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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 (up)
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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 (up)
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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 (up)
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Call Number Equine Behaviour @ team @ Shi2005 Serial 6257
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Author Dunbar, R.I.M.
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 (up) 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
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Language English Summary Language Original Title
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Series Volume Series Issue Edition
ISSN 1741-7007 ISBN Medium
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Notes PMID:17493267 Approved no
Call Number Serial 2100
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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 (up) 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
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 Dunbar, R.I.; Dunbar, E.P.
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 (up) 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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ISSN 0003-3472 ISBN Medium
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Notes PMID:817624 Approved no
Call Number Serial 2049
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Author Shultz, S.; Dunbar, R.I.M.
Title Both social and ecological factors predict ungulate brain size Type Journal Article
Year 2006 Publication Proceedings. Biological Sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 273 Issue 1583 Pages (up) 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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Series Editor Series Title Abbreviated Series Title
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.; McAdam, M.R.; O'connell, S.
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 (up) 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 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 (up) 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 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 (up) 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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