Lords of the Fly: "Drosophila" Genetics and the Experimental Life (review)

In this age of historiographical superawareness, when scholars strut across the stage displaying their nostrums for interpreting the past, and when new methodological programs become the goal rather than a means for understanding, one might approach this book with some apprehension. The title, as clever as it is, shouts defiance at a conventional world; the double focus on Drosophila and Drosophilists mimes a Latourian sleight of hand; and the repeated, occasionally forced, metaphors about constructing organisms, ideas, and scientists tentatively resurrect the ghost of a rather dubious epistemology. Nevertheless, this book not only works: it is brilliantly successful.

Robert Kohler is not a historical reductionist—that is, he does not offer a restricted or single-minded explanation of science. He takes what he can find: his archival investigations are thorough and the copious illustrations new and exciting; he is eclectic in the kind of questions he asks, and he selects that which is valuable from any historiographical program and integrates it into an elaborate and rich picture of one of the most fascinating and important experimental traditions in twentieth-century biology, namely, Drosophila genetics. The general messages, of course, may be transferred to other twentieth-century disciplines.

As an eclectic historian Kohler is interested in many facets of his subject. He provides ample and often perceptive portraits of members of two generations of Drosophila workers. He is sensitive to the culture of scientific institutions and examines in detail the operation of Thomas Morgan’s early “flyroom” at Columbia—and to a lesser extent that of the neighboring laboratory in Cold Spring Harbor, and of Morgan’s later institute at Caltech, and many more. He documents the tools of professional behavior, communication, verification, and inventory keeping—the moral economy, as he calls it—that soon built a network of Drosophilists on two continents. He is concerned about the dynamics of team research and provides important insights into the work of “Morgan’s boys,” of George Beadle and Boris Ephrussi, and of Alfred Sturtevant and Theodosius Dobzhansky. And above all, he concentrates throughout on the nature of the organism.

It is his examination of this “material culture”—as the historical trend now brands scientific instruments and organisms—that leads Kohler to his most innovative historical interpretations. Drosophila melanogaster, adapted to human habitation through evolution and reconstructed through genetic manipulation, became in Kohler’s terms a “breeder reactor.” By means of this metaphor he argues that the selective and inbreeding practices of classical genetics created stocks of flies that began revealing their concealed recessive mutations at an ever faster rate. By early March 1912, “the relentless flood of mutants from the breeder reactor left Morgan no choice but to adopt a fundamentally new system of naming and classifying factors” (p. 61). It was then that the group dispensed with the presence/absence formulations of neo-Mendelian genetics, Kohler explains, and that Calvin Bridges and Sturtevant began mapping linkage ratios onto chromosomes.

The reactor metaphor is employed again when Kohler examines Dobzhansky’s research program. Then it is populations of wild Drosophila pseudoobscura, undomesticated and successful at exploiting diverse niches of the West, that provide a different material culture. D. pseudoobscura is seen as a natural “breeder reactor” consisting of small isolated populations, which stretched from Mexico to Alaska and which could be tracked with the help of the newly discovered giant chromosomes of the salivary gland. Mapping contrasting factors onto chromosomes now became quick and easy, and their physical and biogeographic analysis led Dobzhansky to the Jessup Lectures and the modern evolutionary synthesis. Perhaps the most interesting part of Kohler’s telling of the story of this second breeder reactor is the contrast he draws between the evolutionary genetics of Sturtevant and Dobzhansky: the former remained fixed on the phylogenetic lineages suggested by his chromosomal maps; the latter changed focus to the newer problems of niche exploitation...