[FRIAM] random v stochastic v indeterminate
Steven A Smith
sasmyth at swcp.com
Fri Aug 11 13:56:25 EDT 2017
Nick -
>
> I am very glad to note that you are recovering and your scrappiness is
> properly returning!
>
> */[NST==>The best cardio rehab is for you-guys to keep annoying me.
> Thanks for that. <==nst] /*
>
You might check with your cardiologist on this one, I'm not sure a rise
in BP is the same as exercise-stimulated increased heart rate, but in
any case, I'm glad we can be of service!
>
> *//*
>
>
> What’s powerful about it?
>
> Nothing more than it is such a succinct statement negating the popular
> fallacious apprehension of the mechanism of evolution, suggesting that
> there is a causal link between "selection" and "innovation"... the
> innovation step is in the mutation, but as the quote states clearly,
> said *innovation* is *preserved* (selected for) by the natural
> selection mechanism.
>
> */[NST==>Wait a minute! What is the misapprehension of which you
> speak? Can you put it explicitly. /*
>
The misapprehension of which I speak is that natural selection *alone*
gives rise to innovation. Without mutation, all that is achieved by
natural selection is a reduction of diversity in the genotype/phenotype
toward some "optimum" for the selection criteria, or more likely a
"wandering" around geno/pheno space as the selection pressures
"wander". I believe that this is the mechanism behind what is known as
"island dwarfism". There is no *innovation*, merely selection for a
feature within the phenotypic distribution (body size) already in the
population.
I was NOT suggesting that YOU hold this misapprehension, just chiming in
on the point made by Jenny with her original quote.
>
> */And, when you say that mutations are “random”, what precisely do you
> mean./*
>
I don't know that *I* have said that mutations are "random". I agree
that "random" is notional. But I think of a signal as being "random" if
the receiver has no model to correlate it's structure. A highly
organized but encrypted message is "random" if you don't have the key to
decode it. Cosmic radiation knocking holes in your genome is "random"
for all practical purposes, even if it is highly correlated with solar
and magnetosphere activity.
>
> */Unpredictable? Clearly false. We know quite a lot, I think, about
> where DNA is vulnerable, and where mutations are likely to occur. /*
>
A "random" selection can still have a statistical distribution. When
rolling pairs of dice, there is only one way to get a value of 2, (both
dies == 1), 2 ways to get a value of 3 (1,2 and 2,1) and 3 ways to get a
value of 4 (1,3 and 3,1 and 2,2), etc. this distribution is defined by
simple combinatorics, but any given sample is still "random".
Referencing above, in principle every specific set of dice are less than
perfect and every dice-thrower might have some "handedness" which
*might* lend a tiny bias to the distribution (e.g. LOADED dice). The
resulting sequences are still random, just biased in an unexpected
way. Flipping a coin is the same (unless it is two-headed of course!).
I don't think that the DNA (or intermediate RNA?) is more vulnerable in
some regions (or among some sequences) than others to say, "cosmic
radiation" but I will accept that perhaps when the many potential causes
of mutation and the various mechanism for detection/repair are taken
into account, some parts of the sequence are more susceptible to
"effective" mutation? And of course, at the phenotypic level, what is
"effective" is what the natural selection component is all about.
I will pause beating this horse for a moment but will try to respond to
the remainder of your response separately (perhaps even completing the
thought you thought I failed to complete?)
- Steve
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