was just browsing your web site, which has tons of new stuff in it, and came across this
"As an organ developed via the opportunistic twists and turns of
evolutionary processes, the human eye is explainable. As an organ designed and created by
an infinitely wise deity, the human eye is inexcusable. For unlike the invertebrate eyes
..., the human eye is constructed upon the
foundation of an almost incredible error:
The retina has been put together backwards!
Unlike the retinas of octopuses and squids, in which the light-gathering cells are
aimed forward, toward the source of incoming light, the photoreceptor cells (the so called
rods and cones) of the human retina are aimed backward, away from the light source. Worse
yet, the nerve fibers which must carry signals from the retina to the brain must pass in
front of the receptor cells, partially impeding the penetration of light to the receptors.
Only a blasphemer would attribute such a situation to divine design!" - Frank Zindler
It's not my intention to offer rebuttal or to start a controversy or anything of the sort;
this is strictly between you and me. I've heard this argument before, which either
goes, "God is so stupid he doesn't even know how to design an eye," or,
"God must not have designed the eye, else he wouldn't have made such a silly
Regardless of your religious persuasion (which is none of my business), I'm sure you can
see the fallacy in the argument, which is the arrogant assumption that one knows how to
design an eye better than the one we all have.
To that assertion, let me just add the following observations:
1) The human eye is sensitive enough to detect, when dark-adapted, a single
2) The resolution of the human eye exceeds the theoretical diffraction limit (thanks to
brain-powered image enhancement).
The design may be "inexcusable," but it sure seems to work well, don't you
agree? During the last flight of the Mercury series, astronaut Gordon Cooper must have had
exceptional atmospheric seeing conditions, or exceptional eyes, or both. He claimed
to have seen, from orbit, railroad tracks, wakes of ships,
highways, and even trails between huts of mountain villages. I was one of several
scientists who whipped out our sliderules and determined that the things Cooper claimed he
saw were beyond the diffraction limit, even under the most optimistic assumptions.
The responses tended to clump themselves into about three groups:
1) Those who declared, pompously, that Cooper couldn't possibly have seen what he claimed
2) Those who didn't think he could, but weren't about to tell Gordon Cooper he was
dreaming it all
3) Those who thought maybe he somehow did manage to see them.
I was in the third group. As it turns out, when you examine the theoretical
background behind the diffraction limit, it's based upon the ability to resolve two
_POINT_ _SOURCES_ of light. It says nothing at all about seeing a reflecting
straight line, like the wake of a ship or railroad tracks.
Further, the diffraction limit assumes that the peak of one diffraction pattern is at the
trough of the other. This is not really necessary. In computerized image
enhancement, we can now routinely separate point sources that are closer than the
diffraction limit, by examining the shape of the
light-density curve. There's no reason to assume Cooper's brain couldn't do the same
Finally, they did some checking after the fact to see if ships were really where Cooper
said they were; if railroad tracks and trails were where he said. They were.
Re the design of the human retina, there's a very good reason for it that those who think
they could do better or missing.
As it happens, I have an intimate exposure to it, since I suffered a detached retina just
about the time I got out of college with my Ph.D., ca 1968. The human retina has no
blood vessels in it; it depends for its nourishment, strictly on an intimate
contact with the blood vessels lining the sclera of the eye.
The problem with a detached retina is that the retina loses contact with the sclera, which
means that the nerve cells will die, within a day or two for the fovea, within a week or
two for the cells in the peripheral vision (less density <==> less need for energy).
I guess I should count myself fortunate that Frank Zindler, or others that use his
argument, didn't design _MY_ eyes, else I'd be blind by now.
It seems that whoever or whatever designed the human retina, got it right after all. He
knew that making sure all those cells were well-supplied with oxygen and energy was more
important than perfect optics.
And since, apparently, the optics are already plenty good enough anyhow, it was the right
choice. Just so's you know.
One other little tidbit: You may or may not remember that I like to raise baby
birds, chickens, and ducks. My ducks have eyeballs much, much smaller than those of
humans (which means that the diffraction limit should be
Yet they can not only see us humans at 200 yards, they can distinguish one human face from
How the heck do they _DO_ that? In fact, how is it that a duck is more adept
at distinguishing human faces than a _HUMAN_ is? I have trouble understanding the
evolutionary basis for that.
- Jack Crenshaw