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Money from trees: mining, energy, and environmental change in the Spanish Empire.

When the wind is fresh they extract much silver, but when there is no wind they cannot by any means extract silver; so that, as the wind is profitable in the sea for navigating, it is so here for extracting silver.

Pedro de Cieza de Leon (ca. 1550)

World history textbooks and syllabi often emphasize the economic importance of the circulation of silver that tens of thousands of workers extracted from mines controlled by the Spanish crown between the mid-sixteenth and early-nineteenth centuries. Many historians argue that the flows of silver from Potosi (modern Bolivia) and New Spain (modern Mexico) to Europe and China created the first truly global economy. Moreover, sixteenth-century silver mining featured elements that we often associate with twenty-first century economic globalization: long-distance trade networks, technological innovations, migrant labor and piracy. Producing silver also required large inputs of energy, particularly during the refining stage when the precious metal was extracted from the ore. Long before fossil fuels would drive global economies and climate change, silver production's fuel consumption led to environmental degradation on local and regional geographical scales. The environmental history of silver mining, therefore, provides an excellent opportunity to encourage students to think about the significance of energy regimes in the history of economic globalization. If the world economy was born with a silver spoon, then it was nourished by vast quantities of charcoal and water.

I have incorporated the environmental history of silver mining into an introductory survey course called "Latin America and the Global Environment." Drawing from this course, I will provide an example of a writing assignment that requires students to analyze both the regional environmental and social impacts of silver mining, and how historians piece together evidence from disparate sources to produce a coherent interpretation. In other words, I use a dramatic, sometimes tragic, story of global significance to foster student thinking about a perennial question: how do we know what we know?

The Course: Latin America and the Global Environment

The unit on silver mining and environmental change occupies two weeks of a fifteen-week survey course that fulfills a general education requirement for students majoring in the humanities or social sciences at a private, research university. To date, course enrollments have been small enough (approximately 45 students) to permit interactive lectures (twice/week) that are complemented by weekly small group discussions. The primary "skills building" objective of the course is to improve students' ability to write analytical essays and to participate in discussions. There are three paper assignments of increasing length and complexity, a few quizzes to motivate students to keep up with the readings, and a synthetic, take-home final examination. The course structure is not particularly innovative; the novelty lies primarily in the content of lectures and readings that offers an environmental perspective on some classic themes of Latin American/Caribbean history including: first encounters among indigenous people, Africans and Europeans; colonial economies (silver and sugar); chattel slavery and emancipation; political independence and nationalism; export booms; and migrations and urbanization. As indicated by the course title, most, but not all, content stresses "global" exchanges and contexts.

In order to operationalize an environmental perspective, I introduce students to the ecological ideas of biological diversity and energy flows. Biological diversity includes not only the totality of species of flora and fauna, but also the genetic diversity within populations of particular organisms and landscape variation. When discussing biological diversity, we begin with the Columbian Exchange and then complicate Alfred Crosby's original formulation by discussing the importance of exchanges between the Americas and Africa. The theme of biological diversity is carried through to the modern period when we discuss the history of export banana plantations in Central America. However, since many students strongly associate Latin America with tropical rainforests, I also call attention to the diversity of ecosystems and climates found within Latin America, including the Andes (mountains) Pampas (grasslands) and Patagonia (desert steppe). Energy flows, the second idea, are arguably more abstract than a jaguar or the Atacama desert, but they are crucial for getting students to think about environmental dynamics. The course discusses changes in energy flows associated with the transitions from fuelwood and muscle power to fossil fuels and electricity. The real challenge is helping students to see what these changes meant for people living in specific times and places in Latin America and beyond.

There is no textbook used in the course; readings include two scholarly monographs, a few peer-reviewed articles, and some primary sources in English translation. The decision to eschew a single text is a reflection of my steadfast belief that the use of multiple texts is an effective way by which to introduce students to the interpretive nature of historical inquiry. I use (mostly Powerpoint) lectures to provide broad contexts and connecting themes. I frequently incorporate video, popular music, and documentaries into lectures and discussion. The readings cover the topics listed above but also are intended to provide a sense of the different approaches taken by environmental historians. For example, the first monograph, John McNeill's Mosquito Empires, makes an effective and explicit argument about the role played by certain kinds of mosquitoes in making and remaking the geopolitics of the Greater Caribbean. The sweeping narrative, if not global, is at least Atlantic World history. The second monograph, Mark Carey's In the Shadow of Melting Glaciers, is more accurately described as a transnational history of how local people, national governments, scientists and business corporations responded to environmental hazards (namely, melting glaciers) linked to climate change in twentieth-century Peru. The value of using such a work is to demonstrate to students how global phenomena (e.g., climate change) manifest themselves on regional scales. Moreover, local histories and national politics still matter a great deal. The level of detail, including the names of many unfamiliar places and people, potentially derails students from thinking about the "big picture," but Carey's book stands as an effective complement to McNeill's more sweeping work by reminding students that when it comes to policy making, the nitty-gritty details, often only visible from a local vantage point, remain crucial.

I begin the unit on silver mining with a sweeping lecture on the economic dimensions of silver. I combine a "history by the numbers" approach with a qualitative one to stress both the silver trade's scale and geographical scope, and how scholarly interpretations have shifted to recognize the importance of Chinese demand. Providing students with a sense of the economic history of silver mining is important not only to "balance" the diverging views of economists and ecologists, but also because environmental historians often interpret economic data to build their arguments (see below). The second lecture focuses on local/ regional environmental degradation linked to silver mining in Potosi. Students read the 2010 article by Daviken Studnicki-Gizbert and David Schecter, "The Environmental Dynamics of a Colonial Fuel Rush: Silver Mining and Deforestation in New Spain, 1522-1810," which which forms the basis for the paper assignment. (1)

The Alchemy of Globalization: Making Silver in Potosi

According to one Spanish chronicler, a native Andean named Gualpa first called attention to the rich veins of silver found on a mountain peak near the village of Porco, in whose vicinity the Incas had established mines prior to the arrival of the Spanish. By 1549, Potosi had acquired fame for its rich veins of silver and drew indigenous miners from near and afar. However, the Spaniards experienced problems refining the silver ore with their customary bellows and relied upon indigenous technologies known as huayras. Indigenous workers erected thousands of huayras, ceramic ovens shaped like inverted cones with air vents cut into them, in areas where the winds blew strongest. According to Cieza de Leon, at night, the working huayras gave the mountainside the appearance of a luminary. The huayras required not only windy days and nights to function, but also fuel including wood charcoal, grasses, or dried animal dung. One Spanish source from the 1570s stated that no trees were to be found "on the mountains of Potosi nor in its towns, since the area has been well cut over by Indians and Spaniards alike." (2) Other sources report that animal trains hauled fuel for the mines from as far as 150 kilometers. (3) In addition to consuming considerable amounts of fuel, the huayras emitted lead fumes, raising the possibility of health risks for operators and area residents.

Among other things, the huayra system ensured that most of the silver produced in Potosi literally passed through the hands of indigenous subjects-some of whom were able to enrich themselves. The local circulation of silver led to a massive influx of people and goods that transformed Potosi into an urban area whose population reportedly surpassed that of Paris. But this is not a story of accumulation via unfettered markets for labor and goods. Many of the indigenous people who worked in the mines were mitayos, laborers drafted from indigenous highland villages that often lay hundreds of kilometers away. In the seventeenth century, some 16,000 mitayos worked at any given moment. Wage labor also emerged, a reflection not only of the demand for workers but also of the amount of silver that leaked out of official channels. (4) The fuel demands of this growing population undoubtedly contributed to local deforestation; in addition, the need to pasture large herds of llamas and alpacas presumably altered local landscapes by modifying the composition of vegetation.

In the 1560s, the royal share of silver from Potosi (one fifth of official production) declined sharply. This prompted the Spanish crown to authorize Viceroy Francisco del Toledo to investigate the state of silver mining. Toledo's report called for a major reorganization of the industry. Among other things, it recommended that the huayra system be replaced in favor of mercury amalgamation, a process that enabled silver to be extracted from low-grade ore. Spanish authorities had the good fortune of finding important mercury deposits in Huancavelica, Peru, hundreds of kilometers from Potosi, but far closer than the Spanish mines of Almaden. Viceroy Toledo referred to the economic linkage of Huancavelica and Potosi as the "world's most important marriage. " By the 1570s, mercury amalgamation helped increase official silver production dramatically.

However, historians Kendall Brown and Nicholas Robins have examined the severe health risks associated with the mining and use of mercury, a potent neurotoxin. Andean people dreaded working in the mines of Huancavelica and their protests compelled Spanish officials to implement reform measures. In Potosi, mill workers inhaled mercury fumes and absorbed the toxin through their skin when used their feet to mix a slurry of salt, copper sulfate, and mercury. (5)

One environmental dimension of the introduction of mercury amalgamation that has received less attention from historians is the increased consumption of energy that resulted from the Toledan reforms. The molinas of Potosi relied on waterpower to drive machinery that crushed the ore. Spanish authorities directed the construction of aqueducts and the channelization of the river on whose banks Spanish entrepreneurs established more than one hundred mills. The use of hydropower and mercury amalgamation represented key technological changes that help to explain the dramatic increase in silver production that occurred in the late- sixteenth century. However, the use of hydropower, like the earlier system based on wind-dependent huayras, was constrained by natural forces: during the dry season, water levels dropped along with the potential energy available for conversion. The Spanish overcame this obstacle by organizing the construction of thirty-two reservoirs in the Kari Kari mountains between 1573 and 1621. The water stored in these reservoirs powered the mills of Potosi during the dry season. The expansion of silver production in Potosi resulted in part from the construction of a system of energy production and storage.

Disaster struck on March 15, 1626, when the San Ildefonso reservoir burst, releasing a large surge of water that in a matter of two hours destroyed much of Potosi including most of the mills along with hundreds of residences. As is often the case with such disasters, determining precise numbers of fatalities is difficult, but recent research suggests some 2000 people perished (of a total population around 100,000). In addition, a staggering nineteen tons of mercury entered the waters of the Pilcomayo river system, leading to widespread contamination. English-language scholars have written little about this event but it seems reasonable to suggest that it represented one of the world's first "industrial accidents," linked to systems created to store and supply energy for commodity production. (6)

The Alchemy of Globalization II: Making Silver in New Spain

The history of silver production in New Spain (colonial Mexico) is perhaps less dramatic than that of Potosi, but the 450-odd mining areas produced some fifty thousand metric tons of silver between the sixteenth and early nineteenth centuries (40 percent of the world's silver production during that time period). Studnicki-Gizbert and Schecter have explored the consumption of fuel by the mining industry in colonial Mexico, arguing that the scale and intensity of energy use (wood and charcoal) made the colony one of the most important consumers of biomass in the early modern Atlantic world. By way of comparison, the authors assert that late-eighteenth century energy consumption in New Spain's silver industry surpassed fuel consumption in England's iron-making industry by a factor of three. (7)

The authors estimate that from 1558 to 1804, people in New Spain cleared between 315,000 and 392,000 square kilometers of forested lands, an area equivalent to the modern state of Poland or Italy! To convey the scale of environmental change associated with this "colonial fuel rush," the authors include a map with circles representing the theoretical radii of deforestation that extended from colonial Mexico's largest mining regions including Zacatecas, Guanajuato, and San Luis Potosi. Moreover, Studnicki-Gizbert and Schecter briefly "zoom in" to provide a history of San Luis Potosi, drawing on maps and textual sources to document deforestation linked to the work of carboneros (charcoal makers). Within two decades of the opening of mines in the region, evidence suggests that fuel was coming from as far as 120 kilometers away.

Mercury amalgamation played a crucial role in driving environmental and social change in colonial Mexico. Interestingly, Studnicki-Gizbert and Schecter note that Bartolome de Medina, a sixteenth-century advocate for introducing mercury amalgamation, believed that the process not only would enable the profitable refinement of low-grade ores, but also would reduce wood consumption because it did not require heat. Although Medina was technically correct, refiners in New Spain realized that the addition of heat accelerated the chemical process in which mercury bound itself to silver. Consequently, the adoption of hot mercury amalgamation increased both refiners' efficiency and the scale of production, leading to higher temporal rates of deforestation.

Studnicki-Gizbert and Schecter argue that widespread deforestation had major impacts on indigenous populations who carried out extensive hunting and foraging in the highland forests of oaks, pines and willows that would be increasingly felled for fuel in conjunction with the expansion of mining. The result was a "colonial agroecology" in which forests, foragers, and game largely gave way to pastures, carboneros and exotic domesticated animals. In sum, deforestation linked to mining helped pacify indigenous populations.

Finally, although the authors do not invoke the concept, the historical process that they describe seems to be an early modern example of the Jevons paradox: greater energy efficiencies tend to increase total energy consumption by stimulating higher rates of consumption. Stanley Jevons, a nineteenth-century British economist, published his counterintuitive ideas about energy efficiency and energy consumption in 1865 in the context of a debate over British coal consumption. Although its literal application to colonial Mexico is therefore anachronistic, the seeming relevance of the Jevons concept to the historical relationship between mercury amalgamation and fuel consumption points to potential continuities between biological and fossil fuel regimes. (8)

Historians' Alchemy: Turning Silver to Trees

Studnicki-Gizbert and Schecter's concise and clear prose lends itself to writing assignments in an introductory course, provided that most students have a good command of academic English. The writing assignment that I have used is intended to be straightforward yet somewhat open-ended:
   How did silver mining in the Americas help to create global
   economic connections? How did silver mining affect the people and
   environments of New Spain (Mexico) over the course of three
   centuries? What kinds of evidence do the authors Studnicki-Gizbert
   and Schecter use to calculate the scale of deforestation? Describe
   one weakness or limitation of their evidence.

I have given some version of this question three times. Students do reasonably well answering the first two parts of the question that require them to comprehend and synthesize material from lecture and the reading. However, most students have struggled when asked to discuss the evidence. In fact, so many students avoided the final part of the prompt that I felt compelled to break down the total point value of the assignment to indicate that all parts of the prompt carried equal weight. This ploy increased the amount of space that most students devoting to writing about the authors' evidence, but surprisingly few have been able to articulate a potential weakness or limitation in the authors' methods

I say "surprisingly" because Studnicki-Gizbert and Schecter included a three-paragraph appendix bearing the subtitle: "Estimating the ratio of silver production to cleared forest areas, a discussion of sources and methods." The authors' explanation of their methodology is extremely useful for helping students to appreciate the challenges associated with writing environmental history. For example, the authors have little choice but to rely on "proxy" evidence for deforestation. Thanks in large part to economic historian Richard Garner's earlier work with royal treasury documents, Studnicki-Gizbert and Schecter began with good data on official silver production for the sixteenth, seventeenth, and eighteenth centuries. They proceeded to work backward in order to translate silver into trees. They used account books from two haciendas de beneficio (silver refineries) in order to estimate a ratio of charcoal to silver. However, their evidence was thin; the account books consulted cover only two years (1611-12; and 1782-83 respectively) for the two foundries. The large separation of time notwithstanding, the haciendas' charcoal-to-silver ratios were remarkably similar: approximately 1,200 kilograms of charcoal for every kilogram of refined silver. Based on this evidence, the authors assumed that charcoal-to-silver ratios remained roughly constant throughout the colonial period and from one mining region to another. Finally, the authors relied on contemporary fieldwork to estimate a timber-to-charcoal ratio, measured in terms of both volume of wood and surface area of forest timber. (9)

Studnicki-Gizbert and Schecter's methods are not unusual for environmental historians who often rely on contemporary scientific models and/or data to interpret the past. But, the methodology also raises several questions: What if the nearly identical charcoal-to-silver ratios found in the two hacienda account books separated by one hundred and seventy years is a coincidence? Also, can we assume that charcoal-making methods have remained static across time and space, a critical assumption undergirding the reliance on contemporary fieldwork to determine charcoal-to-wood ratios? Finally, how do we know that the species composition and relative population densities of contemporary forests in Mexico are not significantly different from those of a sixteenth- or seventeenth-century forest?

The concise article by Studnicki-Gizbert and Schecter is a wonderful example of how environmental historians can draw on different forms of evidence to make bold claims. Moreover, because the authors' make transparent their methodology, the article can also serve to show how new evidence could undermine (or confirm) the findings. Finally, the attempt to quantify the geographical area potentially deforested over the course of three centuries by silver mining can help students to come away with a stronger sense of what "significant" or "transformative" environmental change meant prior to the advent of fossil fuels. Silver mining's consumption of fuel may not have contributed to environmental change on a planetary scale, but it undeniably degraded forests in Mexico while contributing to at least one catastrophic event in Potosi.

Viewing the history of silver from an environmental perspective encourages students to think about how economic production took place before the rise of fossil fuels: wind, water and wood, along with mammalian muscles powered the first globalization. The interoceanic circulation of silver drove the transformation of regional environments largely due to this biological energy regime. Environmental history, therefore, can help to focus student attention on the specific localities that literally powered the trade circuits that are so central to world history.

John Soluri, Carnegie Mellon University

(1) Note that there is no article-length, English-language text that covers the environmental history of Potosi. Although there is obvious value in comparing silver mining in Potosi and colonial Mexico, some students invariably get the two settings confused when writing their papers (perhaps understandable since few general readers would assume that Potosi and San Luis Potosi are separated by some 5,000 kilometers!)

(2) Marcos Jimenez de la Espada, Relaciones Geograficas de Indias: Peru. A valuable collection of translated primary sources is found in John H. Parry and Robert G. Keith, New Iberian World: A Documentary History of the Discovery and Settlement of Latin America to the early Seventeenth Century, 5 volumes, Times Books and Hector and Rose, 1984. Also see, Mary Van Buren and Barbara H. Mills, "Huayrachinas and Tocochimbos: Traditional Smelting Technology of the Southern Andes," Latin American Antiquity 16 (2005): 3-25.

(3) Daniel W. Gade, Nature and Culture in the Andes, (Madison, Wisconsin: University of Wisconsin Press, 1999).

(4) On the labor power central to silver mines, see Peter Bakewell, Miners of the Red Mountain: Indian Labor in Potosi, 15451650 (Albuquerque, New Mexico: University of New Meixico Press, 1984); and, for colonial Mexico, also by Bakewell, Silver Mining and Society in Colonial Mexico, Zacatecas 1546-1700 (Cambridge: Cambridge University Press, 2002).

(5) Kendall Brown, "Workers' Health and Colonial Mercury Mining at Huancavelica, Peru," The Americas 57 (2001): 467496; and Nicholas A. Robins, Mercury, Mining, and Empire: The Human and Ecological Cost of Colonial Silver Mining in the Andes (Bloomington: Indiana University Press, 2011).

(6) I first came across this event in Spanish- and French language-sources including Alain Gioda, Carols Serrano and Ana Forenza, "Les ruptures de barrages dans le monde: un nouveau bilan de Potosi (1626, Bolivie)" Houille Blanche, 4-5 (2002): 165-170; and Carlos Serrano Bravo, Historia de la Mineria Andina Boliviana, siglos XVI-XX(Potosi, Bolivia: 2004). For an early English-language source see, William Rudolph, "The Lakes of Potosi," The Geographical Review 26 (1936): 529-554.

(7) Daviken Studnicki-Gizbert and David Schecter, "The Environmental Dynamics of a Colonial Fuel Rush: Silver Mining and Deforestation in New Spain, 1522-1810," Environmental History 15 (2010): 94-119.

(8) Note that I do not teach the Jevons Paradox in the introductory survey course discussed here.

(9) Fortunately, for instructors interested in having students work with primary sources, some of the key evidence used by the authors is available via the web. Historian Richard Garner has posted data sets from the Spanish royal treasuries on a website. Interpreting the data tables is not straightforward, but Garner provides user guides: [accessed 23 Aug. 2013]. A print version of the royal treasury documents also exists: John J. TePaske, Herbert S. Klein et al. The Royal Treasuries of the Spanish Empire in America 4 vols. (Durham, NC: Duke University Press, 1982). In addition, a beautiful late sixteenth-century map discussed in the article (but poorly reproduced in the print version of the journal) can be downloaded as a PowerPoint slide http://envhis.oxfordjournals. org/content/15/1/94.full [accessed 23 Aug. 2013].
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Title Annotation:Special Section: Global Environmental History
Author:Soluri, John
Publication:World History Bulletin
Article Type:Essay
Geographic Code:4EUSP
Date:Sep 22, 2013
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