A Cultural Phylogenetic Approach to the Evolution of Complex Societies

Abstract

Human societies became vastly more complex over the course of the Holocene. Cultural evolutionists seek to understand how and why this transition occurred. Key questions are the extent to which cultural evolution follows consistent paths, and the importance of the various factors thought to drive the process. Cultural phylogenetic methods provide a relatively new way of exploring these questions and others. This thesis presents four studies that employ a cultural phylogenetic approach to investigate a range of questions about the course, causes, and consequences of cultural evolution. Three of these studies involve Austronesian-speaking societies, and one is global. In Chapter One, I provide a broad overview of the theoretical and methodological background to these studies. I define key terms, outline the domains into which cultural traits are traditionally divided, and discuss the distinction between 'materialist' and 'idealist' theories of cultural evolution. I also describe phylogenetic methods, their applicability to the study of cultural evolution, and the ways in which they complement and extend upon more traditional methods, before providing a brief overview of the chapters that follow. In Chapter Two, I present a coevolutionary study of intensive agriculture and socio-political complexity, which relates directly to the question of material versus social and ideational drivers of cultural evolution. I find strong evidence that the two traits coevolve, and that the relationship between the two is reciprocal rather than directional. In Chapter Three, I present a study that tests models of the sequential evolution of political complexity in a global sample of societies, and find that political complexity increases, and perhaps also decreases, by one level at a time. In Chapter Four I present a second coevolutionary study, this time focusing on the relationship between two different forms of authority: religious and secular. Again I find strong evidence of coevolution, but no consistent evidence of a directional relationship. In Chapter Five, I present a study of the predictors of population decline in the Pacific Islands, which includes cultural as well as other variables. In Chapter Six, I provide a brief discussion of the overall implications of these studies.