A Quick Apology

February 18, 2009

It turns out that I misunderstood the creationist argument about the human eye.  In doing so, I accidentally created a “straw man” – a figure that resembles their actual argument, but is infinitely stupider and easier to knock down.  Their actual reason given for the eye’s un-evolvability was that each part is not useful without the other; in other words, a partial eye is useless, not partial eyesight. I apologize for misrepresenting this hypothesis.

However, there is still a certain amount of invalidity to this claim.  While it is true that certain parts of the eye – the lens, the iris, the optic nerve, etc. serve no purpose without the rest of the eye to function, other parts – the light-sensing cells in particular – could have developed on their own, as described in my (rather anachronistic) theoretical story in the previous article.  As time goes on, that patch of light-sensing cells changes – it develops a lens to help focus light, a curve to help it determine the direction of light, and other useful features.  These do not spring out fully-formed the way they appear in modern animals.  Instead, the eye structure changes gradually, developing only partial (vestigal) versions of each feature which grow more refined as time goes on, eventually learning to interact with each other in such a way as to become almost entirely co-dependent, like the eye we see today.

Given what we know about primitive animals, it is likely that eyes developed very early in the evolutionary chain – after these creatures had diverged from things like jellyfish and sponge ancestors, but before they had branched into most other species, such as the earliest armored beasties, primitive fish, and early cephalopods.  Even then, eyes were still fairly primitive, and in each kind of animal ended up changing into something very distinctive – from complex human eyes to the dual system used by arthropods to the simple photoreceptors of the vampire squid (if that isn’t a partial eye, I don’t know what is).

TL;DR: Unfortunately, your actual argument is equally as falsifiable as the strawman.

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