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Definition: Mayr from Merriam-Webster's Collegiate(R) Dictionary

Ernst Mayr 1904–2005 Am. (Ger.-born) biol.

Summary Article: Mayr, Ernst Walter from Encyclopedia of Life Sciences

(1904-) German-born American ornithologist with major impacts on evolutionary theory and systematics in the twentieth century; also tireless campaigner for the importance of biogeography, systematics and the study of organisms when biology seemed increasingly reductionist.

Life and Career

Born 5 July 1904 in Kempten (Allgäu, Bavaria), Ernst was the second of three sons born to Otto and Helene Mayr. His father was a judge in the Bavarian court system, and the family had a long tradition of practice in medicine. Following his father's career, the family moved to Würzburg in 1908, then to Munich in 1914. Otto Mayr was an enthusiastic naturalist, and the family took frequent excursions into the countryside. In Würzburg, Ernst began his interest in natural history, especially birds. See also: History of Taxonomy; Evolution: History

Otto Mayr died unexpectedly in July 1917. Afterwards his wife and sons moved to Dresden. Ernst left for university in 1923. Considerable family savings were lost during the hyperinflation of the early 1920s. Each son attended university on scholarships and savings from their mother's pension. Following family tradition, Mayr began medical training at the University of Griefswald in 1923. A professional career was expected by family pressure (his two brothers studied engineering and law, respectively). Mayr later claimed his choice of schools was dictated by a desire to situate himself in an ornithologically interesting region of Europe. Despite high marks in his medical examinations at university, Mayr switched to zoology after earning a candidate in medicine degree in 1925.

In 1923 Mayr observed an occurrence of the migratory duck Netta rufina well outside its expected range. Confident this was important, Mayr visited the Museum of Natural History at the University of Berlin to report his results to the curator of birds, Erwin Stresemann, who was also the editor of Ornithologische Monatsberichte. This first publication fuelled Mayr's interest in ornithology. Stresemann offered him a volunteer position at the Museum during university holidays. This encouragement, including the promise to place him as an expedition-based collector, drew Mayr into the subject.

Mayr completed his PhD in 1926, 16 months after moving to Berlin. With Stresemann as his supervisor, Mayr studied the European distribution and biogeography of the serin finch, Serinus canaria serinus. On completion, he received an assistantship at the Museum.

Several attempts failed to secure a place for Mayr on a collecting expedition, but Stresemann convinced several prominent competitors to hire Mayr in a cooperative venture. In February 1928 Mayr left Berlin on two separate projects. First, he was to collect in Dutch New Guinea jointly for the Rothschild Museum at Tring (UK) and the American Museum of Natural History (AMNH) (USA). Second, he was to collect in the former German Mandated New Guinea for Stresemann. Before returning home Mayr was asked to join the Whitney Expedition in the Solomon Islands, collecting again for the AMNH. This added a year to his travels. Returning to Berlin in 1930, Mayr set to work studying the New Guinea material. His 1932 article ‘A tenderfoot explorer in New Guinea’ provides a taste of this experience.

On his return, Mayr was thought to be a rising star in ornithology. At Tring, he was considered to replace the curator Ernst Hartert. Financial problems meant this post was never offered. Instead, Mayr was recruited by the AMNH to process its backlog of ornithological materials from the South Seas. Mayr began in January 1931.

In 1932, Walter Rothschild sold his ornithological collection to the AMNH. Numbering 280 000 skins and other materials, this accession had to be assimilated into the AMNH collection. Mayr accepted this expansion of duties, becoming associate curator of the Whitney-Rothschild Collection. For twenty years, Mayr's principal responsibility was the curation of this collection.

Mayr worked at the AMN H until 1953, rising to the rank of curator. He resigned to accept an Agassiz Professorship at the Museum of Comparative Zoology (MCZ) at Harvard University. He served as Director of the museum from 1961 to 1970. The Harvard appointment meant an important change in status to Mayr: from museum curator to full professor. Mayr became emeritus professor at Harvard in 1975.

In 1935, Mayr married German-born Margarete (Gretel) Simon (1912-1990). They had two daughters. Mayr always credited his wife for her role in assisting him, his students and visiting colleagues. Both became American citizens in 1950.

Impact on the Life Sciences

Mayr's taxonomic speciality is birds of the southwestern Pacific, authoring both technical publications and field guides, such as his (1945) Birds of the Southwest Pacific, co-authored by Jaques. In the 1930s and 1940s Mayr was active in the Linnaean Society of New York, which mixed Manhattan's birding enthusiasts with professional ornithologists centred at the AMNH. He had a role in cultivating numerous PhD students in the subject. From 1931, Mayr contributed substantially to several editions of James Peters’ Check-list of Birds of the World. When Peters died unexpectedly in 1952, Mayr oversaw the completion of the Check-list’s next edition. See also: David Lack and the Development of Field Ornithology

Speciation and evolution

In the late 1930s, Mayr turned his interest to the process of speciation. His (1942) Systematics and the Origin of Species earned Mayr an international reputation and the Leidy Medal (1946). Mayr was part of a small group of biologists confident that recent developments in genetics, biogeography, ecology and behaviour made possible a new and rigorous understanding of speciation. Through the 1940s, Mayr cultivated this subject as his own speciality. See also: Evolutionary Ideas: the Modern Synthesis

Mayr's approach to speciation emphasized geographic isolation and polytypic species, which collected geographically distinct populations together as varieties within a single species provided these populations interbreed. Mayr became a strong advocate of allopatric speciation, which required physical, geographical isolation of a population prior to their divergence into a new species. For Mayr, geographically distinct populations represented more than mere varieties; they were ‘incipient species’. He also championed the ‘biological’ or ‘genetical’ species concept, which emphasized the role of interbreeding and gene flow in speciation. As gene flow dwindled between separate populations, Mayr argued, a new speciation event was underway. This was ‘evolution in action’. Its study emphasized isolating mechanisms and barriers to gene flow. Though Mayr admitted many isolating mechanisms as plausible, he emphasized the importance of geographic isolation in the process. Physical isolation was necessary, he argued, for evolving barriers to accumulate within populations. See also: Speciation: Allopatric; Speciation: Sympatric and Parapatric; Geographical Variation

Mayr's emphasis on polytypic species and geographic isolation imported ideas from his Berlin mentors, Stresemann and Berhnard Rensch. He was also influenced by many strands of American biology, including the population genetics research of Theodosius Dobzhansky. Animal Species and Evolution (1963) represents the maturation of Mayr's evolutionary theorizing. See also: Dobzhansky, Theodosius

Mayr played an important role in renovating evolutionary studies during the 1930s and 1940s. Intellectually, this involved a multidisciplinary synthesis of data and methodologies. It also involved a shift from documenting evolutionary patterns to examining its mechanisms. Mayr worked hard to convince sceptical naturalists this was a legitimate area for inquiry and to convince sceptical experimental biologists that naturalists could make unique contributions to the subject. By the early 1940s, Mayr was community building among biologists interested in speciation processes. After World War II, this expanded into the Society for the Study of Evolution, and the journal Evolution, which Mayr founded and edited from 1947 to 1949. See also: Speciation: Chromosomal Mechanisms


Mayr's impact on systematics involved several levels. First, he worked to discipline systematics and to establish its place within the life sciences. Pressing for status meant transforming the perception of systematics from diffuse to explicit roles as a cornerstone in the subject. Disciplining the subject meant reform from within: convincing colleagues they had a responsibility to keep up-to-date on developments elsewhere in the life sciences, and convincing them they ought to use their specialized knowledge to speak to general biological problems (such as evolution). See also: Classification

Mayr first asserted himself in these roles during the 1930s within the American Ornithologists Union. He was one of a dozen self-proclaimed ‘bird biologists’ striving to shift the focus of American ornithology away from birding per se and towards general biological subjects: behaviour, physiology, migration and evolution. This also manifested during Mayr's role with the AMNH exhibit ‘biology of birds,’ which opened in 1948. The same desires to assert systematics drove Mayr towards interdisciplinary research in the 1940s.

In the 1950s and 1960s Mayr worked at the national and international level through his role as Director of the MCZ and his position within the National Academy of Sciences. Mayr was key in establishing ‘systematic biology’ as a field within the life sciences. His co-authored (1953) book Methods and Principles of Systematic Zoology became a standard text in the discipline.

Among systematists, Mayr led a faction self-described as ‘evolutionary systematics’. George Gaylord Simpson and Arthur Cain were two other leading proponents of this approach. The basic principle of evolutionary systematics is to use classification to express evolutionary relationships, with a special focus on groups close to the species level and a formal recognition of subspecies using trinomial nomenclature. See also: Simpson, George Gaylord

Evolutionary theory sets the principles guiding the systematist's formulation of these groups. For example, because gene flow became the currency of evolutionary studies, species became the fundamental unit of attention. Geographic and ecological varieties were recognized as incipient species. Species clusters or super species were set neatly within a genus. Variation within populations was understood to be an essential element of population structure. Characters thought to be adaptations to local conditions were highlighted within taxonomic distinctions as the features making a group distinct. The presence of geographic barriers was deemed sufficient to draw boundaries in classifications. In the overall scheme of classification, taxonomic groups were built around a common ancestor and its descendants, following Darwin's emphasis on continuity and descent with modification. See also: Systematics 1800-2000; Systematics: Relevance to the Twenty-First Century; Variation, Within Species: Introduction; Variation: Measures

Not all taxonomists accepted evolutionary systematics. Some preferred artificial classification systems for convenience. The rise of numerical taxonomy and cladistics in the 1960s promoted vigorous debate about the nature of systematics and its relations to evolution. This debate continues today.

History and philosophy of science

Since the 1950s, Mayr has written extensively on the history and philosophy of biology, as with his monumental (1982) Growth of Biological Thought and his additions to Stresemann's (1975) Ornithology From Aristotle to the Present. In the early 1970s, Mayr organized a conference on evolutionary studies in the twentieth century, with proceedings published as Evolutionary Synthesis (1980), coedited with Provine. He also has written extensively on Darwin and leading evolutionists in the nineteenth and twentieth centuries. In addition to his scholarship, Mayr has played an important role as patron and advocate for these subjects. See also: Evolution: History; History of Taxonomy; Canada: Life Science Organizations; Philosophy of Biological Classification

As a historian, Mayr's work revolves around three themes. First, he works to organize the history of biology to explain how interests in his generation arose. Second, he works to credit those in the past who advocated the positions he defends. Third, he defends the historical importance of naturalist traditions in the history of biology when emphasis seems to shift elsewhere, such as towards molecular biology.

In philosophy, Mayr contributed to the notion of causation with a distinction between proximate and ultimate causes. Functional biology, he argued, focuses on proximate causes by investigating the operation and interaction of structural elements. Explanations in physiology are paradigm examples of proximate causes by asking ‘how’ questions (How does this work?). On the other hand, evolutionary biology seeks ultimate causes. These provide explanations for ‘why’ questions (Why does this exist; what is it for?). This distinction nicely describes the division within the life sciences between reductionistic specialities that emphasize physico-mechanical explanations and holistic specialities that emphasize relationships within the broad expanse of evolutionary time. The proximate/ ultimate distinction arose during Mayr's role in conflicts in the 1950s and 1960s between evolutionary and molecular biologists.

Further Reading
  • Mayr, E (1932) A tenderfoot explorer in New Guinea. Reminiscences of an expedition for birds in the primeval forests of the Arfak Mountains. Natural History 32: 83-97.
  • Mayr, E (1942) Systematics and the Origin of Species, from the Viewpoint of a Zoologist. Columbia University Press New York.
  • Mayr, E (1963) Animal Species and Evolution. Belknap Press of Harvard University Press Cambridge, MA.
  • Mayr, E (1982) The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Belknap Press of Harvard University Press Cambridge, MA.
  • Mayr, E; Jaques, FL (1945) Birds of the southwest Pacific, a field guide to the birds of the Area between Samoa, New Caledonia, and Micronesia. Macmillan New York.
  • Mayr, E; Linsley, EG; Usinger, RL (1953) Methods and Principles of Systematic Zoology. McGraw-Hill New York.
  • Cain, J (1994) Ernst Mayr as community architect: launching the Society for the Study of Evolution and the journal. Evolution. Biology and Philosophy 9: 387-427.
  • Greene, J; Ruse, M (1994) Special issue on Ernst Mayr at ninety. Biology and Philosophy 9: 263-427.
  • Haffer, J (1997) ‘We Must Lead the Way on New Paths’: the Work and Correspondence of Hartert, Stresemann, and Ernst Mayr - International Ornithologists. Ludwigsburg: Jochen Hölzinger.
  • Joe Cain
    University College London, London, UK
    Wiley ©2007

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