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Author (up) Dunbar, R.I.; Dunbar, E.P. doi  openurl
  Title Contrasts in social structure among black-and-white colobus monkey groups Type Journal Article
  Year 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.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  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 (up) Dunbar, R.I.M. url  doi
openurl 
  Title The social brain hypothesis and its implications for social evolution Type Journal Article
  Year 2009 Publication Annals of Human Biology Abbreviated Journal Annals of Human Biology  
  Volume 36 Issue 5 Pages 562-572  
  Keywords  
  Abstract The social brain hypothesis was proposed as an explanation for the fact that primates have unusually large brains for body size compared to all other vertebrates: Primates evolved large brains to manage their unusually complex social systems. Although this proposal has been generalized to all vertebrate taxa as an explanation for brain evolution, recent analyses suggest that the social brain hypothesis takes a very different form in other mammals and birds than it does in anthropoid primates. In primates, there is a quantitative relationship between brain size and social group size (group size is a monotonic function of brain size), presumably because the cognitive demands of sociality place a constraint on the number of individuals that can be maintained in a coherent group. In other mammals and birds, the relationship is a qualitative one: Large brains are associated with categorical differences in mating system, with species that have pairbonded mating systems having the largest brains. It seems that anthropoid primates may have generalized the bonding processes that characterize monogamous pairbonds to other non-reproductive relationships (?friendships?), thereby giving rise to the quantitative relationship between group size and brain size that we find in this taxon. This raises issues about why bonded relationships are cognitively so demanding (and, indeed, raises questions about what a bonded relationship actually is), and when and why primates undertook this change in social style.  
  Address  
  Corporate Author Thesis  
  Publisher Taylor & Francis Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0301-4460 ISBN Medium  
  Area Expedition Conference  
  Notes doi: 10.1080/03014460902960289 Approved no  
  Call Number Equine Behaviour @ team @ Serial 6546  
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Author (up) Dunbar, R.I.M. doi  openurl
  Title Male and female brain evolution is subject to contrasting selection pressures in primates Type Journal Article
  Year 2007 Publication BMC Biology Abbreviated Journal BMC Biol  
  Volume 5 Issue Pages 21  
  Keywords Animals; *Brain/physiology; *Evolution; Female; Humans; Male; *Selection (Genetics); *Sex Characteristics  
  Abstract The claim that differences in brain size across primate species has mainly been driven by the demands of sociality (the “social brain” hypothesis) is now widely accepted. Some of the evidence to support this comes from the fact that species that live in large social groups have larger brains, and in particular larger neocortices. Lindenfors and colleagues (BMC Biology 5:20) add significantly to our appreciation of this process by showing that there are striking differences between the two sexes in the social mechanisms and brain units involved. Female sociality (which is more affiliative) is related most closely to neocortex volume, but male sociality (which is more competitive and combative) is more closely related to subcortical units (notably those associated with emotional responses). Thus different brain units have responded to different selection pressures.  
  Address British Academy Centenary Research Project, School of Biological Sciences, University of Liverpool, Liverpool, UK. rimd@liv.ac.uk  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1741-7007 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:17493267 Approved no  
  Call Number Serial 2100  
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Author (up) 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 1974 Publication Primates Abbreviated Journal Primates  
  Volume 15 Issue 4 Pages 341-350  
  Keywords  
  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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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 2062  
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Author (up) 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 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  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  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 (up) Dunbar, R.I.M.; Shultz, S. doi  openurl
  Title Understanding primate brain evolution Type Journal Article
  Year 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  
  Keywords  
  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  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  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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Author (up) Dunbar, R.I.M.; Shultz, S. doi  openurl
  Title Evolution in the Social Brain Type Journal Article
  Year 2007 Publication Science Abbreviated Journal Science  
  Volume 317 Issue 5843 Pages 1344-1347  
  Keywords  
  Abstract The evolution of unusually large brains in some groups of animals, notably primates, has long been a puzzle. Although early explanations tended to emphasize the brain's role in sensory or technical competence (foraging skills, innovations, and way-finding), the balance of evidence now clearly favors the suggestion that it was the computational demands of living in large, complex societies that selected for large brains. However, recent analyses suggest that it may have been the particular demands of the more intense forms of pairbonding that was the critical factor that triggered this evolutionary development. This may explain why primate sociality seems to be so different from that found in most other birds and mammals: Primate sociality is based on bonded relationships of a kind that are found only in pairbonds in other taxa.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 4243  
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Author (up) Joffe, T.H.; Dunbar, R.I. doi  openurl
  Title Visual and socio-cognitive information processing in primate brain evolution Type Journal Article
  Year 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  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0962-8452 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:9332015 Approved no  
  Call Number Serial 2095  
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Author (up) Kudo, H.; Dunbar, R.I.M. url  doi
openurl 
  Title Neocortex size and social network size in primates Type Journal Article
  Year 2001 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 62 Issue 4 Pages 711-722  
  Keywords  
  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.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-3472 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 4726  
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Author (up) O'Connell, S.; Dunbar, R.I.M. doi  openurl
  Title The perception of causality in chimpanzees (Pan spp.) Type Journal Article
  Year 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  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1435-9448 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15322943 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2514  
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