A little knowledge...

Over at Uncommon Descent, the poster Pav has a post entitled “Programmers Only Need Apply”. In it, they note, but fail to discuss this paper, Xue W, et al., Senescence and tumour clearance is triggered by p53 restoration in murine liver carcinomas. Nature. 2007 445; 656-660. What gets the poster excited is not the finding that restoration of the protein p53 can stop tumor growth (which, amusingly, drives yet another nail in the coffin of Discovery Institute Fellow Jonathan Wells’s non-mutational model of cancer ), but that the authors use the word “program” to describe the cellular senescence pathway activated by p53.

The use of the word “program” highlights that proponents of NDE have an even sterner task at hand: explaining how the logical loop of a “program” can be built up using NDE mechanisms. There is a ring of “irreducibility” to the idea of a “program”, since each part of a “program” is indispensable and likewise an integral part of the program’s intended output. Genetics is looking everyday to be more and more like an exercise in computer programming–just as IDists have predicted.

Uh, guys, the use of the word “program” is a convenient analogy, we use the term “program” to help us grasp the timing of activation of the cell death and senescence pathways, but they aren’t human programs. An instructive example comes from John R. Searle:

Because we do not understand the brain very well we are constantly tempted to use the latest technology as a model for trying to understand it. In my childhood we were always assured that the brain was a telephone switchboard. (‘What else could it be?’) I was amused to see that Sherrington, the great British neuroscientist, thought that the brain worked like a telegraph system. Freud often compared the brain to hydraulic and electro-magnetic systems. Leibniz compared it to a mill, and I am told some of the ancient Greeks thought the brain functions like a catapult. At present, obviously, the metaphor is the digital computer.

Get that DI folks? It’s a metaphor, not an actual computer program. The fact that PaV get so exercised over the term “program” is a bit puzzling, The program metaphor is used extensively in biology, for developmental programs to programmed cell death (which p53 plays a key role in as well). In fact, the term “programmed cell death” has been around since 1964, so one is forced to conclude that PaV doesn’t know very much about the biology of cell death (or possibly biology at all).

Certainly, PaV goes on to claim that the cell p53 cell senescence pathways must be irreducibly complex, because Xue et al used the term “program” in their abstract. Would it be too much to ask PaV to actually look up the literature on cell senescence and cell death, rather than pontificate on the basis of an abstract?

A little reading would show that the p53 pathway cannot be IC, as when you knock out p53, other systems take over. P53 is the major, but not the only, gatekeeper of cell senescence. It certainly makes the system more fragile, but knocking out p53 doesn’t make the system fail completely, which is Behe’s criteria for irreducible complexity. Indeed, there is quite a large literature on the origin and evolution of the programmed cell death pathway.

So, the home message folks; don’t build an elaborate scenario on the basis of a metaphor, learn a bit of the biology of the system instead.

PS. I was amused by this statement:

Behe and Snoke’s paper shows the huge improbability of placing two amino acids side-by-side via gene duplication and random mutation.

Actually, it shows that even in the complete absence of selection, binding sites such as the DPG binding site in haemoglobin can evolve in quite reasonable time frames , and the bacterial populations in a bucket of soil will do it much faster. Nice own goal there.