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Author Watts, D.J.; Strogatz, S.H.
Title Collective dynamics of /`small-world/' networks Type Journal Article
Year 1998 Publication Abbreviated Journal Nature
Volume 393 Issue 6684 Pages (down) 440-442
Keywords
Abstract Networks of coupled dynamical systems have been used to model biological oscillators Josephson junction arrays excitable media, neural networks spatial games11, genetic control networks12 and many other self-organizing systems. Ordinarily, the connection topology is assumed to be either completely regular or completely random. But many biological, technological and social networks lie somewhere between these two extremes. Here we explore simple models of networks that can be tuned through this middle ground: regular networks 'rewired' to introduce increasing amounts of disorder. We find that these systems can be highly clustered, like regular lattices, yet have small characteristic path lengths, like random graphs. We call them 'small-world' networks, by analogy with the small-world phenomenon (popularly known as six degrees of separation). The neural network of the worm Caenorhabditis elegans, the power grid of the western United States, and the collaboration graph of film actors are shown to be small-world networks. Models of dynamical systems with small-world coupling display enhanced signal-propagation speed, computational power, and synchronizability. In particular, infectious diseases spread more easily in small-world networks than in regular lattices.
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ISSN 0028-0836 ISBN Medium
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Notes 10.1038/30918 Approved no
Call Number Equine Behaviour @ team @ Serial 4989
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Author Rands, S.A.; Cowlishaw, G.; Pettifor, R.A.; Rowcliffe, J.M.; Johnstone, R.A.
Title Spontaneous emergence of leaders and followers in foraging pairs Type Journal Article
Year 2003 Publication Nature Abbreviated Journal Nature
Volume 423 Issue 6938 Pages (down) 432-434
Keywords Animals; *Energy Metabolism; Food; *Food Chain; *Models, Biological; Motor Activity; *Social Behavior; Time Factors
Abstract Animals that forage socially often stand to gain from coordination of their behaviour. Yet it is not known how group members reach a consensus on the timing of foraging bouts. Here we demonstrate a simple process by which this may occur. We develop a state-dependent, dynamic game model of foraging by a pair of animals, in which each individual chooses between resting or foraging during a series of consecutive periods, so as to maximize its own individual chances of survival. We find that, if there is an advantage to foraging together, the equilibrium behaviour of both individuals becomes highly synchronized. As a result of this synchronization, differences in the energetic reserves of the two players spontaneously develop, leading them to adopt different behavioural roles. The individual with lower reserves emerges as the 'pace-maker' who determines when the pair should forage, providing a straightforward resolution to the problem of group coordination. Moreover, the strategy that gives rise to this behaviour can be implemented by a simple 'rule of thumb' that requires no detailed knowledge of the state of other individuals.
Address Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. s.rands@zoo.cam.ac.uk
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ISSN 0028-0836 ISBN Medium
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Notes PMID:12761547 Approved no
Call Number Equine Behaviour @ team @ Serial 5138
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Author Grosenick, L.; Clement, T.S.; Fernald, R.D.
Title Fish can infer social rank by observation alone Type Journal Article
Year 2007 Publication Nature Abbreviated Journal Nature
Volume 445 Issue 7126 Pages (down) 429-432
Keywords Aggression/physiology; Animals; Cognition/*physiology; Female; Fishes/*physiology; Learning/*physiology; Male; Models, Biological; *Social Dominance; Territoriality
Abstract Transitive inference (TI) involves using known relationships to deduce unknown ones (for example, using A > B and B > C to infer A > C), and is thus essential to logical reasoning. First described as a developmental milestone in children, TI has since been reported in nonhuman primates, rats and birds. Still, how animals acquire and represent transitive relationships and why such abilities might have evolved remain open problems. Here we show that male fish (Astatotilapia burtoni) can successfully make inferences on a hierarchy implied by pairwise fights between rival males. These fish learned the implied hierarchy vicariously (as 'bystanders'), by watching fights between rivals arranged around them in separate tank units. Our findings show that fish use TI when trained on socially relevant stimuli, and that they can make such inferences by using indirect information alone. Further, these bystanders seem to have both spatial and featural representations related to rival abilities, which they can use to make correct inferences depending on what kind of information is available to them. Beyond extending TI to fish and experimentally demonstrating indirect TI learning in animals, these results indicate that a universal mechanism underlying TI is unlikely. Rather, animals probably use multiple domain-specific representations adapted to different social and ecological pressures that they encounter during the course of their natural lives.
Address Department of Biological Sciences, Stanford University, Stanford, California, 94305, USA. logang@stanford.edu
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ISSN 1476-4687 ISBN Medium
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Notes PMID:17251980 Approved no
Call Number refbase @ user @ Serial 600
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Author Flack, J.C.; Girvan, M.; de Waal, F.B.M.; Krakauer, D.C.
Title Policing stabilizes construction of social niches in primates Type Journal Article
Year 2006 Publication Nature Abbreviated Journal Nature
Volume 439 Issue 7075 Pages (down) 426-429
Keywords Animals; Conflict (Psychology); Female; Macaca nemestrina/*physiology/*psychology; Male; Models, Biological; *Social Behavior
Abstract All organisms interact with their environment, and in doing so shape it, modifying resource availability. Termed niche construction, this process has been studied primarily at the ecological level with an emphasis on the consequences of construction across generations. We focus on the behavioural process of construction within a single generation, identifying the role a robustness mechanism--conflict management--has in promoting interactions that build social resource networks or social niches. Using 'knockout' experiments on a large, captive group of pigtailed macaques (Macaca nemestrina), we show that a policing function, performed infrequently by a small subset of individuals, significantly contributes to maintaining stable resource networks in the face of chronic perturbations that arise through conflict. When policing is absent, social niches destabilize, with group members building smaller, less diverse, and less integrated grooming, play, proximity and contact-sitting networks. Instability is quantified in terms of reduced mean degree, increased clustering, reduced reach, and increased assortativity. Policing not only controls conflict, we find it significantly influences the structure of networks that constitute essential social resources in gregarious primate societies. The structure of such networks plays a critical role in infant survivorship, emergence and spread of cooperative behaviour, social learning and cultural traditions.
Address Santa Fe Institute, Santa Fe, New Mexico 87501, USA. jflack@santafe.edu
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ISSN 1476-4687 ISBN Medium
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Notes PMID:16437106 Approved no
Call Number refbase @ user @ Serial 298
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Author Marean, C.W.; Gifford-Gonzalez, D.
Title Late Quaternary extinct ungulates of East Africa and palaeoenvironmental implications Type Journal Article
Year 1991 Publication Nature Abbreviated Journal Nature
Volume 350 Issue 6317 Pages (down) 418-420
Keywords
Abstract UNGULATE communities of two East African savannas, the Serengeti and Athi-Kapiti Plains, are dominated by wildebeest (Connochaetes taurinus) supplemented by zebra (Equus burchelli), topi (Damaliscus lunatus), hartebeest (Alcelaphus buselaphus), buffalo (Syncerus caffer) eland (Taurotragus oryx) and gazelles (Gazella grand and G. thomsoni)1-3. Before this research, little was known of East African large mammal communities in the Late Pleistocene and early to middle Holocene. We document an extinct impala-sized alcelaphine antelope that is numerically dominant in Late Pleistocene archaeofaunal assemblages from the Athi-Kapiti Plains. The extinct giant buffalo Pelorovis antiquus is present, and a number of arid-adapted regionally extinct species are common. The small alcelaphine is rare in northern Tanzania, but regionally extinct arid-adapted species are present in Late Pleistocene deposits. These data indicate that as recently as 12,000 years ago, the large mammal community structure of East African savannas was very different and dry grasslands and arid-adapted ungulates expanded at least as far south as northern Tanzania during the Last Glacial Maximum.
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Notes 10.1038/350418a0 Approved no
Call Number Equine Behaviour @ team @ Serial 2345
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Author Proudman, C.; Pinchbeck, G.; Clegg, P.; French, N.
Title Equine welfare: risk of horses falling in the Grand National Type Journal Article
Year 2004 Publication Nature Abbreviated Journal Nature
Volume 428 Issue 6981 Pages (down) 385-386
Keywords Accidental Falls/prevention & control/*statistics & numerical data; Animal Welfare; Animals; Great Britain; Horse Diseases/prevention & control; Horses/*physiology; Odds Ratio; Risk Assessment; *Sports
Abstract As in other competitive sports, the famous Grand National steeplechase, which is held at Aintree in the United Kingdom and is watched by 600 million people worldwide, sometimes results in injury. By analysing data from the past 15 Grand National races (consisting of 560 starts by horses), we are able to identify several factors that are significantly associated with failure to complete the race: no previous experience of the course and its unique obstacles, unfavourable ground conditions (too soft or too hard), a large number of runners, and the length of the odds ('starting price'). We also find that there is an increased risk of falling at the first fence and at the jump known as Becher's Brook, which has a ditch on the landing side. Our findings indicate ways in which the Grand National could be made safer for horses and illustrate how epidemiological analysis might contribute to preventing injury in competitive sport.
Address Epidemiology Group, Faculty of Veterinary Science, University of Liverpool, Leahurst, Neston, Wirral CH64 7TE, UK. c.j.proudman@liverpool.ac.uk
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ISSN 1476-4687 ISBN Medium
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Notes PMID:15042079 Approved no
Call Number refbase @ user @ Serial 535
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Author Ferrero, D.M.; Moeller, L.M.; Osakada, T.; Horio, N.; Li, Q.; Roy, D.S.; Cichy, A.; Spehr, M.; Touhara, K.; Liberles, S.D.
Title A juvenile mouse pheromone inhibits sexual behaviour through the vomeronasal system Type Journal Article
Year 2013 Publication Abbreviated Journal Nature
Volume 502 Issue 7471 Pages (down) 368-371
Keywords Pheromone Olfactory receptors
Abstract Animals display a repertoire of different social behaviours. Appropriate behavioural responses depend on sensory input received during social interactions. In mice, social behaviour is driven by pheromones, chemical signals that encode information related to age, sex and physiological state1. However, although mice show different social behaviours towards adults, juveniles and neonates, sensory cues that enable specific recognition of juvenile mice are unknown. Here we describe a juvenile pheromone produced by young mice before puberty, termed exocrine-gland secreting peptide 22 (ESP22). ESP22 is secreted from the lacrimal gland and released into tears of 2- to 3-week-old mice. Upon detection, ESP22 activates high-affinity sensory neurons in the vomeronasal organ, and downstream limbic neurons in the medial amygdala. Recombinant ESP22, painted on mice, exerts a powerful inhibitory effect on adult male mating behaviour, which is abolished in knockout mice lacking TRPC2, a key signalling component of the vomeronasal organ2, 3. Furthermore, knockout of TRPC2 or loss of ESP22 production results in increased sexual behaviour of adult males towards juveniles, and sexual responses towards ESP22-deficient juveniles are suppressed by ESP22 painting. Thus, we describe a pheromone of sexually immature mice that controls an innate social behaviour, a response pathway through the accessory olfactory system and a new role for vomeronasal organ signalling in inhibiting sexual behaviour towards young. These findings provide a molecular framework for understanding how a sensory system can regulate behaviour.
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Publisher Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. Place of Publication Editor
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ISSN 0028-0836 ISBN Medium
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Notes Approved no
Call Number Equine Behaviour @ team @ Serial 5732
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Author Pocock Rj,
Title The coloration of the Quaggas Type Journal Article
Year Publication Nature Abbreviated Journal Nature
Volume 68 Issue Pages (down) 356-357
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Notes from Professor Hans Klingels Equine Reference List Approved no
Call Number Serial 1480
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Author Dreber, A.; Rand, D.G.; Fudenberg, D.; Nowak, M.A.
Title Winners don/'t punish Type Journal Article
Year 2008 Publication Abbreviated Journal Nature
Volume 452 Issue 7185 Pages (down) 348-351
Keywords
Abstract A key aspect of human behaviour is cooperation1, 2, 3, 4, 5, 6, 7. We tend to help others even if costs are involved. We are more likely to help when the costs are small and the benefits for the other person significant. Cooperation leads to a tension between what is best for the individual and what is best for the group. A group does better if everyone cooperates, but each individual is tempted to defect. Recently there has been much interest in exploring the effect of costly punishment on human cooperation8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23. Costly punishment means paying a cost for another individual to incur a cost. It has been suggested that costly punishment promotes cooperation even in non-repeated games and without any possibility of reputation effects10. But most of our interactions are repeated and reputation is always at stake. Thus, if costly punishment is important in promoting cooperation, it must do so in a repeated setting. We have performed experiments in which, in each round of a repeated game, people choose between cooperation, defection and costly punishment. In control experiments, people could only cooperate or defect. Here we show that the option of costly punishment increases the amount of cooperation but not the average payoff of the group. Furthermore, there is a strong negative correlation between total payoff and use of costly punishment. Those people who gain the highest total payoff tend not to use costly punishment: winners don't punish. This suggests that costly punishment behaviour is maladaptive in cooperation games and might have evolved for other reasons.
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Publisher Nature Publishing Group Place of Publication Editor
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Notes 10.1038/nature06723 Approved no
Call Number Equine Behaviour @ team @ Serial 4406
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Author Sugiyama Y
Title Tool use by wild chimpanzees Type Journal Article
Year 1994 Publication Nature Abbreviated Journal Nature
Volume 376 Issue Pages (down) 327
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Notes Approved no
Call Number Equine Behaviour @ team @ Serial 3041
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