An Epistemology of Scientific Practice: Positioning Hans-Jörg Rheinberger in Twentieth-Century History and Philosophy of Biology.

In this article, I first outline the professionalization of the history and philosophy of biology from the 1960s onward. Then, I attempt to situate the work of Hans-Jörg Rheinberger with respect to this field. On the one hand, Rheinberger was marginal with respect to Anglo-American philosophical tradition; on the other, he was very influential in building up an integrated history and philosophy of the life sciences community at the Max Planck Institute for the History of Science in Berlin and beyond. This marginality results, I suggest, from three main sources: his use of concepts coming from continental traditions in the study of the life sciences, which are foreign to Anglo-American philosophers of science; his focus on practices instead of theories; and his research trajectory as a molecular biologist, which led him to be critical of disciplinary boundaries. As a first step in situating and historicizing Rheinberger's trajectory, this article invites comparative studies and calls for a history of "continental philosophy of biology" in the twentieth century.

Reconciling Pasteur and Darwin to control infectious diseases.

The continual emergence of new pathogens and the increased spread of antibiotic resistance in bacterial populations remind us that microbes are living entities that evolve at rates that impact public health interventions. Following the historical thread of the works of Pasteur and Darwin shows how reconciling clinical microbiology, ecology, and evolution can be instrumental to understanding pathology, developing new therapies, and prolonging the efficiency of existing ones.

Introduction: microbes, networks, knowledge-disease ecology and emerging infectious diseases in time of COVID-19.

This is an introduction to the topical collection Microbes, Networks, Knowledge: Disease Ecology in the twentieth Century, based on a workshop held at Queen Mary, University London on July 6-7 2016. More than twenty years ago, historian of science and medicine Andrew Mendelsohn asked, "Where did the modern, ecological understanding of epidemic disease come from?" Moving beyond Mendelsohn's answer, this collection of new essays considers the global history of disease ecology in the past century and shows how epidemics and pandemics have made "microbes complex".

Bacterial Transformation and the Origins of Epidemics in the Interwar Period: The Epidemiological Significance of Fred Griffith's "Transforming Experiment".

Frederick Griffith (1879-1941) was an English bacteriologist at the Pathological Laboratory of the Ministry of Health in London who believed that progress in the epidemiology and control of infectious diseases would come only with more precise knowledge of the identity of the causative microorganisms. Over the years, Griffith developed and expanded a serological technique for identifying pathogenic microorganisms, which allowed the tracing of the sources of infectious disease outbreaks: slide agglutination. Yet Griffith is not remembered for his contributions to the biology and epidemiology of infectious diseases so much as for discovering the phenomenon known as 'transformation'. Griffith's discovery, for many, was a pure case of serendipity whose biological relevance had also largely escaped him. In this paper, I argue that the key to understanding the significance of bacterial transformation - and the scientific legacy of Fred Griffith - rests not only on it initiating a cascade of events leading to molecular genetics but also on its implications for epidemiology based on the biology of host-parasite interactions. Looking at Griffith's entire career, instead of focusing only on the transformation study, we can better appreciate the place of the latter within Griffith's overall contributions. Presented in this way, Griffith's experiment on bacterial transformation also ceases to appear as an anomaly, which in turn leads us to rethink some of the most prevalent historical conceptions about his work.

'Birth, life, and death of infectious diseases': Charles Nicolle (1866-1936) and the invention of medical ecology in France.

In teasing out the diverse origins of our "modern, ecological understanding of epidemic disease" (Mendelsohn, in: Lawrence and Weisz (eds) Greater than the parts: holism in biomedicine, 1920-1950, Oxford University Press, Oxford, 1998), historians have downplayed the importance of parasitology in the development of a natural history perspective on disease. The present article reassesses the significance of parasitology for the "invention" of medical ecology in post-war France. Focussing on the works of microbiologist Charles Nicolle (1866-1936) and on that of physician and zoologist Hervé Harant (1901-1986), I argue that French "medical ecology" was not professionally (or cognitively) insulated from some major trends in parasitology, especially in Tunis where disciplinary borders in the medical sciences collapsed. This argument supports the claim that ecological perspectives of disease developed in colonial context (Anderson in Osiris 19: 39-61, 2004) but I show that parasitologists such as Harant built on the works of medical geographers who had called attention to the dynamic and complex biological relations between health and environment in fashioning the field of medical ecology in the mid-1950s. As the network of scientists who contributed to the global emergence of "disease ecology" is widening, both medical geography and parasitology stand out as relevant sites of inquiries for a broader historical understanding of the multiple "ecological visions" in twentieth-century biomedical sciences.

Writing the history of virology in the twentieth century: Discovery, disciplines, and conceptual change.

Concerned with the study of viruses and the diseases they cause, virology is now a well-established scientific discipline. Whereas aspects of its history from the late nineteenth to the mid-twentieth century have often been recounted through a number of detailed case studies, few general discussions of the historiography of virology have been offered. Looking at the ways in which the history of virology has been told, this article examines a number of debates among scientists and historians of biology and show how they are based on a different understanding of notions such as "discipline", of processes such as "scientific discovery" as well as on distinct views about what the history of science is and how it should be written (the opposition between "longue durée" and "micro-history" or between history of "concepts" versus "experimental methods"). The analysis provided here also suggests that a richer historiography of virology will require looking at the variations over time of the relations between conceptual, technological, and institutional factors that fostered its development at the intersection of several other scientific fields in the life sciences.

What is a pathogen? Toward a process view of host-parasite interactions.

Until quite recently and since the late 19(th) century, medical microbiology has been based on the assumption that some micro-organisms are pathogens and others are not. This binary view is now strongly criticized and is even becoming untenable. We first provide a historical overview of the changing nature of host-parasite interactions, in which we argue that large-scale sequencing not only shows that identifying the roots of pathogenesis is much more complicated than previously thought, but also forces us to reconsider what a pathogen is. To address the challenge of defining a pathogen in post-genomic science, we present and discuss recent results that embrace the microbial genetic diversity (both within- and between-host) and underline the relevance of microbial ecology and evolution. By analyzing and extending earlier work on the concept of pathogen, we propose pathogenicity (or virulence) should be viewed as a dynamical feature of an interaction between a host and microbes.

Why do parasites harm their host? On the origin and legacy of Theobald Smith's "law of declining virulence"--1900-1980.

Why do parasites harm their host? The persistence of this question in the history of the life sciences rests partly on a seeming biological paradox. In effect, although the annihilation of the host by a parasite could be depicted as a crude example of "the survival of the fittest," situations where the host dies rapidly often amount to a pyrrhic victory because parasitic colonies harboured within it may die as well before the transmission stage. So why would natural selection favour high virulence if this results in both the host's and the pathogen's deaths? From the last quarter of the nineteenth century to the late 1970s, it was often considered that, all else being equal, pathogen's evolution towards harmlessness was the expected outcome of long-term biological associations, as it would ensure the survival of both species. Frequently dismissed today as naively adaptationist, this perspective was however widely defended by some of those who pioneered an ecological, even evolutionary view of disease in the early-twentieth century, and was often ascribed to American bacteriologist and comparative pathologist Theobald Smith (1859-1934). Since the early 1980s, the mathematical model of the trade-off--based on the idea that pathogens face several compromises between their mode of transmission, the level of virulence, and the cost of resistance--has challenged the assumed tendency towards harmlessness and has gained currency. This paper first analyzes Theobald Smith's conception of disease, his experimental work on Texas cattle fever, and his formulation of the "law of declining virulence." The following sections then trace the legacy of this model of disease evolution from circa 1900 to its widespread acceptance in the mid-twentieth century and until its downfall in the 1980s. Particular attention is given to the case of the myxoma virus and how it acted as an empirical confirmation of Smith's model in the 1950s. Finally, the paper examines both significant empirical and theoretical challenges to the avirulence model. The present study not only fills a gap in the history of disease transmission and ecology but also sheds light on the intermingled relationship between bacteriology, evolutionary biology, and public health in the past century.

Understanding pathogens in the era of next generation sequencing.

What is a pathogen? Medical textbooks usually define a pathogen as any microorganism that causes disease. However, this widespread definition is problematic on a number of counts [1, 11]. Moreover, a generally accepted definition is not forthcoming among medical microbiologists, immunologists, and physicians. Here it is argued that there is another, and more pressing question to be asked, namely: what makes some organisms pathogenic and others not? Asking these questions instead allows for distinguishing pathogens from non-pathogens in a more flexible way, while at the same time emphasizing the roles of ecological and evolutionary processes in determining pathogenicity in infectious diseases.

Research traditions and evolutionary explanations in medicine.

In this article, I argue that distinguishing 'evolutionary' from 'Darwinian' medicine will help us assess the variety of roles that evolutionary explanations can play in a number of medical contexts. Because the boundaries of evolutionary and Darwinian medicine overlap to some extent, however, they are best described as distinct 'research traditions' rather than as competing paradigms. But while evolutionary medicine does not stand out as a new scientific field of its own, Darwinian medicine is united by a number of distinctive theoretical and methodological claims. For example, evolutionary medicine and Darwinian medicine can be distinguished with respect to the styles of evolutionary explanations they employ. While the former primarily involves 'forward looking' explanations, the latter depends mostly on 'backward looking' explanations. A forward looking explanation tries to predict the effects of ongoing evolutionary processes on human health and disease in contemporary environments (e.g., hospitals). In contrast, a backward looking explanation typically applies evolutionary principles from the vantage point of humans' distant biological past in order to assess present states of health and disease. Both approaches, however, are concerned with the prevention and control of human diseases. In conclusion, I raise some concerns about the claim that 'nothing in medicine makes sense except in the light of evolution'.