Orangutan call communication and the puzzle of speech evolution © Adriano Reis e Lameira 2013 Orangutan call communication and the puzzle of speech evolution PhD dissertation, Utrecht University, the Netherlands, January 2013 ISBN: 978-94-6191-583-2 Cover design & lay-out: Adriano R. Lameira Cover illustrations: Aloys Zötl, 1831-1887 Printing: Ipskamp Drukkers, Enschede, the Netherlands Printed on FSC paper Voor Madeleine To Izzy Untuk mawas Aos meus pais Orangutan call communication and the puzzle of speech evolution Orang-oetan geluidscommunicatie en de evolutionaire puzzel van spraak (met een samenvatting in het Nederlands) PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof.dr. G.J. van der Zwaan, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op woensdag 23 januari 2013 des ochtends te 10.30 uur door Adriano Reis e Lameira geboren op 1 september 1982 te Lisbon, Portugal Promotoren: Prof.dr. B.M. Spruijt Prof.dr. S.A. Wich Co-promotor: Dr. E.H.M. Sterck This thesis was (partly) accomplished with financial support from Fundação para a Ciência e Tecnologia (SFRH/BD/44437/2008, Portugal), Wenner-Gren Foundation for Anthropological Research (USA), Dr. J.L. Dobberke voor Vergelijkende Psychologie (the Netherlands), Lucie Burgers Foundation for Comparative Behaviour Research, Arnhem, the Netherlands, Schure-Beijerinck-Popping Fonds (the Netherlands), Ruggles-Gates Fund for Anthropological Scholarship of the Royal Anthropological Institute of Great Britain and Ireland, Primate Conservation, Inc. (USA) and Fundação Calouste Gulbenkian (Portugal). Contents Chapter I General introduction 09 Chapter II Review of geographic variation in terrestrial mammalian 21 acoustic signals: Human speech variation in a comparative perspective Chapter III Call cultures in orangutan? 45 Chapter IV Tool use in wild orangutan modifies sound production: 63 A functionally deceptive innovation? Chapter V Population-specific use of the same tool-assisted alarm sound 75 between two wild orangutan populations (Pongo pygmaeus wurmbii) denotes functional arbitrariness Chapter VI Orangutan whistling and implication for the emergence of 89 an open-ended call repertoire: a replication and extension Chapter VII Predator guild does not influence orangutan alarm call rates 111 and combinations Chapter VIII Orangutan instrumental gesture-calls: Reconciling acoustic 129 and gestural speech evolution models Chapter IX General discussion 137 Chapter X Summary 147 Appendices 153 References 157 Samenvatting in het Nederlands 177 Ringkasan bahasa Indonesia 183 Acknowledgments 189 Curriculum Vitae 191 List of publications 193 Chapter I General introduction The evolutionary puzzle of speech Language, human’s learned communication system, is the most complex communication system known in nature. With the Darwinian theory (Darwin 1859), the study of language opened up to those fascinated by its origins and evolution. Today, the study of language evolution is a multidisciplinary endeavor, mirroring the plurality of its components (Christiansen and Kirby 2003b). One of the pillar components of language evolution is the study of animal communication (aside other components focusing, for example, on language acquisition, language neurological and genetic correlates), in which similarities and differences in characteristics with language are studied. The identification of such differences allows pinpointing features which are unique to language, whereas the identification of similarities allows identifying, either by analogy (i.e. non-primate animal studies) or homology (e.g. nonhuman primate studies), selective pressures that are common in animal and human communication. This task is undertaken by comparative biology and is directly linked to the basic Darwinian premise that language is the result of a gradual evolutionary process stemming from an ancestral form. Speech, the spoken component of humans’ learned communication system, constitutes the acoustic part of language (Fitch 2000). A theory for language evolution in humans must include a valid explanation for the evolution of speech in our ancestors (Christiansen and Kirby 2003b). Allegorically, speech can be understood as a piece of (physical) hardware, together with its respective operations, which has been designed to serve specific (virtual) software – language. As such, speech differs explicitly from language and it may be studied independently, with the advantage of being more accessible to experimental investigation than other components of language (Fitch 2000), just as deconstructing hardware into its composing parts is more straightforward than for software. This is especially true under a comparative approach to speech evolution, where animal calls, the main study subjects of comparative approaches to speech evolution, are readily available to investigation under the natural socio-ecologic settings of the species. There is some consensus about the distinctive ways speech differs from other call communication systems in the animal kingdom (Fitch 2000), that is, which transformations must have occurred in our evolutionary lineage until speech had evolved as we know it at 9 present. It is generally accepted that the evolution of human speech from ape call communication required, at least, a modification of the ape vocal tract morphology (Boer 2009) and the acquisition of the capacity to learn new calls (Fitch 2000; Ghazanfar and Rendall 2008). However, speech evolutionary history remains elusive. That is, the exact primate call communication traits that were targeted by positive selection leading to the necessary transformations remain unclear. As such, this topic has always been controversial (Christiansen and Kirby 2003b), leading some researchers to propose that speech precursors are found beyond call communication, for instance, in gestural communication (e.g. Arbib et al. 2008; Corballis 2003). Whether or not specific speech features may have been brought forth initially by behavioral patterns outside call communication, such putative precursors must have been eventually “translated” into call features in speech’s evolutionary path. Therefore, the question remains, which traits and functions of nonhuman primate call communication served as speech evolutionary feedstock. Hence, it is beneficial to the deciphering of the speech puzzle to assess its building blocks within a comparative approach by focusing on homological features of call communication in nonhuman primates closely related to humans, namely great apes. In this study, I investigate how much of speech features can be found in orangutan call communication. A brief history of primate call communication studies The first primatological studies focusing on call communication were initiated more than a century ago, in the late nineteenth century (Garner 1892; cf. Radick 2007). This was the first time that nonhuman primate calls were recorded and played back to conspecifics to elicit behavioral responses. By comparing the original observation and the replies from monkeys, Garner hoped to get some clues that would eventually enable him to translate the “monkey language” (Radick 2007), although detailed results remained unpublished. Decades later, primate studies featured dominantly in discussions on language and speech evolution (Savage-Rumbaugh et al. 1978; Savage-Rumbaugh et al. 1985; Gardner and Gardner 1969; Premack 1971; Rumbaugh 1977; Terrace et al. 1979; Patterson and Linden 1981; Furness 1916; Hayes 1951; Hayes and Hayes 1952; Miles 1993; Kellogg and Kellogg 1967). These studies characteristically involved great apes who were reared with humans in the course of language training. Despite this concerted effort, the main objective of teaching an ape how to speak largely failed, since the subjects failed to learn calls or only 10 learned very few calls (e.g. Furness 1916). Instead, communication between the apes and their caretakers seemed most successful when using gestures, with some ape individuals learning hundreds of symbolic gestures (e.g. Savage-Rumbaugh and Lewin 1994). Based on this apparent lack of results in call communication, together with neurological studies showing little or no voluntarily call control in monkeys (e.g. Jürgens 1979), the general notion that nonhuman primates have an innate call repertoire and cannot learn new calls (Hammerschmidt and Jischer 2008) was implanted, and scientific thought moved away from the view that great ape calls could represent some type of speech precursors. This corroborated the pervasive theoretical idea of the time that language was the product of a saltational, rather than gradual, event (Chomsky 1957) that divides human language and speech from primate call communication. The foundations of language must have rested, hence, in other primate features such as gestures or facial expressions (cf. Slocombe et al. 2011), rather than call communication, and good animal models for speech evolution are better found in other taxa. This notion has remained influential until today, either in studies resuming century-old ideas based on anti-anthropomorphism (i.e. opposition against the search of human features in animals) defending discontinuity between humans and its closest relatives for the evolution of language and speech (e.g. Wynne and Bolhuis 2008; Hemelrijk and Bolhuis 2011), or in studies postulating gradual and continuous evolutionary processes between humans and nonhuman primates but advocating,