Melissa Charenko is a Ph.D. Candidate in the Department of the History of Science at University of Wisconsin-Madison. She is a 2016-2017 Consortium Research Fellow.
In 1936, ecologist Paul B. Sears went on the radio. Sears urged listeners to “imagine an unbroken prairie… in four thousand years of wind and rain, that prairie would lose only as mush soil as will be washed away in ten years after man arrives. For man must eat. So, he breaks the soil, plows, raises crops, and leaves the land bare.” Human actions, in Sears’ view, were leading to desertification and the Dust Bowl. Sears went on to explain that “the branch of science that deals most directly with this problem is ecology – the science of living things, plants, animals, and man, in relation to their environment. The ecologists sees these in perspective and in that sense can look ahead for the future.” Sears thought that ecological perspective came from uncovering relationships between natural and human history over scales longer than the space of human observation, which offered lessons about the proper ways to manage the land.
Sears was one of many scientists interested in environmental change. In the early twentieth century, these scientists struggled to find ways to know this hidden past in order to help understand the links between human action and environmental change. To understand the past and prognosticate about future change, scientists perfected a new tool: environmental proxies, which permitted indirect measurements of previous environmental states. With these proxies – particularly fossilized pollen, algae and other micro-organisms – scientists began to learn about environmental change over unprecedented historical timescales. Information about environmental change was then correlated with human history to reveal patterns of influence between humanity and its environment. Over the course of the 20th century, the “paleo” sciences that performed this proxy work – “paleoecology,” “paleolimnology,” and “paleooceanography” – moved from relative obscurity to centrally valuable in the study of anthropogenic change; they became the historians of the environment, self-styled prophets who would help prevent us from repeating humanity’s mistakes. My dissertation follows these proxies and prognosticators as they tell the tale of the exploration of deep time in a quest to understand anthropogenic environmental change. I argue that in spite of the uncertainties of working with proxies, proxy work facilitated the integration of humanistic and scientific methods of studying the past, permitting the exchange of evidence and new interpretations of anthropogenic environmental change.
To understand developments in the paleo-disciplines, I examine the techniques that paleo-scientists used to study the past. By the end of the nineteenth century, scientists from a number of disciplines began to suggest that the changing composition of fossilized microorganisms found in sediments could reveal changes in the environments in which the fossils were deposited. Tracing fluctuations within different vegetation genera using fossilized pollen, for example, could help reveal the climatic conditions that give rise to that vegetation and the pollen found in the geologic record. A period of excitement and uncertainty ensued, with scientists eager to harness the potential of fossil pollen, marine microorganisms, microscopic algae and other proxies to reconstruct past conditions. Many, however, were frustrated by the difficulties of carrying out the science, as proxies turned out to be incredibly difficult to correlate with past environments. My work shows that these difficulties led to the marginalization of the paleo-disciplines in the twentieth century, but also created opportunities for collaborations with disciplines such as archeology, which had similar uncertainties when it came to dating artifacts and making inferences from scant or scattered evidence. Exploring the relationship between the paleo-disciplines and other disciplines which examine deeper timescales helps to show that historians need to move beyond the institutions, moral economies, technologies, and intellectual traditions in order to explain scientific collaborations. Historians also need to examine the role of spatial and temporal scales play in cross-disciplinary exchanges: in my work, I show how longer timescales and increasingly large spatial scales engendered some collaborations between paleo-scientists and humanists, but not others.
With the generous support from research fellowship through the Consortium, I was able to visit four archives with holdings that reveal the extent to which ecological study over deep time shed light on anthropogenic change. At Yale University, I examined Paul B. Sears’ papers. Sears was the first to use fossilized pollen to correlate changes in past environments with the rise and fall of ancient civilizations, thereby popularizing pollen analysis in the United States. Yale’s archives are also home to Ellsworth Huntington’s papers. Huntington was a prominent geographer who developed a popular theory of climatic determinism, where environmental conditions predisposed societies to certain forms of development. These archives help to show how an ecologist like Sears sought to determine whether climate or human activities played a larger role in desertification. Huntington had posited that climate was central, but, using pollen analysis in his study of empires like the Maya, Sears claimed that the Mayan civilization had failed because of poor agricultural practices, rather than a changing climate. The records at Yale allowed me to examine the relationship between Huntington’s ideas and Sears’ theories, and to establish how the long time-scales that proxies could be used to investigate started to change the way human’s role in environmental change was understood: no longer was climate the main driver of change; no longer was the engineer or politician the solver of environmental problems. Instead, scientists claimed that anthropogenic actions led to environmental change and ecologists would solve these problems.
With a Consortium fellowship, I visited the Linda Hall Library as well as the Academy of Natural Sciences (ANS) of Drexel University. Both have large collections related to proxies and environmental change: Linda Hall has over a hundred books related to pollen analysis, and the ANS has over 450 texts related to diatoms, a group of algae that was important in studying the health of lakes. The ANS also houses the collections of Ruth Patrick, a leading limnologist who used diatoms to study the effects of pollution on streams. These documents show how Patrick’s investigations into diatoms facilitated multidisciplinary research between limnologists, geologists, and zoologists.
I also traveled to the Smithsonian to examine the Joseph Augustine Cushman collection. Cushman was the leading scholar on foraminifera (a class of small marine invertebrates whose fossils served as proxies for ocean pH) in the first half of the twentieth century, publishing over 500 papers and authoring the first textbook on the subject. I show that his geophysical approach to studying foraminifera, as well as his institutional ties, had important consequences for how environmental change in the oceans was understood. Because of his job at Marland Oil and the US Geological Survey, where he used foraminifera to find petroleum deposits, Cushman was interested in the geology of oceans, and despite using foraminifera, largely ignored the biological dimensions of the ocean, except as they applied to the stratigraphy of organic deposits. Cushman’s prominence in this area of research, I suggest, encouraged other scientists to imitate his methods thus ignoring important biological and ecological questions about the health of the ocean’s marine life that could be addressed with this proxy. I argue that, because ecological concerns were largely ignored, the oceans were long seen as an acceptable sink for atmospheric CO2, despite the consequences of acidification on marine life that would occur.
Overall, a fellowship at the Consortium fellowship provided an opportunity to explore the trajectory of the paleo-disciplines and their relationship to anthropogenic environmental change. As a researcher interested in deep time, passing the triceratops holotype every morning on my way to the archives and the chance to see some rare books with beautiful illustrations of microorganisms was incredible. The archivists and staff at institution made each visit productive and memorable.