Keeping Fire: The Cognitive Implications of Controlled Fire Use by Middle Pleistocene Humans Terrence Matthew Twomey Submitted in total fulfilment of the requirements of the degree Doctor of Philosophy April 2011 School of Social and Political Sciences Faculty of Arts The University of Melbourne Supervisory Committee Dr Edward Douglas Lewis Dr Neil Thomason Prof Andrew Dawson Prof Antonio Sagona i Abstract The thesis investigates the cognitive implications of controlled fire use by Middle Pleistocene humans. My argument is that we can infer features of human cognition from the behaviours required to control fire. This argument is grounded in the following two premises. First, some behaviours imply the operation of distinctively human cognitive abilities. For example, inhibiting prepotent responses, delaying gratification and anticipatory planning provide good evidence for executive functions, such as episodic memory, an extended working memory capacity and detached representations. Similarly, future directed cooperation, resolving social dilemmas and providing a public good imply features of human social cognition, such as theory of mind, collective intentionality and intersubjective communication. Second, fire use involved a range of cognitively demanding behaviours associated with accessing, maintaining and using fire that I argue meet the above behavioural criteria for human cognitive abilities. The thesis aims to show why this is the case. My working hypothesis is that fire related tasks stand as a sound behavioural basis for making inferences about the cognitive abilities of fire using humans. The thesis is warranted because we now have compelling evidence that humans have been using fire for at least 800 thousand years. The cognitive abilities of humans from this early time are not well understood and in dispute. The thesis is pertinent because it has high potential to provide new information about the timing and context in which important human cognitive abilities evolved. ii iii Declaration (i) The thesis comprises only my original work towards the PhD. (ii) Due acknowledgement has been made in the text to all other material used. (iii) The thesis is less than 100,000 words in length, excluding tables, maps, bibliographies and appendices. Terrence Twomey iv v Acknowledgments The encouragement of Dr Douglas Lewis is appreciated. His assistance throughout my candidature was helpful. Dr Neil Thomason has helped me to think and write with some clarity. Without him the thesis would make far less sense. His support in developing and organising the thesis throughout my candidature, and in submitting the final draft, is valued and appreciated. The thesis would not have been possible without the help of Prof Antonio Sagona. He has assisted me greatly where my archaeological knowledge was limited and has encouraged my ideas from their inception. For this, and his help preparing and correcting final drafts, I am greatly indebted. Thanks to Prof Andrew Dawson for supervising the final stages and submission of the thesis. The work, support, time and efforts of all my supervisory committee throughout my candidature and in producing the final product are greatly appreciated. I would like to thank the people around the department and faculty who were always ready to discuss my ideas, listen to my concerns, and offer positive criticisms and advice. In particular Dr Juan Dominguez, Dr Alan Thorald, Prof Mary Patterson, Dr Monica Minnegal, Dr Peter Dwyer, Prof Ron Ridley and Dr Hans Baer. I also appreciate the help of Dr Minnegal and Dr Dwyer for their assistance and support during the submission process. I would also like to thank Dr Victoria Ling, Prof Richard Wrangham and Prof Richard Preece who took the time to discuss my thesis while I was visiting Cambridge University in 2008. These scholars offered both encouragement and perspective for my ideas and approach that is much appreciated and valued. I also thank Prof Thomas Wynn for his initial encouragement to investigate this topic, and for offering helpful criticisms and advice. Prof Wynn took the time to read and critically review the difficult chapter on cognition for which I am greatly indebted. This assisted me in establishing behavioural criteria from which we can infer cognitive abilities. I would also like to thank Angela Tsotsos and Aleks Michalewicz for taking the time to proof read the final draft. vi I also wish to thank my wife Julie and children Shane and Peppa for their ongoing encouragement and support. It is they who bore the brunt of my thesis induced impatience, moodiness, self-doubt and self-focus. It is they who have carried me and the thesis to its completion. To them, and all those above who have made the thesis possible, I am deeply indebted and greatly appreciative. Finally, I thank my wife Julie for helping me edit and proof read the final draft and for drawing the evocative image of fire that appears on the front cover and blank pages throughout the thesis. vii Contents Page Contents Page No. Abstract …………………………………………………………………i Declaration ..……………………………………………………………iii Acknowledgements ………………………………………………………...v Contents Page ……………………………………………………….vii List of Tables and Figures ………………………………………………..xi Chapter One: Introduction 1.1 Introduction ………………………………………………………...1 1.1.1 Key Premises and Conditions ………………………………...2 1.1.2 The Problem ………………………………………………...4 1.2 Aims of the Thesis ………………………………………………...5 1.3 Significance of the Research ………………………………………...6 1.4 Approach ………………………………………………………………...7 1.4.1 Inferring Cognition from Prehistoric Behaviour ………...7 1.4.2 A Three-Stage Model for the Origin of Fire Use ……….10 1.5 Perspective and Focus ……………………………………………….11 1.6 Review and Organization of the Thesis ……………………………….15 1.7 Summary ……………………………………………………………….18 Chapter Two: Literature Review 2.1 Introduction ……………………………………………………….19 2.2 Early Human Cognition ……………………………………………….19 2.3 Fire Use and Communication ……………………………………….25 2.4 Fire Use and the Social Intelligence Hypothesis ……………………….28 2.5 The Expensive Tissue and Cooking Hypotheses ……………………….31 2.6 Fire Use and Central Placed Foraging ……………………………….35 2.7 The Economics of Fire Use ……………………………………….38 2.8 Summary ……………………………………………………………….41 Chapter Three: The Evidence for Early Human Fire Use 3.1 Introduction ……………………………………………………….45 3.2 Identifying Prehistoric Fire Use ……………………………………….45 3.3 The Evidence for Fire Use by Early Humans ……………………….50 3.3.1 Direct Evidence for Domestic Fire ……………………….50 3.3.2 Indirect Evidence for Domestic Fire ……………………….60 3.4 Who Used Fire? .....................................................................................64 3.5 The Pattern of Early Human Fire Use ……………………………….65 3.6 Summary ……………………………………………………………….67 Chapter Four: The Contexts of Early Human Fire Use 4.1 Introduction ……………………………………………………….69 4.2 Early Human Environments ……………………………………….69 4.3 Early Human Demography ……………………………………….72 4.4 Range and Mobility of Early Humans ……………………………….77 4.5 Early Human Time Budgets ……………………………………….79 4.6 Communal Fires ……………………………………………………….80 4.7 Summary and Discussion ……………………………………………….81 Chapter Five: Fire Related Problems 5.1 Introduction ……………………………………………………….85 5.2 Obligate Fire Use ……………………………………………………….86 viii 5.3 Making Fire ……………………………………………………….87 5.4 Accessing Fire ……………………………………………………….91 5.4.1 Accessing Fire from Natural Sources ……………………….91 5.4.2 Accessing Fire from Domestic Sources ……………………….94 5.5 Maintaining Fire ……………………………………………………….97 5.5.1 Provisioning Fire .............................................................97 5.5.2 Protecting Fire ……………………………………………….99 5.5.3 Transporting Fire ………………………………….…..100 5.6 Taking Advantage of Fire ……………………………………...102 5.7 Summary and Discussion ……………………………………………...106 Chapter Six: Solving Fire Related Problems 6.1 Introduction ...................................................................................111 6.2 Accessing Fire ……………………………………………………...112 6.2.1 Access by Stealth or Force ……………………...............114 6.2.2 Free Access and Exchange ……………………………...114 6.2.3 Summary ……………………………………………...116 6.3 Maintaining Fire ……………………………………………………...117 6.3.1 Gathering Fuel ……………………………………………...117 6.3.2 Protecting Fire ……………………………………………...123 6.3.3 Transporting Fire ……………………………………...124 6.4 Using Fire ………………………………………………….......125 6.5 Summary and Discussion ……………………………………………...128 6.6 Conclusions ……………………………………………………...130 Chapter Seven: Defining and Inferring Human Cognition 7.1 Introduction ……………………………………………………...133 7.2 Cognition ……………………………………………………………...134 7.3 Human Cognition ……………………………………………………...134 7.4 Executive Functions ……………………………………………...137 7.4.1 Response Inhibition ……………………………………...139 7.4.2 Anticipatory Planning ……………………………………...141 7.4.3 Delayed Gratification ……………………………………...145 7.4.4 Prospective Memory ……………………………………...146 7.5 Detached Representations ……………………………………...148 7.6 Social Cognition ……………………………………………………...150 7.6.1 Human Cooperation in the Middle Pleistocene ……...152 7.6.2 Understanding and Detecting intention ……………...152 7.6.3 Trust, Tolerance and Cooperation ……………………...156 7.6.4 Public Goods and Social Dilemmas ……………………...159 7.7 Behavioural Criteria ……………………………………………...160 7.8 Summary ……………………………………………………………...162 Chapter Eight: Inferring Executive Functions from Fire Use 8.1 Introduction ………………………………………………….......163 8.2 Inhibiting Responses and Delaying Gratification ……………...163 8.2.1 Fuel Gathering ……………………………………………...165 8.2.2 Transporting Fire ……………………………………...171 8.2.3