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)

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)

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 Angliœ (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. (shrink)

Julian Huxley’s contribution to twentieth-century biology and science popularisation is well documented. What has not been appreciated so far is that despite Huxley’s eminence as a public scientific figure and the part that he played in the rise of experimental zoology in Britain in the 1920s, his own research was often heavily criticised in this period by his colleagues. This resulted in numerous difficulties in getting his scientific research published in the early 1920s. At this time, Huxley started his popular (...) science career. Huxley’s friends criticised him for engaging in this actively and attributed the publication difficulties to the time that he allocated to popular science. The cause might also have its roots in his self-professed inability to delve deeply into the particularities of research. This affected Huxley’s standing in the scientific community and seems to have contributed to the fact that Huxley failed twice in the late 1920s to be elected to the Royal Society. This picture undermines to some extent Peter J. Bowler’s recent portrayal of Huxley as a science populariser. (shrink)

Speciation—the origin of new species—has been one of the most active areas of research in evolutionary biology, both during, and since the Modern Synthesis. While the Modern Synthesis certainly shaped research on speciation in significant ways, providing a core framework, and set of categories and methods to work with, the history of work on speciation since the mid-twentieth century is a history of divergence and diversification. This piece traces this divergence, through both theoretical advances, and empirical insights into how different (...) lineages, with different genetics and ecological conditions, are shaped by very different modes of diversification. (shrink)

Historians and philosophers of science agree that Darwin had an understanding of species which led to a workable theory of their origins. To Darwin species did not differ essentially from ‘varieties’ within species, but were distinguishable in that they had developed gaps in formerly continuous morphological variation. Similar ideas can be defended today after updating them with modern population genetics. Why then, in the 1930s and 1940s, did Dobzhansky, Mayr and others argue that Darwin failed to understand species and speciation? (...) Mayr and Dobzhansky argued that reproductively isolated species were more distinct and ‘real’ than Darwin had proposed. Believing species to be inherently cohesive, Mayr inferred that speciation normally required geographic isolation, an argument that he believed, incorrectly, Darwin had failed to appreciate. Also, before the sociobiology revolution of the 1960s and 1970s, biologists often argued that traits beneficial to whole populations would spread. Reproductive isolation was thus seen as an adaptive trait to prevent disintegration of species. Finally, molecular genetic markers did not exist, and so a presumed biological function of species, reproductive isolation, seemed to delimit cryptic species better than character-based criteria like Darwin’s. Today, abundant genetic markers are available and widely used to delimit species, for example using assignment tests: genetics has replaced a Darwinian reliance on morphology for detecting gaps between species. In the 150th anniversary of The Origin of Species , we appear to be returning to more Darwinian views on species, and to a fuller appreciation of what Darwin meant. (shrink)

During the 1930s, Aleksandr Promptov—a student of the founder of Russian population genetics Sergei Chetverikov—developed an elaborate concept of speciation in birds. He conducted field investigations aimed at giving a naturalistic content to the theoretical formulations and laboratory models of evolutionary processes advanced within the framework of population genetics, placing particular emphasis on the evolutionary role of bird behavior. Yet, although highly synthetic in combining biogeographical, taxonomic, genetic, ecological, and behavioral studies, Promptov's speciation concept was ignored by the architects of (...) the 1930s and 1940s evolutionary synthesis, including Theodosius Dobzhnasky, Ernst Mayr, and Julian Huxley. In this article, I argue that the story of Promptov's concept and its reception by other evolutionists challenges the traditional presentation of the synthesis as a singular, international process of the unification of biology, which led to the creation of a universal synthetic theory of evolution. It suggests that during the same time period, within largely the same theoretical framework, there were multiple, intrinsically local, attempts at creating synthetic evolutionary concepts. These concepts were often quite particular—in their taxonomic applicability, in their explanations of various evolutionary factors, and in the range of disciplines unified in the synthesis. Apparently, these concepts ran contrary to the universal aspirations of the synthesis architects, and as a result, they were disregarded, first by the architects and later by historians of the evolutionary synthesis. (shrink)

Ecology in principle is tied to evolution, since communities and ecosystems result from evolution and ecological conditions determine fitness values. Yet the two disciplines of evolution and ecology were not unified in the twentieth-century. The architects of the Modern Synthesis, and especially Julian Huxley, constantly pushed for such integration, but the major ideas of the Synthesis—namely, the privileged role of selection and the key role of gene frequencies in evolution—did not directly or immediately translate into ecological science. In this paper (...) I consider five stages through which the Synthesis was integrated into ecology and distinguish between various ways in which a possible integration was gained. I start with Elton’s animal ecology, then consider successively Ford’s ecological genetics in the 1940s, the major textbook Principles of animal ecology edited by Allee et al., and the debates over the role of competition in population regulation in the 1950s, ending with Hutchinson’s niche concept and McArthur and Wilson’s Principles of Island Biogeography viewed as a formal transposition of Modern Synthesis explanatory schemes. I will emphasize the key role of founders of the Synthesis at each stage of this very nonlinear history. (shrink)

This paper surveys questions about the nature of the Modern Synthesis as a historical event : was it rather theoretical than institutional? When and where did it actually happen? Who was involved? It argues that all answers to these questions are interrelated, and that systematic sets of answers define specific perspectives on the Modern Synthesis that are all complementary.