Monday, September 20, 2010
Absurd in the Highest Degree (Part One)
An example: Ray states that "this marvelous design [of the eye] occurs not just in humans, but in all the different creatures: horses, ants, dogs, whales, lions, flies, ducks, fish, etc. Think about what the theory of evolution claims: the eyes of all these creatures slowly developed over millions of years. Each of them was blind until all the parts miraculously came together and interrelated with all the others, because all the parts are needed for the eye to function."
Does Ray really believe this is an accurate statement about evolution? All of these animals except for flies are vertebrates (and if Ray has ray-finned fish in mind when he writes "fish," they are all gnathostome vertebrates). According to evolutionary theory, all inherited box-camera eyes from a common ancestor; their last blind ancestor was Precambrian. Flies, for their part, inherited eyes from the insect common ancestor (which in turn inherited eyes from an arthropod common ancestor. Nothing very like a whale or a fly ever existed with partially-formed eyes.
On the other hand, some living species do have eyes that are "partially formed" with respect to other eyes in their phylum. Cephalopods (octopuses and squids) have box-camera eyes superficially similar to the vertebrate type, but the chambered nautilus has a simpler eye without a lens. Still simpler eyes, mere cups or funnels (retinas without lenses or proper apertures) exist in limpets. Structurally similar eyes occur in the lancelet or amphioxus, a primitive chordate similar to the common ancestor of vertebrates. Eyes -- functional for their possessors -- exist in forms ranging from a tiny light-sensitive cluster of nerve endings (the planarian) to highly complex box camera or compound eyes in vertebrates and some trilobites respectively.
But what raises questions in my mind is this: Ray later turns to the "schizochroal" or "optical double" compound lenses of some trilobite eyes to marvel over their elegance and complexity, and notes "you've probably been led to believe that the first simple creatures had simple eyes, and that as creatures slowly evolved their eyes evolved along with them." Here Ray seems to have a faint inkling that evolutionary theory does not posit that whales and lions were not wandering around the Cambrian seafloor with one or two random components of the eye attached to their skulls. Still, he nowhere mentions common ancestors or common descent, and perhaps he has no idea that evolutionary theory holds such ideas.
Note, by the way, that trilobites are not the "first simple creatures;" they appear about 25 million years after the start of the Cambrian, and somewhat longer after the first bilaterians in the Precambrian Ediacarans. Nilsson and Pelger did an infamous computer simulation that seems to indicate that a box-camera eye could evolve from a small light-sensitive patch in a few hundred thousand generations; they did not consider compound eyes, but thirty million years is enough time for a lot of trilobite generations.