This is the second 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. In the first part, I focussed 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 directing evolutionary change, for example by creating the variation that it subsequently acts upon. 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)

The National Academy of Science's 1956 study on the Biological Effects of Atomic Radiation was designed to provide an objective analysis to assess conflicting statements by leading geneticists and by officials in the Atomic Energy Commission. Largely because of its status as a detached, non-governmental evaluation by eminent scientists, no studies have had a broader impact on the development of biological thinking in regard to nuclear policies. This paper demonstrates that despite the first BEAR study's reputation as an objective and (...) independent study, it was the product of careful negotiation between Academy scientists, the Atomic Energy Commission, and Britain's Medical Research Council. This paper also reveals the fragility of the consensus that produced the Academy's report, the range of political uses of the report, and the subsequent disaffection of the scientists who took part in it. (shrink)

This paper extends previous arguments against the assumption that the study of variation at the molecular level was instigated with a view to solving an internal conflict between the balance and classical schools of population genetics. It does so by focusing on the intersection of basic research in protein chemistry and the molecular approach to disease with the enactment of global health campaigns during the Cold War period. The paper connects advances in research on protein structure and function as reflected (...) in Christian Anfinsen’s The molecular basis of evolution, with a political reading of Emilé Zuckerkandl and Linus Pauling’s identification of molecular disease and evolution. Beyond atomic fallout, these advances constituted a rationale for the promotion of genetic surveys of human populations in the Third World, in connection with international health programs. Light is shed not only on the experimental roots of the molecular challenge but on the broader geopolitical context where the rising role of biomedicine and public health had an impact on evolutionary biology. (shrink)

Using the evolution of the stickleback family of subarctic fish as a touchstone, we explore the effect of new discoveries about regulatory genetics, developmental plasticity, and epigenetic inheritance on the conceptual foundations of the Modern Evolutionary Synthesis. Identifying the creativity of natural selection as the hallmark of the Modern Synthesis, we show that since its inception its adherents have pursued a variety of research projects that at first seemed to conflict with its principles, but were accommodated. We situate challenges coming (...) from developmental biology in a dialectic between innovation and tradition, suggesting on the basis of past episodes that even if developmental plasticity and epigenetic inheritance are aligned with its principles the Modern Synthesis will be significantly affected. (shrink)

The 1920-1960 period saw the creation of the conditions for a unification of disciplines in the area of evolutionary biology under a limited number of theoretical prescriptions: the evolutionary synthesis. Whereas the sociological dimension of this synthesis was fairly successful, it was surprisingly loose when it came to the interpretation of the evolutionary mechanisms per se, and completely lacking at the level of the foundational epistemological and metaphysical commitments. Key figures such as Huxley, Simpson, Dobzhansky, and Rensch only paid lip (...) service to the conceptual dimension of the evolutionary synthesis, as they eventually realized that a number of evolutionary phenomena could not be explained by its narrow theoretical corpus. Apparently, the evolutionary synthesis constituted a premature event in the development of evolutionary biology. Not only are the real achievements of the evolutionary synthesis in need of reevaluation, but this reassessment also has important implications for the historiography of Darwinism and the current debates about the darwinian movement. (shrink)

Several prominent debates in biology, such as those surrounding adaptationism, group selection, and punctuated equilibrium, have focused on disagreements about the relative importance of a cause in producing a phenomenon of interest. Some philosophers, such as John Beatty have expressed scepticism about the scientific value of engaging in these controversies, and Karen Kovaka has suggested that their value might be limited. In this paper, I challenge that scepticism by giving a novel analysis of relative significance controversies, showing that there are (...) three forms they can take. I argue that these controversies can have significant epistemic upshots, in that they help scientists form predictions about new instances of the phenomenon of interest. Finally, using two historical examples, I show how engaging in these controversies can improve our understanding of causal relationships. (shrink)

Berichte zur Wissenschaftsgeschichte, Volume 45, Issue 3, Page 332-343, September 2022.

This article describes how empirical discoveries in the 1930s–1950s regarding population variation for chromosomal inversions affected Theodosius Dobzhansky and Richard Goldschmidt. A significant fraction of the empirical work I discuss was done by Dobzhansky and his coworkers; Goldschmidt was an astute interpreter, with strong and unusual commitments. I argue that both belong to a mechanistic tradition in genetics, concerned with the effects of chromosomal organization and systems on the inheritance patterns of species. Their different trajectories illustrate how scientists’ commitments affect (...) how they interpret new evidence and adjust to it. Dobzhansky was moved to revised views about selection, while Goldschmidt moved his attention to different genetic phenomena. However different, there are significant connections between the two that enrich our understanding of their views. I focus on two: the role of developmental considerations in Dobzhansky’s thought and the role of neutrality and drift in Goldschmidt’s evolutionary account. Dobzhansky’s struggle with chromosomal variation is not solely about competing schools of thought within the selectionist camp, as insightfully articulated by John Beatty, but also a story of competition between selectionist thinking and developmental perspectives. In contraposition, Goldschmidt emphasized the role of low penetrance mutations that spread neutrally and pointed out that drift could result from developmental canalization. This account adds to the dominant story about Goldschmidt’s resistance to the splitting of development from genetics, as told by Garland Allen and Michael Dietrich. The story I tell illustrates how developmental thinking and genetic thinking conflicted and influenced researchers with different convictions about the significance of chromosomal organization. (shrink)

During the 1960s and 1970s population geneticists pushed beyond models of single genes to grapple with the effect on evolution of multiple genes associated by linkage. The resulting models of multiple interacting loci suggested that blocks of genes, maybe even entire chromosomes or the genome itself, should be treated as a unit. In this context, Richard Lewontin wrote his famous 1974 book The Genetic Basis of Evolutionary Change, which concludes with an argument for considering the entire genome as the unit (...) of selection as a result of linkage. Why did Lewontin and others devote so much intellectual energy to the “complications of linkage” in the 1960s and 1970s? We argue that this attention to linkage should be understood in the context of research on chromosomal inversions and co-adapted gene complexes that occupied mid-century evolutionary genetics. For Lewontin, the complications of linkage were an extension of this chromosomal focus expressed in the new language of models for linkage disequilibrium. (shrink)

In the years following World War II, and increasingly during the 1960s and 1970s, professional scientific societies developed internal sub-committees to address the social implications of their scientific expertise. This article explores the early years of one such committee, the American Society of Human Genetics’ “Social Issues Committee,” founded in 1967. Although the committee’s name might suggest it was founded to increase the ASHG’s public and policy engagement, exploration of the committee’s early years reveals a more complicated reality. Affronted by (...) legislators’ recent unwillingness to seek the expert advice of human geneticists before adopting widespread neonatal screening programs for phenylketonuria, and feeling pressed to establish their relevance in an increasingly resource-scarce funding environment, committee members sought to increase the discipline’s expert authority. Painfully aware of controversy over abortion rights and haunted by the taint of the discipline’s eugenic past, however, the committee proceeded with great caution. Seeking to harness interest in and assert professional control over emerging techniques of genetic diagnosis, the committee strove to protect the society’s image by relegating ethical and policy questions about their use to the individual consciences of member scientists. It was not until 1973, after the committee’s modest success in organizing support for a retrospective public health study of PKU screening and following the legalization of abortion on demand, that the committee decided to take a more publicly engaged stance. (shrink)

I reconstruct the relationship between the evolutionary geneticists Theodosius Dobzhansky (1900–1975) and Richard Lewontin (1929–2021). Using archival research and published texts, I show that Lewontin inherited his dissertation director’s research program as well as his “biology of democracy.” He did so in circumstances in which the molecular revolution in genetics was threatening both Dobzhansky’s science and his anti-racist social ideals. Lewontin’s sometimes rocky relationship with the person he called “my professor” sprang from his perception that Dobzhansky was not up to (...) managing the research program that Lewontin received from him. I explain how Lewontin took charge and the role his Marxist interpretive lens plays in his argument. (shrink)

I argue that Darwinian evolutionary theory has a rhetorical dimension and that rhetorical criticism plays a role in how evolutionary science acquires knowledge. I define what I mean by rhetoric by considering Darwin’s Origin. I use the Modern Evolutionary Synthesis to show how rhetoric conceived as situated and addressed argumentation enters into evolutionary theorizing. Finally, I argue that rhetorical criticism helps judge the success, limits, and failures of these theories.

The Human Genome Project (HGP) has been criticised from an evolutionary perspective for three reasons: completely ignoring genetic variation; improperly treating either all or some genetic variation as deviation from a norm; and mistakenly seeking to define species in terms of essential properties possessed by all and only member organisms. The first claim is unfounded; the second and third claims are more on target. Nevertheless, it is a mistake to use the typological-population distinction to oppose molecular genetics and evolutionary genetics (...) in order to characterise HGP mapping and sequencing aims, especially the production of a DNA reference sequence, as 'anti-evolutionary' and 'pre-Darwinian.' These aims are consistent with certain strands in twentieth-century evolutionary thought: Muller's classical theory, Kimura's neutral and 'effectively neutral' theories, and, to a lesser extent, Dobzhansky's balance theory of the genetic structure of natural populations. In practice, population-based approaches to human genetic variation are similarly vulnerable to charges of 'typological' and 'essentialist' thinking in their treatment of genetic variation as deviation. This means that the Human Genome Diversity Initiative will not provide a population-based panacea for an overly typological HGP, as its proponents contend. Substituting related, and less rhetorically-charged, conceptual, empirical, and metaphysical distinctions for the typological-population distinction furnishes a better way to assess the concept of the normal genome from an evolutionary perspective. (shrink)

The relationship between biological and social scientists as regards the study of human traits and behavior has often been perceived in terms of mutual distrust, even antipathy. In the interwar period, population study seemed an area that might allow for closer relations between them—united as they were by a concern to improve the eugenic quality of populations. Yet these relations were in tension: by the early post-war era, social demographers were denigrating the contributions of biologists to the study of population (...) problems as embodying the elitist ideology of eugenics. In response to this loss of credibility, the eugenics movement pursued a simultaneous program of withdrawal and expansion: its leaders helped focus concern with biological quality onto the developing field of medical genetics, while at the same moment, extended their scope to improving the social quality of populations through birth control policies, guided by demography. While this approach maintained boundaries between the social and the biological, in the 1960s, a revitalized American Eugenics Society helped reunite leading demographers and geneticists. This paper will assess the reasons for this period of influence for eugenics, and explore its implications for the social and biological study of human populations. (shrink)

A number of areas of biology raise questions about what is of value in the natural environment and how we ought to behave towards it: conservation biology, environmental science, and ecology, to name a few. Based on my experience teaching students from these and similar majors, I argue that the field of environmental ethics has much to teach these students. They come to me with pent-up questions and a feeling that more is needed to fully engage in their subjects, and (...) I believe some exposure to environmental ethics can help focus their interests and goals. I identify three primary areas in which environmental ethics can con- tribute to their education. The first is an examination of who (or what) should be considered to be part of our moral community (i.e., the community to whom we owe direct duties). Is it humans only? Or does it include all sentient life? Or all life? Or ecosystems considered holistically? Often, readings implicitly assume one or more of these answers; the goal is to make the student more sensitive to these implicit claims and to get them to think about the different reasons that support them. The second area, related to the first, is the application of the different answers concerning the extent of the ethical community to real environmental issues and problems. Students need to be aware of how the different answers concerning the moral community can imply conflicting answers for how we should act in certain cases and to think about ways to move toward conflict resolution. The third area in which environmental ethics can contribute is a more conceptual one, focusing on central concepts such as biodiversity, sustainability, species, and ecosystems. Exploring and evaluating various meanings of these terms will make students more reflective and thoughtful citizens and biologists, sensitive to the implications that different conceptual choices make. (shrink)

Lionel Penrose (1898–1972) was an important leader during the mid-20th century decline of eugenics and the development of modern medical genetics. However, historians have paid little attention to his radical theoretical challenges to mainline eugenic concepts of mental disease. Working from a classification system developed with his colleague, E. O. Lewis, Penrose developed a statistically sophisticated and clinically grounded refutation of the popular position that low intelligence is inherently a disease state. In the early 1930s, Penrose advocated dividing “mental defect” (...) (low intelligence) into two categories: “pathological mental defect,” which is a disease state that can be traced to a distinct genetic or environmental cause, and “subcultural mental defect,” which is not an inherent disease state, but rather a statistically necessary manifestation of human variation in intelligence. I explore the historical context and theoretical import of this contribution, discussing its rejection of typological thinking and noting that it preceded Theodosius Dobzhansky’s better-known defense of human diversity. I illustrate the importance of Penrose’s contribution with a discussion of an analogous situation in contemporary medicine, the controversial practice of using human growth hormone injections to treat “idiopathic short stature” (mere diminutive height, with no distinct cause). I show how Penrose’s contributions to understanding human variation make such treatments appear quite misguided. (shrink)

Chance has been a focus of attention ever since the beginning of population genetics, but neutrality has not, as natural selection once appeared to be the only worthwhile issue. Neutral change became a major source of interest during the neutralist–selectionist debate, 1970–1980. It retained interest beyond this period for two reasons that contributed to its becoming foundational for evolutionary reasoning. On the one hand, neutral evolution was the first mathematical prediction to emerge from Mendelian inheritance: until then evolution by natural (...) selection was considered the alternative to the fixity of species; now it appears to be the alternative to continuous change. Second, neutral change generated a set of clear predictions on standing variation. These could be used as a reference for detecting more elusive alternative mechanisms of evolution including natural selection. In the wake of the transition from Mendelism to genomics, the combination of coalescent theory, DNA sequence variation, and numerical analysis made it possible to integrate contingent aspects of the history of species into a new null model, thus opening a new dimension in the concept of population that the Modern Synthesis formerly considered as a mere gene pool. (shrink)

This paper describes the activities of amateur plant breeders and their application of various methods and technologies derived from genetics research over the course of the twentieth century. These ranged from selection and hybridization to more interventionist approaches such as radiation treatment to induce genetic mutations and chemical manipulation of chromosomes. I argue that these activities share characteristics with twenty-first-century do-it-yourself (DIY) biology (a recent upswing in amateur experimental biology) as well as other amateur science and technology of the twentieth (...) century. The characterization of amateur plant breeding as amateur experimental biology offers a corrective to a dominant narrative within the history of biology, in which the turn to experimental research in the early twentieth century is thought to have served as an obvious dividing line between amateur and professional activities. Considered alongside other better-known amateur efforts, it also suggests that we might gain something by taking a more unified approach to the study of amateur science and technology. (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)

This paper examines the controversy surrounding anthropologist Carleton S. Coon's 1962 book, "The Origin of Races." Coon maintained that the human sspecies was divided into five races before it had evolved into Homo sapiens and that the races evolved into sapiens at different times. Coon's thesis was used by segregationists in the United States as proof that African Americans were "junior" to white Americans and hence unfit for full participation in American society. The paper examines the interactions among Coon, segregationist (...) Carleton Putnam, geneticist Theodosius Dobzhansky, and anthropologist Sherwood Washburn. The paper concludes that Coon actively aided the segregationist cause in violation of his own standards for scientific objectivity. (shrink)