Emil Hans Willi Hennig (20 April 1913 – 5 November 1976) was a Germanbiologist and zoologist who is considered the founder of phylogenetic systematics, otherwise known as cladistics.[1][2][3] In 1945 as a prisoner of war, Hennig began work on his theory of cladistics, which he published in German in 1950, with a substantially revised English translation published in 1966. With his works on evolution and systematics he revolutionised the view of the natural order of beings.[4][5] As a taxonomist, he specialised in dipterans (true flies).
Hennig coined the key terms synapomorphy, symplesiomorphy, and paraphyly. He also asserted, in his "auxiliary principle", that "the presence of apomorphous characters in different species 'is always reason for suspecting kinship [i.e., that species belong to a monophyletic group], and that their origin by convergence should not be presumed a priori' (Hennig, 1953). This was based on the conviction that 'phylogenetic systematics would lose all ground on which it stands' if the presence of apomorphous characters in different species were considered first of all as convergences (or parallelisms), with proof to the contrary required in each case."[6] This has been viewed as an application of the parsimony principle to the interpretation of characters, an important component of phylogenetic inference.[7]
He is also remembered for Hennig's progression rule in cladistics, which argues controversially[8] that the most primitive species are found in the earliest, central part of a group's area.
Biography
Early years and studies
Hennig was born in Dürrhennersdorf, Upper Lusatia. His mother Marie Emma, née Groß, worked as a maid and, later, factory worker. His father Karl Ernst Emil Hennig was a rail worker. Willi had two brothers, Fritz Rudolf Hennig, who became a minister, and Karl Herbert, who went missing at the Battle of Stalingrad in 1943.
In the spring of 1919, Willi Hennig started school in Dürrhennersdorf, and subsequently was at school in Taubenheim an der Spree and Oppach. Rudolf Hennig described the family as calm; his father possessed an even temperament.
As of 1927, Willi Hennig continued his education at the Realgymnasium and boarding school in Klotzsche near Dresden. Here he met his first mentor M. Rost, a science teacher, whom he lived with in a house known as the "Abteilung".[9] Rost had an interest in insects and introduced Hennig to Wilhelm Meise, who worked as a scientist at the Dresdener Museum für Tierkunde (State Museum of Zoology, Dresden). In 1930, Hennig skipped a year, and graduated on 26 February 1932. As early as 1931, Willi Hennig composed an essay entitled Die Stellung der Systematik in der Zoologie ("The state of systematics in zoology") as part of his school work, published posthumously in 1978. It showed his interest as well as his deliberate treatment of systematic problems. Besides school, Hennig worked as a volunteer at the museum and, in collaboration with Meise, saw to the systematic and biogeographical investigation of the "flying" snakes of the genus Dendrophis that became his first published work.
From the summer semester of 1932 onwards, Hennig read zoology, botany and geology at the University of Leipzig. He would continue to visit the Museum in Dresden. There, he met the curator of the entomological collection, the Dipteran expert Fritz Isidor van Emden. Hennig saw him regularly until van Emden was expelled from National Socialist Germany for having a Jewish mother and wife.[10]
Hennig developed a deep friendship with Emden's successor, Klaus Günther. Hennig concluded his studies with a dissertation entitled, Beiträge zur Kenntnis des Kopulationsapparates der cyclorrhaphen Dipteren. By this time, Hennig had published eight scientific papers. Besides his 300-page revision of the Tylidae (now classed as Micropezidae), there were further papers on Diptera and the agamid genus Draco of gliding lizards. After his studies, Hennig was Volontär at the State Museum for Zoology in Dresden. On 1 January 1937, he obtained a scholarship from the Deutsche Forschungsgemeinschaft (DFG) to work at the German Entomological Institute of the Kaiser-Wilhelm-Gesellschaft in Berlin-Dahlem. On 13 May 1939, Hennig married his former fellow student Irma Wehnert. By 1945, they had three sons, Wolfgang (born 1941), Bernd (born 1943) and Gerd (born 1945).
As a military entomologist
Willi Hennig was drafted in 1938 to train for the infantry and concluded this course in 1939. As of the start of World War II, he was deployed in the infantry in Poland, France, Denmark and Russia. He was injured by grenade shrapnel in 1942 and was subsequently used as entomologist at the Institute for Tropical Medicine and Hygiene in Berlin, carrying the rank of a Sonderführer (Z). Just before the war ended, he was sent to Italy to the 10th Army, Heeresgruppe C, to fight malaria and other epidemic diseases. At the end of the war in May 1945, he was captured by the British while he was with the Malaria training corps at the Gulf of Trieste, and was only released in the autumn.
Through his active participation in war as soldier and scientist Hennig was later subjected to accusations that he had been a member of the National Socialist party, especially by the Italian biologist and founder of panbiogeography, Leon Croizat. No evidence has been officially presented to support the claim. There is no report of Hennig supporting the National Socialist party views publicly on any occasion.[11] Hennig did believe that Nazi Germany would win World War II.[12]
During his time as prisoner of war, Hennig began to draft his most important contribution to systematics, not published until 1950. The rough draft was composed with pencil and ballpoint pen into an A4 exercise book, spanning 170 pages. During the war, he also published a further 25 scientific papers. Most of the correspondence and literature research was conducted by his wife, Irma.
1950s: Basic outline of a theory of phylogenetic systematics
From 1 December 1945, to 31 March 1947, Willi Hennig stood in for his thesis supervisor Paul Buchner as assistant to Professor Friedrich Hempelmann at the University of Leipzig, giving lectures in general biology, zoology and special zoology of insects. He returned to the German Entomological Institute in Berlin on 1 April 1947, and gave up his position in Leipzig. From 1 November 1949, he led the section for systematic entomology and was second director of the institute. On 1 August 1950, he habilitated in zoology at the Brandenburgische Landeshochschule in Potsdam. On 10 October that year he was offered a professorship with teaching responsibilities, which he fulfilled lecturing on special zoology of invertebrates, systematic zoology and taxonomic practicals. In the same year, he published his Basic outline of a theory of phylogenetic systematics, and further works on the methodology of phylogenetic systematics followed in the ensuing years, accompanied by numerous taxonomic works about Diptera. His two-volume Pocket book of zoology, in which he applied phylogenetic systematics to invertebrates for the first time, was particularly successful.
He continued working at the German Entomological Institute in the Soviet Sector of Berlin, Berlin-Friedrichshagen, all the while living in the American sector in Berlin-Steglitz. On a trip to France with his son on 13 August 1961, he heard of the impending Berlin Wall and returned to Berlin immediately to quit his appointment. Moving to East Berlin was out of the question, as Hennig held anti-communist views and already had a troubled relationship with the Sozialistische Einheitspartei Deutschlands (Socialist Unity Party of Germany, SED) that was the ruling political party of East Germany, as Hennig had repeatedly helped employees of the institute gain employment in the West.
1961 to 1976
Hennig, c. 1970
In West Berlin, Hennig was given an interim post at the Technische Universität Berlin as Distinguished Professor. He rejected offers from the U.S. Department of Agriculture in Washington, D.C., and an offer made by his friend Elmo Hardy, to become a Research Fellow at the University of Hawaii in Honolulu, citing as reasons that the education of his sons took priority for him, and that he needed to have the "cultural witnesses of the antique Greek-Roman Europe within ready access". He instead decided on a post at the State Museum of Natural History in Stuttgart,[13] where he was given a department for phylogenetic research. In April 1963, he moved to Ludwigsburg-Pflugfelden for this position. The scientific collections of the museum had been provisorily kept in Ludwigsburg and remained here until their re-housing at the new site of the museum at Stuttgart's Löwentor, in 1985.
Hennig's works in Stuttgart dealt almost exclusively with taxonomic revisions of Dipterans. For the Stuttgarter Beiträge zur Naturkunde, where he published the majority of his works, he completed 29 issues by the end of his life. Significant are the review articles published in Erwin Lindner's Flies of the Palaearctic Regions and the Handbuch der Zoologie. The cladistic methodology was also represented in several published works, foremost among them the article, Cladistic analysis or cladistic classification? A reply to Ernst Mayr (1974), intended as an internationally accessible reply to the criticism Ernst Mayr had made of Hennig's phylogenetic systematics.
Willi Hennig only visited international institutions abroad twice, in spite of receiving many invitations for guest lectures. From 1 September to 30 November 1967, he worked at the Entomology Research Institute at Canada's Department of Agriculture in Ottawa and participated in the International Congress of Entomology in Canberra from 22 to 30 August 1972. With his wife, he also visited Bangkok, New Guinea (where much of Mayr's understanding of bird taxonomy originated) and Singapore on this latter trip. His stay in Canada was also used for visits to various entomological collections in museums of the US, including Cambridge, Chicago, Washington, D.C., and New York, always in the hope of finding further amber inclusions of Dipterans, that featured prominently in his research of the late 1960s and early 1970s. On the initiative of Klaus Günther, who by then held a chair at the Freie Universität Berlin, Hennig was given an honorary doctorate on 4 December 1968; for health reasons, he could not accept this honour in person, and it was presented to him by Günther on 21 March 1969, in Stuttgart. On the initiative of students whom he had lectured on several animal taxa, Hennig was made an honorary professor at the University of Tübingen on 27 February 1970.
On the night of 5 November 1976, Hennig died of a heart attack at Ludwigsburg. He had previously repeatedly cancelled lectures with reference to his fading health, and had already had an attack on his journey to Ottawa. He was interred on 10 November at the Bergfriedhof in Tübingen.
The Willi Hennig Society, an organization devoted to the advancement of cladistic principles in systematic biology, was founded in 1981. The society publishes the journal Cladistics. A symposium, Willi Hennig (1913-1976): His Life, Legacy and the Future of Phylogenetic Systematics, was held in London by the Linnean Society of London on 27 November 2013.[15] A symposium volume[16] was published in 2016 by the Systematics Association.
Selected works
Books:
Die Larvenformen der Dipteren, 3 vols., Berlin: Akademie-Verlag, 1948-1952.
Grundzüge einer Theorie der phylogenetischen Systematik, Berlin: Deutscher Zentralverlag, 1950.
Phylogenetic Systematics, translated by D. Davis and R. Zangerl, Urbana: University of Illinois Press, 1966 (reprinted 1979).
Die Stammesgeschichte der Insekten, Frankfurt am Main: Verlag von Waldemar Kramer, 1969.
Phylogenetische Systematik, edited by Prof. Dr. Wolfgang Hennig, Berlin and Hamburg: Verlag Paul Parey, 1982.
Aufgaben und Probleme stammesgeschichtlicher Forschung, Berlin: Paul Parey, 1984.
Articles:
"Die Schlangengattung Dendrophis," Zoologischer Anzeiger, vol. 99, 1932, 273-297 (gemeinsam mit W. Meise).
"Beziehungen zwischen geographischer Verbreitung und systematischer Gliederung bei einigen Dipterenfamilien: ein Beitrag zum Problem der Gliederung systematischer Kategorien höherer Ordnung," Zoologischer Anzeiger, vol. 116, 1936, 161-175.
"Revision der Gattung Draco (Agamidae)," Temminckia: a Journal of Systematic Zoology, vol. 1, 1936, 153-220.
"Über einige Gesetzmäßigkeiten der geographischen Variation in der Reptiliengattung Draco L.: „parallele" und konvergente Rassenbildung," Biolog. Zentralblatt, vol. 56, 1936, 549-559.
"Die Gattung Rachicerus Walker und ihre Verwandten im Baltischen Bernstein," Zool. Anz., vol. 123, 1938, 33-41.
"Probleme der biologischen Systematik," Forschungen und Fortschritte, vol. 21/23, 1947, 276-279.
"Kritische Bemerkungen zum phylogenetischen System der Insekten," Beiträge zur Entomologie, vol. 3 (Sonderheft), 1953, 1-85.
"Flügelgeäder und System der Dipteren unter Berücksichtigung der aus dem Mesozoikum beschriebenen Fossilien," Beiträge zur Entomologie, vol. 4, 1954, 245-388.
"Systematik und Phylogenese," Bericht Hunderjahrfeier Dtsch. Ent. Ges., 1956, 50-71.
"Die Familien der Diptera Schizophora und ihre phylogenetischen Verwandtschaftsbeziehungen," Beitr. Ent., vol. 8, 1958, 508-688.
"Die Dipteren-Fauna von Neuseeland als systematisches und tiergeographisches Problem," Beitr. Ent., vol. 10, 1960, 221-329.
"Dixidae aus dem Baltischen Bernstein, mit Bemerkungen über einige andere fossile Arten aus der Gruppe Culicoidea," Beitr. Naturkde, vol. 153, 1966, 1-16.
"Die sogenannten „niederen Brachycera" im Baltischen Bernstein," Beitr. Naturkde, vol. 174, 1967, 1-51.
"Kritische Bemerkungen über den Bau der Flügelwurzel bei den Dipteren und die Frage nach der Monophylie der Nematocera," Beitr. Naturkde, vol. 193, 1968, 1-23.
"Cladistic Analysis or Cladistic Classification? A reply to Ernst Mayr," Syst. Zool., vol. 24, 1975, 244-256.
Related Research Articles
Cladistics is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived characteristics (synapomorphies) that are not present in more distant groups and ancestors. However, from an empirical perspective, common ancestors are inferences based on a cladistic hypothesis of relationships of taxa whose character states can be observed. Theoretically, a last common ancestor and all its descendants constitute a (minimal) clade. Importantly, all descendants stay in their overarching ancestral clade. For example, if the terms worms or fishes were used within a strict cladistic framework, these terms would include humans. Many of these terms are normally used paraphyletically, outside of cladistics, e.g. as a 'grade', which are fruitless to precisely delineate, especially when including extinct species. Radiation results in the generation of new subclades by bifurcation, but in practice sexual hybridization may blur very closely related groupings.
Systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees. Phylogenies have two components: branching order and branch length. Phylogenetic trees of species and higher taxa are used to study the evolution of traits and the distribution of organisms (biogeography). Systematics, in other words, is used to understand the evolutionary history of life on Earth.
Karl Hermann Johannes Thiele was a German zoologist specialized in malacology. Thiele was born in Goldap, East Prussia. His Handbuch der systematischen Weichtierkunde is a standard work. From 1904 until his retirement in 1925 he was the curator of the malacological collection at the Museum für Naturkunde in Berlin. Thiele described more than 1.500 new species of molluscs; until today their types are deposited with the Museum of Natural History in Berlin. Especially important are his works on the Mollusca of the First German Antarctica Expedition and of the German Deep Sea Expedition aboard the vessel Valdivia.
The Sepsidae are a family of flies, commonly called the black scavenger flies or ensign flies. Over 300 species are described worldwide. They are usually found around dung or decaying plant and animal material. Many species resemble ants, having a "waist" and glossy black body. Many Sepsidae have a curious wing-waving habit made more apparent by dark patches at the wing end.
Bernhard Rensch was a German evolutionary biologist and ornithologist who did field work in Indonesia and India. Starting his scientific career with pro-Lamarckian views, he shifted to selectionism and became one of the architects of the modern synthesis in evolutionary biology, which he popularised in Germany. Besides his work on how environmental factors influenced the evolution of geographically isolated populations and on evolution above the species level, which contributed to the modern synthesis, he also worked extensively in the area of animal behavior (ethology) and on philosophical aspects of biological science. His education and scientific work were interrupted by service in the German military during both World War I and World War II.
Friedrich Hermann Loew was a German entomologist who specialised in the study of Diptera, an order of insects including flies, mosquitoes, gnats and midges. He described many world species and was the first specialist to work on the Diptera of the United States.
Entomology, the scientific study of insects and closely related terrestrial arthropods, has been impelled by the necessity of societies to protect themselves from insect-borne diseases, crop losses to pest insects, and insect-related discomfort, as well as by people's natural curiosity. This timeline article traces the history of entomology.
Oswald Duda, full name Pavel Theodor Friedrich Oswald Duda was a German entomologist mainly interested in Diptera.
Theodor Becker was a Danish-born German civil engineer and entomologist primarily known for studies on the taxonomy of flies.
Carnidae, also known as bird flies or filth flies, is a family of flies (Diptera). There are 6 genera, containing about 93 species worldwide.
Adolf Naef was a Swiss zoologist and palaeontologist who worked on cephalopods and systematics. Although he struggled with academic politics throughout his career and difficult conditions during World War I and II, his work had lasting influences on the fields of phylogenetics, morphology, and embryology.
Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional method, by which taxon names are defined by a type, which can be a specimen or a taxon of lower rank, and a description in words. Phylogenetic nomenclature is regulated currently by the International Code of Phylogenetic Nomenclature (PhyloCode).
Walter Max Zimmermann was a German botanist and systematist. Zimmernann’s notions of classifying life objectively based on phylogenetic methods and on evolutionarily important characters were foundational for modern phylogenetics. Though they were later implemented by Willi Hennig in his fundamental work on phylogenetic systematics, Zimmermann's contributions to this field have largely been overlooked. Zimmermann also made several significant developments in the field of plant systematics such as the discovery of the telome theory. The standard botanical author abbreviation W.Zimm. is applied to species he described.
The Willi Hennig Society "was founded in 1980 with the expressed purpose of promoting the field of phylogenetic systematics." The society is represented by phylogenetic systematists managing and publishing in the peer-reviewed journal titled Cladistics. The society is named after Willi Hennig, a German systematic entomologist who developed the modern methods and philosophical approach to systematics in the 1940s and 1950s. The society is also involved in reconstructing the tree of life. The current president, Prof. Dr. Stefan Richter of Universitat Rostock, was elected in 2022, succeeding Prof. Dr. Christiane Weirauch.
The Cryptochetidae are a small family of tiny flies. Some twenty to thirty species are known. Generally they are metallic blue black, stoutly built, with the head broad and high and with clear wings. Like other species in the superfamily Lonchaeoidea, the Cryptochetidae have antennae with a cleft in the second segment. Unlike practically all Schizophora however, they lack an arista, or if they do have one, it is too small to distinguish with any confidence. The family name refers to this unusual distinction; "Cryptochetidae" literally means "those with hidden bristles". The adult flies also are unusual among insects in that they have only a single pair of abdominal spiracles — this is not a serious physiological challenge in such small insects.
Martin Baehr was a German entomologist who mostly worked on ground beetles (Carabidae), but also spiders, grasshoppers and other taxa. He described and named more than 2.000 species, mostly from Southeast Asia and Australia. He studied biology at the university of Tübingen. His doctoral thesis was initially supervised by Willi Hennig, who then died before his graduation.
Peter Ax was a German zoologist. His main work concerned the investigation of interstitial fauna and the exposition of a phylogenetic system for the animals.
Quentin Duane Wheeler is an American entomologist, taxonomist, author and newspaper columnist, and is the founding director of the International Institute for Species Exploration. He was the fourth President of the State University of New York College of Environmental Science and Forestry, in Syracuse, New York until his retirement. Other positions have included: professor of entomology at Cornell University and Arizona State University; Keeper and Head of Entomology at the Natural History Museum in London; and Director of the Division of Environmental Biology at the National Science Foundation.
Transformed cladistics, also known as pattern cladistics is an epistemological approach to the cladistic method of phylogenetic inference and classification that makes no a priori assumptions about common ancestry. It was advocated by Norman Platnick, Colin Patterson, Ronald Brady and others in the 1980s, but has few modern proponents. The book, Foundations of Systematics and Biogeography by David Williams and Malte Ebach provides a thoughtful history of the origins of this point of view.
↑ Hennig, W. 1966. Phylogenetic Systematics. University of Illinois Press, Urbana.
↑ Farris, J. S. 1983. The logical basis of phylogenetic analysis. Pp.7-36 in Advances in Cladistics, vol. 1 (eds. N. I. Platnick and V. A. Funk). Columbia University Press, NY.
↑ Rudolf Meier. Role of Dipterology in Phylogenetic Systematics: The Insight of Willi Hennig in David K. Yeates and Brian M.Wiegmann (Eds) 2005. The evolutionary biology of flies. Columbia University Press. ISBN0-231-12700-6
↑ Williams, David M.; Schmitt, Michael; Wheeler, Quentin D. (2016). The Future of Phylogenetic Systematics: the Legacy of Willi Hennig. Systematics Association Special Volume 86. Cambridge University Press.
Sources
Peters, G. (1995). "Über Willi Hennig als Forscherpersönlichkeit". Veröffentlichungen der Gesellschaft Naturforschende Freunde. 34. Berlin: 3–10.
Schlee, D. (1978). "In Memoriam Willi Hennig 1913-1976. Eine biographische Skizze". Entomologica Germanica. 4. Stuttgart: Fischer: 377–391. doi:10.1127/entom.germ/4/1978/377. ISSN0340-2266.
Schmitt, M. (2001). "Willi Hennig". In Jahn, I.; Schmitt M. (eds.). Darwin & Co. II - Die Geschichte der Biologie in Porträts. München: C.H. Beck. ISBN3-406-44642-6.
Schmitt, M. (2002). "Willi Hennig als akademischer Lehrer". In Schulz J. (ed.). Fokus Biologiegeschichte. Zum 80. Geburtstag der Biologiehistorikerin Ilse Jahn. Berlin: Akadras. pp.53–64 pp. ISBN3-00-009209-9.
Schmitt, M. (2003). "Willi Hennig and the Rise of Cladistics". In Legakis, A.; Sfenthourakis, S.; Polymeni, R.; Thessalou-Legaki M. (eds.). The New Panorama of Animal Evolution - Proceedings of the 18th International Congress of Zoology. Sofia - Moskau: Pensoft Publ. pp.369–379 pp. ISBN954-642-164-2.
Vogel, J.; Xylander, W.R. (1999). "Willi Hennig - Ein Oberlausitzer Naturforscher mit Weltgeltung. Recherchen zu seiner Familiengeschichte sowie Kinder- und Jugendzeit". Berichte der Naturforschenden Gesellschaft Oberlausitz. 7/8: 131–141. ISSN0941-0627.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
