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Author Dunbar, R.I.M. doi  openurl
  Title Observations on the ecology and social organization of the green monkey,Cercopithecus sabaeus, in Senegal Type Journal Article
  Year (up) 1974 Publication Primates Abbreviated Journal Primates  
  Volume 15 Issue 4 Pages 341-350  
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  Abstract The green monkey,Cercopithecus sabaeus, has not been studied in its natural habitat in West Africa. This paper reports observations made during a 3-month study in Senegal. Green monkeys live in multimale groups averaging some 12 individuals. Information is given on home range size, use of habitat, daily activity patterns, diet and birth seasonality. Social organization is discussed and data are given on the relationships between age-sex classes, aggression and leadership. Inter-group relations are discussed and it is suggested that groups defend their ranges as territories. The ecology and social organization of green monkeys is compared with that of populations ofC. aethiops studied in East Africa and they are found to be similar.  
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  Notes Approved no  
  Call Number Serial 2062  
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Author Dunbar, R.I.; Dunbar, E.P. doi  openurl
  Title Contrasts in social structure among black-and-white colobus monkey groups Type Journal Article
  Year (up) 1976 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 24 Issue 1 Pages 84-92  
  Keywords Agonistic Behavior; Animals; *Colobus; Copulation; Female; *Haplorhini; *Hierarchy, Social; Male; *Social Dominance  
  Abstract Three types of Colobus guereza groups may be distinguished on the bases of size and composition, namely small one-male groups, large, one-male groups and multi-male groups. The social structure of each type of group is described in terms of the distribution of non-agonistic interactions, the frequency and distribution of agonistic behaviour and the organization of the roles of vigilance, territorial defence and leadership. A number of differences are found between the group types which appear to be related to the differences in group size and composition. It is suggested that these group types represent stages in the life-cycle of colobus groups, and that such an interpretation may help to resolve some of the conflicting reports in the literature.  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 0003-3472 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:817624 Approved no  
  Call Number Serial 2049  
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Author Joffe, T.H.; Dunbar, R.I. doi  openurl
  Title Visual and socio-cognitive information processing in primate brain evolution Type Journal Article
  Year (up) 1997 Publication Proceedings. Biological Sciences / The Royal Society Abbreviated Journal Proc Biol Sci  
  Volume 264 Issue 1386 Pages 1303-1307  
  Keywords Animals; Brain/anatomy & histology/*physiology; Cognition/physiology; *Evolution; Geniculate Bodies/anatomy & histology/physiology; Humans; Mental Processes/physiology; Neocortex/physiology; Primates/anatomy & histology/*physiology/*psychology; *Social Behavior; Visual Cortex/anatomy & histology/physiology  
  Abstract Social group size has been shown to correlate with neocortex size in primates. Here we use comparative analyses to show that social group size is independently correlated with the size of non-V1 neocortical areas, but not with other more proximate components of the visual system or with brain systems associated with emotional cueing (e.g. the amygdala). We argue that visual brain components serve as a social information 'input device' for socio-visual stimuli such as facial expressions, bodily gestures and visual status markers, while the non-visual neocortex serves as a 'processing device' whereby these social cues are encoded, interpreted and associated with stored information. However, the second appears to have greater overall importance because the size of the V1 visual area appears to reach an asymptotic size beyond which visual acuity and pattern recognition may not improve significantly. This is especially true of the great ape clade (including humans), that is known to use more sophisticated social cognitive strategies.  
  Address School of Life Sciences, University of Liverpool, UK  
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  ISSN 0962-8452 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:9332015 Approved no  
  Call Number Serial 2095  
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Author Kudo, H.; Dunbar, R.I.M. url  doi
openurl 
  Title Neocortex size and social network size in primates Type Journal Article
  Year (up) 2001 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 62 Issue 4 Pages 711-722  
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  Abstract Primates use social grooming to service coalitions and it has been suggested that these directly affect the fitness of their members by allowing them to reduce the intrinsic costs associated with living in large groups. We tested two hypotheses about the size of grooming cliques that derive from this suggestion: (1) that grooming clique size should correlate with relative neocortex size and (2) that the size of grooming cliques should be proportional to the size of the groups they have to support. Both predictions were confirmed, although we show that, in respect of neocortex size, there are as many as four statistically distinct grades within the primates (including humans). Analysis of the patterns of grooming among males and females suggested that large primate social groups often consist of a set of smaller female subgroups (in some cases, matrilinearly based coalitions) that are linked by individual males. This may be because males insert themselves into the interstices between weakly bonded female subgroups rather than because they actually hold these subunits together.  
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  ISSN 0003-3472 ISBN Medium  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 4726  
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Author Zhou, W.-X.; Sornette, D.; Hill, R.A.; Dunbar, R.I.M. doi  openurl
  Title Discrete hierarchical organization of social group sizes Type Journal Article
  Year (up) 2005 Publication Proceedings. Biological sciences / The Royal Society Abbreviated Journal Proc Biol Sci  
  Volume 272 Issue 1561 Pages 439-444  
  Keywords Anthropology, Cultural; *Group Structure; Humans; *Models, Biological; *Social Behavior; *Social Environment  
  Abstract The 'social brain hypothesis' for the evolution of large brains in primates has led to evidence for the coevolution of neocortical size and social group sizes, suggesting that there is a cognitive constraint on group size that depends, in some way, on the volume of neural material available for processing and synthesizing information on social relationships. More recently, work on both human and non-human primates has suggested that social groups are often hierarchically structured. We combine data on human grouping patterns in a comprehensive and systematic study. Using fractal analysis, we identify, with high statistical confidence, a discrete hierarchy of group sizes with a preferred scaling ratio close to three: rather than a single or a continuous spectrum of group sizes, humans spontaneously form groups of preferred sizes organized in a geometrical series approximating 3-5, 9-15, 30-45, etc. Such discrete scale invariance could be related to that identified in signatures of herding behaviour in financial markets and might reflect a hierarchical processing of social nearness by human brains.  
  Address State Key Laboratory of Chemical Reaction Engineering, East China University of Science and Technology, Shanghai 200237, China  
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  ISSN 0962-8452 ISBN Medium  
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  Notes PMID:15734699 Approved no  
  Call Number refbase @ user @ Serial 549  
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Author Dunbar, R.I.M.; McAdam, M.R.; O'connell, S. doi  openurl
  Title Mental rehearsal in great apes (Pan troglodytes and Pongo pygmaeus) and children Type Journal Article
  Year (up) 2005 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 69 Issue 3 Pages 323-330  
  Keywords Algorithms; Animals; Child; Child, Preschool; Food; Frontal Lobe/anatomy & histology/physiology; Humans; *Imagination; Pan troglodytes; Pongo pygmaeus; Problem Solving/*physiology; Psychomotor Performance/physiology; Reward  
  Abstract The ability to rehearse possible future courses of action in the mind is an important feature of advanced social cognition in humans, and the “social brain” hypothesis implies that it might also be a feature of primate social cognition. We tested two chimpanzees, six orangutans and 63 children aged 3-7 years on a set of four puzzle boxes, half of which were presented with an opportunity to observe the box before being allowed to open it (“prior view”), the others being given without an opportunity to examine the boxes before handling them (“no prior view”). When learning effects are partialled out, puzzle boxes in the “prior view” condition were opened significantly faster than boxes given in the “no prior view” condition by the children, but not by either of the great apes. The three species differ significantly in the speed with which they opened boxes in the “no prior view” condition. The three species' performance on this task was a function of relative frontal lobe volume, suggesting that it may be possible to identify quantitative neuropsychological differences between species.  
  Address Evolutionary Psychology Research Group, School of Biological Sciences, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK. rimd@liv.ac.uk  
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  Series Volume Series Issue Edition  
  ISSN 0376-6357 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15896530 Approved no  
  Call Number Serial 2097  
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Author O'Connell, S.; Dunbar, R.I.M. doi  openurl
  Title The perception of causality in chimpanzees (Pan spp.) Type Journal Article
  Year (up) 2005 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 8 Issue 1 Pages 60-66  
  Keywords Animals; *Association Learning; Awareness; *Concept Formation; Female; *Habituation, Psychophysiologic; Male; Pan paniscus/*psychology; Pan troglodytes/*psychology; Perception  
  Abstract Chimpanzees (Pan spp.) were tested on a habituation/dishabituation paradigm that was originally developed to test for comprehension of causality in very young human infants. Three versions of the test were used: a food item being moved by a hand, a human pushing another human off a chair to obtain a food item, and a film clip of natural chimpanzee behaviour (capturing and eating a monkey). Chimpanzees exhibited similar results to those obtained with human infants, with significantly elevated levels of looking on the dishabituation trials. Since the level of response was significantly greater on natural/unnatural sequences than on unnatural/natural sequences, we conclude that the chimpanzees were not responding just to novelty but rather to events that infringed their sense of natural causation.  
  Address Evolutionary Psychology Research Group, School of Biological Sciences, Biosciences Building, University of Liverpool, Liverpool, L69 7ZB, UK  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1435-9448 ISBN Medium  
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  Notes PMID:15322943 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2514  
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Author Shi, J.; Dunbar, R.I.M.; Buckland, D.; Miller, D. url  doi
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  Title Dynamics of grouping patterns and social segregation in feral goats (Capra hircus) on the Isle of Rum, NW Scotland Type Journal Article
  Year (up) 2005 Publication Mammalia Abbreviated Journal  
  Volume 69 Issue Pages  
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  Call Number Equine Behaviour @ team @ Shi2005 Serial 6257  
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Author Shultz, S.; Dunbar, R.I.M. url  doi
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  Title Both social and ecological factors predict ungulate brain size Type Journal Article
  Year (up) 2006 Publication Proceedings. Biological Sciences / The Royal Society Abbreviated Journal Proc Biol Sci  
  Volume 273 Issue 1583 Pages 207-215  
  Keywords Animals; Artiodactyla/*anatomy & histology/*physiology; Brain/*anatomy & histology/physiology; *Ecosystem; Organ Size; Perissodactyla/*anatomy & histology/*physiology; *Social Behavior  
  Abstract Among mammals, the members of some Orders have relatively large brains. Alternative explanations for this have emphasized either social or ecological selection pressures favouring greater information-processing capacities, including large group size, greater foraging efficiency, higher innovation rates, better invasion success and complex problem solving. However, the focal taxa for these analyses (primates, carnivores and birds) often show both varied ecological competence and social complexity. Here, we focus on the specific relationship between social complexity and brain size in ungulates, a group with relatively simple patterns of resource use, but extremely varied social behaviours. The statistical approach we used, phylogenetic generalized least squares, showed that relative brain size was independently associated with sociality and social complexity as well as with habitat use, while relative neocortex size is associated with social but not ecological factors. A simple index of sociality was a better predictor of both total brain and neocortex size than group size, which may indicate that the cognitive demands of sociality depend on the nature of social relationships as well as the total number of individuals in a group.  
  Address School of Biological Sciences, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK. susanne.shultz@liv.ac.uk  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 0962-8452 ISBN Medium  
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  Notes PMID:16555789 Approved no  
  Call Number Serial 2098  
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Author Dunbar, R.I.M.; Shultz, S. doi  openurl
  Title Understanding primate brain evolution Type Journal Article
  Year (up) 2007 Publication Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences Abbreviated Journal Philos Trans R Soc Lond B Biol Sci  
  Volume 362 Issue 1480 Pages 649-658  
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  Abstract We present a detailed reanalysis of the comparative brain data for primates, and develop a model using path analysis that seeks to present the coevolution of primate brain (neocortex) and sociality within a broader ecological and life-history framework. We show that body size, basal metabolic rate and life history act as constraints on brain evolution and through this influence the coevolution of neocortex size and group size. However, they do not determine either of these variables, which appear to be locked in a tight coevolutionary system. We show that, within primates, this relationship is specific to the neocortex. Nonetheless, there are important constraints on brain evolution; we use path analysis to show that, in order to evolve a large neocortex, a species must first evolve a large brain to support that neocortex and this in turn requires adjustments in diet (to provide the energy needed) and life history (to allow sufficient time both for brain growth and for 'software' programming). We review a wider literature demonstrating a tight coevolutionary relationship between brain size and sociality in a range of mammalian taxa, but emphasize that the social brain hypothesis is not about the relationship between brain/neocortex size and group size per se; rather, it is about social complexity and we adduce evidence to support this. Finally, we consider the wider issue of how mammalian (and primate) brains evolve in order to localize the social effects.  
  Address British Academy Centenary Research Project, School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK. rimd@liv.ac.uk  
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  Series Volume Series Issue Edition  
  ISSN 0962-8436 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:17301028 Approved no  
  Call Number Serial 2099  
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