This thesis concerns the cortical connectivity in Primates. The efficacy of Diffusion weighted MRI (dMRI) is examined. White matter (“WM”) systems subjacent to cortex (“superficial WM” ) are found to be a limiting factor to dMRI tractography. Superficial WM systems are examined with dMRI itself, and with analysis of histological data from the scanned brains. dMRI data was acquired ex-vivo at exceptional spatial and angular resolution (250μm in Rhesus, 150μm in Marmoset). The superficial WM was found to be complex, and with current dMRI methods, an effective barrier to tracking to and from around 50% of cortex in Rhesus. The quality of our data allowed Gray matter seeding, so that penetration both into and out of cortex was examined. We summarize the history of cortical connectivity and current work in tractography. We present an account of the formation and properties of the superficial WM. We compare tracking behaviors to tracer results, and develop a series of scalar maps on cortical surface models to summarize tracking behaviors. We attempt to explain these maps by examining the underlying tracking behavior and the brain tissue itself, revealing the intricate nature of the superficial WM. Chapter 4 contains a separate but related project in which a histologically accurate high resolution 3D and surface atlas of the Rhesus cortex is constructed with unprecedented accuracy. A method to rapidly and accurately non-linearly transform the atlas to a scan of another animal is developed, thus labelling its cortex. accuracy is by comparison to histology of the scanned animals.

Understanding the impacts of landscape fragmentation, degradation and hunting on arboreal species of conservation concern, such as the critically endangered brownheaded spider monkey (Ateles fusciceps fusciceps), remains a major challenge in conservation biology. Current research on the population status of this primate and the area it inhabits in the Ecuadorian Choco is urgently needed to aid in the design of specific and effective conservation strategies. I surveyed the population of A. f. fusciceps in the unprotected forest cooperative Tesoro Escondido in the buffer zone of the Cotacachi Cayapas Ecological Reserve during the year 2012-2013. Using the line transect method I estimated a population density of 15.79 individuals/km2. I found an average subgroup size of 3.42 individuals and a female biased population. Identifying key food resources for critically endangered species is vital in their conservation, particularly if these resources are also targeted by anthropogenic activities such as logging. The province where A. f. fusciceps is found is also heavily dependent on commercial logging with no information available on its impacts on key feeding resources for this primate. I characterised the oristic composition of the habitat of A. f. fusciceps and estimated the availability of fruit resources for the annual cycle of 2012-2013 in sixteen 0.1 hectare vegetation plots. I determined feeding preferences for A. f. fusciceps using behavioural observations applying the Chesson ε index to identify key feeding tree species. I reviewed regional logging permits to identify species targeted for extraction by the timber industry and calculated extraction volumes in primary forest for key feeding tree species to identify potential conflict between logging and primate diet. I identified 65 fruiting tree species from 34 families that formed the diet of A. f. fusciceps . The Chesson ε index identified twelve species as preferred species with further phenological observations identifying seven species as staple foods and two palms as potential foods consumed in times of fruit scarcity. Additionally, I found that the lipid rich fruits of Brosimum utile make this an important resource for this primate throughout the year. Furthermore, of 65 feeding tree species identified for A. f. fusciceps , 35 species are also targeted as sources of timber. Five key feeding species would be depleted under current sustainable management extraction protocols while two other species would be significantly impacted in terms of local abundance. Hunting pressure on A. f. fusciceps has been reported as one of the main causes of its population decline. However, no current research on the extent of this activity or its causes was available. I carried out semi-structured interviews in nine indigenous Chachi villages, as well as two Colono towns, to evaluate the occurrence of hunting activity and to identify drivers, attitudes and behaviour of hunters. In total I interviewed 62 people, 41 Chachis and 21 Colonos. From the Chachi interviewees 93% identified themselves as hunters, with subsistence hunting the main driver for this activity and central to their culture, especially for men. Colonos identified less with this activity (only 38%), and with more varied reasons, such as commerce and conflict. Only Chachis accepted the hunting of spider monkeys, with the main reason given as their taste. Keeping spider monkeys as pets was also a regular activity prior to tougher law enforcement by the Ministry of Environment (MAE). Information on medicinal uses from spider monkeys was also gathered, as well as information of other species hunted in the area. Even though Ecuadorian law recognises the right of indigenous peoples to hunt within their territories, it also forbids hunting critically endangered species. From the interviews it is evident that information and understanding of this law has not been successfully transmitted. Determining the effects of fragmentation, hunting and habitat degradation on populations viability of this primate is crucial before investing heavily in local sustainable livelihoods and conservation initiatives. A range of fragmentation metrics are available to study habitat fragmentation, yet their relationship to survival of populations of conservation concern remains to be quantified. I applied an agent-based model (ABM), calibrated on field-collected datasets on forest fruit dynamics, behaviour and feeding ecology of A. f. fusciceps, to first identify an optimised fragmentation statistic to be used to screen satellite imagery and identify remaining priority conservation areas in unprotected, fragmented forests in NW Ecuador. I then used the ABM to further explore the combined impacts of fragmentation, hunting and logging. Mean Patch Area was the best fragmentation metric predictor of population numbers, I identified a MPA of 174.9 hectares as the cut-off point for the survival of brown-headed spider monkeys given the lowest combinations of logging activity and hunting pressure and I used it to identify priority conservation areas in NW Ecuador. Implementing conservation strategies in areas where people and nature interact is a challenging task. I designed a step by step framework for the conservation of critically endangered species. Based on my experience with Ateles fusciceps fusciceps as a case study, I present the design, assessment and implementation of different community-based strategies.

Baboons are a well studied primate, with extensive data from numerous long-term field sites from various ecological contexts across Africa. Underrepresented in this sample, however, are woodland/forest population. In this thesis I investigated the diet and movement ecology in a woodland/forest population of yellow baboons (Papio cynocephalus) at the Issa valley of Ugalla, western Tanzania. I begin by describing the diet of Issa baboons using macroscopic faecal analysis. 1 show they selectively exploited the environment according to the availability of fruits, and unlike for their savannah conspecifics, there appeared to be sufficient food alternatives during periods of low fruit availability. Using day path lengths (DPL) 1 examined what factors are important in determining movement of baboons at a continental scale. Using a mixed modelling approach with data from 39 baboon troops form sub-Saharan Africa, I show factors to be important on a continental scale include plant productivity, anthropogenic influence, primate richness and group size. Next, 1 explored the movement ecology of baboons at a local scale in two ways, using baboons at Issa. First I examined the DPL and Path Trajectories (PTs: speed and tortuosity) where I find they moved slower and over shorter distances on warmer days, and slower and more directly when fruit was more abundant. Second I examined patterns of space use within their home ranges (HR). I find sleep site availability and habitat type significantly influence movement within HRs and that the forest habitat is avoided whilst rocky outcrops are preferred. Additionally, I find PTs were predicted by habitat type, with baboons moving faster and straighter through habitats they tended to avoid. Finally, I explored the potential for competition between baboons at Issa with sympatric chimpanzees (Pan troglodytes) by comparing their diet and patterns of habitat use. I show that despite periods of high overlap in fruits consumed, competition between these primates is unlikely to be important due to key dietary differences and differential utilisation of habitat types.

Mirror image stimulation (MIS) is reported to elicit persistent social responses in monkeys, in contrast to most humans and great apes, who exhibit self-recognition. The abnormal features of a mirror image as a social stimulus have generally been ignored in monkey reports, whereas research with other animals has identified some important differences between MIS and other stimuli. Differential agitation during separations in peer-reared and mirror-reared infant stumptail monkeys suggests that even the limited opportunity for physical contact with a reflection renders it a sub- optimal attachment-eliciting stimulus. Mirror-rearing appeared to only slightly diminish responsiveness to pictures of conspecifics, compared to peer-rearing. Animals reared with no form of social stimulation exhibited less responsiveness to pictorial stimuli, and engaged in more abnormal and self-directed behaviours than mirror- or peer-reared animals, indicating that a mirror can at least partly compensate for the absence of a true social companion during rearing. The extent of abnormal behaviours in alone-reared stumptail monkeys appears to be considerably less than that reported in rhesus monkeys. The mirror was reacted to as a social partner by mirror-reared animals, and correlations between behaviours, and between measures of a single behaviour, were similar in mirror- and peer-reared groups. However, a live cagemate received 50% more social behaviour than did a reflection, with play behaviours producing group differences in rate, duration, bout length, and variability. MIS or a peer behind Perspex reduced separation agitation in pair-reared but not group-reared infants. In comparison to a peer behind Perspex, MIS received positive responses in mirror-reared and pair-reared animals, whereas group-reared animals reacted more ambivalently to the abnormal animal represented in the mirror. Those mirror-reared animals who received additional experience of a peer behind Perspex during rearing reduced responding to the mirror, whereas responsiveness in mirror-only-reared animals persisted. Peer-only-reared animals were also highly responsive to MIS, possibly due to novelty. Alone-reared subjects, when tested in a familiar setting, were the most responsive of all the subjects to MIS. None of the subjects exhibited self-recognition, even although some had approximately 3,500 hours of experience of a triple mirror image effect, and an additional six months group mirror experience. Some results were obtained with small numbers of subjects, so caution is required in interpretation.

This thesis presents the development and application of methods to assess cognitive markers of emotion and psychological wellbeing in a species of nonhuman primate, the rhesus macaque (Macaca mulatta). In humans, vulnerability to emotional disorders such as anxiety and depression is characterized by particular cognitive profiles, known as cognitive biases. For example, anxious people automatically attend to threat-relevant information, interpret ambiguous information negatively, and have negative expectations of future events. In this thesis, I first describe two treatments that were used prior to cognitive testing to induce positive and negative shifts in inferred affective state in the monkeys (enrichment and a health-check, respectively) and discuss the impact of these treatments on the monkeys’ behaviour and physiology (Chapters 2 and 3). In the first cognitive study (Chapter 4), I present a method that uses eye-gaze to assess the extent to which threatening (versus non-threatening) stimuli capture visual spatial attention when two stimuli are presented at different locations. In the second study (Chapter 5), I present a simple operant touch-screen task to assess the extent to which a threatening distractor stimulus captures attention and impairs performance on an ongoing task when presented at the same location as the taskrelevant stimulus. In the third study (Chapter 6), I present a Go/NoGo touchscreen task to assess judgements about the reward value of ambiguous stimuli. In all of these studies, the two treatments led to different cognitive profiles in the monkeys. Monkeys showed a) automatic capture of attention by threatening stimuli, which was followed by avoidance following the health-check, but not Post-enrichment; b) impaired task performance when a threatening distractor stimulus was presented Post-health-check, and improved performance on these trials Post-enrichment; and c) a more negative judgement about the reward value of ambiguous stimuli Post-health-check versus Post-enrichment. I discuss these cognitive biases in light of available data from humans, and recent work with nonhuman animals. These data indicate that furthering our understanding of primate and other animal psychological wellbeing, may be achieved through the development of measures of cognitive bias, such as those presented here.

Social behaviours have been widely studied in behavioural economics and psychology. However, the origins of these behaviours in the brain are poorly understood. In this dissertation I will discuss two main avenues of study which constituted separate projects during my PhD candidacy. The first section contains experiments in which I collaborated with Dr Raymundo Báez-Mendoza on the topic of inequity. The second part includes a study on coordination and cooperation behaviour in macaques. Inequity is a concept ubiquitous in daily life. It is the difference between one’s own reward and that of another. There have been several studies that have suggested inequity affects brain activity. However, few studies have touched upon how this parameter is incorporated in neuronal activity. In the experiments that will be described here, monkeys (Macaca mulatta) performed actions to obtain rewards for both themselves and another. The level of inequity in these rewards was manipulated by varying the magnitude of own and other’s rewards. We then proceeded to study neuronal activity by means of single neuron recordings in the striatum of two macaques. We found that inequity modulated task related activity in about 32% of recorded striatal neurons. In addition to this study on inequity we also recorded some sessions in which one of the animals made choices with varying rewards for self and other. From these results, I attempted to characterise behaviour with regards to own reward and inequity in choice situations. Inequity has been considered a contributing factor in explaining cooperation behaviour. Coordination and cooperation are important and frequently observed behaviours. To study coordination and cooperation, I designed an experiment in which the combination of two monkeys’ choices determined the rewards for both animals. In this dissertation I attempt to address how the animals perform combined choices (playing together vs. alone) as well as the nature of their behaviour (e.g. pro-social vs. self-interested). The aim of this work was to characterise what type of information the animals use to solve these tasks. This is vital if one is to study these concepts in the brain using macaques as a model. In summary, this work contributes to a better understanding of social behaviour and provides an example of how this social behaviour is computed in the brain.

Recent studies on the social life and vocal production, usage and comprehension of nonhuman primates have brought new insights into the evolutionary mechanisms of cognition and communication as well as the emergence of language. A key point in the current literature concerns the flexibility of vocal production. In contrast to humans, some birds and some cetaceans, vocal flexibility is thought to be very restricted in nonhuman primates, which creates a startling phylogenetic gap. At the same time, research has shown that a number of African forest guenons' alarm calls appear to have language-like properties. With the hypothesis that looking at the vocal repertoire more broadly, especially the social calls, was likely to reveal other complex communicative abilities, I studied in detail the social life and vocal behaviour of a guenon species, Diana monkeys. First, the comparison of its social system with the system of another closely related species, Campbell's monkeys, stressed in both species the reduced number of physical interactions, although females maintained preferential relationships that were not biased towards kin. Second, the study of Diana females' vocal repertoire is restricted but flexible. Females emit social calls with a combinatorial structure, the use of which is affected by external events. Third, focusing on a highly frequent and highly social call revealed flexibility in the identity advertisement (divergence – convergence) which accommodates to the context. Fourth, to explore the nature of nonhuman primates' comprehension skills, I performed playback experiments of De Brazza monkey social calls to three species of Old World monkeys; Campbell's monkeys, black-and-white colobus monkeys and red-capped mangabeys. Altogether, the three species were able to discriminate hetero-specific voices of individuals they knew from individuals they had never met. Overall, my results have revealed a considerable degree of flexibility in the vocal communication of nonhuman primates, a finding that is consistent with the hypothesis of a continuous evolutionary transition from animal vocal behaviour to human language.

The feeding ecology, general behaviour, size of groups and use of habitat of the golden-backed uacari, Cacajao melanocephalus ouakary, was monitored for 14 of a 19-month period in Jaú National Park, Amazonian Brazil between October 2006 and April 2008. The botanical composition and phenology of the habitats was also studied. The diet is dominated by seeds of immature hard-husked fruits. Leaves, flowers and pith served as fall-back foods. The diet items eaten were the most abundant at the moment, with items previously ignored incorporated when the abundance of other foods dropped relative to them. Most feeding occurred in the forests upper strata, but with occasional visits to the ground and low bushes when little food was available elsewhere. Feeding bouts were short, with uacaris generally spending less than three minutes in a feeding patch before moving to the next. Individual adults generally foraged one-per-patch, though up to five animals might forage simultaneously in canopies of very large trees. Uacaris were recorded feeding on 136 plant species. Micropholis venulosa, Echweilera tenuifolia, Buchenavia ochrograma, Pouteria elegans and Mabea nitida were the most abundant species in the diet, and were eaten for both leaves and seeds. Flowers of E. tenuifolia were also eaten. The most important diet families were Sapotaceae, Fabaceae and Lecythidaceae. Invertebrates represented less than 2% of the diet, and were mostly ants, termites and caterpillars. Many were free-ranging, but shoot-boring larvae were also extracted and eaten. Additionally, fruits of five species were recorded being eaten with insect larvae still living inside them. ii Uacaris use two habitats, terra firme (a never-flooded mosaic of several forest sub-types) and igapó (a seasonally-flooded forest that occurs between terra firme and the open river). Igapó’s fruiting season match the flood pulse and so are strongly condensed. Those of terra firme are less so. In 14 month, uacaris were seen exclusively in terra firme during 3 months, only in igapó during 9 months and in both during 2 months. Movement between the habitats appears to follow fruit availability. When there is little fruit in either, uacaris remain in the igapó and feed (mostly) on new leaves. The activity budget was dominated by moving, paused feeding and feeding-while-moving. Very little resting was observed and almost no physical social interactions such as aggression or grooming. Adult C. m. ouakary were rarely seen closer than 6m apart, and groups were often diffuse, spreading over several hundred meters. Reproduction appears to occur twice a year, very young animals being seen in December and May. Observed group size varied between 2 and 51. Groups of 6-15 were most commonly seen. Group size varied with the season and habitat, being largest (30-51) in never-flooded rainforest and smallest (4-6) in the igapó when little fruit was available and fall-back foods dominated the diet. At least 10 of the species in the C. m. ouakary diet are used as timber in Amazonia. While this is not a cause of conflict in Jaú National Park, it might be so elsewhere in the animal’s range. This has been the first long-term study of the ecology of golden-backed uacaris in Brazil and suggestions are made for future research.

Primates are known for being highly social species, living in groups of various compositions with different social structures. The study of social or observational learning has largely focussed on investigating non-human primates' abilities to imitate, with a more recent shift towards examining the social context of social learning. This shift has presented opportunities to investigate how the social context of different species affects the diffusion of socially learnt behaviours. In this thesis, I set out to monitor the spread of different experimentally seeded and naturally occurring socially learned behaviours in brown (tufted) capuchin monkeys (Sapajus sp.) and common squirrel monkeys (Saimiri sciureus).These species were selected as they form mixed species groups in the wild, and display marked differences in their social tolerances, thus presenting the opportunity to investigate conspecific and heterospecific social learning in related but differently bonded social groups. My results show evidence of social learning from conspecifics in capuchin and squirrel monkeys, attesting to that already documented in capuchin monkeys and indicating for the first time, that common squirrel monkeys can learn socially. Additionally, I demonstrate that capuchin monkeys are influenced by squirrel monkeys when foraging for food in mixed species groups. Furthermore, although squirrel monkeys are not as socially tolerant as capuchin monkeys, individuals who were better connected within the foraging test area learned experimentally-seeded techniques of models faster and more faithfully. When performing socially contagious anointing behaviours, regardless of tufted capuchin monkeys being influenced by the amount of resources provided for them to anoint with, they still performed more socially anointing than has been previously documented in other captive species, corroborating the levels of social anointing demonstrated in semi-free ranging groups. Further support was found for anointing demonstrating a social bonding and medicinal function in tufted capuchin monkeys.

La structure sociale d'un groupe peut théoriquement réguler la transmission des informations et le risques de maladies via les contacts sociaux et la proximité. En théorie, les mêmes propriétés de réseau qui favorisent la transmission d'information favorisent également la transmission de pathogènes, créant de fait un potentiel compromis entre eux. Dans ma thèse, j'ai utilisé des données empiriques, des analyses de réseaux et modèle de simulation individuel afin de comprendre l'influence des structures sociales sur la transmission sociale chez les primates et dans des réseaux théoriques. Mes études ont montré que i) les macaques japonais centraux dans Je groupe transmettent les pathogènes plus rapidement mais sont également plus susceptibles d' être infectés; ii) le nombre d'individus infectés dans 40 groupes de primates est dépendant des propriétés globales du réseau et de l'étape de l'infection: iii) un pic d'efficacité de réseau à des valeurs intermédiaires de sous­ structure de groupe dans des réseaux empiriques et théoriques ; et iv) des variations dans les propriétés de réseaux sont la conséquence de décisions individuelles en fonction de compromise entre la collecte d'information et l'évitement de l'infection. Ainsi, ma thèse a démontré les mécanismes de transmission social et indiqué que les propriétés de réseau pourrait réflecter un compromise entre transmission de l'information et transmission de pathogène. / Social structure can theoretically regulate information transmission and disease risk via social contact or proximity. In theory, the same network properties that favor information transmission also favor pathogen transmission creating a potential trade-off between them. In my thesis, I used empirical data, network analysis and individual-based modelling to understand the influence of social structure on social transmission in primate and theoretical networks. My studies show that i) central Japanese macaques transmit disease faster but are also more prone to acquiring infectious agents; ii) the number of infected individuals in 40 wild primate groups is dependent on global network properties and epidemic time; iii) network efficiency peaks with intermediate values of group substructure in theoretical and empirical networks; and, iv) variation in the network properties is a consequence of individual decisions given the trade-offs between collecting information and avoiding infection. Altogether, my thesis reveals the mechanisms of social transmission and indicates that network properties might reflect a trade-off between information and pathogen transmission.