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Author Dunbar, R.I.M.
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
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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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Call Number Serial 2062
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Author Dunbar, R.I.M.; Shultz, S.
Title Evolution in the Social Brain Type Journal Article
Year 2007 Publication Science Abbreviated Journal Science
Volume 317 Issue 5843 Pages 1344-1347
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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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Call Number Equine Behaviour @ team @ Serial 4243
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Author Kudo, H.; Dunbar, R.I.M.
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
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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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Call Number Equine Behaviour @ team @ Serial 4726
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Author Pérez-Barbería, F.J.; Shultz, S.; Dunbar, R.I.
Title Evidence for coevolution of sociality and relative brain size in three orders of mammals Type Journal Article
Year 2007 Publication Evolution Abbreviated Journal
Volume 61 Issue Pages
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Call Number Equine Behaviour @ team @ Pérez-Barbería2007 Serial 6221
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Author Stanley, C.R.; Dunbar, R.I.M.
Title Consistent social structure and optimal clique size revealed by social network analysis of feral goats, Capra hircus Type Journal Article
Year 2013 Publication Anim Behav Abbreviated Journal
Volume 85 Issue Pages
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Call Number Equine Behaviour @ team @ Stanley2013 Serial 6253
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Author Shi, J.; Dunbar, R.I.M.; Buckland, D.; Miller, D.
Title Dynamics of grouping patterns and social segregation in feral goats (Capra hircus) on the Isle of Rum, NW Scotland Type Journal Article
Year 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 Dunbar, R.I.M.
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
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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.
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Publisher Taylor & Francis Place of Publication Editor
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Series Volume Series Issue Edition
ISSN 0301-4460 ISBN Medium
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Notes (up) doi: 10.1080/03014460902960289 Approved no
Call Number Equine Behaviour @ team @ Serial 6546
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Author Pérez-Barbería, F.J.; Shultz, S.; Dunbar, R.I.M.; Janis, C.
Title Evidence For Coevolution Of Sociality And Relative Brain Size In Three Orders Of Mammals Type Journal Article
Year 2007 Publication Evolution Abbreviated Journal
Volume 61 Issue 12 Pages 2811-2821
Keywords Brain size, carnivores, coevolution, primates, sociality, ungulates
Abstract Abstract

As the brain is responsible for managing an individual's behavioral response to its environment, we should expect that large relative brain size is an evolutionary response to cognitively challenging behaviors. The “social brain hypothesis†argues that maintaining group cohesion is cognitively demanding as individuals living in groups need to be able to resolve conflicts that impact on their ability to meet resource requirements. If sociality does impose cognitive demands, we expect changes in relative brain size and sociality to be coupled over evolutionary time. In this study, we analyze data on sociality and relative brain size for 206 species of ungulates, carnivores, and primates and provide, for the first time, evidence that changes in sociality and relative brain size are closely correlated over evolutionary time for all three mammalian orders. This suggests a process of coevolution and provides support for the social brain theory. However, differences between taxonomic orders in the stability of the transition between small-brained/nonsocial and large-brained/social imply that, although sociality is cognitively demanding, sociality and relative brain size can become decoupled in some cases. Carnivores seem to have been especially prone to this.
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Notes (up) doi: 10.1111/j.1558-5646.2007.00229.x Approved no
Call Number Equine Behaviour @ team @ Serial 4781
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Author O'Connell, S.; Dunbar, R.I.M.
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
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Language English Summary Language Original Title
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ISSN 1435-9448 ISBN Medium
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Notes (up) PMID:15322943 Approved no
Call Number Equine Behaviour @ team @ Serial 2514
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Author Zhou, W.-X.; Sornette, D.; Hill, R.A.; Dunbar, R.I.M.
Title Discrete hierarchical organization of social group sizes Type Journal Article
Year 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 (up) PMID:15734699 Approved no
Call Number refbase @ user @ Serial 549
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