Re: A Specification for a
pete (VINCENT@REG.TRIUMF.CA)
14 Nov 1995 21:26:49 GMT
HARRY R. ERWIN (herwin@osf1.gmu.edu) sez:
`What we see in genetic algorithms is mosaic evolution, with a good many
`of the characteristics hitchhiking to fixation based on accidental
`association with selectively advantageous innovations. Hence when we see
`a new complex of features emerge in the fossil record (==?speciation
`events), only one of the features will be selectively advantageous; the
`remainder can be expected to be close to being selectively neutral.
Yes! There seems to be a tendency to believe that evolution has
the capabilities of a determined intelligent designer, so that
when a development is required in a species to improve its fitness
to its environment, that particular development can spontaneously
appear, without any other alteration to the organism. But genes
seem to operate more like a series of templates laid over the
entire organism, rather than independent spare parts to be
bolted on. Thus, if for instance a creature could perhaps benefit
from having a longer digit for accessing its food source, the
fortuitous eventuation of this development could have any
number of linked changes, from changing the colour patterning
of its coat, to changing the relative size of any number of
bones or organs, to some more obscure alterations to its
body chemistry. As long as these other changes are not so
deleterious to the animal's survival as to undo the benefits
afforded by the advantageous change, they will `hitchhike'
along, changing the overall form of the creature.
(Just endorsing and elaborating the point.)
--
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vincent@triumf.ca <== faster % Pete Vincent
vincent@freenet.vancouver.bc.ca % Disclaimer: all I know I
% learned from reading Usenet.
|