Re: [asa] Guided evolution mechanism?

Hi Christine,

Reads to me like "control theory" is taken from engineering - basically the idea that a system is self-regulating through means of a feedback mechanism of some sort.

Here a car-cruise control or a home thermostat are excellent analogues.

Basically a control system has two parts: (1) a means of identifying the current state of the system and (2) a means of adjusting system state.

In a car-cruise control (1) might include: a measure of fuel flow to the engine, a measure of vehicle velocity, and a measure (or more correctly calculation) of vehicle acceleration.

(2) might include simply turning the fuel to the motor on or off, or it might include complex fuel flow equations in combination with braking.

So a really simple car cruise control might simply feed fuel at a pre-determined rate to the engine in order to keep the car sitting at, or about, 50 mph. But this is VERY crude and I doubt anybody ever actually would go this way!

The simplest practical cruise control (for a carburettor engine) would consist of a sensor measuring road speed (via, say, a measurement of axle rpm) linked to a servo controlling the carburettor butterfly - when the car exceeds the set velocity the the servo closes the butterfly to reduce air-flow (hence fuel flow) to the engine. When the velocity is too low, the butterfly is opened. The real trick here is to develop an algorithm which relates the difference in desired vs actual vehicle speed to the degree of closure of the butterfly. Which leads to the NEXT level of complexity;

Basing the butterfly position (or the RATE at which the butterfly is opening or closing!) not only on the difference between desired vs actual vehicle speed but also on the RATE at which the desired and actual vehicle speeds are closing. The idea here is that if your car is traveling at 48mph uphill it will need a great deal more fuel than when traveling at the same speed downhill. If one bases butterfly position ONLY on velocity, then when going downhill the resultant acceleration will be much greater. SO if one ALSO takes acceleration into account, one is beginning to solve problems which crude systems based only on velocity won't be able to resolve.

Now, to cut the story short, if it's realized that acceleration is calculable from velocity by means of differentials (acceleration merely being rate of change of velocity), then one can go silly - one can calculate rate of change of acceleration, then rate of rate of change of acceleration, then rate of rate of rate of change of acceleration, etc etc. So one can construct very complex equations determining the _dynamic_ state of a system, and one can then adjust one's control variable(s) accordingly.

Need I also mention that the control variable can be variously "supplied" to the system: a car cruise control could (at its simplest) merely turn fuel to the motor on or off (or between "maximum" and "minimum" if one doesn't want to stall!). But it might equally deliver fuel at a gallon (litre) per minute rate. Or one might vary the variable rate so that the further one is from the set velocity, the greater the rate of fuel flow. Or one might vary the variation in variable rate so that...(and so on ad infinitum).

Ultimately one derives a set of complex quadratic equations relating system output state to ones control variable(s) in order to adjust dynamic system state as finely as one requires. It makes little difference whether the system in question is a car cruise control where one is controlling fuel supply on the basis of vehicle velocity, a high precision milling machine where one is controlling three axis of movement on the basis of head position, or pupil dilation where one is controlling opening diameter on the basis of available light (or attractiveness of members of the opposite sex!) - the theory is all pretty much the same.

In respects of the Science Daily piece: most engineers know the enormous complexity of natural feed-back and control systems - and we'd delight to be able to come anywhere near close! So I'm not surprised that in investigating such systems an evolutionary biologist would want to add a disclaimer against their research bolstering ID theory. Frankly, the _appearance_ of design here is not only overwhelming but, as with most biological systems, what we see surpass ANYTHING our meager efforts can come up with. If people think the bacterial flagellum's grist for the ID mill, I've got news: in design terms the flagellum's got NOTHING on biological feedback / control systems in terms of complexity and my guess is that debate on this front is only likely to increase. Imagine when biochemists of an ID bent discover that not only does (say) the blood clotting cascade involve a number of significantly complex steps, but that those steps involve a complexity of feed-back mechanism which
 
 puts a space shuttle to shame. Won't THAT be fun?

I predict an ever increasing chorus of the "we don't know how it happened, but we KNOW it wasn't designed" all round (or "it looks like a duck, it sounds like a duck, it waddles like a duck, it must be a '48 Buick")!

Blessings,
Murray

Christine Smith wrote:
> Hi all,
>
> Well, I think this would impact some of the discussions we've been having :)
>
>>From the ASA Science & Faith blog: http://www.sciencedaily.com/releases/2008/11/081111183039.htm
>
> Excerpt: "Applying the concepts of control theory, a body of knowledge that deals with the behavior of dynamical systems, the researchers concluded that this self-correcting behavior could only be possible if, during the early stages of evolution, the proteins had developed a self-regulating mechanism, analogous to a car's cruise control or a home's thermostat, allowing them to fine-tune and control their subsequent evolution....
>
> ....The scientists do not know how the cellular machinery guiding this process may have originated, but they emphatically said it does not buttress the case for intelligent design, a controversial notion that posits the existence of a creator responsible for complexity in nature."
>
> Can someone provide some more background on "control theory"?
>
> It sounds to me like they're basically saying that cells, or the chemical components of cells, can actually direct (or at least exercise influence over) their own evolution? If so, does this imply that they are conscious in some manner? How else could they "control" anything in an "intentional" sense? If it is indeed "intentional control" at the cellular level, then besides consciousness residing at that level, I can't help but to think it would bolster the design argument?
>
> Comments? Thoughts?
>
> In Christ,
> Christine
>
> "For we walk by faith, not by sight" ~II Corinthians 5:7
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Received on Wed Nov 12 14:01:47 2008