Intelligent Design Fan DaveScot Demonizes Chance

June 25, 2008

Over at Uncommon Descent, helper-honcho DaveScot has a post up claiming that Richard Lenski’s now famous E Coli. evolution paper commits a fatal error right in the first paragraph.

I started reading Lenski’s full paper myself to see what raw data was provided and I got no farther than the first paragraph beyond the abstract when I encountered a bias error that a chance worshipper (sic) would never notice. My emphasis:

At its core, evolution involves a profound tension between
random and deterministic processes. Natural selection
works systematically to adapt populations to their prevailing
environments. However, selection requires heritable variation
generated by random mutation
, and even beneficial mutations
may be lost by random drift. Moreover, random and deterministic
processes become intertwined over time such that future
alternatives may be contingent on the prior history of an evolving

The bold portion is patently wrong. Selection operates on any heritable variation whether random or not. That the authors would use the language they did (random variation) and the peer reviewers didn’t notice it is testimony to the chance worshipper (sic) bias that pervades evolution

In case you missed him repeating it for emphasis, DaveScot has recently begun to refer to scientists as “chance worshipers,” proving that if you can’t argue on par with someone, your best fallback is to ridicule them with cutesy names that belittle their arguments by implying that they are mere dogma.

But why is it that scientists like Lenski so often speak of “random” mutation? Because that’s exactly what they observe when they look at how variation emerges in genomes over time. While it’s true that selection could, in theory, work on non-randomly selected traits, that’s just not what we see happening in practice, and not particularly relevant to what Lenski is describing in any case. In fact, the whole point of Lenski’s paper is about the power of contingency: the way even random events open or close doors of possibility.

Part of the problem, perhaps, is that DaveScot doesn’t quite understand what scientists mean by “random” in this context. No biologist literally means that events like mutations occur with no causal explanation: that literally anything can happen to anything. What they mean is that the mutations that do occur, caused by all sorts of different processes, copying errors, and so on, are not correlated in any observable way with the outcomes they generate.

This misunderstanding quickly gets DaveScot into trouble when he tries to provide evidence that mutation isn’t random:

The Scripps researchers, in a nutshell, discovered that E. coli, when stressed (such as running out of food as in Lenski’s experiment or in the presence of antibiotics in the Scripps experiment) selectively increases the mutation rate on certain genes. Thus the mutations in this case are not random but rather directed at a certain area in an attempt to solve a certain problem.

But the paper in question does not, in fact, suggest that the mutations in question aren’t random. What it describes is a particular mechanism E. Coli have for essentially inducing more copying error (reducing the fidelity of inherited traits) in response to environmental pressures. There’s no evidence that the E Coli. are actually specifically choosing certain mutations over others based on any foreknowledge of whether those mutations will be beneficial or not. All they’re doing is tossing the dice more often on a particular set of genes.

And while the fact that a particular set of genes is singled out for modification is certainly interesting an interesting feature (though not unlike many other genetic known features that conserve certain parts of the genome), it’s still just a mechanism within the E Coli. itself, not a mark of intelligent intervention, intelligence, or foreknowledge.