Lamarck and Darwin

Lisa Rogers EQDOMAIN.EQWQ.LROGERS at EMAIL.STATE.UT.US
Fri Jun 23 11:51:57 MDT 1995


I thought that Justin's point about Mendel and genetics was one of my
own, and I think of this as a result of much experiment.  But your
(Rahul's) question did have a wider scope as well.

I don't know the whole story of the mice, I've never looked up the
original literature, but your point about the evidence against
Lamarck from circumscision is well taken.  And not only for Jews.
Also for Australian aboriginal subinscision for men, Chinese
foot-binding, head-binding in several places, etc.

I think the Lamarckian answer might have been "well, we're not
talking about cosmetic changes.  It has to be something useful,
adaptive, in order for it to affect one's descendants."  The typical
example I've heard is that of a blacksmith, who is very large and
muscular.  He gets that way from practice.  Since he uses his muscles
all his life, this muscularity somehow (no mechanism suggested)
somehow becomes inheritable.  Therefore, he will have muscular sons,
who of course are well-suited to the blacksmiths' profession.
Another example was the giraffe, whose short-necked ancestors had
[allegedly] physically elongated their own necks during their own
lifetimes by stretching and reaching for leaves.  Each generation had
offspring with slightly longer necks, because physical traits
acquired during life (somehow) become inheritable.

Still, no evidence for Lamarck.  And if neither Darwin nor Lamarck
had a molecular/cellular mechanism to offer, Darwin would still be
supported by observing differential patterns of mortality and
fertility, and many other things.


We did discuss evolution several weeks ago, and I have been intending
and preparing to pick up some of those threads again.  I think the
ball was more-or-less in my court at the time that I became
preoccupied with other priorities, (but now spring quarter is over,
report cards are received, the Slavic festival is done, dance
rehearsals are off for now, and my life is back.)

The "debate on the neo-Darwinian model" and "alternates to Natural
Selection" I'm most aware of lately were on this list.  I'm happy to
continue the discussion.

I'm sure I've posted on Genetic Drift before.  Do you remember?
Wanna check?  I don't want to repeat myself much.

Yes, GD can be significant, under specific and uncommon
circumstances.  It is also very limited in its potential for change,
because it is non-directional, or rather which direction it goes is
random in each generation (another roll of the dice, or spin of the
arrow).  But I would never call GD an "alternative" to NS - they are
simultaneous.

Yes, the definition of evolution as change in gene frequencies is
valid, it is used in "micro-evolution" when viewing changes on a
one-generation-at-a-time scale, when specific genes are known or
hypothesized or used as a model to illustrate some concept.  For some
situations, this definition is not directly applicable, as when
addressing much longer time-scales, speciation, whole new
tissue-types and body plans, etc. ("macro-evolution").

As for structural limitations and constraints upon immediate
possibilities, they are huge.  Every little change must take place
within / build upon / tear down a piece / modify a coordinated
complex system [organism], without destroying it or interfering with
it.  Most random changes are certainly unlikely to improve it!

NS works by trial and error, that is, innumerable random trials, and
errors defined only in terms of fitness, and that only in relation to
a given environment [social, physical, whatever.]  (BTW, this
biologist means social in terms of any interaction with
con-specifics, so it's not just human.)

But maybe we ought to chew on GD a while first, for example, and come
to some agreement on "where we have got to" before or while we go on
to another piece.  I'm not familiar with Vavilov - perhaps you could
enlighten me?

Thanks,
Lisa

P.S.  For newcomers, I hope you enjoyed this, since you have already
read this far.  In case you are wondering what this is doing on
marxism-list, evolution talk started out in connection with a
discussion of "human nature" and its relation to the possibility of
socialism.  It was also a way to talk about chaos, self-organizing
systems and their relation to evolution and socialism.  Also
implicated:  marxian view of science, marxishness in science, etc.




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