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Author 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 (up) 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  
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  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 Pérez-Barbería, F.J.; Shultz, S.; Dunbar, R.I. url  doi
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  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 (up) 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. url  doi
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  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 (up) Pages  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Stanley2013 Serial 6253  
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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 2005 Publication Mammalia Abbreviated Journal  
  Volume 69 Issue (up) Pages  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Shi2005 Serial 6257  
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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 1976 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 24 Issue (up) 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 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 (up) 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 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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Author Barrett, L.; Henzi, P.; Dunbar, R. doi  openurl
  Title Primate cognition: from 'what now?' to 'what if?' Type Journal Article
  Year 2003 Publication Trends in Cognitive Sciences Abbreviated Journal Trends. Cognit. Sci.  
  Volume 7 Issue (up) 11 Pages 494-497  
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  Abstract The 'social brain' hypothesis has had a major impact on the study of comparative cognition. However, despite a strong sense, gained from both experimental and observational work, that monkeys and apes differ from each other, we are still no closer to understanding exactly how they differ. We hypothesize that the dispersed social systems characteristic of ape societies explains why monkeys and apes should differ cognitively. The increased cognitive control and analogical reasoning ability needed to cope with life in dispersed societies also suggests a possible route for human cognitive evolution. This hypothesis is supported by behavioural and neurobiological data, but we need more of both if we are to fully understand how our primate cousins see the world.  
  Address School of Biological Sciences, University of Liverpool, Biosciences Building, Crown St, Liverpool, UK L69 7ZB. louiseb@liv.ac.uk  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1364-6613 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:14585446 Approved no  
  Call Number Serial 2096  
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Author Pérez-Barbería, F.J.; Shultz, S.; Dunbar, R.I.M.; Janis, C. doi  openurl
  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 (up) 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 doi: 10.1111/j.1558-5646.2007.00229.x Approved no  
  Call Number Equine Behaviour @ team @ Serial 4781  
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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 1997 Publication Proceedings. Biological Sciences / The Royal Society Abbreviated Journal Proc Biol Sci  
  Volume 264 Issue (up) 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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  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 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 (up) 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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