The Case for a Creator, Chapter 8
In my review of Darwin’s Black Box, I listed three ways that an irreducibly complex system can evolve:
The first can be summed up as scaffolding: extra parts which support a partially functional system until it is completely assembled, at which point the extra parts become unnecessary and are pruned away by selection. The second is the case of improvement becomes necessity, where an adaptation is at first merely beneficial, but as later changes build on it, it becomes indispensable. The third, possibly the most important, is change of function, also called cooption… A system which originally evolved to perform one function may take on a new function, starting out with multiple functioning parts rather than having to acquire them one piece at a time.
In his interview with Lee Strobel, Behe doesn’t address the first two. But Strobel does ask about the third, in reference to Behe’s account of the cilium:
“Maybe these three components were being used for other purposes in the cell and eventually came together for this new function… Isn’t it possible that they might all come together by chance?” [p.203]
Behe’s response is as follows:
“It’s extraordinarily improbable,” he replied. “Let me illustrate it for you. Say there are ten thousand proteins in a cell. Now, imagine you live in a town of ten thousand people, and everyone goes to the county fair at the same time. Just for fun, everyone is wearing blindfolds and is not allowed to speak. There are two other people named Lee, and your job is to link hands with them. What are the odds that you could go grab two people at random and create a link of Lees?” [p.203]
This is a clever argument, and probably seems very convincing to people who don’t understand how evolution works. It can’t be doubted that the odds against random chance giving rise to the right mutations to produce a cilium must be incredibly large. Has Behe put his finger on a critical flaw in evolution?
Let’s say you’re a poker player playing a game of five-card draw. In the initial deal, you get a full house:
9♦ 9♥ 9♣ Q♣ Q♠
The betting begins, and none of your opponents fold. The showdown comes, and one of them has two pair:
2♦ 2♥ 7♣ 7♠ K♥
One has three of a kind:
3♥ 3♦ 3♣ 8♠ 6♥
and one has a lowly ace high:
A♥ 10♦ 6♠ 4♣ 3♠
You win. Success!
At first, you bask in your victory and congratulate yourself for your good luck. But then you make a dramatic realization – the probability of getting the specific hand you were dealt was astoundingly small. After all, there are 52 cards in a standard deck! The odds of being dealt the exact hand that won you the round can be computed as just one chance in 2,598,960, or 0.0000003847693%. Given that you triumphed despite such improbability, is it really believable that your victory came about by chance? Especially if you win more than one hand, shouldn’t you consider the hypothesis that there’s an Intelligent Designer influencing the workings of the game?
When it’s put in these terms, the fallacy is obvious. The odds of drawing one particular hand are low, but the question you should be asking is the odds of drawing any winning hand. There are many different winning hands in any particular round, and depending on what your opponents were dealt, your chances could be quite high.
This is the exact fallacy that Behe is committing. He’s trying to calculate the odds of one specific set of mutations occurring to produce the cilium as it exists today. That probability, like the poker player’s probability of his one exact winning hand, is fairly low. But that number is completely irrelevant, because the real question is this: what are the odds of evolution putting together any system, from any set of interactions among those ten thousand proteins, that could result in a unicellular organism gaining increased mobility? Needless to say, this number is much harder to calculate, but it’s also certain to be much larger.
Behe has no excuse for not knowing this. Someone with his level of education and scientific background should be fully aware that this is how evolution works. And there’s no chance that this is just a sloppy paraphrase or misquotation on Strobel’s part, because Behe has used this same argument on at least two other occasions: once in his own book, and once in the paper that I alluded to in my previous post – the only peer-reviewed journal article that Behe has published in more than ten years. It appeared in 2004 in Protein Science, with the title “Simulating evolution by gene duplication of protein features that require multiple amino acid residues“.
The contributors on The Panda’s Thumb, in a lengthy reply to this paper, point out the numerous unrealistic and restrictive assumptions that Behe makes:
…the paper says that if you have a protein function that requires two or more specific mutations in specific locations in a specific gene in a specific population, and if the function is not able to be acted on by natural selection until all mutations are in place and if the only form of mutation is point mutation, and if the population of organisms is asexual, then it will take a very large population and very long time to evolve that function. This is not unexpected.
The reply also castigates Behe for buying into the creationist myth of the “one true sequence”:
The evolution of new functions is not a process that requires a certain target to be hit. There can be multiple new functions that any starting protein can acquire. Likewise, there can be multiple ways of acquiring any given function.
…the fact that [Behe and Snoke] only consider specific changes at specific locations makes their model meaningless because it assumes a fundamentally different process than the one that occurs in nature.
Ironically, as the PT post also points out, even Behe’s artificially restrictive assumptions still imply that new protein functions should be easy to evolve in a relatively small population of bacteria!
By the standards of creationists who think “why are there still monkeys?” is a clever gibe, this is a far more sophisticated argument. But it’s still an argument whose huge flaws should be apparent to anyone who knows even a little about evolutionary and molecular biology. Yet Michael Behe still treats it as not just valid but devastating. The only conclusions I can see fit to draw are that he’s either an incredible incompetent, despite his education, or he’s deliberately misleading his readers with an argument that he knows is fallacious. Which of these is more likely to be the case?
Other posts in this series: