Mayr, Ernst Walter
Mayr, Ernst Walter
MAYR, ERNST WALTER
(b. Kempten, Bavaria, Germany, 5 July 1904; d. Bedford, Massachusetts, 3 February 2005),
ornithology, zoogeography, systematics, evolutionary biology, history and philosophy of biology.
As an architect of the synthetic theory of evolution of the 1940s, Mayr analyzed the origin of biodiversity and the concept of biological species, making the species problem a central concern of evolutionary biology. Later he became an influential historian and philosopher of biology.
Early Ornithological Career . Mayr was the middle of three brothers. Their father Otto Mayr was a successful jurist and an enthusiastic naturalist. On weekends, he and his wife Helene Pusinelli showed their children birds, flowers, mushrooms, and fossils. Mayr thus became a young naturalist and soon spent nearly every free minute of his life watching birds around Dresden, where Mrs. Mayr had moved with her boys after the death of her husband in 1917. Immediately after Ernst had passed his high school examination in February 1923, he discovered a pair of rare migrating ducks, an observation that brought him in contact with Dr. Erwin Stresemann in Berlin, Germany’s leading ornithologist.
Following a family tradition Mayr intended to become a medical doctor and entered medical school in Greifswald on the coast of the Baltic Sea in 1923. He had selected this university because of the excellent birding areas nearby. Between semesters he worked as a volunteer for short periods at the Museum of Natural History in Berlin with Erwin Stresemann, who wrote of him in a letter: “I have discovered … a rising star, a young studiosus med[icinae] by the rare name of Mayr, of fabulous systematic instinct. Unfortunately, he will probably have to wither away as a medical doctor. If only one could always place the right man in the right position!” (12 July 1924; see Haffer, 1997, p. 215). In February 1925 Stresemann persuaded Mayr to switch to zoology and to major in ornithology, partly by promising to place him on an expedition to the tropics later on. This was a temptation Mayr could not resist. He transferred to the University of Berlin, passed his doctoral examination summa cum laude in June 1926, and was immediately employed as an assistant curator at the Museum of Natural History in Berlin.
Mindful of his earlier promise, Stresemann arranged, in late 1927, a one-man expedition for Mayr to New Guinea, jointly financed by the Berlin museum, the American Museum of Natural History in New York, and Lord Walter Rothschild in Tring, United Kingdom. Mayr collected birds on five poorly known mountain ranges in New Guinea between early 1928 and June 1929. When he was ready to return home, he received an invitation to join the American Museum’s Whitney South Sea Expedition in the Solomon Islands. He did so and returned to Germany only in April 1930 and then worked on his collections from eastern New Guinea. In January 1931 he accepted the American Museum’s invitation to be a visiting research associate for one year to study the bird collections from the islands of the southwest Pacific. When, in 1932, the American Museum purchased Rothschild’s large bird collection, Mayr became the curator of the Whitney-Rothschild collections in New York. His motivation for leaving Germany was not political but rather the simple reason that his position in the United States was better, scientifically, than any he could expect in Germany.
Ornithology and Zoogeography . During the 1930s Mayr studied primarily bird collections from Oceania. A continuous stream of research articles appeared, followed by book-length contributions on the birds of New Guinea (1941), the southwest Pacific (1945), the Philippines (1946, with J. Delacour), and northern Melanesia (2001a, with J. Diamond). These studies formed the basis for Mayr’s analysis of variation and speciation in birds. He described twenty-six new species and 445 new subspecies of birds, many cases of simple and complex geographic variation of species, and discussed numerous borderline cases between subspecies and species.
Based on these studies Mayr established the basic principles of an equilibrium theory of island biogeography. The size of an island fauna is determined by an equilibrium between immigration and extinction, size and elevation of the island, and distance from other land masses. His interpretation of the origin of several forms of Australian tree runners (Neositta) in humid refuges during dry climatic periods of the geological past was the first detailed presentation of Pleistocene speciation for birds of the Southern Hemisphere. His studies of the birds of the Indonesian Archipelago convinced him that most species had reached the various islands by dispersal across ocean barriers rather than over land bridges for which he found no evidence. Mayr also influenced ornithology by encouraging amateurs in the New York region to undertake serious biological studies of birds, by publishing Margaret M. Nice’s pioneering population study of the song sparrow, by establishing bird family relations when cataloging and arranging the Rothschild collection, and as well as by editing, in later years, the continuation of James L. Peters’s Check-List of Birds of the World.
The Evolutionary Synthesis . In the 1930s, based on Darwinian evolutionary theory, Mayr also collected data for a comprehensive evolutionary analysis of geographical variation and speciation in birds (and other animals), especially after establishing contact with Theodosius Dobzhansky in 1935. At a symposium organized by Dobzhansky in December 1939, Mayr spoke on “Speciation Phenomena in Birds.” This was a decisive step into his evolutionary career and led to his giving (jointly with Edgar Anderson) the Jesup Lectures at Columbia University (New York) in March 1941. Mayr expanded the manuscript of his lectures, which was published as Systematics and the Origin of Species (1942). This volume became a cornerstone of the evolutionary synthesis of the late 1930s and 1940s, when a largely unified evolutionary theory emerged.
Biological evolution comprises two major components: adaptive development of populations through time, and multiplication of species or the origin of organic diversity. The mathematical population geneticists Ronald Aylmer Fisher, Sewall Wright, and J. B. S. Haldane had solved, with their publications in 1930 through 1932, the first of these problems (the Fisherian synthesis, Mayr, 1999a, p. xiv): They had convincingly shown that small mutations and natural selection play the main roles in the gradual process of adaptive evolution of populations over time (phyletic evolution, anagenesis, or evolution as such). The other main problem, the origin of diversity (multiplication of species, speciation, or cladogenesis), was solved during the evolutionary synthesis between 1937 and 1950 (Mayr, 1993).
In general, this period saw a synthesis: (1) between the thinking in three major biological disciplines— genetics, systematics, and paleontology; (2) between an experimental-reductionist approach (geneticists) and an observational-holistic approach (naturalists-systematists); and (3) between an anglophone tradition with an emphasis on mathematics and adaptation and a continental European tradition with emphasis on populations, species, and higher taxa. The three genetical aspects (then not new insights) that were firmly and universally adopted during the evolutionary synthesis were: (1) that inheritance is “hard,” there is no “soft” inheritance of acquired characters; (2) that inheritance is particulate, that is, the genetic contributions of the parents do not blend but remain separate, to be differently recombined in future generations; and (3) that most mutations are very small and evolution therefore is gradual. This latter aspect in particular permitted a synthesis between genetics and systematics, because the naturalists had always insisted that evolution and speciation are gradual (continuous) and occur without sudden steps. The naturalists had to give up any belief in soft inheritance and to learn that a selective advantage of even small changes of the genotype could account for gradual evolution. In addition, the evolutionary synthesis led to a refutation of the three anti-Darwinian paradigms—(a) the typological-saltational, (b) the teleological-orthogenetic, and (c) the transformationist-Lamarckian theories.
Based on his background as a naturalist-systematist in Russia during the 1920s, Dobzhansky (1937) produced a first synthesis between the views of the naturalists-systematists and the geneticists. The other architects of the evolutionary synthesis widened the path that Dobzhansky had blazed—Ernst Mayr (1942, species and speciation), Julian Huxley (1942, general evolution), George Gaylord Simpson (1944, paleontology), Bernhard Rensch (1947, macroevolution), and G. Ledyard Stebbins (1950, botany). At an international conference in Princeton, New Jersey, in January 1947 there was general agreement among the participating geneticists and naturalistssystematists on the nature of species, the gradualness of evolution, the importance of natural selection, and the populational aspect of the gradual origin of species. A synthesis indeed had taken place. Some differences that remained at that time included the problem of the target of selective demands, which, for the population geneticists, continued to be the gene, whereas the naturalistssystematists insisted it was the individual as a whole. In general, a unification of biology
was not an objective in the minds of any of the architects of the synthesis during the 1930–1940 period. They were busy enough straightening out their own differences and refuting the antidarwinians to have time for such a far-reaching objective. It wasn't until the 1950s when most of the previous difficulties had been resolved that one could begin to think seriously about the role of evolutionary biology in the whole of biology and about the capacity of evolutionary biology to achieve a unification of the previously badly splintered biology. (Mayr, 1993, p. 33; see also Smocovitis, 1996, p. 202)
Recent research has indicated that the evolutionary synthesis was an international program to which also several other workers in Germany contributed (Mayr, 1999b; Reif et al., 2000).
During the 1940s, Mayr was also active as a community architect founding specialty groups beyond ornithology, first within the Committee of Common Problems of Genetics, Paleontology, and Systematics (1942–1949) and later within the Society for the Study of Evolution (1946 ff.). He also served as founding editor of the society’s journal Evolution (1947–1949). Each year, between 1943 and 1952, Mayr and his family spent several summer weeks at Cold Spring Harbor Biological Laboratory, Long Island, where, in discussions with colleagues, he acquired his extensive knowledge of advanced genetics and molecular biology.
Biological Species . Many researchers thought of species as morphologically defined groups of individuals, whereas others, including Mayr, considered species as breeding groups. His concise definition reads “Species are groups of interbreeding natural populations that are reproductively [i.e., genetically] isolated from other such groups” (Mayr, 1969, p. 26; see also 1942, p. 120). Isolating mechanisms maintain the integrity of species by protecting their gene pools from hybridization with other species and, as Mayr showed, arise as a by-product of divergence during the process of speciation (see below). Criteria to infer subspecies or species status of geographically separated populations are derived from the study of related forms that are in contact and do or do not hybridize. The rather frequent occurrence of closely similar (“sibling”) species and of conspicuous variants within species convinced many biologists of the validity of the biological species concept.
The history of this concept goes back to the early nineteenth century. Building on the work of Stresemann, Rensch, and Dobzhansky, Mayr combined systematic, genetic, and ecological aspects and thus established the biological species concept in all its ramifications. Although he was not the originator of the biological species concept, he demonstrated its validity more convincingly than anyone else before and proposed a superior definition.
The Problem of Speciation . Evolutionists understood since the Fisherian synthesis (see above) how and why populations of species change over time, yet species are distinct—they do not hybridize with or blend into one another. How can one separate species arise from another (parental) species? Some geneticists (saltationists like William Bateson, Hugo de Vries, and Richard Gold-schmidt) believed that new species arise instantaneously by large mutations, sudden steps in which either a single character or a whole set of characters together become changed. By contrast, the naturalists-systematists were gradualists and believed that speciation is a populational process, a gradual accumulation of small changes often by natural selection. The rate of such gradual change varies from slow to relatively fast depending on the strength of selective demands and on the size of the populations in which the changes are taking place (faster in small populations).
Mayr’s theory of allopatric speciation from geographically separated populations had been proposed earlier by some evolutionists, but it was his clear synthesis that convinced geneticists and zoologists generally of the common occurrence of such processes: Either a previously continuous species range is split into two or more parts (through sea-level changes or climatic-vegetational changes) or a small isolated founder population is established by dispersal of a few individuals of a parental species across a barrier. Each isolated population then evolves independently, gradually diverging from one another. When sufficient genetic differences have accumulated, the parental and daughter populations may come in contact without hybridizing—a new (daughter) species has originated. Mayr emphasized that, despite the striking gaps between the species of a local flora and fauna, the gradual evolution of new species is no longer a puzzle, and can indeed be illustrated by numerous examples in extant faunas. He never ruled out that sympatric speciation (without geographic isolation) occurs in certain groups of animals, but felt for a long time that convincing evidence was lacking. When the simultaneous acquisition of mate preference and niche preference in a population was demonstrated for cichlid fishes and parasitic insects during the 1980s and 1990s, he accepted this mode of speciation. These preferences isolate two populations in a similar manner as geographic separation.
Mayr’s specific contributions to the evolutionary synthesis were his analyses of the nature of biological species and of the origin of organic diversity. Speciation and other processes in evolution are not simply a matter of genes but of populations and of species. His 1942 volume explained a large part of evolutionary theory well known to naturalists-systematists but not to geneticists, particularly species and speciation and the role of geography in the evolution of populations and species. The volume demonstrated the importance of taxonomic research for evolution.
In more general terms and including later contributions, Mayr dealt with variation and population thinking, species concepts, the dual nature of evolution (phyletic evolution and speciation), the unity of the genotype, and accident versus adaptation in evolution. His most important papers have been reprinted in two volumes of essays (1976, 1988). He did not publish a textbook on evolution, although his books Animal Species and Evolution (1963) and Populations, Species, and Evolution (1970) come close. In the book What Evolution Is (2001b), published when he was ninety-seven years old, he gave a clear and concise exposition of modern evolutionary biology.
Mayr opposed the early view of population geneticists that evolutionary change is an input and output of genes, like adding certain beans to a beanbag and withdrawing others. Instead he called attention to the frequency of interaction among genes, to their changing selective values, and to the general cohesion of the genotype. Other topics he studied and discussed were behavior and evolution, the emergence of evolutionary novelties, sexual selection, and Haeckel’s biogenetic law. Mayr proposed or introduced from foreign languages many terms in systematics and evolutionary biology like allopatric (geographically separated), founder principle, population thinking, semispecies, and superspecies. He also showed that, if the individual is the target of selective demands, neither the theory of neutral evolution nor the adaptationist program are in conflict with Darwinism. The same applies to the theory of punctuated equilibrium proposed by Niles Eldredge and Stephen J. Gould; Charles Darwin was already aware of highly unequal rates of evolution. On the other hand, Mayr emphasized that biologists are still quite ignorant about evolution in most groups of invertebrate animals, of fungi, protists, and the prokaryotes.
Career after the Evolutionary Synthesis . In 1953 Mayr accepted the position of Alexander Agassiz Professor of Zoology at the Museum of Comparative Zoology (MCZ), Harvard University, in Cambridge, Massachusetts, and entered the second phase of his life work. He lectured on evolutionary biology and taught seminars on specific topics, because such courses had not been offered at Harvard for a long time and leading textbooks of biology treated evolution quite superficially. Sixteen graduate students obtained PhD degrees under his guidance between 1955 and 1973. Mayr was director of the MCZ during the period from 1961 to 1970.
As advisor to the U.S. National Academy of Sciences, he served as a member of the Biology Council during the 1950s and of the Committee on Research in the Life Sciences during the 1960s, for which services he received the National Medal of Science in 1969. Later he was awarded the Balzan Prize of Italy and Switzerland (1983) as “the greatest living evolutionary biologist,” Japan’s International Prize for Biology (1994) as “the outstanding systematist in the world,” and Sweden’s Crafoord Prize (1999) for his “fundamental contributions to the conceptual development of evolutionary biology”—these awards constitute the “Triple Crown of Biology.”
History and Philosophy of Biology . The third phase of Mayr’s career, devoted to developmental historiography and a modern philosophy of biology, began during the late 1950s when, at the same time, he continued as an active worker in the fields of systematics, species, and evolution. His contributions to the history and philosophy of biology were based on several decades of empirical research in biology (1976, 1988, 2004). He was particularly interested in the history of scientific problems and their solutions, in tracing an idea, concept, or controversy back to its sources, devoting sufficient attention to the general context of different time levels. Mayr began his work on the history of biology from the perspective of someone who had been very active in shaping that history. Some historians have faulted his approach to history, even labeling it Whiggish, a criticism that Mayr (1990) rejected from his personal point of view. Because the evolutionary synthesis is so central to contemporary biology, historians continue to revise our understanding of how it happened (Smocovitis, 1996).
Mayr’s historical magnum opus is The Growth of Biological Thought: Diversity, Evolution, and Inheritance (1982), where he traced the complete life history of each problem of evolutionary biology and exposed the historical and philosophical relations between systematics, evolution, and genetics. In general, Mayr saw the development of science as an increasing emancipation of scientific knowledge from religious, philosophical, and other ideological beliefs. He advocated that, in scientific progress, various competing paradigms may exist side by side and more or less pronounced “revolutions” may occur in times of normal science. Changes of concepts have a much stronger effect on the development of the sciences than new factual discoveries.
He wrote extensively on Charles Darwin and his times (1991), emphasizing that in 1859 Darwin had proposed not one theory of evolution but five independent theses with respect to evolution: (1) Evolution as such, that is, change of populations through time; (2) common descent of all living organisms; (3) multiplication of species; (4) gradual evolutionary change instead of sudden (saltational) changes within populations; and (5) natural selection as a mechanism of evolutionary change. Analysis of these five theses constitute Mayr’s most significant contribution to the history of evolutionary biology. The differing fate of these theses after 1859 indicate their independence. Most authors, who had accepted the first thesis, rejected one or several of Darwin’s other four theses. The core thesis of natural selection was not generally accepted until the 1940s during the modern synthesis. Likewise, the term Darwinism has several different meanings: Darwinism as the creed of the Darwinians refers to their rejection of special creation: he who believed in the origin of the diversity of life through natural causes was a Darwinian. Darwinism as selectionism has been a primary meaning since the evolutionary synthesis of the 1940s as well as for a few early naturalists. Neo-Darwinism is Darwinism without soft inheritance, the inheritance of acquired characteristics.
Mayr argued that Darwin was the first to apply “population thinking” when he proposed the concept of natural selection (based on the uniqueness of individuals in a population). Mayr considered most or all of Darwin’s contemporaries to be typologists, to whom the underlying type or essence of a species had reality and variation was irrelevant. “The replacement of typological thinking by population thinking is perhaps the greatest conceptual revolution that has taken place in biology” (1963, p. 5). Mayr’s conceptualization of population thinking is a major contribution to the philosophy of biology.
He also emphasized that no biological phenomenon is explained fully until both its functional/environmental (proximate) causes and its evolutionary (ultimate) causes are determined. For example, a northern warbler starts its fall migration on a particular night because of certain physiological/environmental (proximate) causes and because of the general genetic disposition of the bird (evolutionary causes). According to Mayr, the genetic program of an individual is the result of selection that acted upon untold generations and that program is a causal factor which differs fundamentally from physicochemical causes. The many peculiarities of life such as uniqueness and variability, historical contingency, genetic program, diversity, and natural selection necessitate a specific philosophy of biology that excludes both essentialism (typology) and reductionism (explanation purely by molecular structure). In the face of the growth of molecular biology, Mayr vigorously defended organismic and evolutionary biology, but he welcomed molecular biology as such. Experiment is not the only valid method of science, Mayr stated; observation, comparison, and the construction of historical-narrative explanations are also legitimate and important methods in the physical and biological sciences.
Mayr drew ethical implications from three of the five Darwinian theses (1984): The theory of common descent deprived humans of their unique position in the world and of their right to exterminate any other species of animals or plants. The theory of natural selection showed Mayr that altruistic behavior is of selective advantage in closely related individuals of small populations of early humans. Evolution as such countered the idea that humans have no obligation for the future, either with respect to the world’s environment or its fauna and flora. His world view of evolutionary humanism is conscious of the evolutionary past of humans and is aware of their responsibility for the community as a whole and for posterity. Humans are challenged to develop an ethic that can cope with the new situation. Mayr believed overpopulation is the core problem that faces humankind and a change in attitude toward family size is needed: voluntary birth control appears to be not enough and he recommended a set of incentives to be built into the tax system, pension system, and welfare system in the hope that this will lead to zero population growth throughout the world.
Mayr was very skeptical about the existence of extraterrestrial intelligence. Living molecular assemblages might have originated on other planets at some stage of their history. However, it is highly improbable that intelligence followed and humans are most probably alone in this vast universe.
Mayr received the George Sarton Medal of the History of Science Society (1986) and was nominated a Fellow of the Center for the Philosophy of Science in Pittsburgh (1993). The Rockefeller University in New York awarded him the Lewis Thomas Prize: Honoring the Scientist as Poet (1998) and an annual Ernst Mayr Lecture was established in Berlin, Germany (1997). He received a total of seventeen honorary doctoral degrees from universities around the world. Mayr served as president of the Society for the Study of Evolution (1950), of the American Ornithologists’ Union (1956–1959), of the Thirteenth International Ornithological Congress (1962), of the American Society of Naturalists (1962–1963), and of the Society of Systematic Zoology (1966). He published twenty-one books and over 750 scientific articles, about 200 after his retirement in 1975.
Summarizing, Mayr was a cataloger in much of his ornithological work, which formed the empirical basis for his later theoretical studies. He was a major synthesizer of biology, an effective disseminator of biological principles, and a master analyst who dissected such complex concepts as population thinking and Darwin’s five theses of evolution. New theories that Mayr proposed as an innovator include his theories of island biogeography and of the founder principle of speciation. He was convinced of the uniqueness of each individual organism (population thinking) and of the necessity of the historical approach for an understanding of organic beings.
Personality . Exceptional energy, resolution, ambition, and self-confidence were personal traits that guided Mayr when he went on his one-man expedition to New Guinea in 1928 and during many other periods in his life, in his leadership role in evolutionary studies in the United States during the 1940s, and in his spokesmanship for systematics and evolutionary biology when molecular biology threatened to dry up all the research funds during the 1960s. He was driven by an unlimited curiosity, had strong opinions, hated beating around the bush, and made sweeping statements. To take an unequivocal stand and to fight for his views appeared to him of greater heuristic value than to evade the issue. Therefore some of his colleagues considered him to be dogmatic.
However, he was friendly and easygoing. He had no fixed visiting hours as director of the MCZ and anybody could meet with him any time. He promptly reviewed manuscripts in detail for friends, students, and journal editors, and supported students and young colleagues in many other ways. Mayr helped found the Society for the Study of Evolution and served as secretary and first editor of its journal Evolution, and he helped the Journal of the History of Biology to get started in the 1960s. He was generous with his time and with the money he received for academic prizes, all of which he gave to purposes of education and conservation. He was tolerant regarding racial, religious, and ethnic differences and he appreciated the unknown in science and religion. His driving enthusiasm for scientific work until the last month of his life was remarkable.
Mayr influenced the history and philosophy of biology by all the help he gave to neophyte historians and philosophers. His views were strongly held, but he also thought that others had the right to disagree with him, even if they were lowly graduate students.
Mayr had married Margarete (“Gretel”) Simon of Freiburg, Germany, in 1935; they had two daughters, Christa (1936) and Susanne (1937), and became U.S. citizens in December 1950. He enjoyed generally good health throughout most of his long adult life. In 1934 his left kidney had to be removed but he lived to be over one hundred years old. After his wife had passed away in 1990, he managed his household alone until he moved to a comfortable retirement home in Bedford near Cambridge, Massachusetts, in 1997. On 5 July 2004 he celebrated his hundredth birthday in excellent physical and mental health.
During his last year he gave numerous interviews and published his last book, What Makes Biology Unique? Four symposia were held in his honor, two of which he attended. After a short illness he died quietly and peacefully on 3 February 2005. His ashes were scattered by his family and a few close friends along a path overlooking a lake at his beloved country place in New Hampshire, which he had acquired in 1954 and where he had spent many months of his long life.
A complete bibliography is provided by J. Haffer in the volume edited by W. J. Bock and M. R. Lein (2005), and in Haffer’s biography of Mayr, Ornithology, Evolution, and Philosophy— The Life and Science of Ernst Mayr (1904–2005) (2007). Mayr papers containing his correspondence are kept in the following archives: (1) Pusey Library, Harvard University Archives, Cambridge, MA, and (2) Staatsbibliothek Preussischer Kulturbesitz Berlin, Potsdamer Str., Manuscript Division.
WORKS BY MAYR
List of New Guinea Birds. New York: American Museum of Natural History, 1941.
Systematics and the Origin of Species from the Viewpoint of a Zoologist. New York: Columbia University Press, 1942.
Birds of the Southwest Pacific. New York: Macmillan, 1945.
With J. Delacour. Birds of the Philippines. New York: Macmillan, 1946.
Animal Species and Evolution. Cambridge, MA: Belknap Press of Harvard University Press, 1963.
Principles of Systematic Zoology. New York: McGraw-Hill, 1969.
Populations, Species, and Evolution. Cambridge, MA: Belknap Press of Harvard University Press, 1970. An abridgment of Animal Species and Evolution.
Evolution and the Diversity of Life: Selected Essays. Cambridge, MA: Belknap Press of Harvard University Press, 1976.
With William B. Provine, eds. The Evolutionary Synthesis: Perspectives on the Unification of Biology. Cambridge, MA: Harvard University Press, 1980.
The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Cambridge, MA: Belknap Press of Harvard University Press, 1982.
“Evolution and Ethics.” In Darwin, Marx, and Freud: Their Influence on Moral Theory, edited by A. L. Caplan and B. Jennings. New York: Plenum Press, 1984.
Toward a New Philosophy of Biology: Observations of an Evolutionist. Cambridge, MA: Harvard University Press, 1988.
“When Is Historiography Whiggish?” Journal of the History of Ideas 51 (1990): 301–309.
One Long Argument: Charles Darwin and the Genesis of Modern Evolutionary Thought. Cambridge, MA: Harvard University Press, 1991.
“What Was the Evolutionary Synthesis?” Trends in Ecology and Evolution 8 (1993): 31–34.
“Introduction, 1999.” Systematics and the Origin of Species from the Viewpoint of a Zoologist. Paperback ed. Cambridge, MA: Harvard University Press, 1999a.
“Thoughts on the Evolutionary Synthesis in Germany.” In Die Entstehung der Synthetischen Theorie: Beiträge zur Geschichte der Evolutionsbiologie in Deutschland 1930–1950, edited by T. Junker and E.-M. Engels. Verhandlungen zur Geschichte und Theorie der Biologie 2. Berlin: Verlag für Wissenschaft und Bildung, 1999b.
With J. Diamond. The Birds of Northern Melanesia: Speciation, Ecology, and Biogeography. New York: Oxford University Press, 2001a.
What Evolution Is. New York: Basic Books, 2001b.
What Makes Biology Unique: Considerations on the Autonomy of a Scientific Discipline. New York: Cambridge University Press, 2004.
Bock, W. J., and M. R. Lein, eds. Ernst Mayr at 100: Ornithologist and Naturalist. Ornithological Monographs, no. 58. Washington, DC: American Ornithologists’ Union, 2005.
Dobzhansky, Theodosius. Genetics and the Origin of Species. New York: Columbia University Press, 1937.
Greene, John, and Michael Ruse, eds. “Special Issue on Ernst Mayr at Ninety.” Biology and Philosophy 9, no. 3 (July 1994).
Haffer, Jürgen. Ornithologen-Briefe des 20. Jahrhunderts. Ökologie der Vögel, vol. 19. Ludwigsburg, Germany: Holzinger, 1997.
_____. Ornithology, Evolution, and Philosophy—The Life and Science of Ernst Mayr (1904–2005). New York: Springer, 2007.
Huxley, Julian. Evolution, the Modern Synthesis. London: Allen & Unwin, 1942.
Reif, W.-E., T. Junker, and U. Hossfeld. “The Synthetic Theory of Evolution: General Problems and the German Contribution to the Synthesis.” Theory in Biosciences 119 (2000): 41–91.
Rensch, Bernard. Neuere Probleme der Abstammungslehre. Stuttgart, Germany: Enke, 1947.
Ruse, M. “Ernst Mayr 1904–2005.” Biology and Philosophy 20 (2005): 623–631.
Simpson, George Gaylord. Tempo and Mode in Evolution. New York: Columbia University Press, 1944.
Smocovitis, Vassiliki Betty. Unifying Biology: The Evolutionary Synthesis and Evolutionary Biology. Princeton, NJ: Princeton University Press, 1996.
_____, et al. “Collection of Articles on Ernst Mayr at Ninety.” Evolution 48 (1994): 1–43.
Stebbins, G. Ledyard. Variation and Evolution in Plants. New York: Columbia University Press, 1950.