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From: rte@anchor.ho.att.com (R.EDWARDS(HOY002)1305)
Subject: Re: Language and genes
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References: <634@percep.demon.co.uk> <D02y75.K2n@inter.NL.net> <3bihbv$40t@amy13.stanford.edu>
Date: Thu, 8 Dec 1994 23:56:24 GMT
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In article <3bihbv$40t@amy13.stanford.edu>,
Nathaniel Michael Pearson <raindrop@leland.stanford.edu> wrote:
>In article <D02y75.K2n@inter.NL.net>,
>Miguel Carrasquer <mcv@inter.NL.net> wrote:
>>In article <634@percep.demon.co.uk>,
>>rmallott <rmallott@percep.demon.co.uk> wrote:
>>>Miguel Carrasquer <mcv@inter.NL.net> writes: [abbreviated]
>
>>
>>The sources of biological change are random: some changes have
>>a positive effect on the phenotype and proliferate, some
>>changes are detrimental and disappear.  This is traditionally
>>called "survival of the fittest".  The great majority of changes
>>are neither detrimental nor advantageous: they just happen.

In particular, some changes occur in junk DNA, that portion that
is never expressed, because it lies outside genes (by definition,
DNA that codes for a protein).  These changes have no effect.
Unless junk DNA has a more subtile purpose, such as a storehouse
of once used genes that may someday be useful again.

>>(However, when external circumstances change they can prove to be
>>detrimental or advantageous after all).
>
>If you mean "stochastic" by "random" (as opposed to merely unpredictable
>given present knowledge) then both of these assertions rely on negative 
>evidence, and, as was previously noted, one cannot set out to prove them,
>but only to disprove them.
>
>Under a model of complex causality (e.g. chaos theory), such phenomena as
>chromosome separation during meiosis, DNA base changes, brownian motion, sound
>change, etc. are not stochastic but fully deterministic, despite their ability
>to elude our prediction.  The best challenge to this assertion that I know of 
>is the assertion of truly random processes in quantum mechanics, which I
>understand too poorly to assess.
>

Some DNA damage occurs as a result of radiation.  If the radiation comes from
decay of a radioactive nucleus, this process is truly random, that is the timing
is not predictable even in principle.  Other damage may arise from cosmic
radiation.  Mu particles pass through your body at the rate of several a
minute.  They are produced in the upper atmosphere in a process which is
equally random, as a result of collisions of primary cosmic rays (mostly
protons) with the upper atmosphere.  Other damage occurs from the interaction
of viruses with chromosomes.  The diffusion of viruses in tissue surely
is highly random.  Science has not viewed the world as deterministic since
1920.  (Well, physicists haven't anyway.)


>>Precisely because of the slow nature of genetic evolution, our brains,
>>articulatory and auditory apparatus have been essentially the same
>>for the last 100,000 years or more.  

I believe the transition to HSS begins only about 125 ky ago, and was 
not compete (whatever that means) until 50 ky ago, or even later.
It is entirely possible, even probable (my feeling, not science)
that we are in a cusp of evolution.
How do you know there has not been significant change in average language
ability in the last 25 ky, for example?  This seems hard to show to me.


>-Nathaniel Pearson
>Stanford University


>>Miguel Carrasquer         ____________________  ~~~
>>Amsterdam                [                  ||]~  


Ralph Edwards
