Over in Rocky's blog, there has been a discussion going on the subject of Intelligent Design. It has been a remarkably civil discussion given how strongly so many people feel about the subject. One of the arguments that came up is irreducile complexity, which is the idea that various biological systems or organs could not have developed through a process of incremental variation and selection, because lack of any one component makes the system or organ non-functional, ergo it does not enhance survival and is possibly detrimental to the organism. The eye is often cited by proponents of ID as one of the irreducibly complex organs.
Today's New York Times reports about an article about sponges recently published by April and Malcolm Hill of the University of Richmond in the journal Development Genes and Evolution. It seems that sponges have genes that control growth of eyes, brains and central nervous systems -- none of which they have.
What does this say about irreducible complexity? It says that genes can exist and yet remain unexpressed until some other genes come along, or until additional epigenetic factors come into play, Thus, complexity may simply be reducible if things happen in the right order. A complex system can, to some extent and in some circumstances, develop substantailly in a "submarine mode" with no physical manifestation of a collection of genes until it reaches a stage where enough the genes can be switched on. That's when the new beneficial trait comes to the surface. Numerous false turns along the way undoubtedly take place during this process when genes are added and switched on in a non-optimal order, and those experiments are selected against, but over thousands of generations the right combination and sequence of genes finally emerges.
Sponges are some of the simplest, or lowliest if you will, multi-cellular creatures on earth. They don't have any nerve cells at all, yet they have this gene. This isn't to say that sponges are about to develop human eyes and brains... except in cartoons, of course, but they have a gene that you wouldn't expect to be there. It doesn't help him, but it also doens't harm them. This tells us that genes don't necessarily develop in the order that features associated with them surface. Sponges demonstrate one stage of the reducible complexity of the eye.
1. Ben Langhinrichs08/17/2005 10:36:50 AM
Interesting, but it could be fairly easily argued by the intelligent design people that this proves the opposite. Why do sponges have this gene? It doesn't fill any biological or evolutionary imperative, so doesn't it practically prove that an omnipotent designer built in that feature, say as a rough prototype, even though evolution would have no need for it?
2. Richard Schwartz08/17/2005 08:18:57 PM
Right. They win either way. Irriducible complexity? Proves ID. Complexity developing slowly through non-expressed genes? Proves ID. Sigh.
3. Alex Wilson08/18/2005 09:27:27 AM
ID has been a very big subject around my home town (York PA). Dover Area School District is one of the big cases going on right now. The school board tried to introduce ID into the 9th grade science class. It started a heck of a fight. A parents group is now suing the board for violations of seperation of church and state and other things.
There are holes in Darwin's theory. Doesn't mean it is wrong. There are holes in many theories - we are still learning and researching. I am a firm believer in evolution, but evolution occurs over thousands of years. It is not like our society over the past 200 years (revolutionary). Just because a sponge doesn't have eyes but has the gene does not mean ID is the reason... it means the species did not have a need for the eye, therefore didn't develop it over millions of years.
Of course, I am sure some ID expert would say it was put there by design so that if it ever needed it, it would be able to generate the eye. I need to find an ID expert and ask them if the world was created by God, why did dinosaurs exist before humans? I think biblical experts forgot about that part of Earth's history.
4. Jerry Carter10/06/2005 11:35:32 AM
Here is an article by a prominent creationist addressing the Dinosaurs.