Date: Fri, 23 Jun 1995 11:51:57 -0600 From: Lisa Rogers <EQDOMAIN.EQWQ.LROGERS-AT-EMAIL.STATE.UT.US> Subject: Re: Lamarck and Darwin 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. --- from list marxism-AT-lists.village.virginia.edu --- ------------------
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