hall at deleteme.ns.utk.edu
Tue Sep 15 16:44:16 EDT 1998
> Lamarckian ideas have been coming back into vogue, as you will see
> biologists talking about a species being "forced" into an adaptation.
> This is clearly a Lamarckian concept.
> The Central Dogma says that mutation is not affected by outsid forces,
> but only by random mutations in the somatic cells. However it has been
> shown that mutation rates in many creatures is accellerated during
> stressful times This has been shown in Darwin's finches, and the
> mutations were not all deleterious.
> To say most mutations are deleterious is not viewing the whole
> process. We cause mutations in cells by artificially applying
> chemicals, radiation etc., and then say they are mostly bad. However,
> it has been shown that some portions of some code strands are much
> more susceptible to mutation than others, and these can give rise to
> mutations that are not bad.
> Wings may have developed as a response to difficult environmrntal
> times, not as a "random" event.
> Perhaps it is time to take Lamarck out of the bone yard and dust him
> off and examine him thouroughly.
The processes you describe are hardly Lamarckian because they merely
increase mutation rates. Lamarckian change would involve mutating only
those genes related to an acquired trait, and presumably would include
mutating them so that they would produce the desired outcome, a longer
neck, for example. It is completely beyond me to imagine how an
organism would know which genes related to which traits, much less how
to change them so to achieve a specific outcome. Certainly this
knowledge is way beyond what science is currently capable of.
The only Lamarckian scenario I can think of that is remotely sensible,
given our understanding of heredity, is if giraffes started suffering
major, reproduction limiting neck problems due to constant stretching of
the upper spine. Giraffes with longer necks, then, would be selected
because they didn't have to stretch so much as to induce skeletal
problems. This is sort of Lamarckian. Of course, they would at the
same time experience selection due to their greater ability to exploit
available food resources. Anyway, this is only barely Lamarckian, if
that. I think it best to leave him where he lies.
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