Hominin Landscapes and Co- Evolutionary Ecology: Accommodating Logical Incoherence and Complexity Isabelle Catherine Winder Thesis submitted for the degree of PhD University of York, Department of Archaeology September 2012 Abstract Understanding primate (and human) evolutionary environments is a key goal of palaeoanthropology. The most recent contribution to this debate, the ‘tectonic landscape model’ (TLM) is the first to explicitly invoke either the spatial structure of environments generally or the physical landscape specifically as important to hominin evolution. It adds a layer of complexity to existing models and – if correct – has broader implications for the nature and analysis of evolutionary change. This thesis evaluates the TLM and its implications for palaeoanthropology. It explores the conceptual structure that surrounds the TLM to establish how this has so far impacted palaeoanthropology, then surveys the state-of- the-art in hominin landscape research to establish existing levels of knowledge. This suggests that little basic information is available about the structure of African landscapes themselves, their interactions with primates, or the possibility that complex cognition ‘removes’ humans from their influence. Three analytical designs are therefore developed which use landscape mapping techniques and a series of socioecological and anatomical case studies of Papio baboons and Homo sapiens to develop this baseline understanding. Although the landscape system is complex, it argues that it should be possible to explore the impacts of individual factors like topography and that there are interesting perspective- dependent relationships between landscapes and primate anatomy and socioecology, which persist in modern humans despite the considerable cultural ‘filter’ through which they view and interact with their surroundings. These insights are then used to extract three predictions from the TLM that are tested against existing knowledge of the fossil record and evolutionary pattern and process in the mammals. The key output is a new theory of human evolution, the ‘complex topography hypothesis’, which is shown to work at least as well as traditional explanations of the human evolutionary trajectory and the distinctive anatomies and ecologies of hominins including Homo sapiens. ~ 2 ~ Table of Contents ABSTRACT .................................................................................................................................. 2 TABLE OF CONTENTS ............................................................................................................ 3 TABLE OF FIGURES ................................................................................................................ 9 TABLE OF TABLES ................................................................................................................ 18 ACKNOWLEDGEMENTS ...................................................................................................... 21 AUTHOR DECLARATION ..................................................................................................... 22 CHAPTER ONE: INTRODUCTION AND THE CURRENT STATE-OF-THE-ART ..... 23 Introduction .................................................................................................................. 23 Background: Evolutionary Ideas and Palaeoanthropology ...................................... 25 The Implications of an Evolutionary Perspective ....................................................... 27 Dealing with the Hominins: Concepts and Approaches ............................................ 28 Hominin Taxonomy and Palaeoanthropological Philosophy ..................................... 28 Defining and Diagnosing the Hominins ................................................................. 29 Palaeoanthropological Philosophy: Are Hominins “Humans” or Animals? .......... 30 Agents and Actors: The Importance of Choice and Cognition ................................... 33 Analytical Approaches to Hominin-Environment Interaction .................................... 34 Direct Palaeoecological and Palaeoenvironmental Reconstruction ....................... 34 Indirect Reconstruction (Modelling) of Past Conditions ........................................ 36 Comparative Approaches to Hominin-Environment Interactions .......................... 36 Dealing with Evolutionary and Environmental Complexity .................................... 37 A Spectrum of Evolutionary Theories ........................................................................ 39 Current Perspectives on the Role of Environment ..................................................... 42 Evolution in Small Samples: Drift and Neutral Processes ..................................... 43 Statistical Evolution: Adaptationism and the Role of Environment ....................... 44 Complex Evolution: Co-evolution, Niche Construction and Symbiosis ................ 45 Concepts of “Landscape” ............................................................................................. 47 Conclusions: Research Strategy in this Thesis ........................................................... 49 CHAPTER TWO: MATERIALS AND METHODS ............................................................. 51 Introduction .................................................................................................................. 51 Methodological Background: Principles and Paradigms ......................................... 51 Biogeography and Environmental Patterning ............................................................. 52 Primate Biogeography ............................................................................................ 52 ~ 3 ~ Hominin Biogeography .......................................................................................... 53 Landscape Use in Extant Primates ......................................................................... 54 Evolutionary Morphology and Morphometrics .......................................................... 55 Studying Morphology: Evolutionary Explanations ................................................ 57 Traditional and Geometric Morphometrics ............................................................ 58 Materials and Data Collection ..................................................................................... 59 Environmental Data .................................................................................................... 59 Basemaps: Coasts, Rivers and Political Boundaries ............................................... 59 Landscape Variables: Topography, Roughness, Soils and Surface Geology ......... 59 Climate Variables – Temperature, Rainfall and Seasonality .................................. 60 Biological Variables – Vegetation, Land Cover and Species Distributions ........... 60 GIS Display Conventions ........................................................................................... 61 Anatomical Data ......................................................................................................... 63 Skeletal Materials: Baboons and Humans .............................................................. 64 Measurements of the Talus ..................................................................................... 65 Measurements of the Calcaneus ............................................................................. 67 Measurements of the Cuboid .................................................................................. 69 Measurements of the Navicular .............................................................................. 70 Measurements of the Medial Cuneiform ................................................................ 71 Measurements of Metatarsals I, III and V .............................................................. 72 Data Correction Prior to Analyses .......................................................................... 73 Anatomical Display Conventions ............................................................................... 74 Analytical Software ...................................................................................................... 74 Specific Methods for This Thesis ................................................................................ 75 CHAPTER THREE: EXTANT AFRICAN LANDSCAPES ................................................. 76 Introduction .................................................................................................................. 76 An Overarching Context: the Earth System ............................................................... 77 African Landscapes: The Large Scale ........................................................................ 78 Climatic Variables: Rainfall, Temperature and Seasonality ....................................... 78 Physical Landscape Variables: Topography, Roughness, Geology and Soils ............ 79 Biotic Variables: Vegetation, Ecoregions and Species Richness ............................... 81 Summarising Large-Scale Environmental Pattern in Africa ...................................... 84 African Landscapes: the Regional Scale ..................................................................... 87 ~ 4 ~ Environmental Patterning in East Africa .................................................................... 88 Environmental Patterning in South Africa ................................................................. 94 Environmental Patterning in West Africa