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Thread: Darwin and Lamarckism

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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by zzpluralz
    But regardless, one should remember that Darwin had no idea how evolution by natural selection could have worked - he knew nothing about genes - but it didn't prevent him coming up with his theory.
    The situations are not comparable. We have observations that contradict the possibility of EET. Such was not the case for Darwin. and evolution...
    Darwin's study showed that physical adaptations could become inheritable characteristics, and argued that cumulative generations of physical adaptations passed on to offspring eventually leads to a situation where widely variant descendants would not be co-fertile, and could thus be described as separate species - based on the contemporaneous definition of a species. Within the scope of Darwin's theory, knowledge of DNA and genetic inheritance was not required ...

    just as quantum mechanics was not required to describe the formation of ionic solids, nor to describe the meaning of discontinuous spectra of sunlight filtered through a glass prism ...

    .........

    Quote Originally Posted by florian
    ... As long as the observations are compatible with the model, there is no requirement for a first principle description of the underlying mechanism. This is a serious epistemological mistake to consider that a physical mechanism is required.
    All observations lead to the conclusion that the planets that are growing, have grown or will grow, do so by accumulation of matter inside them, leading to a redistribution of material toward the surface.
    That may well be how things are on your world - welcome to Earth - it's a bit different here ...


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    Quote Originally Posted by Cran
    Darwin's study showed that physical adaptations could become inheritable characteristics, and argued that cumulative generations of physical adaptations passed on to offspring eventually leads to a situation where widely variant descendants would not be co-fertile, and could thus be described as separate species - based on the contemporaneous definition of a species. .
    What you are describing here is Lamarkianism, not Darwinism. It is true that Darwin was troubled by the lack of a mechanism for generating the variation upon which he believed natural selection operated. Consequently, at times, he attributed this to various degrees of some ill-defined Lamarkian process.

    This absence of a mechanism was seen as a major weakness of the theory. Consequently, when Mendel's work was rediscovered at the opening of the 20th century many, perhaps most, saw this as disposing of Darwin's idea. It took the work of Mayr, Haldane, Fisher, Simpson and the like to blend the two threads together in the Modern Synthesis.

    Quote Originally Posted by florian
    (Referring to greenstone belts.)Again, the byproducts of diapirism, aka surfaceward migration of mantle material.
    I know of no instance in which denser rocks become involved in diaparism as the intruding body. The whole point of diaparism is that the less dense material rises through the denser. Greenstone belts, composed as they are of basic and ultra-mafic materials are not lighter than the granitic crust through which you claim they have risen.


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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by Cran
    Darwin's study showed that physical adaptations could become inheritable characteristics, and argued that cumulative generations of physical adaptations passed on to offspring eventually leads to a situation where widely variant descendants would not be co-fertile, and could thus be described as separate species - based on the contemporaneous definition of a species. .
    What you are describing here is Lamarkianism, not Darwinism.
    I was paraphrasing his own words in relation to the study of island finches -
    I don't recall any such citations in that part of his journal ...

    but I'm prepared to accept any post-publication critical analysis of Darwin's work ...
    Nature abhors perfection; cats abhor a vacuum.

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    Quote Originally Posted by Cran
    I was paraphrasing his own words in relation to the study of island finches -
    I don't recall any such citations in that part of his journal ...

    but I'm prepared to accept any post-publication critical analysis of Darwin's work ...
    Sorry Cran, I am slightly confused as to what you are actually saying. I think you mean that
    a) your flawed explanation of evolution was a paraphrase of Darwin. (I can readily accept that. It confirms what I have stated about his leaning to a Lamarkian element in evolution.)
    b) but I'm wholly unclear as to what your last sentence means. Could you clarify please. It will be more productive than me responding to an inaccurate guess.
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by Cran
    I was paraphrasing his own words in relation to the study of island finches -
    I don't recall any such citations in that part of his journal ...

    but I'm prepared to accept any post-publication critical analysis of Darwin's work ...
    Sorry Cran, I am slightly confused as to what you are actually saying. I think you mean that
    a) your flawed explanation of evolution was a paraphrase of Darwin. (I can readily accept that. It confirms what I have stated about his leaning to a Lamarkian element in evolution.)
    b) but I'm wholly unclear as to what your last sentence means. Could you clarify please. It will be more productive than me responding to an inaccurate guess.
    only that I've read Darwin's work (An Essay on the Origin of Species etc ... not The Descent of Man - which, I believe is the one that caused the stir), but have not studied it in the context of other workers nor later refinements - ie, I have not critically analysed Darwin's ideas, but am aware that others more qualified have - in simpler terms, I have not read Lamarck (not even an English translation), so am not in a position to compare the two, although I am aware that others have pointed to Lamarck's influence on Darwin's thinking ...

    nor do I claim any standing in the science of biological evolution (I was put off the idea of a lifetime spent cutting up mice and various animal organs in high school, and could never see the attraction in breeding flies with varying numbers of wings), which as I understand it has progressed and refined far beyond its beginnings (not unlike the BBT in cosmology, again as I understand it - the original ideas, such as Lemaitre's "cosmic egg", have also been described as flawed, primitive, incomplete, etc, by later generations of qualified commentators - but does not remove its value in its original context) ...
    a chemical analogy might be Mendeleev and his development of the periodic table, to which column VIII later had to be added ...

    actually, I went looking for Darwin's journal of his voyage on the Beagle mostly for his descriptions of volcanic bombs in the Indonesian Islands and his views of Australia - the rest was really outside of my field; but the descriptions of the finches, and the arguments he extrapolated from that study caught my interest ...
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    the strange thing is that darwin himself added lamarckian-sounding ideas to later versions of the "Origin", presumably influenced by his contemporaries who often were quite forceful in their views that natural selection could not be the only, and many cases not even an important, driver behind evolution - this viewpoint was only corrected from the 1920s onwards when the modern synthesis starting taking shape

    as for darwin's "Descent" book, it did not really create the stir you might have expected of it, since by then ideas about human evolution were 13 a dozen, and darwin was only one of many, even though his take on sexual selection was a novel addition to the list of evolutionary mechanisms
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    Quote Originally Posted by marnixR
    the strange thing is that darwin himself added lamarckian-sounding ideas to later versions of the "Origin", presumably influenced by his contemporaries who often were quite forceful in their views that natural selection could not be the only, and many cases not even an important, driver behind evolution -
    This is just wrong. Darwin was plagued with the absence of a mechanism to account for the variation upon which natural selection could work. It was the apparent absence of such a mechanism that drove him towards a Lamarkian element in his theory. An individual who singlehandedly tears up a paradigm lying at the heart of science, religion and society is not going to be unduly influenced by contemporaries, no matter how forceful they are.
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    how do you know that's wrong ? admittedly his search for a mechanism to explain variation was one part of the equation, but his tinkering at the edges of his theory was very often instigated by attempts to counter criticisms of his original theory which in the full length of time proved more right than he dared to give it credit for

    you're not going to tell me that anyone is totally immune to peer pressure, especially when you know there's a gap in your explanation somewhere, even if you're not sure where + how to handle it
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    Quote Originally Posted by marnixR
    how do you know that's wrong ?
    From his writings, from his letters, from his biographers. While part of the reason for his delay in publishing for many years was his wish to avoid defending his wife part of it was also because he was struggling to find a mechanism. Why would he write The Variaiton of Animals and Plants Under Domestication if it were not to explore mechanisms? He knew this was a major lack in his theory.

    You suggest he may have reacted to peer pressure. I reply the man had no peers. He stood above any. He stood against Kelvin's persistent attack upon the age of the Earth that, were it true, would have robbed evolution of the time necessary to act.

    Lord Kelvin was a giant, yet Darwin had sufficient belief in the reality of evolution and the need for time in which it could act that he would say " I feel a conviction that the world will be found rather older than Thompson believes."
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    he did, however, care a lot for the professional opinion of the likes of Huxley and Hooker, and he decidedly felt needled by the criticisms of Mivart, to whose criticisms he replied at length in later editions of the Origin

    to claim that the opinions of people who mattered to him were of no concern is to claim that Darwin stood above all criticism
    as has been shown many times, he took criticism of his theory as if they were criticisms of himself, and went to great lengths to defend it against all comers, in the process watering aspects of his original theory down to avert the full brunt of these criticisms, since he knew that in parts its foundations were weak (never mind that it was shown after his death that no such watering down was needed, in this life that knowledge was not available)
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    This should be a separate thread. I don't have access to my library at present. When I get home next week I'll present the evidence that shows your interpretation to be flawed.
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    split off from original thread - hope i got the split more or less correct
    presumably this should go to the biology part of the forum ?
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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