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Bacteria are highly social organisms that frequently engage in cooperative and competitive interactions to successfully survive and reproduce. Examples include cell-to-cell communication, nutrient scavenging, and chemical warfare. However, the vast majority of our understanding of bacterial sociality has come from the laboratory strains of a small number of gram-negative social evolution model organisms, such as Pseudomonas spp. and Escherichia coli. In my thesis, I aim to expand our understanding of bacterial sociality in natural populations and further across the bacterial tree of life. I do this using two different approaches. Firstly, I use laboratory experiments and sequence analysis to study the evolution and ecology of bacteriocin-mediated competition in natural S. aureus populations, sampled as part of a carriage study on human nasal passages. Theory and laboratory experiments to date have provided extensive evidence that bacteriocin production plays a key role in determining the competitive dynamics of bacterial strains, however evidence from natural populations to support this hypothesis is lacking. I find that inhibitory strains were associated with the propensity to displace competing strains from the nasal cavity, which occurs despite inhibitory activity not being displayed by the majority of strains and targeting interspecific over intraspecific competitors. I also provide evidence for the genetic underpinnings of bacteriocin activity, by identifying five bacteriocin gene clusters associated with inhibition. Secondly, I use a comparative approach to study the role of horizontal gene transfer in stabilising cooperation across bacteria. Bacterial cooperation is typically mediated by the secretion of extracellular public goods, which are costly molecules that provide a fitness benefit to neighbouring cells. Cooperation can be destabilised by the invasion of selfish 'cheats' that reap the benefit of public good production without paying a cost. It is widely accepted that horizontal gene transfer, especially via plasmids, can allow cooperators to 're-infect' cheats with the gene for a cooperative trait, thus stabilising cooperation. Although theoretical and experimental studies have provided evidence to support this hypothesis, a comprehensive genomic study that controls for phylogenetic non-independence across species remains to be conducted. The results from our analysis of plasmid genes from 51 diverse bacterial species do not support the cooperation hypothesis across bacteria and are instead supportive of environmental variability as a determining factor in the relationship between horizontal gene transfer and extracellular proteins. Taken together, this thesis provides a body of work that emphasises the importance of testing predictions from theoretical and laboratory experiments in natural populations, and across diverse species.

Background: The epidemiology of inflammatory bowel disease (IBD) in the UK is poorly described. Primary care contraceptive prescribing data published by the NHS are not linked to individual patients. Studies have linked contraceptive pills to the development of IBD. However, there is a paucity of literature on how contraceptive formulation and duration of therapy affect IBD risk. Aims: To describe changes in the incidence and prevalence of IBD in the UK from 2000-2018. To describe non-barrier contraceptive prescribing patterns in primary care over the same period. To investigate the associations between exposure to contraception and development of IBD. Methods: Three epidemiological studies using IQVIATM Medical Research Data; a cohort study examining temporal trends in IBD incidence and prevalence, a repeated cross-sectional study exploring trends in contraceptive prescribing, a nested case-control study investigating the associations between a range of contraceptives and development of IBD. Results: Overall, the incidence of IBD is falling, but prevalence continues to rise. Some of the highest recorded incidence and prevalence rates globally were observed, with a 94% rise in incidence in adolescents since the year 2000. Over the same period, combined hormonal contraception prescribing has halved whereas progestogen-only pill prescribing has more than doubled. Methods of contraception prescribed by GPs are influenced by social deprivation. Withdrawal of a pay-for-performance incentive may have adversely affected adolescent long-acting reversible contraception uptake. Results suggest that oestrogen-containing contraception is associated with development of IBD whereas progestogen-only methods have minimal to no effect. Conclusion: This thesis provides evidence relating to a wide range of temporal trends in the epidemiology of IBD and patterns of contraceptive prescribing in the UK. Although previous associations between oral contraceptive pills and IBD have been made, this thesis provides the first epidemiological evidence that oestrogen-containing contraceptives, but not progestogen-only methods, are associated with development of IBD.

Some have claimed that human life is inevitably meaningless because we are mortal. Others have claimed the opposite: that life would be meaningless if we never died, and our being mortal is actually an essential condition for our lives to have any meaning at all. The aim of this thesis is to evaluate the arguments that have or could be used to support these claims, and come to a conclusion about which position, if either, is correct. Part One provides an introduction to the problem and an overview of various accounts of meaningfulness which can be found in the literature before outlining a broader and more defensible amalgam theory of meaningfulness. According to this theory, a life is ideally meaningful if and only if, and to the extent that, it contains sufficient degrees of purposefulness, significance, and coherence. In Part Two, the thesis moves on to systematically consider arguments that immortal life would be meaningless because it would lack each of these three essential ingredients of meaningfulness. In every case, immortality is defended against such arguments. Part Three covers the counterpart arguments which might be aimed at mortal life and reaches a comparable conclusion. Part Four summarises the findings and lessons of the thesis. In short, mortality can affect the meaningfulness of our lives in various ways, as would its absence. Nevertheless, mortality is neither entirely destructive of life’s meaningfulness nor one of its necessary conditions; a life can be meaningful whether or not it ends in death.

Introduction - The submission consists of six visual artist’s book-works (1988-2009) that form the content of the landmark geographical visual art project, The Atlas of Emptiness and Extremity (1987- ). The accompanying essay describes the context, method and contributions of this immense sea-picture project. Context - The Atlas photographs identify, examine and report on the seas surrounding us. The Atlas publications accentuate the visual immediacy of the individual site specific, mutually indexical experiences of singularly making sea-photographs in “the far field”, and later, viewing these thematic picture-groups as a reader. The publications provide short locatory texts for each picture and basic background information into the adjoining cartographical, historical and cultural geographies particular to these remote places. The Atlas publications probe the complacent visual vocabulary of traditional sea-pictures, challenging their customary pictorial conventions. The Atlas pictures declare the establishment of a recognisably new pictorial space within the sea-picture tradition. They develop an abstracted visual narrative to portray the abstract metaphorical human concerns around - extremity, the edge and emptiness. Method - The Atlas Project requires a process of on going, far-distanced expeditionary, site specific, remote field exploration, to enable its picture-making goals. I organise the direction, purpose and content of all of these expeditions. The methods employed are simple and strict. I only ever make one single, unique photograph from any site. I always use the same nineteenth century camera and lens. The precise placements of locational field events are layered into the photographs to ensure a convincing indexical picture space. The nuanced use of an extreme photographic grey-scale is built into the photographs at the negative exposure and darkroom printing stages. This extensive optical tonal-range physically provides The Atlas pictures with their intense pictorial surface densities and increases the sensation of their complex visual tactility. Most photographs are unable to, or incapable of, physically conveying these visual-emotional perceptions. Every stage of the project is my original concept, work and the result of my own thought processes. The results of this effort are unique images made in remote places. Three of those places were newly charted and explored as the result of my expeditions. Contributions - The interiorised pictorial approach developed for the entire Atlas restores compressed, complex indexical pictorial space to photographic depiction. The Atlas publications examine this space, and through it expand the notions of representation and expectation in outdoor photographs. The Atlas photographs speak to the improvisational opportunities available beyond the edge of representational certainly, determined in their new abilities to photographically heed the remote liminal territorial experiences close to this project. The publications propose and verify a new territorial form of terra incognita. The Atlas of Emptiness and Extremity provides the only visual geographical map of the imagination for this unexplored territory. Conclusion - The Atlas of Emptiness and Extremity is one of the most inventive, geographically comprehensive, single-author analogue photographic fine art projects in the world today.

This thesis examines the scope and nature of natural science in the Hellenistic world using a diverse assemblage of artistic and visual material surviving from Hellenistic and Imperial times. In doing so, it provides a fresh insight into the intellectual climate that is often heralded as a hallmark of the Hellenistic age. Following an introductory chapter that sketches some of the historical background against which developments in the natural sciences need to be set, the thesis is divided into two principal parts. The first focuses on a series of compositions containing representations of animals accompanied by identifying labels composed in Greek: the painted frieze of the Tomb of Apollophanes in Marisa; the Nile Mosaic at Praeneste; and the verso of the Artemidoros Papyrus. These compositions, it is argued, testify to a culture of describing, depicting, cataloguing and classifying exotic animals upon encountering them in faraway lands, which originated in royal circles in Ptolemaic Alexandria, before spreading down the social and artistic spectrum. The second part of the thesis concerns a selection of mosaics and wall paintings that contain astonishingly naturalistic representations of animals: the late Hellenistic fish mosaics from Praeneste, Pompeii and Panisperna; a series of mosaics excavated in and associated with Attalid Pergamon; and our surviving corpus of garden paintings from Latium and Campania. These compositions demonstrate that animals were sometimes kept in captivity and studied in close detail in the Hellenistic world, probably with a combination of scientific and decorative ends in mind. They also provide important information concerning the ways in which detailed images were transmitted and re-produced during antiquity. A picture will emerge of a world in which the animal kingdom played an important role in defining power and privilege, particularly among the uppermost echelons of society.