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Author (down) 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 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 Editor Series Title Abbreviated Series Title
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ISSN 0962-8452 ISBN Medium
Area Expedition Conference
Notes PMID:15734699 Approved no
Call Number refbase @ user @ Serial 549
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Author (down) Wittig, R.M.; Crockford, C.; Wikberg, E.; Seyfarth, R.M.; Cheney, D.L.
Title Kin-mediated reconciliation substitutes for direct reconciliation in female baboons Type Journal Article
Year 2007 Publication Proceedings. Biological sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 274 Issue 1613 Pages 1109-1115
Keywords
Abstract It has been hypothesized that group-living mammals engage in reconciliation (post-conflict affiliation between former opponents) to reduce the disruptive costs of aggression and restore opponents' tolerance to baseline levels. Recipients of aggression are sometimes reluctant to tolerate the proximity of a recent opponent, however, in apparent fear that aggression will be renewed. In such cases, reconciliatory behaviour by the aggressor's close kin may substitute for direct reconciliation. We describe a playback experiment with free-ranging baboons (Papio hamadryas ursinus) that examines whether friendly behaviour by the aggressor's kin can substitute for direct reconciliation by the aggressor herself. In the test condition, female subjects who had recently been threatened heard the friendly grunt of one of their aggressor's relatives, mimicking kin-mediated vocal reconciliation. In the control condition, subjects heard the grunt of a dominant female from a different matriline. Subjects responded significantly more strongly in test than in control trials. Moreover, in the next hour they were significantly more likely to tolerate the proximity of both their aggressor and the relative whose grunt they had heard. In contrast, subjects' behaviour towards both control females and other members of their aggressor's matriline was unaffected. We conclude that kin-mediated vocal reconciliation can substitute for direct reconciliation in baboons.
Address Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
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ISSN 0962-8452 ISBN Medium
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Notes PMID:17301022 Approved no
Call Number refbase @ user @ Serial 342
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Author (down) Wich, S.A.; de Vries, H.
Title Male monkeys remember which group members have given alarm calls Type Journal Article
Year 2006 Publication Proceedings. Biological Sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 273 Issue 1587 Pages 735-740
Keywords Animals; Behavior, Animal/*physiology; Cercopithecidae/*physiology/*psychology; Cognition/physiology; Fear/physiology/*psychology; Female; Indonesia; Male; Vocalization, Animal/*physiology
Abstract Primates give alarm calls in response to the presence of predators. In some species, such as the Thomas langur (Presbytis thomasi), males only emit alarm calls if there is an audience. An unanswered question is whether the audience's behaviour influences how long the male will continue his alarm calling. We tested three hypotheses that might explain the alarm calling duration of male Thomas langurs: the fatigue, group size and group member behaviour hypotheses. Fatigue and group size did not influence male alarm calling duration. We found that males only ceased calling shortly after all individuals in his group had given at least one alarm call. This shows that males keep track of and thus remember which group members have called.
Address Behavioural Biology, Utrecht University, Padualaan 14, 3584 Utrecht, The Netherlands. s.a.wich@bio.uu.nl
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ISSN 0962-8452 ISBN Medium
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Notes PMID:16608694 Approved no
Call Number Equine Behaviour @ team @ Serial 2816
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Author (down) 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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ISSN 0962-8452 ISBN Medium
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Notes PMID:16555789 Approved no
Call Number Serial 2098
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Author (down) Peake, T.M.; Terry, A.M.R.; McGregor, P.K.; Dabelsteen, T.
Title Do great tits assess rivals by combining direct experience with information gathered by eavesdropping? Type Journal Article
Year 2002 Publication Proceedings. Biological sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 269 Issue 1503 Pages 1925-1929
Keywords Aggression; *Animal Communication; Animals; Male; Songbirds/*physiology; Territoriality; *Vocalization, Animal
Abstract Animals frequently use signals that travel further than the spacing between individuals. For every intended recipient of a given signal there are likely to be many other individuals that receive information. Eavesdropping on signalling interactions between other individuals provides a relatively cost-free method of assessing future opponents or mates. Male great tits (Parus major) extract relative information from such interactions between individuals unknown to them. Here, we show that male great tits can take information gathering a stage further and obtain more information about a previously unencountered intruder, by the hitherto unknown capability of combining information gathered by eavesdropping with that derived from their own direct interaction with an individual. Prior experience with an intruder (A) was achieved by subjecting a focal male to different levels of intrusion simulated using interactive playback. This intruder (A) then took part in a simulated interaction with an unknown male (B) outside the territorial boundary of the focal males. In response to subsequent intrusion by the second male (B), focal males showed low song output in response to males that had lost to a male that the subject was able to beat. Males of known high quality, or those about which information was ambiguous, elicited a high level of song output by focal males. We discuss the implications of this finding for the evolution of communication and social behaviour.
Address Department of Animal Behaviour, Zoological Institute, Copenhagen University, Tagensvej 16, DK 2200 Copenhagen N, Denmark. tmpeake@zi.ku.uk
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ISSN 0962-8452 ISBN Medium
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Notes PMID:12350255 Approved no
Call Number refbase @ user @ Serial 501
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Author (down) Peake, T.M.; Terry, A.M.; McGregor, P.K.; Dabelsteen, T.
Title Male great tits eavesdrop on simulated male-to-male vocal interactions Type Journal Article
Year 2001 Publication Proceedings. Biological sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 268 Issue 1472 Pages 1183-1187
Keywords Animals; Male; Songbirds/*physiology; *Vocalization, Animal
Abstract Animal communication generally occurs in the environment of a network of several potential signallers and receivers. Within a network environment, it is possible to gain relative information about conspecifics by eavesdropping on signalling interactions. We presented male great tits with the opportunity to gain such information by simulating singing interactions using two loudspeakers. Interactions were presented so that relevant information was not available in the absolute singing behaviour of either individual, only in the relative timing of their songs in the interaction as a whole. We then assayed the information extracted by focal males by subsequently introducing one of the 'interactants' (i.e. loudspeakers) into the territory of the focal male. Focal males responded with a reduced song output to males that had just 'lost' an interaction. Focal males did not respond significantly differently to 'winners' as compared with intruders recently involved in an interaction that contained no consistent information. Focal males also responded by switching song types more often when encountering males that had recently been involved in a low-intensity interaction. These results provide the clearest evidence yet that male songbirds extract information from signal interactions between conspecifics in the field.
Address Department of Animal Behaviour, Zoological Institute, Tagensvej 16, University of Copenhagen, 2200 Copenhagen N, Denmark. tmpeake@zi.ku.dk
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ISSN 0962-8452 ISBN Medium
Area Expedition Conference
Notes PMID:11375107 Approved no
Call Number refbase @ user @ Serial 712
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Author (down) Nocera, J.J.; Forbes, G.J.; Giraldeau, L.-A.
Title Inadvertent social information in breeding site selection of natal dispersing birds Type Journal Article
Year 2006 Publication Proceedings. Biological Sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 273 Issue 1584 Pages 349-355
Keywords Animals; *Behavior, Animal; *Breeding; *Environment; Female; Logistic Models; Male; Songbirds/growth & development/*physiology
Abstract Several species use the number of young produced as public information (PI) to assess breeding site quality. PI is inaccessible for synchronously breeding birds because nests are empty by the time the young can collect this information. We investigate if location cues are the next best source of inadvertent social information (ISI) used by young prospectors during breeding site choice. We experimentally deployed ISI as decoys and song playbacks of breeding males in suitable and sub-optimal habitats during pre- and post-breeding periods, and monitored territory establishment during the subsequent breeding season for a social, bobolink (Dolichonyx oryzivorus), and a more solitary species, Nelson's sharp-tailed sparrow (Ammodramus nelsoni). The sparrows did not respond to treatments, but bobolinks responded strongly to post-breeding location cues, irrespective of habitat quality. The following year, 17/20 sub-optimal plots to which bobolink males were recruited were defended for at least two weeks, indicating that song heard the previous year could exert a “carry-over attraction” effect on conspecifics the following year. Sixteen recruited males were natal dispersers, as expected when animals have little opportunity to directly sample their natal habitat quality. We suggest that differences in breeding synchronicity may induce an equivalent clinal distribution of ISI use.
Address Department of Biology, University of New Brunswick, Bag Service #45111, Fredericton, NB E3B 6E1, Canada. j.nocera@unb.ca
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Notes PMID:16543178 Approved no
Call Number Serial 2129
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Author (down) McComb, K.; Clutton-Brock, T.
Title Is mate choice copying or aggregation responsible for skewed distributions of females on leks? Type Journal Article
Year 1994 Publication Proceedings. Biological sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 255 Issue 1342 Pages 13-19
Keywords Animals; Deer/*physiology; Estrus/physiology; Female; Male; Phenotype; Sexual Behavior, Animal/*physiology; Territoriality
Abstract In several lek-breeding populations of birds and mammals, females arriving on leks tend to join males that already have females in their territories. This might occur either because females have an evolved preference for mating with males that are attractive to other females, or because they join groups of other females to obtain greater safety from predation or dangerous harassment by males. We have previously used controlled experiments to show that oestrous fallow deer females join males with established harems because they are attracted to female groups rather than to the males themselves. Here we demonstrate that the preference for males with females over males without females is specific to oestrous females and weak or absent in anoestrous ones, and that it is not associated with a preference for mating with males that have previously been seen to mate with other females. Furthermore, oestrous females given the choice between males that do not already have females with them show no significant preference for antlered over deantlered males or for older males over younger ones. We conclude that female attraction to other females on the lek is likely to be an adaptation to avoiding harassment in mixed-sex herds. In this situation, a male's ability to maintain the cohesion of his harem may be the principal cause of variation in mating success between males.
Address Department of Zoology, University of Cambridge, U.K
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ISSN 0962-8452 ISBN Medium
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Notes PMID:8153135 Approved no
Call Number Serial 1823
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Author (down) 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
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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ISSN 0962-8452 ISBN Medium
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Notes PMID:9332015 Approved no
Call Number Serial 2095
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Author (down) Healy, S.D.; Braham, S.R.; Braithwaite, V.A.
Title Spatial working memory in rats: no differences between the sexes Type Journal Article
Year 1999 Publication Proceedings. Biological Sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 266 Issue 1435 Pages 2303-2308
Keywords Animals; Estrus/metabolism; Female; Male; Memory/*physiology; Rats; Sex Factors; Swimming
Abstract In a number of mammalian species, males appear to have superior spatial abilities to females. The favoured explanations for this cognitive difference are hormonal, with higher testosterone levels in males than females leading to better spatial performance, and evolutionary, where sexual selection has favoured males with increased spatial abilities for either better navigational skills in hunting or to enable an increased territory size. However, an alternative explanation for this sex difference focuses on the role of varying levels of oestrogen in females in spatial cognition (the 'fertility and parental care' hypothesis). One possibility is that varying oestrogen levels result in variation in spatial learning and memory so that, when tested across the oestrous cycle, females perform as well as males on days of low oestrogen but more poorly on days of high oestrogen. If day in the oestrous cycle is not taken into account then, across an experiment, any sex differences found would always produce male superiority. We used a spatial working memory task in a Morris water maze to test the spatial learning and memory abilities of male and female rats. The rats were tested across a number of consecutive days during which the females went through four oestrous cycles. We found no overall sex differences in latencies to reach a submerged platform in a Morris water maze but, on the day of oestrus (low oestrogen), females took an extra swim to learn the platform's location (a 100% increase over the other days in the cycle). Female swim speed also varied across the oestrous cycle but females were no less active on the day of oestrus. These results oppose the predictions of the fertility and parental care hypothesis.
Address Department of Psychology, University of Newcastle, UK. s.healey@ed.ac.uk
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ISSN 0962-8452 ISBN Medium
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Notes PMID:10629980 Approved no
Call Number Equine Behaviour @ team @ Serial 2818
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