Recently, a number of philosophers of biology have endorsed views about random drift that, we will argue, rest on an implicit assumption that the meaning of concepts such as drift can be understood through an examination of the mathematical models in which drift appears. They also seem to implicitly assume that ontological questions about the causality of terms appearing in the models can be gleaned from the models alone. We will question these general assumptions by showing how the same equation (...) — the simple 2 = p2 + 2pq + q2 — can be given radically different interpretations, one of which is a physical, causal process and one of which is not. This shows that mathematical models on their own yield neither interpretations nor ontological conclusions. Instead, we argue that these issues can only be resolved by considering the phenomena that the models were originally designed to represent and the phenomena to which the models are currently applied. When one does take those factors into account, starting with the motivation for Sewall Wright’s and R.A. Fisher’s early drift models and ending with contemporary applications, a very different picture of the concept of drift emerges. On this view, drift is a term for a set of physical processes, namely, indiscriminate sampling processes. (shrink)
: Where there are cases of underdetermination in scientific controversies, such as the case of the molecular clock, scientists may direct the course and terms of dispute by playing off the multidimensional framework of theory evaluation. This is because assessment strategies themselves are underdetermined. Within the framework of assessment, there are a variety of trade-offs between different strategies as well as shifting emphases as specific strategies are given more or less weight in assessment situations. When a strategy is underdetermined, scientists (...) can change the dynamics of a controversy by making assessments using different combinations of evaluation strategies and/or weighting whatever strategies are in play in different ways. Following an underdetermination strategy does not end or resolve a scientific dispute. Consequently, manipulating underdetermination is a feature of controversy dynamics and not controversy closure. (shrink)
The neutral and nearly neutral theories of molecular evolution are sometimes characterized as theories about drift alone, where drift is described solely as an outcome, rather than a process. We argue, however, that both selection and drift, as causal processes, are integral parts of both theories. However, the nearly neutral theory explicitly recognizes alleles and/or molecular substitutions that, while engaging in weakly selected causal processes, exhibit outcomes thought to be characteristic of random drift. A narrow focus on outcomes obscures the (...) significant role of weakly selected causal processes in the nearly neutral theory. (shrink)
This article offers three contrasting cases of the use of neutrality and drift in molecular evolution. In the first, neutrality is assumed as a simplest case for modeling. In the second and third, concepts of drift and neutrality are developed within the context of population genetics testing and the development and application of the molecular clock.
Richard Goldschmidt was one of the most controversial biologists of the mid-twentieth century. Rather than fade from view, Goldschmidt's work and reputation has persisted in the biological community long after he has. Goldschmidt's longevity is due in large part to how he was represented by Stephen J. Gould. When viewed from the perspective of the biographer, Gould's revival of Goldschmidt as an evolutionary heretic in the 1970s and 1980s represents a selective reinvention of Goldschmidt that provides a contrast to other (...) kinds of biographical commemorations by scientists. (shrink)
The vast network of Drosophila geneticists spawned by Thomas Hunt Morgan's fly room in the early 20th century has justifiably received a significant amount of scholarly attention. However, most accounts of the history of Drosophila genetics focus heavily on the "boss and the boys," rather than the many other laboratory groups which also included large numbers of women. Using demographic information extracted from the Drosophila Information Service directories from 1934 to 1970, we offer a profile of the gendered division of (...) labor within Drosophila genetics in the United States during the middle decades of the 20th century. Our analysis of the gendered division of labor supports a reconsideration of laboratory practices as different forms of work. (shrink)
In the 1960s molecular population geneticists used Monte Carlo experiments to evaluate particular diffusion equation models. In this paper I examine the nature of this comparative evaluation and argue for three claims: first, Monte Carlo experiments are genuine experiments: second, Monte Carlo experiments can provide an important meansfor evaluating the adequacy of highly idealized theoretical models; and, third, the evaluation of the computational adequacy of a diffusion model with Monte Carlo experiments is significantlydifferent from the evaluation of the emperical adequacy (...) of the same diffusion model. (shrink)
Using an analogy between moths and men, in 1916, Richard Goldschmidt proposed that homosexuality was a case of genetic intersexuality. As he strove to create a unified theory of sex determination that would encompass animals ranging from moths to men, Goldschmidt's doubts grew concerning the association of homosexuality with intersexuality until, in 1931, he dropped homosexuality from his theory of intersexuality. Despite Goldschmidt's explicit rejection of his theory of homosexuality, Theo Lang, a researcher in the Genealogical-Demographic Department of the Institute (...) for Psychiatric Research in Munich, revived it, maintained Goldschmidt's association with it, and argued on its behalf in publications from 1936 to 1960. Lang's appropriation of Goldschmidt's theory did not depend on his resolution of the difficulties Goldschmidt had found with his own theory. Lang and Goldschmidt, I argue, had fundamentally different scientific and social commitments that allowed one to reject this theory of homosexuality and the other to accept it. (shrink)
In the early twentieth century, Tatsuo Aida in Japan, Øjvind Winge in Denmark, Richard Goldschmidt in Germany, and Calvin Bridges in the United States all developed different experimental systems to study the genetics of sex reversal. These locally specific experimental systems grounded these experimenters’ understanding of sex reversal as well as their interpretation of claims regarding experimental results and theories. The comparison of four researchers and their experimental systems reveals how those different systems mediated their understanding of genetic phenomena, and (...) influenced their interpretations of sex reversal. (shrink)
Many biologists appeal to the so-called Krogh principle when justifying their choice of experimental organisms. The principle states that “for a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied”. Despite its popularity, the principle is often critiqued for implying unwarranted generalizations from optimal models. We argue that the Krogh principle should be interpreted in relation to the historical and scientific contexts in which it has (...) been developed and used. We interpret the Krogh Principle as a heuristic, i.e., as a recommendation to approach biological problems through organisms where a specific trait or physiological mechanism is expected to be most distinctively displayed or most experimentally accessible. We designate these organisms “Krogh organisms.” We clarify the differences between uses of model organisms and non-standard Krogh organisms. Among these is the use of Krogh organisms as “negative models” in biomedical research, where organisms are chosen for their dissimilarity to human physiology. Importantly, the representational scope of Krogh organisms and the generalizability of their characteristics are not fixed or assumed but explored through experimental studies. Research on Krogh organisms is steeped in the comparative method characteristic of zoology and comparative physiology, in which studies of biological variation produce insights into general physiological constraints. Accordingly, we conclude that the Krogh principle exemplifies the advantages of studying biological variation as a strategy to produce generalizable insights. (shrink)
Through a case study of the controversies surrounding the molecular clock, this paper examines the role of visual representation in the dynamics of scientific controversies. Representations of the molecular clock themselves became objects of controversy and so were not a means for closure. Instead visual representations of the molecular clock became tools for the further articulation of an ongoing controversy.