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Author Zhou, W.-X.; Sornette, D.; Hill, R.A.; Dunbar, R.I.M. doi  openurl
  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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  Series Volume Series Issue Edition  
  ISSN 0962-8452 ISBN Medium  
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  Notes PMID:15734699 Approved no  
  Call Number refbase @ user @ Serial 549  
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Author Janik, V.M. openurl 
  Title Whistle matching in wild bottlenose dolphins (Tursiops truncatus) Type Journal Article
  Year 2000 Publication Science (New York, N.Y.) Abbreviated Journal Science  
  Volume 289 Issue 5483 Pages 1355-1357  
  Keywords Animals; Animals, Wild/physiology; Dolphins/*physiology; *Imitative Behavior; *Learning; *Social Behavior; *Vocalization, Animal  
  Abstract Dolphin communication is suspected to be complex, on the basis of their call repertoires, cognitive abilities, and ability to modify signals through vocal learning. Because of the difficulties involved in observing and recording individual cetaceans, very little is known about how they use their calls. This report shows that wild, unrestrained bottlenose dolphins use their learned whistles in matching interactions, in which an individual responds to a whistle of a conspecific by emitting the same whistle type. Vocal matching occurred over distances of up to 580 meters and is indicative of animals addressing each other individually.  
  Address School of Biology, University of St. Andrews, Bute Building, Fife KY16 9TS, UK  
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  Series Volume Series Issue Edition  
  ISSN 0036-8075 ISBN Medium  
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  Notes PMID:10958783 Approved no  
  Call Number refbase @ user @ Serial 550  
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Author Reeve, H. Kern url  doi
openurl 
  Title Evolutionarily stable communication between kin: a general model Type Journal Article
  Year 1997 Publication Proceedings of the Royal Society B: Biological Sciences Abbreviated Journal Proc. Roy. Soc. Lond. B Biol. Sci.  
  Volume 264 Issue (1384) Pages 1037-1040.  
  Keywords Signalling Systems  
  Abstract At present, the most general evolutionary theory of honest communication is Grafen's model of Zahavi's 'handicap' signalling system, in which honesty of signals about the signaller's quality (e.g. mate suitability or fighting ability) is maintained by the differentially high cost of signals to signallers having lower quality. The latter model is here further generalized to include any communication between signallers and receivers that are genetically related (e.g. parents and begging offspring, cooperative or competing siblings). Signalling systems involving relatives are shown to be evolutionarily stable, despite a potential pay-off for false signalling, if the Zahavian assumption of differential signal costs holds and there are diminishing reproductive returns to the signaller as the receiver's assessed value of its attribute increases, or if, regardless of whether the Zahavian assumption holds, signallers with high values of the attribute benefit more from a given receiver assessment than signallers with low values (e.g. begging chicks that are hungrier benefit more from being fed). In stable systems of signalling among kin, it is also shown to be generally true that (i) levels of signalling and thus observed signal costs will decline as relatedness increases or as the receiver's reproductive penalty for erroneous assessment increases, and (ii) receivers will consistently, altruistically overestimate the true value of the signalled attribute.  
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  Call Number refbase @ user @ Serial 557  
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Author Brilot, B.O.; Johnstone, R.A. doi  openurl
  Title The limits to cost-free signalling of need between relatives Type Journal Article
  Year 2003 Publication Proceedings. Biological sciences / The Royal Society Abbreviated Journal Proc Biol Sci  
  Volume 270 Issue 1519 Pages 1055-1060  
  Keywords *Animal Communication; Animals; Birds/physiology; Models, Biological; *Social Behavior  
  Abstract Theoretical models have demonstrated the possibility of stable cost-free signalling of need between relatives. The stability of these cost-free equilibria depends on the indirect fitness cost of cheating and deceiving a donor into giving away resources. We show that this stability is highly sensitive to the distribution of need among signallers and receivers. In particular, cost-free signalling is likely to prove stable only if there is very large variation in need (such that the least-needy individuals stand to gain much less than the most-needy individuals from additional resources). We discuss whether these conditions are likely to be found in altricial avian breeding systems--the most intensively studied instance of signalling of need between relatives. We suggest that cost-free signalling is more likely to prove stable and will provide parents with more information during the earlier phases of chick growth, when parents can more easily meet the demands of a brood (and chicks are more likely to reach satiation). Later, informative yet cost-free signalling is unlikely to persist.  
  Address Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. bob21@cam.ac.uk  
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  ISSN 0962-8452 ISBN Medium  
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  Notes PMID:12803895 Approved no  
  Call Number refbase @ user @ Serial 558  
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Author Bergstrom,C. T.; Lachmann, M. openurl 
  Title Signalling among relatives. I. Is costly signalling too costly? Type Journal Article
  Year 1997 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc. Natl. Acad. Sci. U.S.A.  
  Volume 352(1353) Issue Pages 609-617  
  Keywords Signalling  
  Abstract ahavi's handicap principle,originally proposed as an explanation for sexual selection ofelaborate male traits, suggests that a sufficient cost to dishonest signals can outweigh the rewards of deception and allow individuals to communicate honestly. Maynard Smith (1991) and Johnstone and Grafen (1992) introduce the Sir Philip Sidney game in order to extend the handicap principle to interactions among related individuals, and to demonstrate that stable costly signalling systems can exist among relatives.

In this paper we demonstrate that despite the benefits associated with honest information transfer, the costs incurred in a stable costly signalling system may leave all participants worse off than they would be in a system with no signalling at all. In both the discrete and continuous forms of the Sir Philip Sidney game, there exist conditions under which costly signalling among relatives, while stable, is so costly that it is disadvantageous compared with no signalling at all. We determine the factors which dictate signal cost and signal benefit in a generalized version of this game, and explain how signal cost can exceed signal value. Such results raise concerns about theevolutionary pathways which could have led to the existence of signalling equilibria in nature. The paper stresses the importance of comparing signalling equilibria with other possible strategies, beforedrawing conclusions regarding the optimality of signalling.
 
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  Call Number refbase @ user @ Serial 559  
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Author Bergstrom, C.T.; Lachmann, M. openurl 
  Title Signaling among relatives. III. Talk is cheap Type Journal Article
  Year 1998 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc. Natl. Acad. Sci. U.S.A.  
  Volume 95 Issue 9 Pages 5100-5105  
  Keywords Animal Communication; Animals; Costs and Cost Analysis; *Evolution; Interpersonal Relations; Models, Biological  
  Abstract The Sir Philip Sidney game has been used by numerous authors to show how signal cost can facilitate honest signaling among relatives. Here, we demonstrate that, in this game, honest cost-free signals are possible as well, under very general conditions. Moreover, these cost-free signals are better for all participants than the previously explored alternatives. Recent empirical evidence suggests that begging is energetically inexpensive for nestling birds; this finding led some researchers to question the applicability of the costly signaling framework to nestling begging. Our results show that cost-free or inexpensive signals, as observed empirically, fall within the framework of signaling theory.  
  Address Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA. carl@charles.stanford.edu  
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  ISSN 0027-8424 ISBN Medium  
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  Notes PMID:9560235 Approved no  
  Call Number refbase @ user @ Serial 561  
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Author Lindberg, A.C.; Kelland, A.; Nicol, C.J. url  doi
openurl 
  Title Effects of observational learning on acquisition of an operant response in horses Type Journal Article
  Year 1999 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 61 Issue 3 Pages 187-199  
  Keywords Horse; Observational learning; Stereotyped behaviour; Operant behaviour; Breed influence; Age influence  
  Abstract The effect of observational learning on the acquisition of an operant response was examined in eighteen riding horses and ponies. The test horses were randomly divided into three groups of six and individually exposed to one of three treatments. An additional horse was trained as a demonstrator, to perform the operant response. The observer horses watched either the demonstrator performing the bin-opening response (Group D+B); the demonstrator standing passively (Group D); or the operant bin in the absence of the demonstrator (Group B). Observers had access to and were free to interact with an identical bin during testing. Observers in Groups D+B and D were socially familiar with the demonstrator. Each test horse was tested once a day for 10 days. An ANOVA revealed no significant differences between treatment groups in the number of responses or the time taken to reach the learning criterion. However, there were highly significant differences between breed types, with non-warmbloods performing more bouts of opening the bin and feeding (p=0.02), feeding from the bin sooner (p=0.01) and reaching the criterion for learning sooner than warmbloods (p=0.05). There was also a significant negative linear relationship between horses' ages and time spent investigating the bin, with younger horses performing more investigative behaviour (y=-3.08x+106.86; p=0.02).  
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  Call Number refbase @ user @ Serial 562  
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Author Clarke, J.V.; Nicol, C.J.; Jones, R.; McGreevy, P.D. url  doi
openurl 
  Title Effects of observational learning on food selection in horses Type Journal Article
  Year 1996 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 50 Issue 2 Pages 177-184  
  Keywords Horse; Observational learning; Food discrimination  
  Abstract Fourteen riding horses of mixed age and breed were randomly allocated to observer and control treatments. An additional horse was pre-trained as a demonstrator to walk the 13.8 m length of the test arena and select one of two food buckets using colour and pattern cues. Observer horses were exposed to correct performances of the task by the trained demonstrator, for 20 trials held over 2 days. Control horses were subjected to the same handling and placement procedures as the observer horses but without exposure to the behaviour of the demonstrator. The third day for all subjects was designated as a test day. Each subject was released individually in a predetermined place in the arena, and the latency to walk the length of the test arena to the food buckets, the latency to feed, the identity of the bucket approached and the identity of the bucket selected were recorded on ten consecutive trials. During tests both food buckets contained food to minimize the possibility of individual trial and error learning. On the first trial the mean latency to approach the goal area was 18 s for observer horses, compared with 119 s for control horses (t = 2.8, d.f. = 12, P < 0.01) and the mean latency to eat was 35 s for observer horses, compared with 181 s for control horses (t = 4.86, d.f. = 11, P < 0.001). However, observer horses were no more likely to choose the demonstrated bucket than control horses on the first trial. Twelve of the 14 horses decreased their latency to approach the goal area during the series of ten trials, but there were no significant changes in the buckets selected.  
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  Call Number refbase @ user @ Serial 563  
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Author Nicol, C.J. url  doi
openurl 
  Title How animals learn from each other Type Journal Article
  Year 2006 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 100 Issue 1-2 Pages 58-63  
  Keywords Social learning; Chickens; Demonstrators; Dominance  
  Abstract This paper explores ways by which animals may learn from one another, using examples drawn mostly from the chicken, an animal for which social learning is likely to be less dangerous than individual learning. In early life, the behaviour of the hen is important in encouraging chicks to peck at edible items. Maternal display not only attracts chicks to profitable food items, but also redirects their attention away from harmful or non-profitable items. Older chicks can enhance their foraging success by observing the behaviour of conspecifics within their own social group. Hens have been trained to perform a novel behaviour (key-pecking for food) by observation of a trained demonstrator bird. Moreover, observers learnt most from watching dominant demonstrators. Thus the ability to learn from others is not `fixed', but depends on the context and the social identity of both the observer and the demonstrator.  
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  Call Number refbase @ user @ Serial 564  
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Author Nicol, C.J. url  openurl
  Title The social transmission of information and behaviour Type Journal Article
  Year 1995 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 44 Issue 2-4 Pages 79-98  
  Keywords Social learning; Imitation; Social facilitation; Cultural transmission; Stereotypies  
  Abstract Social influences on established behaviour and on the acquisition of new information and behaviour are reviewed. Distinctions between social facilitation and contagious behaviour are drawn and suggestions for further research on contagious behaviour are made. Socially derived visual, olfactory and auditory cues are considered as important influences on behaviour and subsequent learning. The evidence supporting two potential mechanisms of social learning, i.e. stimulus enhancement followed by individual learning, and imitation, is reviewed in detail. It is argued that the functions of social learning are similarly heterogeneous and include motor skill acquisition, gathering of environmental information, and social conformity. Factors affecting the spread of socially acquired skills, including the social relationship between demonstrator and observer, are highlighted. Lastly, the few studies of social learning that have been conducted with domestic species are reviewed and potential applied goals that could stimulate further research in this area are suggested.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 577  
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