07 September 2009

Weasels, clouds and biomorphs, part I

There's usually no point in piling on when the minions of the ID movement get their just deserts after some typically brainless culture-war test launch. Consider the responses (by, most notably, Ian Musgrave at the Panda's Thumb) to the most recent rendition of the ID movement's hilariously idiotic fixation on a particular computer program written by Richard Dawkins. It seems there is little to add. But I think something important is being lost in this conversation, probably because the level of the "conversation" is the level of the ID movement. So let's start with a little quiz.

1. True or false: Richard Dawkins' 1986 classic The Blind Watchmaker used a computer model (a simulation) as a key teaching device while explaining the effectiveness of cumulative selection in evolution. The program is the main focus of chapter 3 ("Accumulating small change") of the book.

Answer: True.

2. True or false: the computer program used for this purpose was made available to the public and has since been adapted for free use on the web.

Answer: True.

3. True or false: the computer program in question is called WEASEL (or similar) and it demonstrates the stepwise generation of a famous phrase from Hamlet.

Answer: False.

Now if this surprises you, then either you haven't read The Blind Watchmaker or you haven't read it in a long time. Because even if you've been influenced by the hysterical antics of the ID crowd, you could not long believe its claims about the Weasel program if you had recently read the book. If you haven't recently read The Blind Watchmaker, you might consider a stroll through some representative ID musings on WEASEL followed by a visit to Chapter 3 of the book (and, if you have a copy from 1989 or later, a visit to the two appendices.) The experience could be jarring for those who have a positive view of these arguments by ID apologists.

But if you don't have a copy of The Blind Watchmaker handy, I can help. First, in this post, I'll discuss the Weasel program and its place in the thesis of The Blind Watchmaker – in the context of the current ID fixation on the program. Then I'll introduce the program that Dawkins really did emphasize in the book, a program called EVOLUTION (or later, when it was expanded and made commercially available, The Blind Watchmaker Evolution Simulation program) but commonly known as the biomorph(s) program. In the second post I'll talk more about the biomorph program and its usefulness.

Chapter 3 of The Blind Watchmaker is a tour de force of expository scientific writing. Called "Accumulating small change", the chapter has a single and simple thesis, laid out in the first paragraph:

We have seen that living things are too improbable and too beautifully 'designed' to have come into existence by chance. How, then, did they come into existence? The answer, Darwin's answer, is by gradual, step-by-step transformations from simple beginnings, from primordial entities sufficiently simple to have come into existence by chance. Each successive change in the gradual evolutionary process was simple enough, relative to its predecessor, to have arisen by chance. But the whole sequence of cumulative steps constitutes anything but a chance process, when you consider the complexity of the final end-product relative to the original survival. The purpose of this chapter is to demonstrate the power of this cumulative selection as a fundamentally nonrandom process.
The Blind Watchmaker, page 43, italics in the original
Dawkins immediately tackles the crazy misconception of evolution as a process that is akin to the impossibly improbable flying-together of the parts of a machine in a single step. Echoing Isaac Asimov, he calculates the probability of the spontaneous assembly of a hemoglobin molecule in a single step, and arrives at a number of predictably indescribable magnitude. It can't just happen.

In a 1987 BBC television show , he uses a much better metaphor: the opening of a safe by entering a combination. To open the safe, a banker (or thief) must correctly enter all of the correct numbers, in order, at the same time. His point is: of course it can't "just happen." The concept that Dawkins aims to communicate is this: from an evolutionary perspective, "success" doesn't happen all at once; it is accumulated. Evolutionary change is cumulative change; it's as though the safe opens a little when one correct number is entered, and allows the banker to reach in and get a little money. ("Small change" is the topic, remember.)

This is a very basic and very important aspect of the Darwinian mechanism, and yet it is maddeningly common to see it ignored or completely misunderstood. So in the first few pages of Chapter 3, Dawkins looks for an illustration of the difference between "randomly getting the whole thing right in one fell swoop" and "accumulating random improvements till the whole thing is assembled." He starts with the old saw about monkeys, typewriters and Shakespeare. Choosing a single phrase from Hamlet, "Methinks it is like a weasel," he first calculates the probability of a random character generator (a monkey) spontaneously banging out Hamlet's phrase. The calculation charmingly indicates that there isn't enough time in the universe for such a thing to occur. Yeah, yeah, yeah. Now, it's easy enough to get a computer (even a 1986-vintage machine) to churn out 28-character strings randomly, and so Dawkins describes a program that can do this. Then he introduces the occurrence of cumulative selection in the program, to illustrate its profound effectiveness compared to mere randomness.
We again use our computer monkey, but with a crucial difference in its program. It again begins by choosing a random sequence of 28 letters... It now 'breeds from' this random phrase. It duplicates it repeatedly, but with a certain chance of random error – 'mutation' – in the copying. The computer examines the mutant nonsense phrases, the 'progeny' of the original phrase, and chooses the one which, however slightly, most resembles the target phrase... the procedure is repeated, again mutant 'progeny' are 'bred from' the phrase, and a new 'winner' is chosen.
The Blind Watchmaker, pages 47-48, italics in the original
Dawkins shows that this procedure can get from a random monkey-phrase to "Methinks it is like a weasel" in mere seconds. And the point is simply this: cumulative selection is more effective than mere "randomness" by incomprehensibly gigantic magnitudes. Dawkins makes it very clear that the Weasel program is meant to demonstrate nothing more than that. After pointing out that single-step selection would take a near eternity to type the phrase, he reiterates the simple purpose of the comparison, and the whole weasel exercise:
Actually it would be fairer just to say that, in comparison with the time it would take either a monkey or a randomly programmed computer to type our target phrase, the total age of the universe so far is a negligibly small quantity, so small as to be well within the margin of error for this sort of back-of-an-envelope calculation. Whereas the time taken for a computer working randomly but with the constraint of cumulative selection to perform the same task is of the same order as humans ordinarily can understand, between 11 seconds and the time it takes to have lunch.
The Blind Watchmaker, page 49, italics in the original
Folks, that's all the silly weasel thing was ever about. So what's all the fuss then?

Well, some ID partisans are all agitated about whether Dawkins' program allowed mutations in positions of the string where the correct letter had been hit upon. They wonder: if cumulative selection had gotten us "Methinks it is like a measel", could 'measel' mutate back to 'measer' and thus take the program a step away from the target? And why does this matter? Well, for Dawkins' purposes it really doesn't matter, but the ID scholars seem to think there's a big speed difference. If you're interested you can read some nice work by Wesley Elsberry or Anders Pedersen that shows clearly that it simply doesn't matter.

But. Here's what's lost in all this. Dawkins never intended the silly little weasel exercise to be a persuasive argument for evolution as it actually occurs in the world. In fact, he is quick to point out why it's deficient (remember Bohr models of the atom in grade school?), noting that it is "misleading in important ways." And at that point, he abandons the Weasel program in favor of a simulation that is far better. That simulation, the Biomorph program, is the topic of the entirety of the rest of Chapter 3 of The Blind Watchmaker (and of my next post).

The absurdity of the ID fixation on the Weasel program is hard to capture with mere words. Perhaps this table will help put the two programs into better perspective.

Number of times program is mentioned* on Uncommon Descent4442
Number of pages devoted to program in The Blind Watchmakerless than 5 45, including two appendices

*All I did was Google the word 'weasel' or 'biomorph' at uncommondescent.com. The two uses of 'biomorph' were in comments by ID critics (one being Wes Elsberry). The uses of 'weasel' surely include insults that aren't references to the program.

The real focus of Chapter 3 of The Blind Watchmaker is the biomorph program. Seven figures, 23 pages, 22 more pages in two appendices which include a small user's manual for the program. The biomorph program constitutes the heart of Dawkins' book and his argument, so much so that the program is named The Blind Watchmaker. The Weasel program was a tiny stepping-stone for Richard Dawkins, a simplistic teaching tool meant to illustrate a single simple point. It's a hill to die on for the ID movement, and that says a lot about the state of that confused community.