Re: Human design and natural "design"

In article <XcqdnVEAGr5HjpDeRVn-3g@xxxxxxxxxxx>,
dkomo <dkomo871@xxxxxxxxxxx> wrote:
>Robert Grumbine wrote:
>> In article <KtqdnVuscLa0yJbeRVn-tw@xxxxxxxxxxx>,
>> dkomo <dkomo871@xxxxxxxxxxx> wrote:
>>
>>>Keith H Duggar wrote:
>>>
>>>>dkomo wrote:
>>>>
>>>>>True feedback in a control system is a set of actual
>>>>>*signals* received from the environment which allow that
>>>>>system to make appropriate responses or changes. In the
>>>>>case of evolution this means that the environment would
>>>>>need to supply signals to the organism which would cause
>>>>>*direct* changes to that organism's genome. In other
>>>>>words, directed mutations. This is lamarckism, which in
>>>>>the current received view doesn't exist.
>>>>
>>>>Why are you fixated on individuals (Lamarckism)? Think
>>>>POPULATIONS to understand how it is feedback. This Lamarck
>>>>bashing is a red herring.
>>>
>>>Why are you fixated on populations?
>>
>> I hope he's doing it because evolution is defined by populations.
>> I will:
>>
>>
>>>Even in the case of populations the
>>>environment is not making *direct* changes to the genomes of the
>>>organisms. The changes were made by mutations which are completely
>>>decoupled from the needs of those organisms. There is no feedback loop
>>>here.
>>>
>>>Changes to the genomes of those organisms. Not changes to the
>>>statistical distribution of alleles. See the difference?


[snip]

>> Selection is a filter, hence a feedback. So natural selection
>> is a feedback on the system, 'system' being the allele distribution
>> in a population.
>>
>
>"Selection is a filter." Hey, I like that! Selection can indeed be
>seen as a filter. But the rest of what you say doesn't follow.
>Filtering something doesn't mean you're applying feedback to it. For
>example passing an audio signal through a filter to boost its base
>frequencies has nothing to do with applying feedback to the signal. It's
>just an input-output change to that signal.
>
>Let's pursue this filter analogy a bit further. Suppose you sift some
>gravel through a screen. You've just altered the size distribution of
>gravel particles of this "population" of gravel. With no feedback
>involved. The screen acted as a filter.
>
>This is exactly how selection acts. It is a filter which sifts through
>a population of organisms and alters the allele frequencies of the
>population. Voila, evolution!
>
>And no feedback was involved. Which is what I've been saying all along.
>Evolution is an open loop, not a closed loop process.
>
>Thanks for the filter metaphor.

You pay far too little attention to 'the system'. More below.

>> Sampling is also a filter, so neutral drift in a population is
>> also a feedback on the system.
>>
>> In terms of most trivial signal processing, the mutations are
>> introducing noise. The result of that noise after filtering is
>> indeed dependant on the nature of the noise. But it's still
>> noise, and the filtering (feedback) is an essential part of
>> the 'end' signal (biology).
>>
>> While 'allele distribution in a population' is a poor tool
>> for talking about evolution to general audiences, it's appropriate
>> here, and avoiding it seems to be causing problems. If you
>> don't take evolution to involve allele distribution in populations,
>> it'd be good to define what you mean by evolution.
>>
>
>I do agree with this definition. I was trying to stick with individual
>genomes because it more clearly illustrates that there is no feedback
>that changes these genomes. When we look at populations, that seems to
>confuse everybody into thinking that selection is supplying feedback
>just because the allele frequencies change. Not true. We've just shown
>that selection is an open loop filtering process.

The system, we're agreeing, is the distribution of alleles in a population
of organisms. For specificity, let's say it is the alleles of bacteria in
a particular petri dish. Before applying selection (filter), we have
alleles of bacteria in a petri dish, after doing so, we still have alleles
of bacteria in a petri dish. The results of the filter are fed entirely
back into the system. Not only is it feedback, it is fully closed loop.

For the case of generator -> filter -> speakers, you could take some limit
of this being fully feed-forward or open. The signal is propagating to
different, nominally independant, systems. In your gravel case, you are
applying a similar separation of systems. Separate systems finely enough,
and no system ever has feedbacks. But that isn't a useful division.

For the biological case, that petri dish has temporal continuity, as
does the allele distributions of the bacteria. We can watch the evolution
of that distribution through time, as it is operated on by the feedback
processes of neutral drift and selection.

Aren't you arguing elsewhen in favor of multiple complexities? That
doesn't make sense to me for the same person here who is ignoring that
populations have properties not mapped by study of an individual. Individuals
don't evolve, we know and are agreed to by the above definition of evolution.

--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur activities notes and links.
Sagredo (Galileo Galilei) "You present these recondite matters with too much
evidence and ease; this great facility makes them less appreciated than they
would be had they been presented in a more abstruse manner." Two New Sciences

.

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