Which is ironic, becuse the human eye is one of the best examples of how evolution is only concerned with function, rather than elegance.
1) Our sensory cells face the wrong way. Light has to bounce off the back of our eye to reach them.
2) But wait, the sensory cells themselves are in the way - along with a nice spiderweb of blood vessels and nerves that supply them.
3) not to mention the blind spot caused by the hole where all these blood vessels and ocular nerves come into the eye.
4) Those sensory cells themselves? Recent re-adaptation for seeing color. We have good color vision for mammals... but seeing as most mammals see the world in murky shades of brown, yellow, and brownish-yellowish-blue, that's not saying an awful lot. Compared to birds and reptiles, we're missing 1/4 of the light spectrum. Compared to most invertebrates, we might as well be colorblind. You think that apple is red? That's cute.
5) What actually reaches our brain is a blurry, semi-pixellated blob of light that is given shape only by movement. It's also upside-down and backwards to reality, due to the refractory effect of our lens (we could go on for days about the joke that thing is) and the reflection off our retina. It goes into our brain, which then takes that information and constructs a CGI model that is a roughly 85% accurate depiction of what is really going on.
6) Also, the eyeball of land vertebrates has a lot of evolutionary kludges needed in order for the damn thing to even work out of the water. As usual, evolution used the least effort possible with the cheapest materials.
Compare the human eye to say, the squid. Squid eyes are tetrachromatic, for starters. They perceive colors in the spectrum we literally can't imagine. They plug right into the squid's brain from the back - there is no lattice of blood and nerve conduits poking into the squid eye and spidering across the seeing surface. Since it lives underwater, the squid never had to evolve all the oddball patches and fixes to make those eyes work in dry air.
Creationists like to claim that the human eye is too fine-tuned, too complex to have "just evolved." Yet... so many of them wear glasses. Why is that?
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