Mendel vs Darwin: Ciência vs Naturalismo (Mats):«Um dos grandes mitos darwinistas fortemente propagado pelos discípulos de Darwin é a de que as descobertas científicas do monge cristão Gregor Mendel estão em pleno acordo com a mitologia evolucionista.
A sua lógica deve-se muito à crença de que evolução nada mais é que a "variação" . Como os genes de facto variam, então Mendel e Darwin tem que estar de acordo.
O problema é que o trabalho de Mendel foi largamente ignorado pelos darwinistas. Isso deve-se a dois factos importantes:
1. Darwin acreditava que as formas de vida poderiam variar de um modo quase infindável, desde que houvesse necessidade disso.
2. Mendel, com as suas experiências descobriu que, sim, há variações mas que essas variações ocorrem dentro de um campo genético limitado, tal como esta descrito neste site: (Ênfase adicionado)
Mendel's ideas on heredity and evolution were diametrically opposed to those of Darwin and his followers. Darwin believed in the inheritance of acquired characters (and tried to back up his ideas with his pangenesis hypothesis, which even Stebbins called an "unfortunate anomaly") and, most important of course, continuous evolution. Mendel, in contrast, rejected both, the inheritance of acquired characters as well as evolution. The laws discovered by him were understood to be the laws of constant elements for a great but finite variation, not only for culture varieties but also for species in the wild (Mendel 1866, pp. 36, 46, 47).
In his short treatise EXPERIMENTS IN PLANT HYBRIDIZATION mentioned above Mendel incessantly speaks of "constant characters", "constant offspring", "constant combinations", "constant forms", "constant law", "a constant species" etc. (in such combinations the adjective "constant" occurs altogether 67 times in the German original paper).
He was convinced that the laws of heredity he had discovered corroborated Gärtner's conclusion "that species are fixed with limits beyond which they cannot change"» ...
«Não contentes em ignorar a ciência, os darwinistas fizeram outra coisa que lhes é tão característica:
"Fisher's claims of fraud in Mendel's data have already been disproved by several geneticists and historians of biology (Lamprecht 1968, Pilgrim 1986, Weiling 1995, Vollmann and Ruckenbauer 1997, and many other authors, see below)"Por outras palavras, perturbados pelo que a ciência tinha descoberto em relação ao limitado numero de variações que podem ocorrer num ser vivo, o darwinista Ronald Fisher atacou o carácter de Mendel. (Faz-vos lembrar alguma coisa?)» ...
Fonte primária traduzida para inglês
Experiments in Plant Hybridization (1865), Gregor Mendel:«Gärtner especially in his work Die Bastarderzeugung im Pflanzenreiche , has recorded very valuable observations; and quite recently Wichura published the results of some profound investigations into the hybrids of the Willow.»
«The value and utility of any experiment are determined by the fitness of the material to the purpose for which it is used, and thus in the case before us it cannot be immaterial what plants are subjected to experiment and in what manner such experiment is conducted.» ... «The experimental plants must necessarily: 1. Possess constant differentiating characteristics» ... «The first includes those with the signs AB, Ab, aB, and ab: they possess only constant characters and do not vary again in the next generation.»
«It requires indeed some courage to undertake a labor of such far-reaching extent; this appears, however, to be the only right way by which we can finally reach the solution of a question the importance of which cannot be overestimated in connection with the history of the evolution of organic forms.» ... «We meet with an essential difference in those hybrids which remain constant in their progeny and propagate themselves as truly as the pure species.» ... «For the history of the evolution of plants this circumstance is of special importance, since constant hybrids acquire the status of new species.»
«So far as experience goes, we find it in every case confirmed that constant progeny can only be formed when the egg cells and the fertilizing pollen are of like character, so that both are provided with the material for creating quite similar individuals»
«Gärtner, by the results of these transformation experiments, was led to oppose the opinion of those naturalists who dispute the stability of plant species and believe in a continuous evolution of vegetation. He perceives in the complete transformation of one species into another an indubitable proof that species are fixed with limits beyond which they cannot change. Although this opinion cannot be unconditionally accepted we find on the other hand in Gärtner's experiments a noteworthy confirmation of that supposition regarding variability of cultivated plants which has already been expressed.»
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- MendelWeb : Note: Concluding remarks: «This section, and thus Mendel's paper, ends on an almost hurried, somewhat ambiguous note. It is not clear whether Mendel is claiming that Gärtner's experiments confirm Gärtner's view about the natural fixity of species, or whether his experiments merely confirm the extensive variability of hybrids described in the opening paragraphs. Clearly, Mendel was not as interested in taking a position on the fixity of species question as he was in offering an explanation for the variability of the hybrids.»
- MendelWeb : Glossary : constant combinations: «Mendel uses this phrase to refer both to the individual terms of the combination series (ignoring their coefficients), and to the combination of different characters within a particular organism. For example, in a single-character cross between two hybrids, Aa, we have seen that the experimental outcome can be represented by the combination series A + 2Aa + a. Here there are three constant combinations: A (the pure dominant), Aa (the hybrid), and a (the recessive).»
- MendelWeb : Glossary : continuous evolution: «Although Gärtner was certainly opposed to at least elements of an evolutionary theory, Bateson's translation of Fortbildung as "continuous evolution" is not particularly accurate; the German term implies both development and improvement (here it probably should be translated as "progressive development"), and one can certainly oppose a directional notion of development, without being opposed to evolution. When Mendel appears to be referring to a theory of evolution, elsewhere in the paper, he consistently uses the term Entwicklung. Whether the latter ought to be translated as "evolution" or "development", given Mendel's knowledge of Darwin and other evolutionists, is a debatable question.»
Ronald Fisher sobre o relatório de Mendel
"Has Mendel's work been rediscovered?", Ronald Fisher:
«The suggestion that Mendel was prompted by disagreement with Darwin's views to undertake his experiments is easily disproved. Mendel's experiments cannot have commenced later than 1857. Darwin's views on evolution were known only to a few friends prior to the papers which he communicated, jointly with Wallace, to the Linnean Society in 1858.» ... «More probably he knew nothing of Darwin's existence, and certainly nothing of the theory of Natural Selection, at this date. When, in 1865, Mendel reported his experiments, the situation had doubtless changed. Mendel now recognizes that the study of inheritance has a special importance in relation to evolutionary theory. He alludes to the subject, in his introductory remarks, in words which suggest not doubts, but rather a simple acceptance of the theory of evolution (p. 318)» ...
«It will be seen that Mendel expressly dissociates himself from Gartner's opposition to evolution, pointing out on the other hand that Gartner's own results are easily explained by the Mendelian theoryof factors» ... «It is seen from these, the only two allusions to evolution in Mendel's paper, that he did not regard his work as a direct contribution to that subject. What he does claim for the laws of inheritance he established is that they make sense of many of the results of the hybridists, and that they form a necessary basis for the understanding of the evolutionary process. On this point he shows himself fully aware of the importance of what he had done. Had he considered that his results were in any degree antagonistic to the theory of selection it would have been easy for him to say this also.» ...
«Bateson notes :— "This statement of Mendel's in the light of present knowledge is open to some misconception. Though his work makes it evident that ' such varieties may exist, it is very unlikely that Mendel could have had seven pairs of varieties such that the members of each pair differed from each other in only one considerable character. The point is probably one of little theoretical or practical consequence, but a rather heavy stress is laid on the word wesentlich."» ...
«In 1930, as a result of a study of the development of Darwin's ideas, I pointed out that the modern genetical system, apart from such special features as dominance and linkage, could have been inferred by any abstract thinker in the middle of the nineteenth century if he were led to postulate that inheritance was particulate, that the germinal material was structural, and that the contributions of the two parents were equivalent. I had at that time no suspicion that Mendel had arrived at his discovery in this way. From an examination of Mendel's work it now appears not improbable that he did so and that his ready assumption of the equivalence of the gametes was a potent factor in leading him to his theory. In this way his experimental programme becomes intelligible as a carefully planned demonstration of his conclusions.» ...
«There can, I believe, now be no doubt whatever that his report is to be taken entirely literally, and that his experiments were carried out in just the way and much in the order that they are recounted. The detailed reconstruction of his programme on this assumption leads to no discrepancy whatever. A serious and almost inexplicable discrepancy has, however, appeared, in that in one series of results the numbers observed agree excellently with the two to one ratio, which Mendel himself expected, but differ significantly from what should have been expected had his theory been corrected to allow for the small size of his test progenies. To suppose that Mendel recognized this theoretical complication, and adjusted the frequencies supposedly observed to allow for it, would be to contravene the weight of the evidence supplied in detail by his paper as a whole. Although no explanation can be expected to be satisfactory, it remains a possibility among others that Mendel was deceived by some assistant who knew too well what was expected. This possibility is supported by independent evidence that the data of most, if not all, of the experiments have been falsified so as to agree closely with Mendel's expectations.»
«In view of the parallel failure of the biological world to appreciate and follow up Darwin's experiments, it is difficult to suppose that, had Mendel's paper been more widely read, there would have been many mentally prepared to appreciate its significance.»
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- American Scientist > CSI: Mendel: «Fisher dissected the 1866 article with a keen appreciation of Mendel's likely state of mind» ... «But Fisher also called attention to a troubling aspect of the reported data: They not only fit the Mendelian theory well, they fit it too well, as judged by the use of the chi-square test Karl Pearson had introduced in 1900. The chance of getting such a good fit under standard genetic models was judged to be less than 0.0001. And this was not just in one simple experiment; Fisher found the phenomenon to be systematically true» ... «The suggestion by Wright in 1966 that the classification of 3 percent of some 1,000 plants studied in this case might be off due to subconscious bias toward expected ratios passes William of Occam's test more easily, given the general agreement that something like this happened in Mendel's other experiments.» ... «Essentially because they believe that no further resolution can be reasonably expected, and the existence of the controversy in any case is partly based on misreading Fisher as accusing Mendel of fraud.»
- A Publication of The Genetics Society of America > On Fisher's Criticism of Mendel's Results With the Garden Pea : «IT is generally agreed that the overall results from experiments with the garden pea reported by Gregor MENDEL 1866
conform more closely with the ratios theoretically expected (such as 3:1, 1:2:1, etc.) than one might reasonably expect to obtain on a chance basis.» ...
História sobre a aceitação do darwinismo na comunidade científica
"A heresia de Darwin - O Eterno Retorno do Criacionismo", Thomas Lepeltier (cap.3, "O evolucionismo antidarwinista" - "O eclipse do darwinismo", pp.102-111):
«Não era a ideia de evolução que constituía um problema: de uma forma geral, era muito bem recebida pelos eruditos, ao ponto de 1880, não haver praticamente um naturalista ou um biólogo que a recusasse (o que não era o caso da população). O que constituía um problema era a selecção natural. Darwin não pretendia que ela fosse o único mecanismo responsável pela evolução, mas era a esse que o seu nome estava associado.» ... «A hipótese concorrente mais popular em finais do século XIX e inícios do século XX foi a do mecanismo, dito lamarckiano, da hereditariedade de caracteres adquiridos» ...
«Um outro golpe sofrido pelo lamarckismo veio do desenvolvimento da Genética, na sequência da redescoberta, na década de 1900, das leis da hereditariedade do botânico austríaco Gregor Mendel (1822-1884). Com efeito, o conceito de gene, concebido como uma espécie de "átomo do ser vivo", ao transmitir-se dos organismos progenitores aos seus descendentes desde o seu nascimento, e assim, em seguida, de geração em geração, deixava pouco espaço à ideia de transmissão dos caracteres adquiridos. Não dependendo já a hereditariedade do desenvolvimento individual, também já não havia qualquer razão para supor que este último recapitulasse a evolução. O único processo que poderia produzir a evolução seria a produção de novos caracteres por mutação. Esta teoria genética da hereditariedade não só trazia assim uma sentença para o lamarckismo, como permitia resolver certas dificuldades com que o darwinismo se confrontara, especialmente assinalada a Jenkin (se o novo carácter vantajoso era transmitido como uma unidade inalterada, não podia ser diluído, e as suas proporções na população poderiam, então, aumentar graças à selecção natural). No entanto, isto não provocou um renovado interesse pelo darwinismo. A grande beneficiária foi a teoria da evolução dita "saltacionista", que estipulava que a transmutação das espécies se fazia aos saltos e não de forma gradual. Esta ideia remontava aos trabalhos do anatomista francês Étienne Geoffroy Saint-Hilaine, que, em inícios do século XIX, estabelecera uma analogia entre a transformação das espécies e o aparecimento de indivíduos "monstruosos". A Genética emergente trouxera-lhe o conceito de mutação. Com efeito, a primeira utilização deste termo dizia respeito a transformações tão drásticas que podiam corresponder à criação instantânea de novas espécies. Por exemplo, quando flores de uma mesma espécie apresentam um número de pétalas diferente, parecia improvável que uma pétala tivesse sido perdida ou adquirida de forma gradual.» ...
«Portanto, na práctica, em inícios do século XX, a Genética era antidarwinista. Ao nível dos princípios, porém, nada a impedia de se tornar darwinista.» ... «Para que esta compatibilidade teórica entre Genética e darwinismo se transformasse em união, era preciso confirmar o afastamento dos opositores e que entre os dois se encontrassem pontos de aproximação - o que veio a acontecer entre as décadas de 1920 e 1940, sob o impulso da própria Genética, que se encarregou de dar o golpe de misericórdia aos seus rivais e de mostrar as virtudes da explicação darwinista. Primeiro, os darwinistas compreenderam que, de um modo geral, as mutações genéticas não implicam grandes variações anatómicas (o que, por exemplo, poderia parecer serem novas formas de plantas, devido a mutações genéticas, afinal surgia uma recombinação de caracteres já existentes).» ... «Por fim, no que dizia respeito à ortogénese, as experiências, nomeadamente com moscas, animais de predilecção dos geneticistas, não mostraram qualquer tendência particular na sucessão de mutações. Destas observações retirou-se um princípio que estipulava que as mutações eram aleatórias. Quanto à aproximação da Genética com o darwinismo, veio principalmente daquele ramo da Genética chamado "genética das populações", que demonstrou, graças aos modelos matemáticos, que, em grandes populações, a selecção natural poderia conduzir ao surgimento de novos caracteres ao acumular os efeitos das mutações genéticas aleatórias. Foram estes desenvolvimentos que permitiram o grande regresso do darwinismo. Sob o apelo da teoria sintética da evolução, tornou-se, a partir da década de 1950, no plano de trabalho de uma larga maioria dos biólogos, naturalistas e paleontólogos.»
A hipótese de Darwin e o modelo da Herança por Mistura
Review of The Origin of Species, Fleeming Jenkin ("North British Review", 1867):
«We all believe that a breeder, starting business with a considerable stock of average horses, could, by selection, in a very few generations, obtain horses able to run much faster than any of their sires or dams; in time perhaps he would obtain descendants running twice as fast as their ancestors and possibly equal to our race-horses. But would not the difference in speed between each successive generation be less and less?» ... «Here is the analogy with our cannon-ball; the rate of variation in a given direction is not constant, is not erratic; it is a constantly diminishing rate, tending therefore to a limit.» ...
«Let us consider what will be its influence on the main stock when preserved. It will breed and have a progeny of say 100; now this progeny will, on the whole, be intermediate between the average individual and the sport.» ...
«As the numbers of the favoured variety diminish, so must its relative advantage increase, if the chance of its existence is to surpass the chance of its extinction, until hardly any conceivable advantage would enable the descendants of a single pair to exterminate the descendants of many thousands if they and their descendants are supposed to breed freely with the inferior variety, and so gradually lose their ascendancy» ...«If it is impossible that any sport or accidental variation in a single individual, however favourable to life, should be preserved and transmitted by natural selection, still less can slight an imperceptible variations, occurring in single individuals be garnered up and transmitted to continually increasing numbers; for if a very highly-favoured white cannot blanch a nation of negroes, it will hardly be contended that a comparatively very dull mulatto has a good chance of producing a tawny tribe; the idea, which seems almost absurd when presented in connexion with a practical case, rests on a fallacy of exceedingly common occurrence in mechanics and physics generally.» ...«The number of possible combinations of a given number of elements is limited, however numerous these elements may be. The limits to the possible number of combinations become more and more restricted, as we burden these combinations with laws more and more complicated»
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"The Origin of the Species", Charles Darwin (5th ed., pp.105,105):
«I saw, also, that the preservation in a state of nature of any occasional deviation of structure, such as a monstrosity, would be a rare event; and that, if preserved, it would generally be lost by subsequent intercrossing with ordinary individuals. Nevertheless, until reading an able and valuable article in the 'North British Review' (1867), I did not appreciate how rarely single variations, whether slight or strongly-marked, could be perpetuated.»
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Carta de Darwin para Wallace de 6 de Fevereiro de 1866 (ditado em "O Espectáculo da Vida - A Prova da Evolução", Richard Dawkins; tradução de Isabel Mafra):
«Meu caro Wallace,
não me parece que tenha percebido o que eu queria dizer com a não-mistura de certas variedades. Não se refere à fertilidade. Vou exemplificar: cruzei as variedades de ervilhas-de-cheiro "Painted Lady" e "Purple", cujas cores são muito diferentes, e obtive, inclusive na mesma vagem, as duas variedades puras mas nenhuma intermédia. Suponho que algo do género possa suceder com as suas borboletas. [...] Embora estes casos pareçam maravilhosos, não vejo em que possam ser superiores ao fenómeno de uma fêmea produzir descendentes masculinos e femininos.»
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Letter 2166 — Darwin, C. R. to Huxley, T. H., [before 12 Nov 1857]:
«I have lately been inclined to speculate very crudely & indistinctly, that propagation by true fertilisation, will turn out to be a sort of mixture & not true fusion, of two distinct individuals, or rather of innumerable individuals, as each parent has its parents & ancestors:— I can understand on no other view the way in which crossed forms go back to so large an extent to ancestral forms.»
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