Social behaviour is common in nature. Yet, for over a century and half, scholars have struggled in vain to offer a satisfactory account of its evolution under Darwinian natural selection. In this thesis I propose that three fundamental assumptions in the Darwinian explanation of social behaviour are at the root of the problem. They are: 1. The basic Darwinian philosophy that evolutionary change occurs by one inherent trait replacing another in an organism. 2. The collapse of social behaviour, in its entirety, into a single, narrow concept called “altruism.” 3. The assumption that such “altruism” arises from a mutation at a single gene locus, where it supplants “selfishness” as an alternative allele. The thesis identifies some insights from Hume’s analysis of human morality and sociality that suggest the proper circumstances of social interactions in humans. We see from Hume’s analysis that nothing inherent in human nature needs to change in order to move beyond parenting to sociality. Hume identifies two principles in human nature — selfishness and empathy — that are the ultimate basis of human sociality. Empathy expands self-interest to include relatives and associates, but not strangers. And that suffices to form small, primitive human societies. For large, cosmopolitan societies, Hume suggests they are maintained only through human inventions such as governments and justice. Hume’s explanation precludes the need for a weaker “altruistic gene” to supplant a fitter “selfish gene” as a condition for social evolution, which has been the basis of the Darwinian explanatory difficulty. / Thesis / Doctor of Philosophy (PhD)

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Cooperation and cheater control have helped shape life as we know it, but there is still much to learn. A eukaryote microbial model organism, like Dictyostelium discoideum , is an excellent system for advancing our understanding. When faced with starvation, multiple genetically distinct clones of D. discoideum aggregate together to form a chimeric fruiting body with a sterile stalk that holds aloft a sorus of hardy reproductive spores. One clone may be able to cheat and form disproportionately more spores, while forcing others to form more stalk. Here we discuss the impact of genetic relatedness on cooperation, and how social actions are temporally organized and can be affected by environmental conditions. First, we documented a potential strategy for facultative cheating within chimeras. We showed that the first cells to starve, and initiate the social stage, cheat cells that starved later. In another paper, we reviewed recent studies of social microbes, which demonstrate the importance of high relatedness in the evolution of cooperation and cheater resistance. In an experimental evolution study, we tested the hypothesis that de novo cheater mutants readily evolve under low relatedness conditions. We found that the majority of our lines evolved to cheat their ancestor. Further, we studied obligate cheaters, which pose a great threat to sociality. They gain a reproductive advantage in chimeras, but cannot cooperate clonally to form fruiting bodies. Wild obligate D. discoideum cheaters have never been documented, but we found that obligate cheaters readily evolved under low relatedness conditions in the laboratory. In another study, we looked at the effects of light level on spore production in D. discoideum and Dictyostelium citrinum . Overall, more spores were produced in the light than in the dark, probably because of reduced movement and cell loss during the motile multicellular slug stage. We found that these effects were species, clone, and environment dependent. Taken together, this work helps us understand how cooperation thrives in nature, despite the threat of cheaters.

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The goal of this study is to develop a general theoretical perspective for the archaeological study of intersocietal interaction among hunter-gatherers. Several theoretical frameworks have been offered for the study of interaction, including acculturation, ecological interdependency, peer polity interaction, world-system theory, and a number of more particularist approaches. Although all offer valuable insights, only world-system theory has the potential for application to all types and scales of intersocietal interaction, past and present. The perspective developed here represents an experimental modification of the world-system perspective, with the addition of aspects of previous hunter-gatherer studies, most of which are strongly influenced by cultural ecology. / This theoretical perspective is used to develop a model of change in hunter-gatherer world-systems. Particularly important factors in this model are the density and spatio-temporal distribution of subsistence resources, and the availability of "preciosities" (exchanged objects of high value). These factors are hypothesized to affect hunter-gatherer world-systems in terms of three variables: (1) "breadth", the number of interacting regional groups; (2) "depth", the relative importance of the interaction to each regional group; and (3) "internal differentiation", the degree of variability among regional groups within the interacting system. Finally, the model is tested on the archaeological and ethnographic records of the Inuit inhabitants of Herschel Island, northern Yukon Territory, and adjacent regions during the "contact period" of the past 500 years. The test predictions are largely supported by the data, which indicate that the increasing availability of preciosities and the changing distribution of subsistence resources during the contact period caused the indigenous world-system to increase in depth and breadth, and to begin to change in pattern of internal differentiation.

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Florida State University, 2006. / Advisor: Neil Jumonville, Florida State University, College of Arts and Sciences, Dept. of History. Title and description from dissertation home page (viewed June 14, 2006). Document formatted into pages; contains vii, 273 pages. Includes bibliographical references.

Thesis (M.A.)--Bowling Green State University, 2006. / Document formatted into pages; contains v, 45 p. Includes bibliographical references.

'Culture' is defined as information, such as knowledge, beliefs, skills, attitudes or values, that is passed from individual to individual via social (or cultural) transmission and expressed in behaviour or artifacts. 'Cultural evolution' holds that this cultural inheritance system is governed by the same Darwinian processes as gene-based biological evolution. In Part A of this thesis it is argued that as compelling a case can now be made for a Darwinian theory of cultural evolution as Darwin himself presented in The Origin Of Species for biological evolution, If culture does indeed evolve, then it follows that the structure of a science of cultural evolution should broadly resemble that of the science of biological evolution. Hence Part A concludes by outlining a unified science of cultural evolution based on the sub-disciplines of evolutionary biology. Parts B and C comprise original empirical and theoretical work constituting two branches of this science of cultural evolution. Part B describes a series of experiments testing for a number of hypothesised biases in cultural transmission. Evidence was found for a 'social bias' that acts to promote information concerning third-party social relationships over equivalent non-social information, and a 'hierarchical bias' that acts to transform knowledge of everyday events from low-level actions into higher-level goals. Three other hypothesised biases concerning status, anthropomorphism and neoteny were not supported, although each gave rise to potential, future work using this methodology. Part C presents a theoretical investigation into the coevolution of the genetic bases of human mating behaviour and culturally inherited folk beliefs regarding paternity. Gene-culture coevolution and agent-based models suggested that beliefs in 'partible paternity' (that more than one man can father a child) create a new more polygamous form of society compared with beliefs in singular paternity (that only one man can father a child).

The continuing rise of antibiotic resistance is threatening a return to the world of pre-antibiotic medicine. Multi-drug resistant pathogens are already claiming lives and causing economic losses in developing and developed countries alike. We need, therefore, to understand what allows resistant strains to spread; what makes them evolutionarily competitive in and amongst other strains and species. The majority of laboratory studies of antibiotic resistance focus on simple growth in liquid culture. By contrast, microbes commonly grow as surface-associated communities, in which interactions between neighbouring cells have strong consequences for competition and evolution. My first goal was to understand how growth in such environments affects the success of a resistant strain. By competing an antibiotic resistant and susceptible strain of the pathogenic bacterium Pseudomonas aeruginosa, I found that growth in dense colonies on agar allowed a resistant strain to protect susceptible strains, to the extent that the susceptible strain may even prevail under antibiotic treatment. This effect was specific to a cooperative mechanism of antibiotic resistance, however; a β-lactamase enzyme that digests the antibiotics surrounding a resistant cell. A further, unexpected reason that susceptible cells could prevail was that they elongate under antibiotic treatment, allowing them to push shorter resistant cells aside in the competition for the growing edge of a colony. My work suggests that the rise of cooperative resistance mechanisms should be more easily suppressed than for non-social mechanisms. However, one major strategy to overcome antibiotic resistance is the use of antibiotic-adjuvants, drugs which inhibit a mechanism of antibiotic resistance. It is not clear if these adjuvants will tend to suppress or promote cooperative resistance mechanisms. I performed experiments to test the effects of inhibitory adjuvants on cooperative resistance. These revealed that the effects of adjuvants are varied. In liquid culture, an adjuvant inhibited resistance evolution, while, in colony experiments, it promoted resistance evolution by removing the cross protection of susceptible strains. Given the complexity and importance of antibiotic adjuvants, I developed an eco-evolutionary model to dissect these complexities associated with the combination of interacting microbial and molecular species. As in my experiments, the models identified conditions where an inhibitory adjuvant can increase selection for resistance. However, the theory also identifies scenarios for which adjuvants will delay resistance evolution by shutting down the associated evolutionary pathway. Broadening the modelling framework to include the stochastic effects of rare mutation, I found that early administration of adjuvant inhibitors can be a powerful way to suppress the emergence of antibiotic resistance. Microbial interactions are complex and affected by the growth environment. My thesis underlines that the study of antibiotic resistance will benefit from greater consideration of how bacteria interact and, more broadly, how their ecology and evolution determine the rise, or fall, of resistance.