“Agnes Arber’s Unity in Diversity: The Role of Analogies in Plant Morphology, Philosophy of Science, and Beyond”

Andre Hahn (Oregon State University)

When dealing with large amounts of observational information in the life sciences, comparative approaches have offered an initial step in bringing conceptual order. With plant morphology, the information in question is plant forms, out of which morphologists have developed conceptual types. These types have identified commonalities both internal to individual plants and across groups of plants, often times within one theory. Agnes Arber's (1879-1960) partial-shoot theory of the leaf offered one such attempt at integration. Faced with a strong movement among botanists to reorient morphology around phylogeny, Arber sought to maintain a “pure morphology” characteristic of pre-Darwinian morphologists like Johann Wolfgang von Goethe (1749-1832). Arber’s theory united Goethe’s identification of the “leaf” as the proteus plant form with contemporary theories identifying the shoot as the fundamental morphological unit, thus reinterpreting floral structures as analogous to both partial-shoots and metamorphosed leaves.

While honing her comparative skills in plant morphology, Arber worked towards a larger perspective. For one, she integrated physiology and biochemistry into her morphological comparisons. Additionally, inspired by her mentor Ethel Sargant (1863-1918), Arber developed the use of analogical proof in morphology and identified its fundamental role in the thought of scientists such as Newton and Darwin. By playing such a foundational role, analogy opened up the sciences to epistemic connections with other modes of human inquiry such as art and mysticism. Overall, analogy offered Arber a synthetic mode of thought which could potentially bring unity, not only to plant forms, but human thought.

“Comparing Place: The Challenges of Deep Time to Ecological Reconstructions”

Melissa Charenko (University of Wisconsin-Madison)

Beginning in the 1910s, paleoecologists in Scandinavia and North America began reconstructing past vegetation and climate using fossilized microorganisms which served as indirect measurements of those variables. To use these microscopic proxies for historical reconstructions, paleoecologists commonly compared the genera present at a given location at different moments of time. By examining fluctuations within the different genera and accounting for their ecological preferences, paleoecologists created a picture of the changes that took place at that location. Yet conclusions in paleoecology were rarely straightforward, in part because many inferences were required to support these comparisons and the resulting conclusions.

Using a discussion of “place,” the particular ecological features of a field site, as a window into the comparative nature of paleoecology, this paper explores how ecological conclusions depended on correctly characterizing the spatial and temporal extent captured by fossilized microorganisms, which were the basis of conclusions in paleoecology. Paleoecologists knew that particular material environments affected their results. Their results were highly place-specific due to local processes like erosion and deflation. Yet, at the same time, paleoecologists recognized that the microorganisms which were the basis of their comparisons were likely not bound to the area immediately surrounding these sites as there were differential production, dispersal and preservation rates among their microscopic proxies. How did paleoecologists balance the local with the more placeless to create a robust picture of the past? What was the status of knowledge generated through these methods? This paper explores these questions.

“Comparative Imperial Caribbean Botany and The New York Botanical Garden”

Darryl Brock (CUNY Borough of Manhattan Community College)

The New York Academy of Sciences initiated the Scientific Survey of Puerto Rico in 1913, driven by the New York Botanical Garden; the project helped the Garden pursue comparative studies at multiple levels. First, evolution represented a key Garden interest. These new Caribbean collections from Puerto Rico could be compared with other Garden flora holdings from Cuba, Jamaica and even South America to characterize plant distributions and thus determine evolutionary relationships. A second basis for comparative study arose from the imperial nature of the Survey. The Garden sought to emancipate American botanical science from European type collections; accordingly, the institution paid careful attention to filling lacunae in American holdings. This had the benefit of providing a chronological basis for exploring potential speciation in that European collections represented specimens taken fifty years to a century earlier than those made under the Survey. Finally, a third basis for comparative study rested in the expertise on the cactus (plant family Cactaceae) by the Garden’s founder, Nathaniel L. Britton. These plants represented a taxon native almost exclusively to the Americas; accordingly, Britton prepared the definitive study on them during 1919-1923 while also directing the Scientific Survey. He sought not only to define the distribution of the cactus, but to understand its evolutionary adaptations to diverse environments. The Scientific Survey afforded an opportunity to study the cactus in Puerto Rico’s key terrain, as well as its uninhabited, undisturbed islands, to compare their distribution and phylogenetic differences from specimens on the South and Central American mainland.

“'Parasites, Moochers, Looters': Comparative Narratives of Adaptation in mid-20th-Century Parasitology”

Rachel Mason Dentinger (University of Utah)

Parasites have long had a bad rap; from freeloaders to menacing agents of disease, rhetoric has tarnished an entire mode of animal nutrition with social censure. Ayn Rand’s 1961 vision of human society illustrates this discourse, in which idealized “independent” and “productive” people are preyed upon by dependent “parasites, moochers, [and] looters.” Such analogies have intuitive appeal, especially after comparing parasitic organisms with their close kin: Who wouldn’t feel some disdain for the liver fluke, lurking in the bile ducts of its host, while its free-living planarian relative roams the pond-floor, stalking its own food? Since the early 20th century, parasitologists have regularly drawn comparisons like these, between parasites and their free-living relatives, using them to argue that parasites evolved from autonomous ancestors. This reconstruction of the history of parasitism seems to suggest freedom restricted, options constricted, and lost adaptation—all of which resonate with the cultural connotations of parasitism. However, parasitologists themselves have interpreted these comparisons differently, using them to directly challenge narratives that paint parasites as products of regressive evolution. To them, parasitism represents superior adaptation, exquisite specialization that is characterized—if paradoxically—by evolutionary simplification in anatomical and physiological features. This paper examines how mid-20th-century parasitologists in the United States and Europe used comparative methods to argue that being “independent” and “productive” was overrated. Instead, these scientists openly admired their parasitic subjects, using comparison to argue that loss of function was actually a refined form of evolutionary gain.

“Coming into its Own as a Science? Comparing Human and non-Human Animal Brains in the mid-20th Century”

Kathryn Schoefert (King's College London)

Historical analyses of Big Data have highlighted the continued relevance of comparative approaches throughout the twentieth century, but support has not been universal. Some disciplinary traditions heavily dependent on comparison struggled to remain relevant after 1900—notably, among them, animal morphology. Repeated accusations of ‘brain mythologies’, for instance, challenged neuropathologists’ and neuroanatomists’ on-going morphological studies of human, and non-human animal, brains. After the Second World War, comparative studies, however, found new impetus. RJM Innes and LZ Saunders thus positioned their joint-authored Comparative neuropathology (1962) as a vital counter-balance to obsessive microbe-hunting, highlighting disease analogies and arguing that comparative neuropathology had now ‘come into its own as a science’. Whereas pre-war investigators had concentrated on typical species—cat, dog, and monkey—, peers of Innes and Saunders were mapping out species diversity and normal variation within genus and family. This paper examines the state of the comparative project in the brain sciences in the 1960s, speculating on the significance of comparison for its relationships to clinical and biological disciplines. How did researchers, moreover, perceive and present their comparative approach in light of the emerging identity of the ‘neurosciences’ which lionised modelling biological processes?