| Records |
| 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 |
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Journal Article |
| Year |
2007 |
Publication |
Evolution |
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61 |
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Equine Behaviour @ team @ Pérez-Barbería2007 |
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6221 |
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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 |
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2013 |
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Anim Behav |
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85 |
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Equine Behaviour @ team @ Stanley2013 |
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6253 |
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Shi, J.; Dunbar, R.I.M.; Buckland, D.; Miller, D. |
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Dynamics of grouping patterns and social segregation in feral goats (Capra hircus) on the Isle of Rum, NW Scotland |
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Journal Article |
| Year |
2005 |
Publication |
Mammalia |
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69 |
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Equine Behaviour @ team @ Shi2005 |
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6257 |
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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 |
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| 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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doi: 10.1111/j.1558-5646.2007.00229.x |
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no |
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Equine Behaviour @ team @ |
Serial |
4781 |
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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 |
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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English |
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0962-8452 |
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PMID:16555789 |
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no |
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Serial |
2098 |
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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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English |
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1435-9448 |
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PMID:15322943 |
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no |
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Equine Behaviour @ team @ |
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2514 |
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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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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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0003-3472 |
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no |
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Equine Behaviour @ team @ |
Serial |
4726 |
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| Author |
Joffe, T.H.; Dunbar, R.I. |
| 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 |
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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. |
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School of Life Sciences, University of Liverpool, UK |
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English |
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0962-8452 |
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PMID:9332015 |
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no |
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2095 |
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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 |
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Journal Article |
| Year |
2005 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
| Volume |
272 |
Issue |
1561 |
Pages |
439-444 |
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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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English |
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0962-8452 |
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PMID:15734699 |
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no |
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refbase @ user @ |
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549 |
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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 |
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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0376-6357 |
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PMID:15896530 |
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no |
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2097 |
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