Mosquito Empires: An Inference to Explanation, but Is it the Best Explanation?

McNeill, J.R. Mosquito Empires: Ecology and War in the Greater Caribbean 1620-1914. New York: Cambridge University Press, 2010. ISBN: 978-0-521-45910-5. Paperback. 390 pages.

Professor J.R. McNeill, Georgetown University, has accomplished an incredible achievement. To wit, he has more than accomplished his objective; he has excelled in its completion. No doubt a thesis that synthesizes nearly three hundred years of history, spans geographies as diverse as the “Greater Caribbean,” and explains the rise and fall of empires by appeal to one significant causal mechanism is the sort of ambitious goal dreamt of by graduate students, denied by their advising committees, and is only successfully realized by the most thoughtful, analytic, clever, and courageous scholars. McNeill is a member of the rare class of academic scholars, satisfying the lattermost conditions.

The accomplishment, of course, is Mosquito Empires: Ecology and War in the Greater Caribbean, 1620-1914 (hereafter: “ME”). Broadly, McNeill’s thesis is this: quests for wealth and power changed ecologies in the Greater Caribbean, and these changes, in turn, shaped empires, wars, and revolutions, between 1620-1914 (2). More specifically, McNeill argues through a wealth of case studies that ecological conditions resulting from a plantation economy were such that mosquitoes carrying yellow fever and malaria enjoyed optimal breeding conditions. These mosquitoes, the carriers of diseases, are but one side of the coin. At the heart of McNeill’s argument is the notion of “differential immunity” (4): the state of affairs in which particular classes of peoples, namely recently-immigrated and visiting Europeans, are more susceptible to infection than other classes, namely, to a small extent, some indigenous populations but mostly African-born slaves brought to the Greater Caribbean to fuel the very plantation economy that sparked the proliferation of yellow fever and malaria via mosquitoes.

The pillars of McNeill’s argument, then, are two-fold: first, the sugar-plantation-driven “creole ecology” (23) of the Atlantic coastal regions, referred to by McNeill as the “Greater Caribbean, was such that human-directed ecological change coupled with an influx of African slaves introduced yellow fever and malaria to the region via mosquitoes. Of course this introduction of disease by itself presumably would help or hinder all parties with equal consequence—no different than crowd diseases, “which played a fairly consistent role in world history” (10). It is this crucial second premise McNeill needs to make his case: “differential immunity” ensured that yellow fever and malaria would disproportionately impact recent residents of the Greater Caribbean more so than others. This differential immunity, all other things being equal, made the geopolitical difference in the region and explains the significance of mosquitoes in the shaping of Greater Caribbean history.

McNeill’s argument is a significant contribution to environmental history, military history, and the histories of empire and revolution during the stained centuries of the Atlantic slave trade. His argument shows the unconsidered effects of human environmental agency while simultaneously lifting up factors of human non-agency as significant drivers of ecological and geopolitical change. ME flirts with environmental determinism, but it is noted that although ecological changes influence history in ways human actors could not predict, these changes are brought about only by human agency (6). This distinction may appear subtle, but it is appropriate to make clear McNeill’s stance as to respond to the potential objector who worries that McNeill’s framework is deterministic.

Considerations of ME, however, are not wholly without complaint. In the remaining paragraphs I will raise two worries of my own: first, I take it as uncontroversial that McNeill thinks he is providing a causal explanation, the best explanation, of the geopolitical changes in the Greater Caribbean between the 17th and 20th centuries. I worry that in service of rhetoric, McNeill sacrifices thoroughgoingness; by this I mean to say that his appeal to mosquitoes as the agents of historical change appears prima facie justified, but I worry that his argument may suffer damage from closer scrutiny. My second worry is this: McNeill may have missed the forest for the trees. I will argue that a meta-narrative could be argued for using ME, but when McNeill has the opportunity to connect the dots, so to speak, at the bookends of his work, he misses a greater point. That is, power begets power—and I don’t discount the irony of my own deterministic leanings inherent in this claim. I will take these worries in turn.

It is wise of McNeill to begin ME with a rough sketch of his argument. If McNeill can get his reader on board with his thesis in the first few pages, the balance of the book seems to just fall out of these central ideas. This is an effective argument strategy, but effectiveness strategies and sound arguments are not perfectly correlated. I want to pause and temper my remarks before continuing: undoubtedly the central features of McNeill’s argument are well supported. Indeed, human agency influenced ecological change in ways agents would not anticipate. Indeed, differential immunity was a difference maker. ME is a well-reasoned defense of an exciting contribution to history, as noted above. My worry is not plainly that McNeill is wrong. I have a more nuanced complaint. I worry that if McNeill’s project is to explain geopolitical changes in the Greater Caribbean during the 17th through 20th centuries, is the mosquito the primary actor?

The mosquito is the carrier of yellow fever and malaria. Yellow fever and malaria are the essential ingredients to both the successful and failed attempts at empire expansion and revolution. It would seem from this simple analysis that the mosquito is the best explanation of historical change. I argue that mosquitos are the consequence of more fundamental events.

One way to test for identifying the explanatory cause of an event is to consider counterfactually what would happen in the absence of the identified cause. McNeill leaves us with little insight as to what would happen just if the mosquito had not been present. McNeill explains that an influx of slaves brought disease to the Greater Caribbean, plantation conditions facilitated the breeding of mosquitoes, no disease among Cornwallis’s troops may have left would-be United States more fractured across North/South lines, and without certain hospital practices (planting beds in buckets of water to prevent crawling insects, or grouping patients by ethnicity) disease may not have spread so readily. These are pristine examples of difference making differences that counterfactually explain what would have happened in their absence. However, when a critical reader wonders what would have happened had their been no mosquitoes, McNeill is silent. In the opening argument McNeill baldly asserts mosquitoes as dramatis personae (3). I wonder why the book could not be titled Differentially Immune Empires or Medically Inept Empires. It’s not clear to me why the phenomena explained by appeal to mosquitoes are not equally well explained by other factors. No doubt mosquitoes are explanatorily relevant to the geopolitics of the Greater Caribbean (I repeat my point, McNeill isn’t wrong), but I’m curious if he’s provided evidence that mosquitoes are the best explanation of ecology and geopolitics.

My first worry calls into question the explanatory priority of the causal mechanisms at work in the geopolitics of Atlantic coastal communities during the Atlantic slave trade, in this sense I complain about an ordering of reasonably inferred facts. My second worry is much more interpretative in nature. I fear that when bookending ME, McNeill has failed to acknowledge his work as both beginning and ending with the search for empire propagated by wealthy nations.

The colonization of the Greater Caribbean and Americas is nothing short of the search for wealth, resources, and laborers (McNeill makes this point, 3). The story of ME is imperialism highlighted by unforeseen consequences. In his conclusion McNeill explains the groundbreaking work of US Army doctor Walter Reed and one of his “converts” future Surgeon General William Gorgas. It was America’s investment in mosquito population control and prevention that helped to eradicate yellow fever and malaria in Cuba and the Panamanian Canal Zone. McNeill is explicit that this creates an opportunity for America to expand unabated by the diseases we’ve discussed throughout. Says McNeill, “[i]n effect, the rich got healthier and the healthy got richer (and more powerful)” (313). McNeill does acknowledge his worry that perhaps the health revolution will never become universal (ibid.), but the interpretation not made explicit is that geopolitics are shaped by the unforeseen consequences of human agency. This is not determinism, but it is a failing for humans to account for their own actions. If McNeill were to turn toward prescriptiveness, this is the position to take up.

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