Tuesday, June 13, 2006

Meditations on an eyeball: Part 1 -- If I only had a brain...

A few years ago I read an article in "Nature" about jellyfish eyes. I didn't even know they had eyes, but I learned that this particular type of jellyfish (Cubozoans) not only has eyes, they have twenty-four of them. While this particular species of jellyfish is well equipped with eyes there is one significant gap in their overall setup—there is no brain to use the eyes! The scientists involved with the study were pretty confident that these jellyfish manage to do something useful with these eyes other than actually look at things, but that is not the main point of their paper.

What surprised the scientists was not the quantity of eyes, but rather that some of the eyes are damn good ones. Specifically the lenses of the upper eyes are structured to support “well-corrected, aberration-free imaging, otherwise known only from the much larger eyes of vertebrates and cephalopods. The gradient in the upper eye lenses comes very close to the ideal solution.” Screwing this all up, even before we get to the brain part, is the fact the jellyfish retina for these eyes is located out of focus with respect to these well-corrected lenses. The perfectly formed image that the eye forms is out of focus by the time it reaches the retina. In the article the scientists go on to speculate how this setup is useful to the jellyfish.

My initial reaction to this section of the paper was to think how absurd it seems that this setup would evolve. What possible natural selection mechanisms would evolve a perfect eye in an organism with no brain to use it and then degrade it to boot? My friend John suggested that at one time the jellyfish might have had a brain and then lost it, but a brain does seem like overkill for a jellyfish. It seemed much more likely to me that this is just another example of God as the intelligent designer that re-used designs from other animals, and simplified them as appropriate. This would be analogous to using a GPS receiver/processor as the speedometer mechanism on a car—it’s overkill, but it would do the job.

Subsequent thoughts were more confused. Why would God be concerned about reusing designs? Why not use an optimized design for each organism? It is not like He has project deadlines to meet (running short of time on day 4?) , a lack of energy, or a crabby boss to appease. Is this jellyfish an example of intelligent design, or perhaps something way subtler?

Part 2

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