In the six decades since the publication of Julian Huxley's Evolution: The Modern Synthesis, spectacular empirical advances in the biological sciences have been accompanied by equally significant developments within the core theoretical framework of the discipline. As a result, evolutionary theory today includes concepts and even entire new fields that were not part of the foundational structure of the Modern Synthesis. In this volume, sixteen leading evolutionary biologists and philosophers of science survey the conceptual changes that have emerged since Huxley's (...) landmark publication, not only in such traditional domains of evolutionary biology as quantitative genetics and paleontology but also in such new fields of research as genomics and EvoDevo. Most of the contributors to Evolution—The Extended Synthesis accept many of the tenets of the classical framework but want to relax some of its assumptions and introduce significant conceptual augmentations of the basic Modern Synthesis structure—just as the architects of the Modern Synthesis themselves expanded and modulated previous versions of Darwinism. This continuing revision of a theoretical edifice the foundations of which were laid in the middle of the nineteenth century—the reexamination of old ideas, proposals of new ones, and the synthesis of the most suitable—shows us how science works, and how scientists have painstakingly built a solid set of explanations for what Darwin called the "grandeur" of life. (shrink)

In 1937, just as Dobzhansky published the book that later generations would laud as the foundation of the modern synthesis, the American Naturnlist published a symposium on "supraspecific variation in nature and in classification." Alfred C. Kinsey, who later became one of America's most controversial intellectuals for his study of basic behaviors in another sort of WASP,1 led off the symposium with a summary of his extensive work on a family of gall wasps, the Cynipidae. In his article, Kinsey strongly (...) advocated the central theme of the developing synthesis: Evolution at all scales, particularly macroevolution, could be explained by the genetic mechanisms observed in laboratories and local populations. He first complained that some geneticists and naturalists were still impeding a synthesis with their insistence upon causal separation of levels: "Just as some of the geneticists have insisted that the laboratory genetics may explain the nature and origin of Mendelian races, but not of natural species, so others indicate that the qualities of higher categories must be explained on bases other than those involved in species" (1937, p. 208). He then defended the central postulate. (shrink)

Since the 1940s, microbiologists, biochemists and population geneticists have experimented with the genetic mechanisms of microorganisms in order to investigate evolutionary processes. These evolutionary studies of bacteria and other microorganisms gained some recognition from the standard-bearers of the modern synthesis of evolutionary biology, especially Theodosius Dobzhansky and Ledyard Stebbins. A further period of post-synthesis bacterial evolutionary research occurred between the 1950s and 1980s. These experimental analyses focused on the evolution of population and genetic structure, the adaptive gain of new functions, (...) and the evolutionary consequences of competition dynamics. This large body of research aimed to make evolutionary theory testable and predictive, by giving it mechanistic underpinnings. Although evolutionary microbiologists promoted bacterial experiments as methodologically advantageous and a source of general insight into evolution, they also acknowledged the biological differences of bacteria. My historical overview concludes with reflections on what bacterial evolutionary research achieved in this period, and its implications for the still-developing modern synthesis. (shrink)

With the rejection of group selectionist derivations of ecological phenomena so incisively given by George Williams in 1966,43 Nicholson's long-ignored messages met with acceptance. Species benefit became, explicitly, incidental. But the reorientation was not just about a point of ecological theory. It was more fundamentally about theoretical style, the element shared by Wynne-Edwards' work and the newer, evolutionary ecology. That current approach is well expressed in an already classic paper by the British plant ecologist John Harper: Ultimately all the discoveries (...) of descriptive, production or population ecology must find their meaning in evolutionary phenomena... Evolutionary thinking concentrates attention on the behaviour of the individual and his descendants. If nothing in biology has meaning except in the light of evolution and if evolution is about individuals and their descendants — i.e. fitness — we should not expect to reach any depth of understanding from studies that are based at the level of the superindividual... What we see as the organised behaviour of systems is the result of the fate of individuals.44The emphasis in this passage is on style of thinking more than on study matter. What is so different from earlier ecologists is the rejection of the superorganism and its associated baggage of selfimposed constraints in an end-oriented process, such as balance of nature or species-level adaptation.The hallmark of post-1959 evolutionary ecology is the recognition, the making explicit of the question that the selective, genetical process of fitness (fates of genes) has to be separated from the observations of different levels of adaptiveness. An easy conflation of cause and result is no longer satisfying; now attempts to disentangle the complex strands tying population phenomena to the different levels of selection are providing the excitement of a new research program. In this program evolutionary theory is used to define the appropriate questions, as exemplified by the organization of the textbook Evolutionary Ecology.45 Our discussion of the invention of a new approach, with a characteristic style and set of interests, must also be about how the practitioners of ecology have perceived themselves. The early attempts of Poulton and Nicholson were not taken up by the vigorously growing science of ecology, which developed first - and intentionally — along a narrower, hierarchically restrained set of questions about population. The depth of Poulton's and Nicholson's submergence is indicated by the fact that even Wynne-Edwards did not argue in the manner of one rescuing a minor tradition. Rather, he thought he had a new approach, that of placing evolution in the foundations of ecology. Although this approach was not exactly original, we should be cautious in grouping all evolutionary concerns within ecology in one intellectual tradition. The particular style of selectionist deduction invigorated by Wynne-Edwards was successful only in the volatile situation of a rapidly growing discipline, full of self-critical examination and new rigor. Whereas in 1930 evolutionary concerns did not provide that rigor, by 1960 they could - and did. (shrink)

In this paper, I analyze George Gaylord Simpson's response to the molecularization of evolutionary biology from his unique perspective as a paleontologist. I do so by exploring his views on early attempts to reconstruct phylogenetic relationships among primates using molecular data. Particular attention is paid to Simpson's role in the evolutionary synthesis of the 1930s and 1940s, as well as his concerns about the rise of molecular biology as a powerful discipline and world-view in the 1960s. I argue that Simpson's (...) belief in the supremacy of natural selection as the primary driving force of evolution, as well as his view that biology was a historical science that seeks ultimate causes and highlights contingency, prevented him from acknowledging that the study of molecular evolution was an inherently valuable part of the life sciences. (shrink)

In Darwinism's Struggle for Survival Jean Gayon offers a philosophical interpretation of the history of theoretical Darwinism. He begins by examining the different forms taken by the hypothesis of natural selection in the nineteenth century and the major difficulties which it encountered, particularly with regard to its compatibility with the theory of heredity. He then shows how these difficulties were overcome during the seventy years which followed the publication of Darwin's Origin of Species, and he concludes by analysing the major (...) features of the genetic theory of natural selection, as it developed from 1920 to 1960. This rich and wide-ranging study will appeal to philosophers and historians of science and to evolutionary biologists. (shrink)

I propose we abandon the unit concept of "the evolutionary synthesis". There was much more to evolutionary studies in the 1920s and 1930s than is suggested in our commonplace narratives of this object in history. Instead, four organising threads capture much of evolutionary studies at this time. First, the nature of species and the process of speciation were dominating, unifying subjects. Second, research into these subjects developed along four main lines, or problem complexes: variation, divergence, isolation, and selection. Some calls (...) for 'synthesis' focused on these problem complexes (sometimes on one of these; other times, all). In these calls, comprehensive and pluralist compendia of plausibly relevant elements were preferred over reaching consensus about the value of particular formulae. Third, increasing confidence in the study of common problems coincided with methodological and epistemic changes associated with experimental taxonomy. Finally, the surge of interest in species problems and speciation in the 1930s is intimately tied to larger trends, especially a shifting balance in the life sciences towards process-based biologies and away from object-based naturalist disciplines. Advocates of synthesis in evolution supported, and were adapting to, these larger trends. (shrink)

Conceptions of adaptation have varied in the history of genetic Darwinism depending on whether what is taken to be focal is the process of adaptation, adapted states of populations, or discrete adaptations in individual organisms. I argue that Theodosius Dobzhansky’s view of adaptation as a dynamical process contrasts with so-called “adaptationist” views of natural selection figured as “design-without-a-designer” of relatively discrete, enumerable adaptations. Correlated with these respectively process and product oriented approaches to adaptive natural selection are divergent pictures of organisms (...) themselves as developmental wholes or as “bundles” of adaptations. While even process versions of genetical Darwinism are insufficiently sensitive to the fact much of the variation on which adaptive selection works consists of changes in the timing, rate, or location of ontogenetic events, I argue that articulations of the Modern Synthesis influenced by Dobzhansky are more easily reconciled with the recent shift to evolutionary developmentalism than are versions that make discrete adaptations central. (shrink)

Ernst Mayr''s contributions to 20th century biology extend far beyond his defense of certain elements in evolutionary theory. At the center of mid-century efforts in American evolutionary studies to build large research communities, Mayr spearheaded campaigns to create a Society for the Study of Evolution and a dedicated journal,Evolution, in 1946. Begun to offset the prominence ofDrosophila biology and evolutionary genetics, these campaigns changed course repeatedly, as impediments appeared, tactics shifted, and compromises built a growing coalition of support. Preserved, however, (...) were designs to balance the community and journal with careful equation of status and explicit partitioning of responsibilities within the working coalition. Choice terms such as cooperation and unity carried a strong political message. Mayr''s editorship ofEvolution provides a superb example of these balancing efforts. The mid-century infrastructural activities described herein also represented aggressive attempts to leverage control across several layers of community. Leaders of these campaigns sought: (1) to promote evolutionary studies as a modernized research discipline and place it at the center of American biology, (2) to promote evolutionary studies within existing disciplines — e.g. systematics, genetics, and paleontology, (3) to foster certain research styles within evolutionary studies, and (4) to emphasize certain solutions to prominent research questions. Throughout, Mayr interjected his priorities, tactics and energy. (shrink)

The dichotomy between ‘typological thinking’ and ‘population thinking’ features in a range of debates in contemporary and historical biology. The origins of this dichotomy are often traced to Ernst Mayr, who is said to have coined it in the 1950s as a rhetorical device that could be used to shield the Modern Synthesis from attacks by the opponents of population biology. In this two-part essay, I argue that the origins of the typology/population dichotomy are considerably more complicated and more interesting (...) than is commonly thought. In the first part, I argued that Mayr's dichotomy was based on two distinct type/population contrasts that had been articulated much earlier by George Gaylord Simpson and Theodosius Dobzhansky. Their distinctions made eminent sense in their own, isolated contexts. In this second part, I will show how Mayr conflated these type/population distinctions and blended in some of his own, unrelated concerns with ‘types’ of a rather different sort. Although Mayr told his early critics that he was merely making “a temporary oversimplification,” he ended up burdening the history and philosophy of biology with a troubled dichotomy. (shrink)

In Darwinism's Struggle for Survival Jean Gayon offers a philosophical interpretation of the history of theoretical Darwinism. He begins by examining the different forms taken by the hypothesis of natural selection in the nineteenth century and the major difficulties which it encountered, particularly with regard to its compatibility with the theory of heredity. He then shows how these difficulties were overcome during the seventy years which followed the publication of Darwin's Origin of Species, and he concludes by analysing the major (...) features of the genetic theory of natural selection, as it developed from 1920 to 1960. This rich and wide-ranging study will appeal to philosophers and historians of science and to evolutionary biologists. (shrink)

WE HAVE LEARNED in the preceding chapter that a revolutionary change of the species concept is in the making, a change which not only affects taxonomic procedure, but which also contributes considerably toward a better understanding of ...

The Committee on Common Problems of Genetics, Paleontology, and Systematics (United States National Research Council) marks part of a critical transition in American evolutionary studies. Launched in 1942 to facilitate cross-training between genetics and paleontology, the Committee was also designed to amplify paleontologist voices in modern studies of evolutionary processes. During coincidental absences of founders George Gaylord Simpson and Theodosius Dobzhansky, an opportunistic Ernst Mayr moved into the project's leadership. Mayr used the opportunity for programmatic reforms he had been pursuing (...) elsewhere for more than a decade. These are evident in the Bulletins he distributed under Committee auspices. In his brief tenure as Committee leader, Mayr gained his first substantial foothold within the coalescing community infrastructure of evolutionary studies. Carrying this momentum forward led Mayr directly into the project to launch the journal Evolution. The sociology of interdisciplinary activity provides useful tools for understanding the Committee's value in the broad sweep of change in evolutionary studies during the synthesis period. (shrink)

This paper explores the complex relationship between the plant evolutionist G. Ledyard Stebbins and the animal evolutionist Theodosius Dobzhansky. The manner in which the plant evolution was brought into line, synthesized, or rendered consistent with the understanding of animal evolution (and especially insect evolution) is explored, especially as it culminated with the publication of Stebbins's 1950 book Variation and Evolution in Plants. The paper explores the multi-directional traffic of influence between Stebbins and Dobzhansky, but also their social and professional networks (...) that linked plant evolutionists like Stebbins with Edgar Anderson, Carl Epling, and the 'Carnegie team' of Jens Clausen, David Keck, and William Hiesey with collaborators on the animal side like I. Michael Lerner, Sewall Wright and L.C. Dunn and other 'architects' of the synthesis like Ernst Mayr, Julian Huxley and George Gaylord Simpson. The compatibility in training, work styles, methodologies, goals, field sites, levels of analysis, and even choice of organismic systems is explored between Stebbins and Dobzhansky. Finally, the extent to which coevolution between plants and insects is reflected in the relationship is explored, as is the power dynamic in the relationship between two of the most visible figures associated with the evolutionary synthesis. (shrink)

As frequently pointed out in this discussion, one of the most characteristic features of Mayr's approach to the history of biology stems from the fact that he is dealing to a considerable degree with his own professional history. Furthermore, his main criterion for the selection of historical episodes is their relevance for modern biological theory. As W. F. Bynum and others have noted, the general impression of his reviewers is that “one of the towering figures of evolutionary biology has now (...) written a towering history of his discipline.”138 Bynum is here referring to The Growth of Biological Thought, but this observation holds equally true for Mayr's other historical writings: One must surely read this book [One Long Argument] not only for its content in itself, but for what it tells of its author. And certainly as one does so, one comes away full-handed. Many, if not all, of the disputes and controversies that have driven Mayr through his long intellectual life reappear, stated as forcefully and elegantly as ever.139Up to this point, most reviewers agree; the bone of contention is, rather, how to evaluate Mayr's historical work, considering this observation. The two related characteristics of his work-I will call them subjectivity and presentism-stand in opposition to a widespread approach in the history of science exemplified by Kuhn's suggestion that “insofar as possible..., the historian should set aside the science that he knows. His science should be learned from the textbooks and journals of the period he studies.”140 There are, however, historians who consider the close connection between Mayr and the subject matter of his historical studies to be an advantage.141On the other hand, it is assumed that the connection between past and present must result in a distortion of the historical truth and lead to a historiographical fallacy, commonly referred to as “Whig history”. Herbert Butterfield, who in 1931 gave the term its now generally accepted meaning, believed that “real historical understanding is not achieved by the subordination of the past to the present, but rather by our making the past our present and attempting to see life with the eyes of another century than our own”142. Unfortunately, Butterfield's definition of what he considers Whig history remains somewhat vague, and modern authors have emphasized what they consider most important. Butterfield's “subordination of the past to the present” is referred to in respect to the selection of subjects (there are more biographies of Charles Darwin than of, let's say, Louis Agassiz),143 to the evaluation of historical authors,144 or, more generally, to all kinds of histories “with one eye, so to speak, upon the present.”145 The underlying tendency of Whig historians is to produce a “historical account told from the viewpoint of those in power,”146 leading to a “glorification of the present.”147 It is obvious that Mayr's strongly presentist approach to the history of biology can be called Whiggish, if we apply the criteria of “selection” or “reference.” However, it might be worth mentioning that the program of writing a strictly historicist account of the history of science is challenged by various authors.148 For Mayr, it is not only legitimate but necessary to compare the present situation with the past. “Whiggish” is only the evaluation of an author in terms of our time.149I cannot discuss the Whit/anti-Whig controversy in any detail here, apart from saying that Mayr has defended himself rather extensively against the charges of being Whiggish.150 Nevertheless, it may be useful to touch on some of the criticisms that are predominant in reviews of his writings. First, we encounter the notion that historians can write a true and convincing historical account only if they have no personal interest or interpretation of their own; Mayr, on the other hand, because he “has such strong interpretations of his own, ... cannot possibly convince everyone that he is right about everything.”151 It makes one wonder, what historian has ever been able to convince everyone that he or she is right about everything? But apart from this peculiar idea, it unquestionably poses certain dangers if the subject matter of historical scrutiny and the author are identical. At the same time, this identity brings certain advantages with it, especially firsthand experiences of the period in discussion. Whether these personal memories ultimately result in a distorted picture of the past has to be decided in every particular instance. The notion that a scientific study can be conducted by a completely detached observer from a neutral standpoint has been shown to be impossible in physics, and it is also an illusion in historiography. The question is not whether, but which kind of interest are the underlying motivation for a historian. At this point, Mayr is ahead of his critics when he suggests that our understanding of the past always has a subjective component: The main reason, however, why histories are in constant need of revision is that at any given time they merely reflect the present state of understanding; they depend on how the author interpreted the current zeitgeist of biology and on his own conceptual framework and background. Thus, by necessity the writing of history is subjective and ephemeral.152Second, the temporal proximity between the event and the historical analysis makes difficulties inevitable and will finally result in certain false assessments. But this applies to all historians when they discuss recent problems, regardless of whether they are personally involved or not: As long as the battle between Darwinism and Lamarckism was raging, it was quite impossible to undertake an unbiased evaluation of Lamarck. ...[The] definite refutation of Lamarck's theory of evolutionary causation clears the air. We can now study him without bias and emotion and give him the attention that this major figure in the history of biology clearly deserves.153Third, Mayr is primarily interested in biological problems and not, for instance, historiographical, sociological, or psychological questions. Several authors have remarked that since the beginning of the professionalization of the history of science in the 1960s, a rift between two groups has developed, resulting from the heterogeneous professional backgrounds and interests of the people involved: the authors who were originally biologists and became interested in the history of their discipline only later on, and the authors who were trained as historians.154 Whereas the first group, the “biologists,” tend to be laymen in history proper, the “historians” are in most cases laymen in biology. Different professional backgrounds obviously shape the historical perspective in both groups, but neither approach is necessarily superior. The great number of important books in the history of biology written by “biologist” documents how valuable this point of view can be. On the other hand, it cannot be denied that the writings of biologists in the history of science tend to have a strong “internalist” tendency and often neglect the professional, cultural, and political context of science. Mayr's approach is that of a “biologist”; it is “internalist,” and typical for scientists who turn to the history of their discipline.I want to conclude my analysis with a quotation from a review by Douglas J. Futuyma, which gives a perceptive glimpse of Mayr's personality and style: One cannot help standing in awe of the germanic capacity for vast, allembracing synthesis: consider the lifelong devotion of Goethe to Faust, or Wagner's integration of the arts into a Gesamtkunstwerk in which all of human history and experience is wrought into epic myth. It is perhaps in this tradition that Ernst Mayr's The Growth of Biological Thought stands: a history of all of biology, a Ring des Nibelungen complete with leitmotivs such as the failures of reductionism, the struggle of biology for independence from physics, and the liberation of population thinking from the bounds of essentialism.155 Within this style of thinking Mayr has “to offer...nothing less than a vision of biology that places neodarwinian evolutionary theory firmly at the centre.”156 There may be other visions of biology, but few of them have as indefatigable and able representatives as Darwinism has in Ernst Mayr. (shrink)

This is the first of a two-part essay on the history of debates concerning the creativity of natural selection, from Darwin through the evolutionary synthesis and up to the present. Here I focus on the mid-late nineteenth century to the early twentieth, with special emphasis on early Darwinism and its critics, the self-styled “mutationists.” The second part focuses on the evolutionary synthesis and some of its critics, especially the “neutralists” and “neo-mutationists.” Like Stephen Gould, I consider the creativity of natural (...) selection to be a key component of what has traditionally counted as “Darwinism.” I argue that the creativity of natural selection is best understood in terms of selection initiating evolutionary change, and selection being responsible for the presence of the variation it acts upon, for example by directing the course of variation. I consider the respects in which both of these claims sound non-Darwinian, even though they have long been understood by supporters and critics alike to be virtually constitutive of Darwinism. (shrink)

Intellectual and professional reforms in evolutionary studies between 1935 and 1950 included substantial expansion, diversification, and realignment of community infrastructure. Theodosius Dobzhansky, Julian Huxley and Alfred Emerson organized the Society for the Study of Speciation at the 1939 AAAS Columbus meeting as one response to concerns about ‘isolation’ and ‘lack of contact’ among speciation workers worried about ‘dispersed’ and ‘scattered’ resources in this newly robust ‘borderline’ domain. Simply constructed, the SSS sought neither the radical reorganization of specialities nor the creation (...) of some new discipline. Instead, it was designed to facilitate: to simplify exchange of information and to provide a minimally invasive avenue for connecting disparate researchers. Emerson served as SSS secretary and was its principal agent. After publishing one block of publications, however, the SSS became ‘quiescent’. Anxious to promote his own agenda, Ernst Mayr tried to manoeuvre around Emerson in an effort to revitalize the project. After meeting impediments, he moved his efforts elsewhere. The SSS was too short-lived to merit a claim for major impact within the community; however, it reveals important features of community activity during the synthesis period and stands in contrast to later efforts by George Simpson, Dobzhansky, and Mayr. (shrink)