This inaugural roundtable for H-Environment centers upon one of the key concepts that students and scholars of environmental history confront: environmental determinism. Many found their way to the field after reading Alfred W. Crosby’s 1972 The Columbian Exchange, which brought plants, animals, and diseases out of the footnotes and into a prominent place in the grand sweep of history. In that book, Europeans gained syphilis from North America while Native Americans gained smallpox. Europeans gained tomatoes and chocolate, while Native Americans gained large beasts of burden. Some of these ideas Crosby later disavowed (particularly his emphasis on syphilis). However, most of the book, especially its overall premise, has stood the test of time for several decades. It was a kind of approach to history that emphasized how biological entities had lives of their own, often determining outcomes in human history beyond the usual political, social, and economic explanations. Younger scholars may have encountered this perspective more recently, due to high-profile books emphasizing the importance of geography and climate in the development of societies, as with the Pulitzer Prize-winning book Guns, Germs and Steel by Jared Diamond.
For J. R. McNeill, the key influence clearly was Crosby. As he wrote in a forward to the 2003 edition of The Columbian Exchange, “My first encounter with the book came on a rainy afternoon in 1982 when I picked it off of a shoulder-high shelf in an office I temporarily occupied. I read it in one gulp, neglecting the possibility of supper. Only rarely can I recall precisely the circumstances in which I read a book long ago, but The Columbian Exchange, and the sense of excitement it provoked in me, etched itself into my memory.” We can also see influence upon McNeill by a later book by Crosby, Ecological Imperialism, which emphasized the myriad ways in which biological exchanges could be asymmetrical, benefiting some while crippling others. McNeill has applied this approach toward answering one of the tough problems of colonial and Caribbean history: why were powerful Atlantic powers unable to dislodge the waning Spanish empire in the Caribbean during the seventeenth and eighteenth centuries, despite numerous costly efforts to do so?
The result is Mosquito Empires, a book that spans nearly three centuries and the histories of many peoples, nations, and empires in the American tropical world. As the title suggests, it places considerable responsibility for the course of events upon mosquitoes, those formidable vectors of yellow fever and malaria. McNeill’s focus is on differential resistance—an inequality in disease susceptibility that killed off some humans while others soldiered on unperturbed. It not only reinforced the status quo before the late eighteenth century, disallowing serious imperial reconfigurations, but also strengthened independence movements from the 1770s onward.
I approached Lisa Brady to comment upon Mosquito Empires because she has demonstrated a keen interest in the intersections between war and the environment. Her article “The Wilderness of War” explained the relationship between nature and strategy in ways beyond the usual determinants of the battlefield such as terrain and weather. Instead she argued that nature, physically and conceptually, assumed an active role in warfare, particularly in the American Civil War. Like McNeill, she highlighted not simply the constraints of the environmental factors upon conflict, but their psychological importance, as when General Sherman’s march to the sea laid waste to what she called “the ecological foundation of the Confederacy.” In her review of McNeill she applies this expertise in Civil War history to assess the impact of differential immunity in the “Greater Caribbean,” which includes the American South.
Stuart McCook has written extensively about the process of nation-building in the Spanish Caribbean during the same period that McNeill investigates. For McCook, the key story has been the development what he called “creole science,” a cooperative relationship between scientists and agricultural elites as they attempted to maintain agricultural, export-based economies. McCook has made clear that the ability to exert power in the Caribbean has often depended upon the ability to understand nature and the desire to control it.
Richard Tucker’s work also has honed in on the tropical world, though not limited to the Caribbean. His work has educated numerous scholars—and more of my own undergraduates than I can count—on the disturbing effects of viewing nature as a commodity in a global capitalist economy. Whereas McNeill emphasizes the ability of empires, governments and armies to dig in for the long term, Tucker has written about the dislocations of power in the region due to corporations and expanding markets.
Paul Sutter’s work has ranged quite broadly, from cars and the twentieth-century wilderness movement to the history of American imperialism in the tropics. Like McNeill, he has devoted considerable attention to the significance of insects and disease vectors in the projection of power in the Caribbean. A recent article in Isis, the recipient of the Alice Hamilton Prize (of the American Society for Environmental History), explores the role of entomological workers in combating yellow fever and malaria in the Panama Canal Zone. Sutter wrote that scientists were not just attempting to control nature, but that the threat from nature was a direct result of American practices in the Zone. This perspective is shared by McNeill, who makes clear in Mosquito Empires that imperialism itself, particularly the transformation of landscapes to support agriculture for export, created ideal environments for mosquitoes and the diseases they carried.
Before turning to the comments and response, I wish to thank all five contributors to this roundtable for their thoughtful comments. Their willingness to raise issues for scholarly discussion and debate will undoubtedly aid in creating fruitful dialogue about the shifts in power and ecological relationships during this long and tumultuous period.
 Jared Diamond, Guns, Germs, and Steel: The Fates of Human Societies (New York: W. W. Norton, 1997).
 J. R. McNeill, “Forward,” in Alfred W. Crosby, The Columbian Exchange: Biological and Cultural Consequences of 1492 (Westport, Conn.: Praeger, 2003), xi-xvi. Quote on p. xii.
 Alfred W. Crosby, Ecological Imperialism: The Biological Expansion of Europe, 900-1900 (Cambridge: Cambridge University Press, 1986).
 Lisa M. Brady, “The Wilderness of War: Nature and Strategy in the American Civil War,” Environmental History 10:3 (2005), 441-427.
 Stuart McCook, States of Nature: Science, Agriculture, and Environment in the Spanish Caribbean, 1760-1940 (Austin: University of Texas Press, 2002).
 Richard P. Tucker, Insatiable Appetite: The United States and the Ecological Degradation of the Tropical World, Concise revised edition (Lanham: Rowman and Littlefield, 2007).
 Paul S. Sutter, “Nature’s Agents or Agents of Empire? Entomological Workers and Environmental Change during the Construction of the Panama Canal,” Isis 98:4 (2007), 724-753.