Fritz Müller

For the Swiss doctor and zoologist, see Fritz Müller (doctor)

Johann Friedrich Theodor Müller PhD (March 31, 1821–May 21, 1897), always known as Fritz, was a German biologist who emigrated to Brazil, where he studied the natural history of the Amazon rainforest and was an early advocate of evolutionary theory. Müllerian mimicry is named after him.

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Life

Müller was born in Windischholzhausen, near Erfurt, Germany, on March 31 1821, the son of a minister. Unlike most of his contemporaries in Britain, Müller had what would be seen today as a normal scientific education at the universities of Berlin and Greifswald, culminating in a PhD. Then, he decided to study medicine. As a medical student, he began to question religion and in 1846 became an atheist, joining the Free Congregation and supporting free love. Despite completing the course, he did not graduate because he refused to swear the graduation oath, which contained the phrase "so help me God and his sacred Gospel".

It is of some historical interest that Müller's formal education should be so extensive, whereas his British equivalents seldom gained the same kind of qualification. Darwin had an MA, but Faraday, Huxley, Wallace and Bates were autodidacts who had no university degrees at all. Not until Huxley—a great Germanophile—engineered a change in British attitudes to science were nascent British scientists able to get appropriate education.

Müller was disappointed by the failure of the Prussian Revolution in 1848, and realised there might be implications for his life and career. As a result, he emigrated to Brazil in 1852 with Hermann Blumenau to the new colony of Blumenau. In Blumenau, Müller, living with his wife Caroline, became a farmer, doctor, teacher and biologist, sometimes employed by the provincial government, sometimes surviving on his own efforts, sometimes defending against Indians but always collecting evidence of life in the Atlantic Forest – vegetal comunity typical of the Brazilian coast – of the Itajai River Valley, in Santa Catarina State, south of Brazil, where is located the former colony and actual city of Blumenau.

Biology

His great discovery was about the resemblance between two or more unpalatable species who are strikingly protected from predators capable of learning: say birds or reptiles. The protection is often a noxious chemical, perhaps gained from the larva eating a particulat plant; or it may be a sting or other defence. It is an advantage for such potential prey to advertise their status in a way clearly perceptible to their predators; this is called aposematic or warning coloration. The aposematic colours are most often some combination of red, yellow, black, white, whereas palatable animals are usually cryptic. The noxious animals may display by slow flying, and in general are prominently visible. Noxious animals usually have thick, leathery cuticles through which, at certain points, they extrude noxious fluids when pecked; they will often survive a 'trial'.

In Mullerian mimicry an advantage is gained when unpalatable species resemble each other, especially when the predator has a good memory for colour (as birds, for instance, do have). Thus one trial may work to dissuade a bird from several species of butterfly which all fly the same 'flag'. Brazilian butterflies provide some of the most extraordinary examples of mimicry, and Müller, Bates and Wallace all had lengthy experience of this. All three travellor-naturalists believed firmly that such systems of mimicry could only come about by means of natural selection, and all of them wrote about it.

Müller became a strong supporter of Darwin. He wrote Für Darwin in 1864, arguing that Charles Darwin's theory of evolution by natural selection was correct, and that Brazilian crustaceans and their larvae could be affected by adaptations at any growth stage. This was translated into English by W.S. Dallas as Facts and Arguments for Darwin in 1869 (Darwin sponsored the translation and publication). If Müller had a weakness it was that his writing was much less readable than that of Darwin or Wallace; both the German and English editions are hard reading indeed, which has limited the appreciation of this significant book.

Extensive correspondence exists between Müller and Darwin, and Müller also corresponded with Hermann Müller, Alexander Agassiz, Ernst Krause, and Ernst Haeckel.

Between 1874 and 1891, Müller worked as a travelling naturalist for the Brazilian National Museum, working with basic materials. He was a contemporary of several other foreign naturalists and scientists who were invited by Pedro II of Brazil to work at the museum, such as Émil Goeldi and Hermann von Ihering.

Biographies

• Alfred Moeller 1920. Fritz Müller. Werke, Briefe und Leben [virtually the sole biographical source for this significant biologist]
• David A. West 2003. Fritz Müller: a naturalist in Brazil. Blacksburg: Pocahontas Press. ISBN 0-936015-92-6 [modern, and most welcome, though the biographical information rests on Moeller's book]

See also

• Henry Walter Bates
• Science and technology in Brazil