Monday, January 01, 2007

Front loading???

A pro ID blogger (Nathan) states in one of his posts:

As the articles states, "sea urchins are echinoderms, marine animals" and
the purple sea urchin, "has 7,000 genes in common with humans, including genes
associated with Parkinson’s, Alzheimer’s and Huntington’s diseases and muscular
dystrophy." Of great interest to intelligent design advocates of front loading
is the fact that although the sea urchin has no eyes, nose or ears it does have
genes that are homologous to genes found in humans that are involved in vision,
hearing and the sense of smell.

Are we actually to accept that this is evidence of one-of-many-ways-in-which-the-creator-could-have-done-it? The thinking here is that the common ancestor of mammals and sea urchins would have had these genes and since (the ancestors of) mammals later did develop eyes, the case for front-loading is strengthened. Let's examine that, shall we?

The assumption you have to accept here is that these genes are only useful in vision, hearing and smell (if you do not accept that assumtion, you would reject irreducible complexity, which is after all a cornerstone of ID). Under this assumption, these genes in the sea urchins would have been conserved for some 500 million years (since the last common ancestor of mammals and echinoderms was alive) in the absense of selective pressures to maintain them. That is an extraordinary feat that would be nothing short of miraculous. But maybe you could argue that these genes will become important for the sea urchins in the future when they will acquire vision, hearing and smell themselves. Problem is, this does not get rid of the problem. Since the sea urchins have not got these abilities today, there is no selective pressure to maintain the genes (and again, don't try to argue that maybe the genes also have other functions since this still is an argument against irreducible complexity).

Maybe we should just accept a scientific explanation for why these genes have been conserved instead. Like, the genes have slightly different functions in the two lineages of organisms.


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