Several questions on evolution, and mutation (rate)

Karl kingke at perkin-elmer.com
Fri Aug 23 09:47:16 EST 1996


Felix J. Thibault wrote:
> 
> 
> I have been wondering about this argument for a while,as well,so maybe
> someone can clear up something for me. It seems that since the argument is
> probability based we can interpret it as follows:
>       Given a multitude of earths,with evolution occuring as it does here,
> it the probability of  the human eye arising again on one of these earths
> in the 4.5 billion years(from my early 80's geology book) it took here is
> infinitesmial.

Then there was that old nonsense about an infinite number of monkeys
typing the complete works of Shakespeare in a kajillion years or so. The
fallacy is that the frequency of letters in the English language is not
random. Ie, e is more common than z, which is not what a proper
randomizer would produce.

The whole business of mutations has been confused by the radiation guys
who so enjoyed torturing fruitflies.

In fact, as has been demonstrated, point mutations (nucleotide
substitutions) have not played a major role in evolution. Modern
proteins compared to proteins of archaeobacters: the amino acid
sequences have been "highly conserved" for all the intervening millions
of years.

Instead of calculating around nucleotide substitutions, let's pay more
attention to the conserved "boxes" -- the "words" of DNA. This basic
vocabulary has not changed appreciably since the archaeobacters, but the
phrases and sentences and paragraphs have become far, far more complex.

Also, once a line of development has begun, progress along that line can
become accellerated, as Prof. Devries (the mutation theory guy)
described in 'Plant Breeding'.

Finally, it is a rarely discussed fact that inbreeding can lead to a
pronounced _increase_ in variation. I doubt that these "mutations" are
entirely random. For one thing, the character of theses mutations is not
the same as that of radiation induced mutations.

Mutations don't really explain anything, anyway. Darwin supposed that
the origin of variation is Variation. Devries clarified: that organisms
change by mutating (=changing). All this tautology.

But Devries may be forgiven, almost, because he was using Lamarck's word
... though in a different sense. Lamarck spoke of mutations in the
environment, changes to which organisms had to adapt. Nothing
metaphysical there.


Karl King, 
currently mutating from computer professional to rosarian for the
weekend.
-- 
http://www.geocities.com/RainForest/1978/



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