The proximate/ultimate distinction in the multiple careers of Ernst Mayr

Ernst Mayr's distinction between “ultimate” and “proximate” causes is justly considered a major contribution to philosophy of biology. But how did Mayr come to this “philosophical” distinction, and what role did it play in his earlier “scientific” work? I address these issues by dividing Mayr's work into three careers or phases: 1) Mayr the naturalist/researcher, 2) Mayr the representative of and spokesman for evolutionary biology and systematics, and more recently 3) Mayr the historian and philosopher of biology. If we want to understand the role of the proximate/ultimate distinction in Mayr's more recent career as a philosopher and historian, then it helps to consider hisearlier use of the distinction, in the course of his research, and in his promotion of the professions of evolutionary biology and systematics. I believe that this approach would also shed light on some other important “philosophical” positions that Mayr has defended, including the distinction between “essentialism: and “population thinking.”     

On the origin of the typological/population distinction in Ernst Mayr’s changing views of species, 1942–1959

Ernst Mayr’s typological/population distinction is a conceptual thread that runs throughout much of his work in systematics, evolutionary biology, and the history and philosophy of biology. Mayr himself claims that typological thinking originated in the philosophy of Plato and that population thinking was first introduced by Charles Darwin and field naturalists. A more proximate origin of the typological/population thinking, however, is found in Mayr’s own work on species. This paper traces the antecedents of the typological/population distinction by detailing Mayr’s changing views of species between 1942 and 1955. During this period, Mayr struggles to refine the biological species concept in the face of tensions that exist between studying species locally and studying them as geographically distributed collections of variable populations. The typological/population distinction is first formulated in 1955, when Mayr generalizes from the type concept versus the population concept in taxonomy to typological versus population thinking in biology more generally. Mayr’s appeal to the more general distinction between typological and population thinking coincides with the waning status of natural history and evolutionary biology that occurs in the early 1950s and the distinction plays an important role in Mayr’s efforts to legitimate the natural historical sciences.     

Species concepts and floras: what are species for?

In 1992, in a special paper in the American Journal of Botany, Ernst Mayr attempted to ‘prove’ the biological species concept (BSC) worked as well in plants as it did in animals by analyzing the flora of the Concord region of northern Massachusetts. He concluded that there were minimal difficulties when applying the BSC for the plants of this particular area, and concluded that botanists were misguided in not accepting the BSC. He suggested that what he called ‘typological’ thinking was prevalent in the taxonomic community, and that this was a factor in botanical resistance to the BSC. Typology, as defined by Mayr in his 1992 foray into botany, is to a certain extent a straw‐man and, by the late 20th Century, no longer a way of thinking in widespread use in the taxonomic community in any organismal group. Here, I examine his analysis in the light of current interest in plant diversity. Species can be characterized as hypotheses about the distribution of variation in nature, subject to test with new data of many kinds. Species concepts like the BSC, although of interest philosophically and to researchers looking at mechanisms of speciation, may actually get in the way of achieving a baseline understanding of the diversity of life on Earth. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 17–25.     

Adaptation and the origin of species

As reflected in the title of his masterwork On the Origin of Species, Darwin proposed that adaptation is the primary mechanism of speciation. On this, Darwin was criticized for his neglect of reproductive isolation, his lack of appreciation for the role of geographic barriers, his failure to distinguish varieties from species, and his typological species concept. Two developments since Darwin, the biological species concept of Ernst Mayr and the methods of Coyne and Orr for estimating the contribution of different barriers to the total reproductive isolation, provide a framework for reconciling Darwin's view on the primacy of adaptation in speciation with later proposals that emphasize reproductive isolation. A review of the few studies that have estimated the contributions of multiple isolating barriers suggests that habitat isolation and other barriers that operate before hybrid formation are much stronger than intrinsic postzygotic isolation. In light of these data, I suggest that Darwin's focus on adaptation in the origin of species was essentially correct, a conclusion that calls for future studies that explore the links between adaptation and speciation, in particular, ecogeographic isolating barriers that result from adaptive divergence in habitat use. The recent revival in thinking about ecological factors and adaptive divergence in the origin of species echoes Darwin's much-criticized "principle of divergence" and suggests that the emerging views from today's naturalists are not so different from those espoused by Darwin some 150 years ago.     

His Own Synthesis: Corn, Edgar Anderson, and Evolutionary Theory in the 1940s

Tracing the contributions of Edgar Anderson (1897--1969) of the Missouri Botanical Garden to the important discussions in evolutionary biology in the 1940s, this paper argues that Anderson turned to corn research rather than play a more prominent role in what is now known as the Evolutionary Synthesis. His biosystematic studies of Iris and Tradescantia in the 1930s reflected such Synthesis concerns as the species question and population thinking. He shared the 1941 Jesup Lectures with Ernst Mayr. But rather than preparing his lectures as a potentially key text in the Synthesis, Anderson began researching Zea mays -- its taxonomy, its origin, and its agronomic role. In this study, Anderson drew on the disciplines of taxonomy, morphology, genetics, geography, anthropology, archaeology, and agronomy among others in his own creative synthesis. Though his maize research in the 1940s represented the most sustained work of his career, Anderson was also drawn in many directions during his professional life. For example, he enjoyed teaching, working with amateurs, and popular writing. This revised version was published online in July 2006 with corrections to the Cover Date.     

The excluded philosophy of evo-devo? Revisiting C.H. Waddington's failed attempt to embed Alfred North Whitehead's "organicism" in evolutionary biology

Though a prominent British developmental biologist in his day, a close friend of Theodosius Dobzhansky, and a frequent correspondent with Ernst Mayr, C.H. Waddington did not enter the ranks of "architect" of the Modern Synthesis. By the end of his career, in fact, he recognized that other biologists reacted to his work "as though they feel obscurely uneasy"; and that the best that some philosophers of biology could say of his work was that he was not "wholly orthodox" (Waddington 1975c, 11). In this essay, I take Waddington's self-assessments at face value and explore three potential reasons why his work did not have more of a direct impact: Waddington's explicit support for the philosophy of Alfred North Whitehead; a lack of institutional support; and Waddington's occasional marginalization from the core network of American neo-Darwinians. Though excluded from the Modern Synthesis in the mid-20th century, it now appears that Waddington's work does undergird the emerging evo-devo synthesis. Whether this indicates concomitant, if implicit, support for Whiteheadian philosophy is an interesting question not explored here.     

Mayr's view of Darwin: was Darwin wrong about speciation?

We commonly read or hear that Charles Darwin successfully convinced the world about evolution and natural selection, but did not answer the question posed by his most famous book, ‘On the Origin of Species …’. Since the 1940s, Ernst Mayr has been one of the people who argued for this point of view, claiming that Darwin was not able to answer the question of speciation because he failed to define species properly. Mayr undoubtedly had an important and largely positive influence on the study of evolution by stimulating much evolutionary work, and also by promoting a ‘polytypic species concept’ in which multiple, geographically separated forms may be considered as subspecies within a larger species entity. However, Mayr became seduced by the symmetry of a pair of interlocking ideas: (1) that coexistence of divergent populations was not possible without reproductive isolation and (2) reproductive isolation could not evolve in populations that coexist. These beliefs led Mayr in 1942 to reject evidence of the importance of intermediate stages in speciation, particularly introgression between hybridizing species, which demonstrates that complete reproductive isolation is not necessary, and the existence of ecological races, which shows that ecological divergence can be maintained below the level of species, in the face of gene flow. Mayr's train of thought led him to the view that Darwin misunderstood species, and that species were fundamentally different from subspecific varieties in nature. Julian Huxley, reviewing similar data at the same time, came to the opposite conclusion, and argued that these were the intermediate stages of speciation expected under Darwinism. Mayr's arguments were, however, more convincing than Huxley's, and this caused a delay in the acceptance of a more balanced view of speciation for many decades. It is only now, with new molecular evidence, that we are beginning to appreciate more fully the expected Darwinian intermediates between coexisting species. © The Author. Journal compilation © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 3–16.     

Georges Teissier (1900–1972) and the Modern Synthesis in France

This Perspectives is devoted to the ideas of the French zoologist Georges Teissier about the mechanisms of evolution and the relations between micro- and macroevolution. Working in an almost universally neo-Lamarckian context in France, Teissier was one of the very few Darwinians there at the time of the evolutionary synthesis. The general atmosphere of French zoology during the 1920s and the 1930s will first be recalled, to understand the specific conditions in which Teissier became a zoologist. After a brief overview of his joint work with Philippe L’Héritier on the experimental genetics of Drosophila, this article describes the ways Teissier, during the 1950s, conceptualized the mechanisms that could allow for macroevolutionary transitions.IT is usually acknowledged that France did not significantly participate in the elaboration of 20th century evolutionary theory, often designated The Modern Synthesis. In their classical book on the history of the synthesis, Ernst Mayr and William B. Provine devoted a whole—nonetheless small—chapter to this specific issue (Mayr and Provine 1998, pp. 309–328). Mayr clearly stated that “France is the only major scientific nation that did not contribute significantly to the evolutionary synthesis” (Mayr 1998, p. 309). In the absence of a French architect of the synthesis, Mayr and Provine asked Ernest Boesiger, a Swiss population geneticist and a former student of Georges Teissier, to tell the story of what had happened in French biology at the time of the evolutionary synthesis. Boesiger, who died in 1975, wrote a paper in 1974 that provided the firm basis of the chapter. In very strong terms, he depicted French biology as “a kind of living fossil in the rejection of modern evolutionary theories” (Boesiger 1998, p. 309). He insisted on the fact that, even in 1974, most French biologists and philosophers were still reluctant to accept Darwinism. As regards the period of the 1930s, Boesiger was able to think of only two exceptions: Georges Teissier and Philippe L’Héritier. He then referred to their joint research in population genetics, which was based on the new technique of the population cages with the species Drosophila melanogaster, and listed their contributions to this new discipline.If Teissier and L’Héritier’s works on Drosophila are nowadays more widely recognized than in 1974, due in particular to the efforts of Jean Gayon and Michel Veuille (Gayon and Veuille 2001), this recognition could have as an unintended consequence the reduction of both Teissier and L’Héritier to being simply the inventors of a useful technique, namely the population cages (see especially how Mayr presented their work in his other classical book, Mayr 1982, p. 574), or as the founders of a French school of population geneticists (Gayon and Veuille 2001). The aim of this article is to reevaluate the way Georges Teissier (1900–1972) conceived Darwinian natural selection not only as an important mechanism for evolution at the population level but more fundamentally as a general key for the unification of biology, exactly as Julian Huxley or Ernst Mayr did during the same period (1930–1970). However, starting in the early 1950s, Teissier went on to conceive a very specific understanding of the evolutionary synthesis.In this article, I will first describe the general atmosphere of evolutionary issues in French biology at the time when Teissier started working as a zoologist, to understand against what he developed his joint research program with L’Héritier and afterward his general conceptions about evolution. During the 1930s and the 1940s, only a very few scientists in France could be seen as Darwinians. In addition to Teissier and L’Héritier, one may also consider Marcel Prenant, Boris Ephrussi, and the mathematician Gustave Malécot. Building on Jean Gayon and Michel Veuille’s work, I will then give a quick overview of L’Héritier and Teissier’s most important achievements in the field of population genetics. In the third part, I will discuss the discovery made by Teissier and L’Héritier of a case of cytoplasmic inheritance in Drosophila. This unexpected finding led them into the field of non-Mendelian heredity. I will then develop in detail the way Teissier finally went on to conceive the relation between microevolution and macroevolution, in light of the general context of French biology and of the development of the field of cytoplasmic inheritance.     

The ‘Disadapted’ Animal: Niko Tinbergen on Human Nature and the Human Predicament

This paper explores ethologist Niko Tinbergen’s path from animal to human studies in the 1960s and 1970s and his views about human nature. It argues, first, that the confluence of several factors explains why Tinbergen decided to cross the animal/human divide in the mid 1960s: his concern about what he called “the human predicament,” his relations with British child psychiatrist John Bowlby, the success of ethological explanations of human behavior, and his professional and personal situation. It also argues that Tinbergen transferred his general adaptationist view of animal behavior to the realm of human biology; here, his concern about disadaptation led him to a view of human behavior that was strongly determined by the species’ evolutionary past, a position that I call evolutionary determinism. These ideas can be seen in the work he carried out with his wife, Elisabeth Tinbergen, on autism. The paper concludes that Tinbergen’s vision of human nature constitutes another version of what anthropologist Clifford Geertz called in 1966 the “stratigraphic” conception of the human: a view of human nature as a composite of levels in which a universal ancestral biological core is superimposed by psychological and cultural layers that represent accidental variation at best and pathological deviation at worst.     

The Origins of Species: The Debate between August Weismann and Moritz Wagner

Weismann’s ideas on species transmutation were first expressed in his famous debate with Moritz Wagner on the mechanism of speciation. Wagner suggested that the isolation of a colony from its original source is a preliminary and necessary factor for speciation. Weismann accepted a secondary, facilitating role for isolation, but argued that natural and sexual selection are the primary driving forces of species transmutation, and are always necessary and often sufficient causes for its occurrence. The debate with Wagner, which occurred between 1868 and 1872 within the framework of Darwin’s discussions of geographical distribution, was Weismann’s first public battle over the mechanism of evolution. This paper, which offers the first comprehensive analysis of this debate, extends previous analyses and throws light on the underlying beliefs and motivations of these early evolutionists, focusing mainly on Weismann’s views and showing his commitment to what he later called “the all sufficiency of Natural Selection.” It led to the crystallization of his ideas on the central and essential role of selection, both natural and sexual, in all processes of evolution, and, already at this early stage in his theoretical thinking, was coupled with sophisticated and nuanced approach to biological organization. The paper also discusses Ernst Mayr’s analysis of the debate and highlights aspects of Weismann’s views that were overlooked by Mayr and were peripheral to the discussions of other historians of biology.     

The creation of the essentialism story: an exercise in metahistory

The essentialism story is a version of the history of biological classification that was fabricated between 1953 and 1968 by Ernst Mayr, who combined contributions from Arthur Cain and David Hull with his own grudge against Plato. It portrays pre-Darwinian taxonomists as caught in the grip of an ancient philosophy called essentialism, from which they were not released until Charles Darwin's 1859 Origin of Species. Mayr's motive was to promote the Modern Synthesis in opposition to the typology of idealist morphologists; demonizing Plato served this end. Arthur Cain's picture of Linnaeus as a follower of 'Aristotelian' (scholastic) logic was woven into the story, along with David Hull's application of Karl Popper's term, 'essentialism', which Mayr accepted in 1968 as a synonym for what he had called 'typological thinking'. Although Mayr also pointed out the importance of empiricism in the history of taxonomy, the essentialism story still dominates the secondary literature. The history of the first telling of the essentialism story exposes its scant basis in fact.     

Are species sets?

I construe the question ‘Are species sets?’ as a question about whether species can be conceived of as sets, as the term ‘set’ is understood by contemporary logicians. The question is distinct from the question ‘Are species classes?’: The conception of classes invoked by Hull and others differs from the logician's conception of a set. I argue that species can be conceived of as sets, insofar as one could identify a set with any given species and that identification would satisfy three desiderata: the set would be a set of organisms, the identification would be apposite, and the identification would permit the formulation of statements about species in set-theoretic terms. One cannot, however, identify a species with any given set. Understanding the claim that species are sets in this way enables one to understand better the dispute between some who accept the claim (e.g., Kitcher 1984, 1987) and some who apparently reject it (e.g., Mayr 1987).     

Darwin's species category realism

Ever since Charles Darwin's On the Origin of Species was published, the received view has been that Darwin literally thought of species as not extra-mentally real. In 1969 Michael Ghiselin upset the received view by interpreting Darwin to mean that species taxa are indeed real but not the species category. In 1985 John Beatty took Ghiselin's thesis a step further by providing a strategy theory to explain why Darwin would say one thing (his repeated nominalistic definition of species) and do another (hold that species taxa are real). In the present paper I attempt to take this line of interpretation to a new level. Guided by the principle of charity, I provide and analyze a considerable amount of evidence from Darwin's mature writings (both private and published) to show that (contra Ghiselin and Beatty) Darwin did not simply accept the species delimitations of his fellow naturalists but actually employed, repeatedly and consistently, a species concept in a thoroughly modern sense, albeit with an implicit definition, a concept uniquely his own and fully in accord with his theory of evolution by natural selection. This implicit concept and definition is carefully reconstructed in the present paper. A new strategy theory is then provided to account for why Darwin would define species (both taxa and category) nominalistically on the one hand but delimit species realistically on the other.     

Threads that Guide or Ties that Bind: William Kirby and the Essentialism Story

Nineteenth-century British entomologist William Kirby is best known for his generic division of bees based on tongues and his vigorous defence of natural theology. Focusing on these aspects of Kirby’s work has lead many current scholars to characterise Kirby as an “essentialist.” As a result of this characterisation, many important aspects of his work, Monographia Apum Angliæ (1802) have been over-looked or misunderstood. Kirby’s religious devotion, for example, have lead some scholars to assume Kirby used the term “type” for connecting an ontological assumption about essences with a creationist assumption about species fixity, which I argue conceals a variety of ways Kirby employed the term. Also, Kirby frequently cautioned against organising a classification system exclusively by what he called “analytic reasoning,” a style of reasoning 20th century scholars often associate with Aristotelian logic of division. I argue that Kirby’s critique of analytic reasoning brought the virtues of his own methodological agenda into sharp relief. Kirby used familiar metaphors in the natural history literature – Ariadne’s thread, the Eleusinian mysteries, and Bacon’s bee and spider metaphors – to emphasise the virtues of building tradition and cooperation in the goals and methodological practices of 19th century British naturalists.     

Mystery of mysteries: Darwin and the species problem

Darwin offered an intriguing answer to the species problem. He doubted the existence of the species category as a real category in nature, but he did not doubt the existence of those taxa called “species”. And despite his scepticism of the species category, Darwin continued using the word “species”. Many have said that Darwin did not understand the nature of species. Yet his answer to the species problem is both theoretically sound and practical. On the theoretical side, Darwin’s answer is confirmed by contemporary biology, and it offers a more satisfactory answer to the species problem than recent attempts to save the species category. On the practical side, Darwin’s answer frees us from the search for the correct theoretical definition of “species”. But at the same time it does not require that we banish the word “species” from biology as some recent sceptics of the species category advocate. © The Willi Hennig Society 2010.     

How has evolution shaped human behavior? Richard Alexander's contribution to an important question

Richard Alexander has been a major contributor to the development of theory concerning the evolution of human sociality. His most important contributions include (1) a theory of the evolution of morality as a form of indirect reciprocity that aids in intergroup competition, (2) a theory of the relationship between biological evolution and culture, (3) an elaboration of Humphrey's theory of the human intellect as a social tool, (4) theories about human parental investment and nepotism, and (5) theories about scenario building, consciousness, and human communication. He also has offered a hypotheses on a large range of other human traits. He is a biologist and has also made major contributions to theories of speciation, communication, eusociality, and social organization in nonhuman animals and has contributed extensively to the study of a number of specific taxa other than the human species: crickets, katydids, cicadas, naked mole rats, and horses. His contribution to the study of nonhuman animals and evolutionary theory, in general, are sufficient to earn him a reputation as an outstanding leader in biology without reference to his work on humans. The same can be said for his contribution to the understanding of human sociality taken alone.     

Speciation on islands: what are we learning?

Systematics and the Origin of Species from the Viewpoint of a Zoologist has remained an essential text on the bookshelves of evolutionary biologists since it was first published. Here, I expand upon several topics touched upon by Ernst Mayr to look at how our thinking has evolved, and is evolving, with particular reference to molecular phylogenetic studies on islands. At the time of publication, apart from the fossil record, inferences of temporal trends or patterns could only be speculative, deduced from the distributions of species and the patterns that these present. Much like the subject material itself, evolutionary biology evolves as a discipline, with an increasing availability of tools and resources. The development of molecular phylogenetics and molecular markers has given biologists a new window on the past and, as such, the ideas and explanations of Mayr have become more accessible to testing. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 47–52.     

Ernst Mayr,naturalist: His contributions to systematics and evolution

Ernst Mayr's scientific career continues strongly 70 years after he published his first scientific paper in 1923. He is primarily a naturalist and ornithologist which has influenced his basic approach in science and later in philosophy and history of science. Mayr studied at the Natural History Museum in Berlin with Professor E. Stresemann, a leader in the most progressive school of avian systematics of the time. The contracts gained through Stresemann were central to Mayr's participation in a three year expedition to New Guinea and The Solomons, and the offer of a position in the Department of Ornithology, American Museum of Natural History, beginning in 1931. At the AMNH, Mayr was able to blend the best of the academic traditions of Europe with those of North America in developing a unified research program in biodiversity embracing systematics, biogeography and nomenclature. His tasks at the AMNH were to curate and study the huge collections amassed by the Whitney South Sea Expedition plus the just purchased Rothschild collection of birds. These studies provided Mayr with the empirical foundation essential for his 1942Systematics and the Origin of Species and his subsequent theoretical work in evolutionary biology as well as all his later work in the philosophy and history of science. Without a detailed understanding of Mayr's empirical systematic and biogeographic work, one cannot possibly comprehend fully his immense contributions to evolutionary biology and his later analyses in the philosophy and history of science.     

Ernst Mayr through time on the biological species concept — a conceptual analysis

Summary An analysis is made of Ernst Mayr’s treatment of the biological species definition over time. To avoid misunderstandings, it is important to distinguish between the varying conceptual assumptions which Mayr associates with this definition and the unchanged wording of the definition. A polytypic species, that is a geographical aggregate of allopatric populations, does not fit the biological species definition very well. There is an undeniable tension between these two aspects [the polytypic and nondimensional] of the word species and from 1942 until the present time, I have never ceased to struggle with this problem (Mayr 1992b, p. 9). ... indeed, I pride myself on having changed my mind on frequent occasions (Mayr 1982a, p. 9).