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""Science without Laws "inspires with its breathtaking scope. Delving from ethology to economics, molecular biology to microhistory, the authors illuminate crucial congruences in the way experts make their cases. Generations of scholars have taken physics as their model for right thinking, in science and beyond. This volume demonstrates that we are all biologists now."--David Kaiser, author of "Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics"

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SCIENCE WITHOUT LAWS

Duke University Press

Contents

PART 1: BIOLOGY........................................................................................................................................23Redesigning the Fruit Fly: The Molecularization of Drosophila MARCEL WEBER............................................................................46Wormy Logic: Model Organisms as Case-Based Reasoning RACHEL A. ANKENY.................................................................................59Model Organisms as Powerful Tools for Biomedical Research E. JANE ALBERT HUBBARD......................................................................73PART 2: SIMULATIONS....................................................................................................................................93From Scaling to Simulation: Changing Meanings and Ambitions of Models in Geology NAOMI ORESKES........................................................125Models and Simulations in Climate Change: Historical, Epistemological, Anthropological, and Political Aspects AMY DAHAN DALMEDICO.....................157PART 3: HUMAN SCIENCES.................................................................................................................................189The Psychoanalytic Case: Voyeurism, Ethics, and Epistemology in Robert Stoller's Sexual Excitement JOHN FORRESTER.....................................212"To Exist Is to Have Confidence in One's Way of Being": Rituals as Model Systems CLIFFORD GEERTZ......................................................225Democratic Athens as an Experimental System: History and the Project of Political Theory JOSIAH OBER..................................................243Latitude, Slaves, and the Bible: An Experiment in Microhistory CARLO GINZBURG.........................................................................264Afterword: Reflections on Exemplary Narratives, Cases, and Model Organisms MARY S. MORGAN.............................................................275Contributors...........................................................................................................................................279

Chapter One

MARCEL WEBER

Laboratory organisms such as the fruit fly Drosophila melanogaster, the soil nematode Caenorhabditis elegans, or the budding yeast Saccharomyces cerevisiae are often described as model systems or model organisms. These terms suggest that biologists cultivate and study these organisms because they provide a basis for extrapolating theoretical knowledge to other organisms, in particular Homo sapiens. While this is clearly one of the roles that such organisms play in research, this fact alone can hardly explain the widespread distribution of just a few of these organisms in laboratories all around the world. Taking an ecological perspective, we can ask what makes certain organisms so well adapted or, perhaps, adaptable to certain types of laboratories. Robert Kohler has shown for the case of Drosophila that this species entered the laboratory mostly for contingent reasons, but then turned out to be extremely well adapted and adaptable for laboratory life. In addition, there now exists an impressive body of scholarship documenting how such organisms, once they have successfully colonized a few laboratories, start to affect the investigative pathways followed by the scientists.

While Drosophila proved instrumental for the rise of genetics during the first decades of the twentieth century, the molecularization of genetics in the 1950s and 1960s largely resulted from research on microorganisms, especially Escherichia coli and bacteriophage. The latter organisms offered the advantage that they could be handled in the laboratory in vast numbers, thus allowing the detection of extremely rare genetic events (e.g., mutation or recombination events). Even tiny Drosophila was much too bulky for this task. Furthermore, most of its genes are far too complex in terms of their phenotypic effects for fine-structure mapping. Even though Drosophila did not vanish into complete obscurity during the so-called molecular revolution, it clearly lost some of its scientific glamour. However, the fly made a spectacular comeback in the 1980s. One of the favorite experimental animals of developmental biologists today, the fruit fly even closed the race as only the second multicellular organism for which the full genomic DNA sequence became available. Indeed, the fly has come a very long way since T. H. Morgan found the first mutant white eyes in 1910.

There are probably several factors that contributed to Drosophila's comeback. Developmental biologists had kept an interest in the fly because it offered certain possibilities for the genetic analysis of development. For example, Drosophila can produce genetic mosaics, that is, individuals in which some lineages of somatic cells have mutated. This allowed developmental biologists to determine the fate of certain embryonic cell lineages. Furthermore, the old "breeder-reactor" (Kohler's term) proved useful for a systematic screen for mutants that affect embryonic development. Initially, there was little reason to believe that Drosophila would turn out to be a good model system for understanding the molecular basis of development in other organisms, perhaps even humans. Flies show quite a special developmental mechanism, one not only characterized by the phenomenon of metamorphosis but also by other unusual features like the syncytial stage, in which the embryo contains thousands of nuclei but no cells. Drosophila's success as an experimental organism cannot be explained by its being typical or characteristic in terms of development. In fact, it is unclear in what sense Drosophila is really a model for other organisms, especially mammals.

In this article, I want to show that the main advantage responsible for Drosophila's reproductive success in molecular laboratories lies in the enormous experimental resources associated with this organism. Drosophila became a powerful research tool for molecular biology because geneticists were able to mobilize these resources for molecular cloning, which gave them access to genes and gene products not confined to Drosophila. I also show that a hybrid technology was instrumental for this mobilization. The experimental resources include, first, classical genetic and cytological mapping techniques; second, highly detailed genetic maps; and third, research materials such as thousands of mutants and genetically well-characterized fly strains.

In addition, I will show that the successful deployment of these experimental resources for molecular studies depended on certain theoretical concepts from classical genetics, in particular, the classical gene concept itself. I am hoping that this will shed new light on the old philosophical problem of the relationship between classical and molecular genetics.

In the following section, I will examine how the first Drosophila genes were isolated and characterized at the molecular level in the later 1970s and early 1980s. Then I examine the relationship between the classical genes that had already been studied by the pioneers of Drosophila genetics and the new molecular...