Wild Orangutan Tool Use NEW INSIGHTS FOR HUMAN EVOLUTION Dissertation zur Erlangung der naturwissenschaftlichen Doktorwürde (Dr. sc. nat.) vorgelegt der Mathematisch-naturwissenschaftlichen Fakultät der Universität Zürich von Ellen J.M. Meulman aus den Niederlanden Promotionskomitee Prof. Dr. Carel P. van Schaik (Leitung der Dissertation/Vorsitz) Dr. Judith M. Burkart Zürich, 2014 For all the great apes (human or non-human), I have had the luck to know or meet and be inspired by in one way or another… Table of Contents ABSTRACT .............................................................................................................. 7 ZUSAMMENFASSUNG (GERMAN ABSTRACT) ............................................. 9 ABSTRAK (INDONESIAN ABSTRACT) ........................................................... 12 CHAPTER 1 ........................................................................................................... 14 General introduction .......................................................................................................... 14 How to define tool use? .................................................................................................... 14 Did tool use make us human? .......................................................................................... 15 Is tool use cognitively demanding? .................................................................................. 16 How orangutans can contribute to the study of tool use .................................................. 18 Aims and contents of this study ........................................................................................ 19 References ........................................................................................................................ 20 CHAPTER 2 ........................................................................................................... 26 Orangutan tool use and the evolution of technology ....................................................... 26 Introduction ...................................................................................................................... 26 This study .......................................................................................................................... 30 Methods ............................................................................................................................ 34 Results .............................................................................................................................. 37 Discussion ........................................................................................................................ 45 Future directions .............................................................................................................. 48 Acknowledgments ............................................................................................................. 50 References ........................................................................................................................ 50 CHAPTER 3 ........................................................................................................... 56 The role of terrestriality in promoting primate technology ........................................... 56 Abstract ............................................................................................................................ 56 Terrestriality as a facilitating condition .......................................................................... 60 Testing the terrestriality effect ......................................................................................... 63 Discussion ........................................................................................................................ 67 Conclusion ........................................................................................................................ 72 Acknowledgements ........................................................................................................... 72 References ........................................................................................................................ 73 CHAPTER 4 ........................................................................................................... 80 Prosocial tool transfers in wild great apes? Implications for the evolution of technology ........................................................................................................................... 80 Abstract ............................................................................................................................ 80 5 Introduction ...................................................................................................................... 81 Results .............................................................................................................................. 84 Discussion ........................................................................................................................ 91 Conclusion ........................................................................................................................ 93 Experimental procedures ................................................................................................. 93 Acknowledgements ........................................................................................................... 95 References ........................................................................................................................ 96 CHAPTER 5 ..................................................................................................................... 100 If at first you don’t succeed… Studies of ontogeny shed light on the cognitive demands of habitual tool use ........................................................................................................... 100 Abstract .......................................................................................................................... 100 1. Introduction ................................................................................................................ 101 2. Observational field studies reveal typical tool-acquisition patterns ......................... 103 3. Experimental evidence: cognition and tool use ......................................................... 107 4. Developmental evidence for the role of social input .................................................. 111 5. Discussion .................................................................................................................. 114 Acknowledgements ......................................................................................................... 118 References ...................................................................................................................... 118 CHAPTER 6 ......................................................................................................... 128 Flexible tool use and its acquisition in wild Sumatran orangutans, Pongo abelii ...... 128 Abstract .......................................................................................................................... 128 Introduction .................................................................................................................... 129 Methods .......................................................................................................................... 131 Results ............................................................................................................................ 135 Discussion ...................................................................................................................... 145 Acknowledgements ......................................................................................................... 148 References ...................................................................................................................... 149 CHAPTER 7 ......................................................................................................... 160 Conclusion ......................................................................................................................... 160 EPILOG ................................................................................................................ 161 Preserving our vanishing natural and cultural heritage .............................................. 161 ACKNOWLEDGEMENTS ................................................................................. 163 CURRICULUM VITAE ...................................................................................... 171 PUBLICATION LIST .......................................................................................... 175 6 ABSTRACT Tool use has traditionally been considered cognitively demanding and a hallmark of human evolution. However, the numerous findings of tool use across the animal kingdom have cast doubt on this notion. Using the existing variation among wild orangutans this thesis aimed to evaluate traditional evolutionary and cognitive theories on tool use. I updated the tool catalogue for wild orangutans and evaluated in how far variation in extractive-foraging tendencies, intelligence, and opportunities for social learning explained the variation in tool repertoires within orangutans and of orangutans relative to chimpanzees (Chapter