CONTENTS Foreword Jane Goodall Preface 1 / CURRENT FIELDWORK: Pan troglodytes Gombe Gombe: Highlights and Current Research 2 Jane Goodall Chimpanzee Use of Medicinal Leaves 22 Richard W. Wrangham and Jane Goodall Methods for Isolating Chimpanzee Vocal Communication 38 Christopher Boehm The Research at Gombe: Its Influence on Human Knowledge 60 Roger S. Fouts Mahale Mountains Research at Mahale 66 Toshisada Nishida Social Interactions between Resident and Immigrant Female Chimpanzees 68 Toshisada Nishida Sexual Behavior of Immigrant and Resident Female Chimpanzees at Mahale 90 Toshikazu Hasegawa Sex Differences in the Behavioral Development of Chimpanzees at Mahale 104 Mariko Hiraiwa-Hasegawa Additional Sites Feeding Ecology of Chimpanzees in the Kibale Forest, Uganda 116 G. Isabirye-Basuta Recent Research on Chimpanzees in West Africa 128 William C. McGrew Population Dynamics of Chimpanzees at Bossou, Guinea 134 Yukimaru Sugiyama The Use of Stone Tools by Wild-living Chimpanzees 146 Adriaan Kortlandt ChimpanZoo 148 Jane Goodall 2 / CURRENT FIELDWORK: Pan paniscus Introduction: The Fourth Ape 152 Frans Β. Μ. de Waal Behavioral Contrasts between Bonobo and Chimpanzee 154 Frans Β. Μ. de Waal The Sexual Behavior of Pygmy Chimpanzees 176 Takayoshi Kano Developmental Retardation and Behavioral Characteristics of Pygmy Chimpanzees 184 Suehisa Kuroda Social Organization of Pygmy Chimpanzees 194 Frances J. White 3 / THE CHIMPANZEE MIND Are Animals Intelligent? Wolfgang Köhler's Approach 210 Emil W. Menzel, Jr. Cross-fostered Chimpanzees: I. Testing Vocabulary 220 R. Allen Gardner and Beatrix T. Gardner Cross-fostered Chimpanzees: II. Modulation of Meaning 234 Beatrix T. Gardner and R. Allen Gardner Signing Interactions between Mother and Infant Chimpanzees 242 Deborah H. Fouts Spontaneous Pattern Construction in a Chimpanzee 252 Tetsuro Matsuzawa Symbol Acquisition and Use by Pan troglodytes, Pan paniscus, Homo sapiens 266 Sue Savage-Rumbaugh, Mary Ann Romski, William D. Hopkins, and Rose A. Sevcik Current and Future Research on Chimpanzee Intellect 296 Duane M. Rumbaugh 41 CHIMPANZEE CONSERVATION Population Status of Wild Chimpanzees (Pan troglodytes) and Threats to Survival 312 Geza Teleki Demography of Chimpanzees in Captivity 354 Katherine Latinen Area Status Report: Tanzania 360 Jane Goodall Conservation Status of Pan paniscus 362 Richard K. Malenky, Nancy Thompson-Handler, and Randall L. Susman 5 / EVOLUTION and EPILOGUE Hominoid Sociobiology and Hominid Social Evolution 370 Michael P. Ghiglieri Epilogue: Understanding Chimpanzees and Bonobos, Understanding Ourselves 380 Paul G. Heltne Contributors 385 Name Index 387 Subject Index 393 .