Wednesday, June 18, 2008

Pournelle II

Novelist and social observer Jerry Pournelle had recently posted his objections and rejections to an editorial written by Richard Dawkins. The original piece by Dawkins was a protest against his mangled interview for the creationist movie “Expelled.”

Pournelle ignores or is ignorant of the context of the Dawkins piece. None the less, while Pournelle repeatedly says he does not want to argue the Intelligent Design creationism case, he reiterates it and ignores any counter arguments and even implied there were none.

On the other hand, intelligent design theorists do have scientific critiques of Natural Selection’s ability to explain what we observe. I have already alluded to one, irreducible complexity, which states that certain organism or organs are simply too complex to have arisen in stages.

The refutations of Behe’s notion of “irreducible complexity” begin with its definition.

Behe's definition of IC is”

A single system composed of several well-matched, interacting parts that contribute to the basic function of the system, wherein the removal of any one of the parts causes the system to effectively cease functioning. (Darwin's Black Box, pg. 39)

Unnoticed by Behe was a deadly flaw, the existence of something that is IC under that definition merely loses a particular function if damaged. It says nothing about how such an entity or process could have evolved by the combinations of otherwise functional entities. Behe’s favorite example is a five part mousetrap. But, every single part has independent functions, and multiple functions exist for various combinations of these individual parts. This is well known in biology as “Cooption” the common occurrence when one, or a group of genes is duplicated, and then modified resulting in new functions. One concrete example is the evolution of nylonase. Only a slightly more difficult notion is scaffolding; two or more existing processes are combined and the result is then simplified by reduction in the number of steps or parts. We see biological examples most easily in the reduction of genes in obligate parasites, and the most famous example is endosymbiosis.

So, then Behe then tried to salvage his cherry with a redifinition;

An irreducibly complex evolutionary pathway is one that contains one or more unselected steps (that is, one or more necessary-but-unselected mutations). The degree of irreducible complexity is the number of unselected steps in the pathway.

Note well that Behe has abandoned the entire core of his original argument regarding function. In its place he has substituted “necessary-but-unselected mutations.” Real science has shown that even mildly unfavorable mutations are commonly transmitted; ie the unselected steps in Beheland. We have known this for decades. These unselected, or even detrimental mutations are then material available for recombination, and the expression of new complex functional genomes.

Behe’s latest is to take a page from Bill Dembski and adopt a probability argument. In the just released “The Edge of Evolution,” he claimed that there is a limit on the number of genetic changes, mutations, that can be allowed. His example is protein to protein binding, and Behe insisted that more than two sites just cannot evolve independently. This is of course nonsense. A very well illustrated and easy to follow refutation is available from Ian Musgrave, “ Behe versus ribonuclease; the origin and evolution of protein-protein binding sites”

Another of Behe’s arguments in “The Edge of Evolution” bites the dust with the recent publication from Richard Lenski’s research group at the Michigan State University. (Z.D. Blount, C.Z. Borland, and R.E. Lenski, "Historical Contingency and the Evolution of a Key Innovation in an Experimental Population of Escherichia coli." PNAS). Carl Zimmer’s “Microcosm: E. coli and the New Science of Life” (Pantheon, May 6, 2008), places this research in the context of broader scientific questions. An easy to understand presentation of their most recent article is available at “A New Step In Evolution.”

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