The Human Eye:
Darwin or Design?
v Even Charles Darwin conceded that “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 been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.”1
v The eye is essentially a living video camera of extraordinary sensitivity. Like any good manmade camera, the eye has a black interior to prevent light scattering, and an automatically focusing lens and adjustable diaphragm to control the light. And like the most sophisticated modern digital cameras, the eye has a light-sensitive layer (the retina) that can adjust to a wide range of brightness.
v But unlike any camera made by man, the retina can automatically change its sensitivity to brightness over a range of ten billion to one! The retina’s light-sensitive cells (photoreceptors) can perceive a range of light, from bright sunlit snow to a single photon (the smallest unit of light). The eye also has the amazing ability to assemble and repair itself, unlike man made cameras.
v How good is the lens of the human eye? Actually, the human eye has two excellent lenses—the cornea and the lens proper. During our development in the womb, embryonic skin over the developing eye turns into a clear window. To be so crystal clear, this special type of skin lacks the blood vessels, hair, and glands in most other skin, though it contains many nerves (and is highly sensitive to touch). Although we tend to think of the cornea as a protective window rather than a lens, it really functions as a lens. In fact, the cornea is about four times more powerful in bringing light to focus on our retina than the lens itself.
The lens proper, like the cornea, is also derived from embryonic skin and is marvelously transparent. Most cameras focus by physically moving their hard lenses, but the lens of the eye is flexible like rubber and can quickly focus by changing its shape.
v There are also three pairs of muscles attached to the outside of the eye. These muscles rotate the eyeball so we can look in different directions without moving our heads. Just think of it. Everywhere we turn our gaze, twelve separate muscles (six on each eye) move in perfect coordination for us to see the object we’re looking at. If our eyes are even slightly misaligned, we see double. This remarkable coordination is like a marksman so accurate with a pair of pistols that he can make only one bullet hole every time he fires both guns!
> We Even Have Window Wipers and Washers - each eye has a special reservoir of eye-washing fluid called the lachrymal glands. These glands secrete a watery tear fluid that has just the right acid level (pH) and osmotic (concentration) properties. The fluid also contains special enzymes that keep the eye clean of things that cause infection, and it has special oils to reduce evaporation. It also gives our cornea a smooth surface for optimum vision.
v The eyeball of a human weighs approximately 28 grams.
v The eye of a human can distinguish 500 shades of the gray.
v The eye muscles are most active muscles in the whole body.
v The external muscles that move ht eyes are the strongest muscles in the human body for the job that they have to do. They are 100 times powerful than they need to be.
v Eyes are composed of more than 2 million working parts.
v The eye can process 36,000 bits of information every hour.
v The average persons blink their eyes about 11,500 times per day; over 10,000,000 times a year!
v A normal lifespan will bring you almost 24 millions images of the world around you.
"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 been formed by natural selection, seems, I freely confess, absurd in the highest degree."
— Charles Darwin
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