Evidence for conceptual semantics is well established in monkeys, however this basis of human language is less evident in the great apes. In order to study semantic communications in chimpanzees, I analyzed alarm calls produced towards a blimp as it was flying overhead. I then replayed a set of these alarm calls to the chimps on a different day. The chimps appeared to act in a manner consistent with the presence of the blimp. The calls they produced in response to the playback stimuli were nearly identical to the calls that were produced during the actual flyover. Though the data collected were not sufficient to support a definitive claim, it does appear that the chimpanzees of the study have a meaning-laden vocalization for the aerial stimuli. Whether this call is specific to the blimp or generalizable to other aerial threats is yet to be determined. / by Alyssa M. Raymond. / Thesis (M.A.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

Between the years of 1991 and 1995, two different chimpanzee nursery rearing strategies were employed by caregivers and research staff at the Yerkes National Primate Research Center. One of these strategies included, in addition to the basic care provided by both nurseries, an additional 4 hours of human contact for 5 days each week. This human contact was provided by caregivers instructed in the behavior of chimpanzee mothers toward their offspring and instructed to emulate that behavior as much as possible. Various measures of cognitive and motor development were taken during the first year of the nursery-reared chimpanzees' lives; additionally, a modified version of the Strange Situation Test, used to measure attachment, was used to assess the chimpanzees' attachment style to their primary human caregiver. Based on these measures, chimpanzees reared in the standard care nursery (without the additional human contact) were significantly more likely to exhibit disorganized attachment styles towards their human caregiver; additionally, the standard care chimpanzees displayed less advanced motor and cognitive development. The responsive care chimpanzees (reared with the additional human contact) developed cognitively and in terms of motor function at a faster rate than the standard care chimpanzees; they also exhibited less coping skills. After one year of rearing in these two nurseries, all the chimpanzees were reared in conspecific social groups and the differential nurseries were terminated. In 2011-2012, 22 out of 49 of the original chimpanzee subjects were reassessed in an attempt to determine of long term effects of these differential rearing styles could still be detected. Chimpanzees that were identified as exhibiting disorganized attachment at one year of age exhibited significantly higher rates of abnormal behavior as compared to those that did not exhibit a disorganized attachment style at one year of age. Chimpanzees reared in both nurseries exhibited significantly higher rates of abnormal behavior, solicitation of, and attendance to humans as compared to chimpanzees that were mother-reared. Additionally, chimpanzees reared in either nursery were rated by survey respondents as exhibiting significantly higher human orientation and significantly lower subjective well-being as compared to mother-reared chimpanzees. Finally, trends found in the data consistently indicated that chimpanzees reared with more extensive human contact (responsive care) exhibited higher rates of abnormal behavior, solicitation of, and attendance toward humans as compared to standard care chimpanzees. Trends also indicated consistently that responsive care subjects were scored higher on human orientation and lower on subjective well-being by survey respondents. Sign tests were conducted to explore these differences and consistent support was found for these trends as significant. Further research should be conducted to explore welfare-related issues as related to differential nursery rearing strategies for chimpanzees.

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

Increasing and unsustainable demands on Africa's natural resources are having a profound effect on wild primate populations. Whilst wild populations are decreasing, numbers of orphaned primates, sanctuaries and attempts to reintroduce primates back to the natural environment, are increasing. Data were collected on the present status of African ape sanctuaries from questionnaires distributed to sanctuary managers. Across Africa there are 18 sanctuaries housing over 500 African great apes. Facilities and ideologies vary but the majority of sanctuaries profess a commitment to conservation through education, local capacity building, facilitating the enforcement of wildlife laws and other activities. From 1996 to 2001 the non-governmental organisation Habitat Ecologique et Liberte des Primates has released 37 wild-born chimpanzees(Pan troglodytes troglodytes) from an island sanctuary to mainland forest in the Conkouati-Douli National Park, Republic of Congo. Twenty-seven chimpanzees have been successfully reintroduced, three are known to have died and the status of seven remains unknown. This thesis investigated the behavioural adaptation of 15 of these released chimpanzees and reviews the reintroduction process employed. Analyses of post-release behavioural data revealed that activity budgets and diet were comparable to those of wild chimpanzees, and that seasonal variation influenced feeding behaviour and plant speciess election. The chimpanzees utilised both terrestrial and arboreal zones and all nested in trees. A number of recommendations are made for future reintroduction projects. These include selecting a release site that has no, or a low density of, wild conspecifics; developing a relationship of trust between chimpanzee and caretakers without excessive dependency; using the release site for pre-release training; use of radio telemetry; post-release support and monitoring. This study has revealed the many complex factors that are involved in the reintroduction process. Future attempts to reintroduce chimpanzees should be guided by the experiences and recommendations of the present study to maximise success.

Diffusion Tensor Magnetic Resonance Imaging was used to examine the age-related changes in white matter structural integrity in the common chimpanzee. Fractional Anisotropy(FA), a measure derived from the diffusion tensor data is sensitive to developmental and pathological changes in axonal density, myelination, size and coherence of organization of fibers within a voxel and thus reflects the white matter structural integrity. There is substantial evidence that white matter structural integrity decreases with age in humans. The long-term goal of this study is to compare the age-related changes in the white matter structural integrity among humans and chimpanzess to provide potential insights into the unique features of human aging. Different methods, including Region Of Interest (ROI) analysis, Tract Based Spatial Statistics (TBSS) are used to describe age-related changes in FA in a group of 21 chimpanzees. Strengths and limitations of these methods were discussed.

Executive functions (EFs) are a set of cognitive operations, including working memory, inhibitory control and attention shifting, that underpin accurate, flexible and coordinated behaviour in many problem-solving contexts. While it seems likely that humans surpass nonhuman animals in EFs, previous research into the evolutionary origins of EFs is limited and lacks systematic comparisons of EFs in human and nonhuman animals. In this thesis, I aimed to overcome these limitations by developing a test battery to study EFs in our closest primate relative, the chimpanzee. Using an individual differences approach, I investigated the performance of 19 chimpanzees on several EF tasks and extracted two factors in an exploratory factor analysis accounting for 70.9 % of the variability. The two measures of working memory loaded onto one factor, suggesting that a common cognitive process underlay performance on both tasks. This factor could be clearly differentiated from a well-established measure of attention shifting, loading onto a second factor. In addition, the measures of inhibitory control did not contribute to a unique factor. Intriguingly, the emerging structure of separable EF processes, paralleled the EF structure suggested for human adults (Miyake et al, 2012). The subsequent comparison of a sub-sample of chimpanzees (n = 12; excluding aged individuals), pre-schoolers (n = 36) and undergraduates (n = 16) on two selected EF tests revealed impressive EF capacities of chimpanzees. Chimpanzees could deal with interference in working memory at levels comparable to four and five year-olds. Additionally, the ability of chimpanzees to shift attention was not significantly different from four year-olds; however, five- year-olds outperformed their primate relatives. My work suggests that important aspects of EFs are shared between humans and chimpanzees; while performance differences in EFs emerge late in human ontogeny. The implications of my results for theories on human cognitive evolution are discussed.

The link between cognitive challenge and captive animal well-being has received increased interest over the past decade, but so far this link in zoo animals has been overlooked. This is particularly surprising for chimpanzees (Pan troglodytes) and bottlenose dolphins (Tursiops truncatus) because these two 'large-brained' species have been the subjects of intensive cognitive research in captivity over the past six decades. In this thesis, I ask whether novel maze-like devices which aim to be cognitively challenging (abbreviated to 'devices with a cognitive component', DCCs) can be enriching for a mixed-sex group of chimpanzees and two single-sex groups of dolphins housed in zoos. I design, implement and evaluate two DCCs, and employ a new definition of cognitive enrichment that incorporates cognitive challenge and indicators of positive well-being. I demonstrate that two types of DCC for chimpanzees, one constructed from a grid of transparent cells and one from an array of opaque pipes, could be mastered using a number of problem-solving strategies (Chapter 5 and 6). DCC-use by chimpanzees increased when the DCC was less predictable (Chapter 5), but the relationship between self-directed behaviour and cognitive challenge was not straightforward (Chapter 6). In dolphins, only male subjects used an underwater DCC constructed from an array of opaque pipes, and could reflect a general sex difference in response to a novel situation (Chapter 7). In general, the chimpanzees and dolphins groups I studied showed some signs of enhanced well-being, for example increased environmental exploration and play, during exposure to DCCs. However, other behavioural responses such as increased vigilance in dolphins were difficult to interpret and did not suggest that DCCs were enriching. Both species 'worked' in the absence of food rewards and their success on the tasks (i.e. the removal of food or non-food rewards) had little effect on wellbeing indicators (Chapter 5 - 7). Finally, I demonstrate that lateralised behaviour (preference to perform behaviour using one side of the body) can be incorporated into the study of cognitive enrichment (Chapter 8).

Captive animals are frequently subject to imposed, uncontrollable stressors to which they respond through behavioural flexibility, or, failing which, exhibit pathology. Chimpanzees provide an intriguing model to examine how captive environments influence the responses of animals to stress. My study investigates the responses of a group of chimpanzees to imposed stressors of captivity at the Johannesburg Zoo, South Africa. My study comprised four components. Firstly, I examined the effects of spatial restriction on chimpanzee behaviour with regard to an enclosure enlargement, testing several existing models of coping with spatial crowding and another model, based on the coping hypothesis of abnormal behaviour. Behavioural observations of the chimpanzees in their indoor and outdoor exhibits before, during, immediately after and 10 weeks after the enclosure reconstruction revealed that the chimpanzees used tension-reduction and conflict-avoidance tactics as a means to cope with spatial crowding. Moreover, abnormal behaviour appears to provide an outlet for stress under crowding. Secondly, I assessed the long-term effects of past spatial environments on the space use and group spacing of the chimpanzees, five years after the enclosure change. Through behavioural observations and mapping the locations of individuals, I found that the chimpanzees exhibit space-use bias and limited group spacing, contingent on the dimensions of the old enclosure that were not explained by factors such as social or thermal conditions and zoo visitor effects. I propose that the spacing patterns may be due to spatial learned helplessness. Thirdly, I examined the effect of two social manipulations, mandated by zoo management, on the behaviour and socio-dynamics of the chimpanzees. The chimpanzees responded to social change through selective social interactions and non-social behavioural responses suggest that removing an individual was less stressful than the merging of two groups. Finally, I investigated the role of shade as a thermoregulatory resource for captive chimpanzees. Individuals used shade frequently despite observations taking place during the austral winter period, suggesting that shade is a valuable thermal resource for chimpanzees. In conclusion, the chimpanzees responded to most imposed stressors (spatial crowding, social change and thermal stress) through behavioural flexibility, implying successful coping, but failed to cope with previous spatial restrictions, resulting in limited space-use behaviour.

Thesis (M.A.)--University of Nevada, Reno, 2006. / "May 15, 2006." Includes bibliographical references (leaves 24-28). Online version available on the World Wide Web.

Thesis (Ph.D)--Biology, Georgia Institute of Technology, 2007. / Committee Chair: John F. McDonald ; Committee Members: Jung Choi, King Jordan, and Soojin Yi. Part of the SMARTech Electronic Thesis and Dissertation Collection.