Friday, June 15, 2007

That's All Ya Got, Huh?

Jerry Coyne knows ID is bunk, because the truth is so simple! Here he is as quoted at Uncommon Descent (from Coyne's "devastating" review of Behe's latest book):

Wrong. If it looks impossible, this is only because of Behe’s bizarre and unrealistic assumption that for a protein-protein interaction to evolve, all mutations must occur simultaneously, because the step-by-step path is not adaptive. Yet Behe furnishes no proof, no convincing argument, that interactions cannot evolve gradually. In fact, interactions between proteins, like any complex interaction, were certainly built up step by mutational step, with each change producing an interaction scrutinized by selection and retained if it enhanced an organism’s fitness. This process could have begun with weak protein-protein associations that were beneficial to the organism. These were then strengthened gradually, involving more and more amino acids to make the interaction stronger and more specific. At the end, you get what we see today: many proteins interacting strongly and specifically. What seems improbable in a single leap becomes much more likely when it evolves gradually, step by step.

A simple example shows this difference. Suppose a complex adaptation involves twenty parts, represented by twenty dice, each one showing a six. The adaptation is fueled by random mutation, represented by throwing the dice. Behe’s way of getting this adaptation requires you to roll all twenty dice simultaneously, waiting until they all come up six (that is, all successful mutations must happen together). The probability of getting this outcome is very low; in fact, if you tossed the dice once per second, it would take about a hundred million years to get the right outcome. But now let us build the adaptation step by step, as evolutionary theory dictates. You start by rolling the first die, and keep rolling it until a six comes up. When it does, you keep that die (a successful first step in the adaptation) and move on to the next one. You toss the second die until it comes up six (the second step), and so on until all twenty dice show a six. On average, this would take about a hundred and twenty rolls, or a total of two minutes at one roll per second. This sequential way of getting twenty sixes is infinitely faster than Behe’s method. And this is the way natural selection and mutation really work, not by the ludicrous scenario presented by Behe.

This is ludicrously flimsy, as pointed out by several commenters to the post:

Protein to protein interactions occur in all useful proteins, just as sewing occurs in most useful garments. By themselves p2p interactions are nothing more than weak glue. In order for protein interactions to be at all useful, they need to be at particular sites on particular proteins. These proteins must be in turn organised into productive groups with purpose.

A replica of the Eiffel Tower made of popsicle sticks has many glued points, but a pile of popsicle sticks, each with a few random dobs of glue on them will never make an Eiffel Tower replica.

I am baffled by the fact that NDEs are happy if they can find a few p2p interactions that may be possible by RM and NS and they think they can build IC.

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It kills me how these guys always present the obviously hyper-speculative as irrefutable fact: “These were then strengthened gradually…” and “…interactions between proteins… were certainly built up step by mutational step…” and “…this is the way natural selection and mutation really work…”

Coyne’s dice example assumes that all biological systems, every single one of them, are such that one six is better than no sixes, two sixes are better than one six, etc. But what if a biological system is like a combination lock with six numbers, and a sequence of 20 specific numbers is required to open the lock? The useful function of the lock is that it opens. Getting one of the 20 numbers right doesn’t make the lock open a little bit, and getting two of the 20 numbers right doesn’t make the lock open a little bit more. In fact, getting 19 of the 20 numbers right doesn’t make the lock function any better than getting none right.

Coyne’s example requires that not even a single biological system be like the combination lock. Yet we now know that these systems are machinery (incredibly sophisticated and tightly functionally integrated machinery), and machines are like combination locks. The more we learn about the machinery of life, the truth is that in all probability almost no (statistically speaking) biological systems are amenable to being generated by Coyne’s dice tossing.

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I think a better analogy for a working protein is a key to unlock a door. You can’t gradually evolve a key, one tumbler at a time, and depend on the improved “door-opening ability” as a guide to finding the right key. Certainly there may be a large number of keys that with a little jiggling might open the door, but in that case each tooth is very nearly the optimum size. Dr. Coyne’s coin-flipping analogy is embarrassing.

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Coyne’s example, while it sounds simple on the surface, actually involves some fairly specific specifications. While I’m sure I’ve left some things out, they would minimally include:
1. Obtain a die. Die must have 6 (or perhaps more) sides.
2. Obtain a mechanism for rolling the die (or wait until something else rolls it or it rolls itself).
3. Obtain a mechanism for evaluating the value of the die when it is rolled.
4. Obtain a mechanism/location for keeping the die when the desired outcome is obtained.
5. Determine that a six is what is wanted.
6. Roll the die.
7. Evaluate the outcome.
8. If desired outcome is obtained, keep the die.
9. Ensure that all retained dice are kept from any further rolling.
10. Repeat steps 1-9 until 20 such dice have been retained.
11. Optional: Stop the rolling and retention processes.
12. Determine a mechanism for assembling the dice into a coherent, functional whole. Presumably, the assembly could be done piecemeal while the die rolling is going on, but the assembly mechanism would have to exist either way.
13. Assemble the dice.
14. Successfully integrate the completed adaptation into the larger organism.
15. Do it all with no intent or plan, no intelligence, while completely blind, and entirely unaware that a “complex adaptation involving 20 parts” is being built.

Coyne and I have something in common: we’re both incredulous.

-sb

1 comment:

Michael Poole said...

It would not surprise me if those commenters believed in a hypothesis of Intelligent Snowing: after all, What Are The Odds of natural processes producing beautifully symmetric, and surprisingly similar, snowflakes which almost never repeat exactly?

(The dice example is an analogy, not a model. It is not meant to describe protein mutations exactly.)