August Weismann

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August Weismann bigraphy, stories - German evolutionary biologist

August Weismann : biography

17 January 1834 – 5 November 1914

Friedrich Leopold August Weismann (17 January 1834 – 5 November 1914) was a German evolutionary biologist.. www.nndb.com Ernst Mayr ranked him the second most notable evolutionary theorist of the 19th century, after Charles Darwin. Weismann became the Director of the Zoological Institute and the first Professor of Zoology at Freiburg.

His main contribution was the germ plasm theory, according to which (in a multicellular organism) inheritance only takes place by means of the germ cells—the gametes such as egg cells and sperm cells. Other cells of the body—somatic cells—do not function as agents of heredity. The effect is one-way: germ cells produce somatic cells and are not affected by anything the somatic cells learn or therefore any ability the body acquires during its life. Genetic information cannot pass from soma to germ plasm and on to the next generation. This is referred to as the Weismann barrier.. Esp.org. Retrieved on 2012-02-25. This idea, if true, rules out the inheritance of acquired characteristics as proposed by Jean-Baptiste Lamarck.Huxley, Julian 1942. Evolution, the modern synthesis. p. 17

The idea of the Weismann barrier is central to the Modern evolutionary synthesis, though it is not expressed today in the same terms. In Weismann’s opinion the largely random process of mutation, which must occur in the gametes (or stem cells that make them) is the only source of change for natural selection to work on. Weismann was one of the first biologists to deny soft inheritance entirely.. Esp.org. Retrieved on 2012-02-25. Weismann’s ideas preceded the rediscovery of Gregor Mendel’s work, and though Weismann was cagey about accepting Mendelism, younger workers soon made the connection.

Weismann is much admired today. Ernst Mayr judged him to be the most important evolutionary thinker between Darwin and the evolutionary synthesis around 1930–40, and was "one of the great biologists of all time".Mayr, Ernst 1982. The growth of biological thought. Harvard. p. 698

Life

Youth and studies

Weis was born a son of high school teacher Johann (Jean) Konrad Weismann (1804–1880), a graduate of ancient languages and theology, and his wife Elise (1803–1850), née Lübbren, the daughter of the county councillor and mayor of Stade, on 17 January 1834 in Frankfurt am Main. He had a typical 19th century bourgeois education, receiving music lessons from the age of four, and drafting and painting lessons from Jakob Becker (1810–1872) at the Frankfurter Städelsche Institut from the age of 14. His piano teacher was a devoted butterfly collector and introduced him to the collecting of imagos and caterpillars. But studying natural sciences was out of the question due to the cost involved and limited job prospects. A friend of the family, Friedrich Wöhler (1800–1882), recommended studying medicine. A foundation from the inheritance of Weismann’s mother allowed him to take up studies in Göttingen. Following his graduation in 1856, he wrote his dissertation on the synthesis of hippuric acid in the human body.

Professional life

Immediately after university, Weismann took on a post as assistant at the Städtische Klinik (city clinic) in Rostock. Weismann successfully submitted two manuscripts, one about hippuric acid in herbivores, and one about the salt content of the Baltic Sea, and won two prizes. The paper about the salt content dissuaded him from becoming a chemist, since he felt himself lacking in apothecarial accuracy.

After a study visit to see Vienna’s museums and clinics, he graduated as a physician and settled in Frankfurt with a medical practice in 1868. During the war between Austria, France and Italy in 1859, he became Chief Medical Officer in the military. During a leave from duty, he walked trough Northern Italy and the County of Tyrol. After a sabbatical in Paris, he worked with Rudolf Leuckart at the University of Gießen. He returned to Frankfurt as personal physician to the banished Archduke Stephen of Austria at Schaumburg Castle from 1861 to 1863.