Tuesday, October 14, 2008
Evolution of the Eye
Contrary to Creationist claims, scientists have a pretty good idea how our eyes evolved.
TalkOrigins raises an interesting point:
intermediate stages through which eyes might have evolved via gradual steps (Darwin 1872).
* photosensitive cell
* aggregates of pigment cells without a nerve
* an optic nerve surrounded by pigment cells and covered by translucent skin
* pigment cells forming a small depression
* pigment cells forming a deeper depression
* the skin over the depression taking a lens shape
* muscles allowing the lens to adjust
All of these steps are known to be viable because all exist in animals living today. The increments between these steps are slight and may be broken down into even smaller increments.