far from having this ability. The electronic eye has a zoom feature that is missing from the human eye. The man-made eye has superior night vision. The silicon eye has a much faster response to changes in movement and will last much longer than the human eye. Since simple humans can design an electronic eye that is superior in performance to their own eye, it is very unlikely that a superior intelligence designed the inferior human eye.