The Fate of the Method of ‘Paradigms’ in Paleobiology

An earlier article described the mid-twentieth century origins of the method of “paradigms” in paleobiology, as a way of making testable hypotheses about the functional morphology of extinct organisms. The present article describes the use of “paradigms” through the 1970s and, briefly, to the end of the century. After I had proposed the paradigm method to help interpret the ecological history of brachiopods, my students developed it in relation to that and other invertebrate phyla, notably in Euan Clarkson’s analysis of vision in trilobites. David Raup’s computer-aided “theoretical morphology” was then combined with my functional or adaptive emphasis, in Adolf Seilacher’s tripartite “constructional morphology.” Stephen Jay Gould, who had strongly endorsed the method, later switched to criticizing the “adaptationist program” he claimed it embodied. Although the explicit use of paradigms in paleobiology had declined by the end of the century, the method was tacitly subsumed into functional morphology as “biomechanics.”     

The anatomy of ‘race trouble’ in online interactions

South Africa has a long history of race-related conflicts in a variety of settings, but the use of the concept ‘racism’ to analyse such conflicts is characterized by theoretical and methodological difficulties. In this article, we apply the alternative ‘race trouble’ framework developed by Durrheim, Mtose, and Brown (2011) to the examination of racialized conflicts in online newspaper forums. We analyse the conflicts using an approach informed by conversation analytic and discursive psychological techniques, focusing in particular on the emergence and use of race and racism as interactional resources. Our findings reveal some mechanisms through which the continuing salience of race in South Africa comes to be reproduced in everyday interactions, thereby suggesting reasons why race continues to garner social and cultural importance. Disagreements over the nature of racism were also recurrent in the exchanges that we examined, demonstrating the contested and shifting meanings of this concept in everyday interactions.     

The fate of ‘biodegradable’ plastics in municipal leaf compost

Summary Blends of starch with polypropylene, starch with polyethylene, polycaprolactone with polyethylene, and a copolymer of -hydroxybutyrate and -hydroxyvalerate (PHB/V) were exposed to degrading leaves in a municipal leaf composting operation. Every month for 6 months, duplicate samples were analyzed for changes in weight and tensile properties, and many of these samples were further analyzed for changes in molecular weight and surface morphology. All results were compared to controls which were incubated for 6 months in moist, sterile leaves at a leaf compost temperature. Very little change was noted for any of the polyolefin blends over the 6-month period. In contrast, PHB/V samples showed massive deterioration with substantial weight loss. Although there was a decrease in molecular weight and a loss of tensile properties in leaf-exposed PHB/V films, the sterile control films also showed similar changes, but without weight loss. Of the microbial isolates from film surfaces, only fungi possessed PHB/V depolymerase activity.     

The fine structure of ‘homology’

There is long-standing conflict between genealogical and developmental accounts of homology. This paper provides a general framework that shows that these accounts are compatible and clarifies precisely how they are related. According to this framework, understanding homology requires both (a) an abstract genealogical account that unifies the application of the term to all types of characters used in phylogenetic systematics and (b) locally enriched accounts that apply only to specific types of characters. The genealogical account serves this unifying role by relying on abstract notions of ‘descent’ and ‘character’. As a result, it takes for granted the existence of such characters. This requires theoretical justification that is provided by enriched accounts, which incorporate the details by which characters are inherited. These enriched accounts apply to limited domains (e.g. genes and proteins, or body parts), providing the needed theoretical justification for recognizing characters within that domain. Though connected to the genealogical account of homology in this way, enriched accounts include phenomena (e.g. serial homology, paralogy, and xenology) that fall outside the scope of the genealogical account. They therefore overlap, but are not nested within, the genealogical account. Developmental accounts of homology are to be understood as enriched accounts of body part homology. Once they are seen in this light, the conflict with the genealogical account vanishes. It is only by understanding the fine conceptual structure undergirding the many uses of the term ‘homology’ that we can understand how these uses hang together.     

The ‘curse’ of Westermarck 1

This article consists of a critical application of recent theory of nationalism to the unusual case of Mauritius. It is a poly‐ethnic and poly‐religious society whose inhabitants neither share a mythical distant past nor consider themselves culturally identical, but where nation‐building has nevertheless been moderately successful since the late 1960s. Through an examination of the processes of institutional and cultural nation‐building in the island, it is argued that the current Eurocentric view of the nation (notably as a culturally homogeneous imagined community) must be modified to fit cases like this one. Thus, the value of nationalism and nationhood as comparative concepts is questioned.     

The spectre of ‘spurious’ correlations

Summary Ecologists often standardize data through the use of ratios and indices. Such measures are employed generally to remove a size effect induced by some relatively uniteresting variable. The implications of using the resultant data in correlation and regression analyses are poorly recognized. We show that ratios and indices often provide surprising and spurious results due to their unusual properties. As a solution, we advocate the use of randomization tests to evaluate hypotheses confounded by spurious correlations. In addition, we emphasize that identifying the appropriate null correlation is of utmost importance when statistically evaluating ratios, although this issue is frequently ignored.     

The message of ‘The Other North Sea’

This paper explains the objectives of organising the symposium ‘The Other North Sea’. A major goal is the submission of the conclusions and content of this symposium to the North Sea Task Force, an initiative of the Second Conference on the Protection of the North Sea (London, 1987) which is responsible for preparing a Quality Status Report on the North Sea by mid-1993. The conclusions and recommendations of the symposium are summarised and presented to the North Sea Task Force in connection with the preparations for the 1993 Quality Status Report. The paper stresses the need to subdivide the North Sea into areas of ecological entity and underlines the advantages of using diatom and meiofauna assemblages as indicators for present and past environmental actors in sediment conditions. A plea is also made for the promotion of research to improve understanding of disturbance of sensory perception and behaviour as an ecologically relevant early warning signal. The major role of fisheries in inducing changes of seabird and harbour porpoise populations is highlighted.     

The Meaning of ‘Self-Starvation’ in Impoverished Black Adolescents in South Africa

Recent surveys in South Africa have demonstrated that disordered eating is equally common among black and white female students. Self-report measures have been used in these surveys to establish levels of disordered eating. One study in Tanzania, where a two-stage design was implemented, showed that upon interview the majority of participants did not present with disordered eating. The absence of two-stage studies in South Africa brings into question some of the findings from these surveys. In the present study, we surveyed a sample of black and white high school students in South Africa to establish the prevalence of disordered eating. In the second phase of this study, we attempted to interview those black students from one particular school who scored high on the eating disorder measures. This process proved both challenging and elucidating. While a significant number of young black females endorsed eating disorder symptoms on self-report, interviews with some participants showed that self-starvation and related symptoms had a different meaning from what we would typically expect from someone with an eating disorder. Consequently, this study highlights the need to revisit the methods typically employed in cross-cultural research in eating disorders. Careful consideration of a variety of cultural factors that may alter the meaning of standard measures is called for.     

The role of ‘soaking’ in spiteful toxin production in Pseudomonas aeruginosa

The ubiquitous production of antibacterial toxins, such as bacteriocins, is an ecologically significant class of interbacterial interactions that have primarily evolved through their indirect fitness benefits to the producer. Bacteria release bacteriocins into the environment at a cost to individual cell, but individual bacteriocin-producing cells are unlikely to gain any direct benefit from their own toxin; indeed, cell lysis is required in many species. There is a growing body of research describing the ecological conditions that can favour the evolution of bacteriocin production. However, an important aspect of many bacteriocins has yet to be investigated: the ability of bacteriocin-producing cells to neutralize toxin (‘soaking’) produced by other clonemates. By competing Pseudomonas aeruginosa bacteriocin-producing wild-type and ‘non-soaking’ strains against a bacteriocin-susceptible strain, we find that soaking markedly reduces the fitness of a bacteriocin-producing strain at both high and low frequencies.     

The role of iron in the formation of Ediacaran ‘death masks’

The Ediacara biota are an enigmatic group of Neoproterozoic soft-bodied fossils that mark the first major radiation of complex eukaryotic and macroscopic life. These fossils are thought to have been preserved via pyritic “death masks” mediated by seafloor microbial mats, though little about the chemical constraints of this preservational pathway is known, in particular surrounding the role of bioavailable iron in death mask formation and preservational fidelity. In this study, we perform decay experiments on both diploblastic and triploblastic animals under a range of simulated sedimentary iron concentrations, in order to characterize the role of iron in the preservation of Ediacaran organisms. After 28 days of decay, we demonstrate the first convincing “death masks” produced under experimental laboratory conditions composed of iron sulfide and probable oxide veneers. Moreover, our results demonstrate that the abundance of iron in experiments is not the sole control on death mask formation, but also tissue histology and the availability of nucleation sites. This illustrates that Ediacaran preservation via microbial death masks need not be a “perfect storm” of paleoenvironmental porewater and sediment chemistry, but instead can occur under a range of conditions.     

The Political Economy of ‘Trauma’ in Haiti in the Democratic Era of Insecurity

This article explores the challenges that emerge at the intersection of economies of compassion and terror: local, national, and international forms of humanitarian assistance; security practices in insecure social and institutional environments; questions of victimization and global reparations; and quests for justice, as revealed through an analysis of political violence and humanitarian interventions in Haiti during and after the 1991-94 coup period. Each domain is constrained by politics and history but can engender "occult economies" that challenge the intended consequences of restitution policies at international, national, and local levels of exchange. 'Trauma' and discourses about traumatic suffering are the hinge around which these economies pivot, generating new forms of political subjectivity for Haitian activists.