Pretty impressive collection of SciAm magazines wofahulicodoc, I couldn't pull up the 2000 issue that you referred to, but if you remember the point of it, it would be nice to know.

The following observations were lifted from the book The Story of Light by Ben Bova (remember him?) They are in no marching order but sorta dance up to the question, Why did Mother Evolution make the sun and moon appear so fat when they are on the horizon?

***Flatworms, like every other animal, tend to keep their eyes (two, four, or six, depending on the species) close to their brains. Even though their eyes are little more than little cups of light-sensitive material, being close to the brain shortens reaction time. And if you make your living preying on the microscopic jungle fauna of protozans, tiny snails, and worms; milliseconds count.

***The molluscs developed true vision. Snails, scallops, the squid, and the octopus all have developed eyes with real lenses and sophisticated retina. Still, it is rather startling to see a row of bright blue eyes peeking out from the edges of a scallop shell.

*** Spiders have eyes remarkably like those of the most advanced snails, a good example of convergent evolution. But like a cheap camera that doesn't have automatic focus, the spider must move back or creep closer to the object of his desire in order to get a clear look.

*** Insects, of course, developed compound eyes. Thousands of individual lenses, packed close together, are individually connected to protorecptor cells by tubes rather like a miniature version of the tube of a telescope. With thousands of individual images being carried to the brain, insects are very sensitive to motion in their field of view. Ever tried to stomp a roach, swat a fly, or slap a mosquito?

*** The human eye is among the best of the image-forming sort that biologists have taken to calling "camera-type" eyes in a sort of reverse wordplay that delights etymologists.

( to be continued in PM )