Talk:August Weismann

Eugenics
Karl Pearson reasoned that, if Weismann's germ plasm theory is correct, then it is a waste of public money to try to improve people who come from inferior stock. 205.188.116.69 17:28, 19 September 2005 (UTC)James Moriarty, Professor of Mathematics


 * Perhaps it should be noted that Professor James Moriarty is a fictional character. I assume (though I did not write it, and would not have written it) that the above comment is to be taken with a pinch of salt, and was made by a character who is not aware that the germ plasm theory was eventually replaced by the theory of chromosomal inheritance, although it may in part also be seen to refer to maternal effects. I will try to put these useful pointers in the article. - Samsara 21:02, 28 December 2005 (UTC)

Karl Pearson did indeed claim a relationship between Weismann's theory of "continuity of the germ plasm" (Pearson's phraseology) and his own belief regarding the viability of "bad stock" (again, Pearson's words). Here’s a short example from pages 26 and 27 Pearson’s The Grammar of Science (1892):
 * Now this conclusion of Weismann's (…) radically affects our judgment on the moral conduct of the individual, and on the duties of the state and society towards their degenerate members. No degenerate and feeble stock will ever be converted into healthy and sound stock by the accumulated effects of education, good laws, and sanitary surroundings.

Pearson’s ignorance of the role played by environment factors - including education, good laws, and sanitary surroundings - in the expression of heritable characteristics may be the most obvious of the defects contributing to Pearson’s view. Possibly more disturbing - if not ironic - is how this notion conflicts with ideas espoused in the pages lead up to the above quote. While it is well worth reading the entire Introduction to The Grammar of Science to appreciate the full extent of this conflict, I’ll leave you with one example from page 9:


 * Minds trained to scientific methods are less likely to be led by mere appeal to the passions or by blind emotional excitement to sanction acts which in the end may lead to social disaster. In the first and foremost place, therefore, I lay stress upon the educational side of modern science, and state my position in some such words as these: Modern Science, as training the mind to an exact and impartial analysis of facts, is an education specially fitted to promote sound citizenship [emphases in the original text]. —Preceding unsigned comment added by ZofC (talk • contribs) 18:51, 24 November 2010 (UTC)

Weakness of this page
Considering that Weissmann's 'doctrine' lies at the heart of the modern evolutionary synthesis, this page appears very lacking in explanation, or criticisms, of what exactly he did and wrote.

In relation to any lesser known name than his, the material given here would be regarded as totally unscientific - one man's POV. We are told that he 'advocated the germ theory', but we can all advocate a theory - what did he do to prove it correct, let alone merit having his name go down in history in relation to the 'Weissman barrier'?

Later we are told, 'In Weismann's opinion it is the only process by which evolution takes place.' That's a hell of a thing to take on one man's opinion, especially given that it contradicts the 'opinions' of Lamarck, Darwin, and many others.

What about the oft repeated 'fact' that he cut off the tails of a good many mice, and so 'proved' that inheritance of aquired characteristics did not occur. If the experiment was done, it should be described here, but I will not add it as I do not speak German, and so cannot research the writings referenced here. Can someone help me with that? Which of his writings say what, in plain english? Of course, I am not the first to point out that such an experiment was both unnecessary (given the evidence from circumcision etc), and irrelevant (Lamarck postulates inheritance of characteristics acquired by trying or willing, not mutilation). Are his writings available in English?

I hasten to add that I am not a promoter of creationism, but given what we now know about retroviruses, transposons, lateral gene transfer, and possible evidence for soma to germline transfer I think it is time Weissman was exposed critically for the fact that his opinion was perhaps no more than that, and that given that he knew absolutely nothing about the limits of genetics he was in no position to propose a theory which, by its negative nature, could only ever be proved by absolutely exhaustive experiment and theory. --Memestream 19:42, 1 August 2007 (UTC)


 * A description of Weismann's mouse experiment appears in an article titled "The Inheritance of Injuries" in the Aug 9, 1889 issue of Science (vol. 14, no. 340, pp. 93-94). This article may be found on the database JSTOR.
 * Also, there were two ways of thinking about the inheritance of acquired characteristics in Weismann's time, though many neo-Lamarckians held both. In the first, the use or disuse of an organ would cause that organ to become larger or smaller in succeeding generations (e.g., the giraffe's neck). In the second, environmental factors could affect heritable traits (e.g., the tanning of people from Africa generation after generation would lead, on a neo-Lamarckian reading, to the current darkness of skin we see in Africans).
 * Either way, Weismann's experiment causes trouble for fans of the inheritance of acquired characters. Environmental factors clearly are not inherited, as far as we can tell from this experiment's results. Use-disuse stuff is also problematic, because mice without tails are clearly not using their tails, and thus one would expect a reduction in tail length, however slight. The primary issue, as can be seen from the Science article, is that mutilations cannot be inherited--a view which ran contrary to a lot of folklore and the environmental-factors aspect of neo-Lamarckism. This idea of heritable mutilations was common
 * As far as the circumcision argument goes, much anecdotal evidence existed which seemed to show that Jewish boys were sometimes born with shorter foreskins (see, e.g., "The Early History of the Idea of the Inheritance of Acquired Characters and of Pangenesis," Conway Zirkle, Transactions of the American Philosophical Society, Jan 1946, p. 114). Many other mutilations were believed to be inherited as well. Weismann's experiments, later successfully repeated by others (http://physrev.physiology.org/cgi/reprint/5/2/244.pdf) showed that this anecdotal evidence was devoid of scientific merit.

Daniel Dickson-LaPrade —Preceding unsigned comment added by 129.15.127.254 (talk) 18:17, 18 February 2008 (UTC)


 * Note also the phenomenon of aposthia(http://en.wikipedia.org/wiki/Aposthia), in which boys are born without foreskins. Many Jewish and Muslim legends talk about this condition. Then there is also E.S. Talbot's article "Inheritance of Circumcision Effects," Medicine, 1898, Volume 4, pp. 473-75 (I can't find the text of this article anywhere, unfortunately).

Daniel Dickson-LaPrade —Preceding unsigned comment added by 129.15.127.254 (talk) 18:28, 18 February 2008 (UTC)

Ants - explanation required please
Can someone explain why, as stated here, 'the existence of non-reproductive castes of ants, such as workers and soldiers, cannot be explained by inheritance of acquired characters. Germ plasm theory, on the other hand, does so effortlessly.'

Is this really true, given what we now know about the haplodiploid nature of social insect genomes. It seems to me that once a random mutation had produced the possibility of workers queens and males then there is no reason why Lamarkian inheritance, if it exists, should not act specifically on workers, just as it could act specifically on males and females of diploid species, given that we now understand the role of imprinting via methylisation etc as a mechanism of differential gene expression between sexes. --Memestream 19:51, 1 August 2007 (UTC)

Intro re-written to correct many factual errors
I have re-written this, keeping old material wherever it was valid. Before anyone reverts, I must stress that the old introduction contained many common errors:

1 The Weissman barrier and the Central Dogma are quite separate ideas, one concerning preservation of the germline, the other the mechanisms of RNA and DNA. Crick did not simply re-state Weissman, and I can provide citations from major works which point out the fallacy of this common error if required.

2 Weissman did not, as was stated in the article, consider natural selection to be the only mechanism of evolution. Nor, for that matter did Darwin!. No one in the field disputes the fact that natural selection occurs but it is only one component. Many do dispute the way in which genetic change occurs - change being the other component of Darwinian evolution. Darwin was mostly Lamarckian. The modern sythesis, also known as neo-Darwinism is not Darwin's theory of evolution, it is Darwin limited by Weissman and Fisher in particular. I hope I have made all this clear.

3 The article as it existed was too bold in stating that we now know Weissman to have been correct. In fact, though the modern synthesis assumes this, experimental proof has never been put forward, and the one thing we do know now, since the discovery of retroviruses and reverse transcriptase, is that there is no theoretical reason to suppose that the Weismann barrier exists, and there is considerable, controversial, evidence that it does not exist. See for example, the book 'Lamarck's signature' by Ted Steele which lists a lot of research evidence.

---Memestream 15:00, 2 August 2007 (UTC)

Images
I have created a category at Commons for Weismann. I note that Britannica also has another image of him here, which would quite likely be public domain? Richard001 (talk) 04:16, 26 October 2008 (UTC)

wiesmann's experiment in rat
I want to know for how much generation wiesmann's experiment in rat was????was it for 19 generations?? Debajyoti2 (talk) 12:13, 13 August 2014 (UTC)

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