Thesis (MS)--University of Montana, 2009. / Contents viewed on November 25, 2009. Title from author supplied metadata. Includes bibliographical references.

Title from title page of PDF (University of Missouri--St. Louis, viewed March 8, 2010). Includes bibliographical references.

An important element in understanding the evolutionary origin of human language is to explore homologous traits in cognition and communication between primates and humans (Burling, 1993, Hewes, 1973). One proposed modality of language evolution is that of gestural communication, defined as communicative movements of hands without using or touching objects (de Waal, 2003). While homologies between primate calls and language have been relatively well explored, we still have a limited understanding of how cognitive abilities may have shaped the characteristics of primate gestures (Corballis, 2003). Chimpanzees (Pan troglodytes) are our closest living relatives and display some complex cognitive skills in various aspects of their gestural behaviour in captivity (de Waal, 2003, Pollick and de Waal, 2007). However, it is not yet currently clear to what extent these abilities seen in captive apes are typical of chimpanzees in general and to what extent cognitive capacities observed in captive chimpanzees have been enhanced by the socio-cultural environment of captivity such as language training. In this Ph.D. research, I investigated the cognitive skills underlying gestural communication in both wild and language trained chimpanzees, with a special focus on the repertoire and the intentionality of production and comprehension. The study of cognitive skills underlying the production of the repertoire and the role of intentionality is important because these skills are cognitively demanding and are a prerequisite in human infants for their ability to acquire language (Baldwin, 1995, Olson, 1993). My research suggests that chimpanzee gestural communication is cognitively complex and may be homologous with the cognitive skills evident in pre-verbal infants on the cusp of language acquisition. Chimpanzees display a multifaceted and complex signal repertoire of manual gestures. These gestures are the prototypes, within which there is variation, and between which the boundaries are not clear-cut, but there is gradation apparent along several morphological components. Both wild and language trained chimpanzees communicate intentionally about their perceived desires and the actions that they want the recipients to undertake. They do not just express their emotions, but they communicate flexibly by adjusting their communicative tactics in response to the comprehension states of the recipient. Whilst chimpanzees communicate their intentions flexibly, the messages conveyed are specific. However, recipients comprehend gestures flexibly in light of the signaller’s overall intentions. Whilst wild and language trained chimpanzee gestural communication revealed similar cognitive characteristics, language trained chimpanzees outperformed wild apes in that they had ability to use signals which made distinctions that human deictic words can make. Whilst these differences between wild and language trained chimpanzees may be due to the different methodological approaches used, it is conceivable that language training may have influenced captive ape cognitive skills in the representational domain. These results from wild and language trained chimpanzees indicate that chimpanzees possess some form of cognitive skills necessary for language development and that cognitive skills underlying repertoire and use in chimpanzees are a shared capacity between humans, other apes and a common ancestor. These findings render theories of the gestural origins of language more plausible. Related publications: 1. Roberts, A. I., Vick, S.-J., Roberts, S. G. B., Buchanan-Smith, H. M. & Zuberbühler, K. 2012. A structure-based repertoire of manual gestures in wild chimpanzees: Statistical analyses of a graded communication system. Evolution and Human Behavior, Published online: http://dx.doi.org/ 10.1016/j.evolhumbehav.2012.05.006 2. Roberts, A. I., Vick, S.-J. & Buchanan-Smith, H. 2012. Usage and comprehension of manual gestures in wild chimpanzees. Animal Behaviour, Published online: http://dx.doi.org/10.1016/j.anbehav.2012.05.022

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Two approaches were taken to investigating constraints on kinship in predicting social behaviour in the vervet monkey Cercopithecus aethiops sabaeus in Barbados. in Chapter 1, behavioural interactions between an adult female and an unrelated adopted infant were compared with those between mothers and their natural offspring. The adoptive mother consistently scored higher than mothers with their own offspring in pre-weaning contact-maintaining behaviours, but the difference was not statistically significant. Post-weaning aggression and support interactions between mothers and infants also suggest no difference in parental behaviour and parental costs between adoptive and natural mothers. During post-weaning, the adopted infant was more aggressive to other troop members, and provided more maternal support in aggressive disputes, than another high ranking infant of the same year. / In Chapter 2, effects of kinship on the distribution of aggression and support in feral vervet monkeys were investigated by comparing aggression and support between full sibs and maternal half sibs (within matrilines), and between paternal-half sibs and unrelated juveniles (between matrilines). The strong tendency to behave affiliatively to matrilineal members in Old World monkeys, and maternal control of offspring rank within matrilines, may constrain the ability of offspring to enhance inclusive fitness by behaving differentially to either paternal or maternal sibs based on their degree of relatedness.

The following research paper was concerned with five basic objectives:(1) outlining the major theoretical and methodological approaches used in the reconstruction of early hominid social behavior/social structure as a context in which to view Richard Wrangham's and Michael Ghiglieri's phylogenetic models of stem-hominid social structure.(2) examining Wrangham's and Ghiglieri's models of stem-hominid and chimpanzee social structure.(3) indicating how theoretical and methodological aspects of structure essentially represent an extension of the theoretical and methodological approaches the same researchers applied to their models of chimpanzee social structure.(4) addressing the theoretical and methodological deficiences of Wrangham's and Ghiglieri's models of chimpanzee social structure.(5) providing suggestions for improved phylogenetic models of early hominid social structure.The first objective was achieved by: (a) reviewing Tooby and Devore's (1986) and Wrangham's (1986) evaluations of the major theoretical approaches and methodologies used in the reconstruction of hominid social behavior/structure (b) defining, classifying and evaluating Wrangham's and Ghiglieri's phylogenetic approaches within this context.The second objective was accomplished by outlining, analyzing, and comparing/contrasting Wrangham's and Ghiglieri's phylogenetic models of stem-hominid social structure (i.e.Wrangham 1986; Ghiglieri 1987, 1989) and Wrangham's and Ghiglieri's models of chimpanzee social structure (i.e. Wrangham 1975, 1979; Ghiglieri 1984, 1985, 1987, 1989).The third objective was achieved by recognizing how Wrangham and Ghiglieri used/stressed principles and concepts derived from evolutionary biology and/or behavioral ecology to develop their models of stem-hominid and chimpanzee social structure. This analysis showed that Wrangham's models of social structure were more favorably inclined toward the method of behavioral ecology than Ghiglieri's models, which favored a sociobiological paradigm. Furthermore, although neither researcher relied exclusively on the above theoretical approaches, the main thrust of their argument often centered around it. For instance, Wrangham's analysis of chimpanzee social structure (Wrangham 1975, 1979) indicated that the ultimate cause of that structure was ecological i.e., patchy food distribution leads to wide female dispersal for optimal foraging efficiency, which in turn favors a male kin breeding group that can maintain a territority that includes several individual female ranges. In contrast, Wrangham's phylogenetic model of the social structure of the stem-hominid (Wrangham, 1986) suggested that phylogenetic inertia may be partially responsible for the shared social features found among African Hominoidea. However, in the same work, Wrangham also suggested that further socioecological analysis of African apes may indicate whether food distribution and its effects on female dispersion/association may partially explain conservative African ape social features.Ghiglieri's phylogenetic model of the stem-hominid (1987, 1989), on the other hand, explained the conservative social features of bonobos, common chimpanzees, and hominids to be primarily a product of phylogenetic inertia and sexual selection. Furthermore, for Ghiglieri the most important sexual selection variable was a male communal reproductive strategy. This, according to Ghiglieri, is the ultimate cause of social structure. Notably, Ghiglieri (1984, 1985) had earlier stressed the overiding importance of a male communal reproductive strategy but was less dogmatic in his insistence that chimpanzees had essentially solved their ecological problems (e.g. that they had solved the food distribution problem by fusion-fission sociality; predators were never a real problem). Nevertheless, Ghiglieri's earlier position similarily expressed the idea that a communal reproductive strategy constituted the ultimate cause of social structure.The fourth objective was accomplished by presentation of an alternative model of chimpanzee social behavior which suggested that structure; the effect of phylogenetic inertia on social structure; chimpanzee social structure is the combined product of ecological and sexual selection forces: female optimal foraging, male mating strategies, and predator pressure. The model was considered by the author to be unique in that it integrated essential aspects of both Wrangham's and Ghiglieri's models and, in addition, provided support for Alexander's (1974) contention that predation pressure is an ultimate cause of ape social structure. The model also outlined scenarios for the evolution of chimpanzee group._ extensibility (fusion-fission sociality) and the capacity for warfare among chimpanzees.The last objective was achieved by a discussion of the implications that the author's model had for phylogenetic models of stem-hominid social structure. In this discussion the author reviewed the following issues as they related to the phylogenetic reconstruction of hominid social structure: the role of phylogeny and/or ecology in the causation of social encountered when using a phylogenetic referential model for the personal biases that enter into phylogenetic econstructions; pitfalls reconstruction of early hominid social evolution; the significance of chimpanzee models of social structure.The importance of the preceding study lay in its ability to stimulate improved conceptual models of African hominoid social structure. / Department of Anthropology

Grooming relationships between adult male chimpanzees are often reciprocal, i.e. individuals receive grooming from those they groom. Grooming may be reciprocated at the same time it is received (mutual grooming), or later within the same grooming session. Alternatively, it can be reciprocated at a much later stage, in another session. An analysis of individual grooming sessions at the dyadic level was used to investigate how chimpanzees reciprocate grooming within these sessions. This study describes the grooming and reciprocation of grooming by male chimpanzees, living in a multi-male, multi-female group at the Edinburgh Zoo, Scotland. A method for the analysis of dyadic grooming relationships was based on the presence or absence of mutual and unilateral grooming in a session, which allows seven types of grooming session to be distinguished. Grooming session was defined empirically, and the duration of the bout criterion interval (BCl) depended on the presence or absence of oestrous females. For comparison, however, the same BCI was used throughout. Without oestrous females, grooming was primarily reciprocated in sessions with mutual grooming and unilateral grooming by both participants. This kind of session proved highly cooperative and each male adjusted the duration of his unilateral grooming to that of mutual grooming, rather than to the duration of unilateral grooming by the other male. Mutual grooming was less important to dyads which had a strong grooming relationship. It is suggested that mutual grooming serves as an indication of the motivation to groom unilaterally. There was no indication that males reciprocated on the basis of TIT-FOR-TAT within these sessions, or between sessions in general. Alternative hypotheses of mutual grooming were only partly confirmed in that some dyads used mutual grooming to reduce the (already very short) time they spent in grooming. However, mutual grooming did not arise from the accidental overlap in the grooming of two partners. In the presence of oestrous females, grooming cooperation between the males broke down, and this was the result of heightened aggression as well as the presence of oestrous females itself. The balance in grooming given and received shifted in the direction of dominants (i.e. dominants received more) under the influence of oestrous females, but in the opposite direction under the influence of aggression. Feeding had no effect on the reciprocity of groormng. There was considerable dyadic variation. Some dyads groomed more when there were oestrous females, others groomed less. Some dyads had proportionally less mutual grooming with increasing numbers of oestrous females, others had more. There were generally no clear patterns of grooming reciprocation over longer time-spans than the session, but the overall degree of reciprocity of a dyad was frequently reached at the end of each day. Tracing the degree of reciprocation over a few weeks indicated that some dyads' grooming was governed by dominance, whereas that of others by cooperation.

Thesis (M.Sc. Biological Sciences)--University of Waikato, 2007. / Title from PDF cover (viewed February 21, 2008) Includes bibliographical references (p. 79-85)

Thesis (Ph.D.) -- University of Western Sydney, Hawkesbury, 2000. / A thesis presented to the University of Western Sydney, Hawkesbury, in partial fulfilment of the requirements for the degree of Doctor of Philosophy, December, 2000. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Dept. of Psychology. / Includes bibliographical references. Also available on the Internet.