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Amé, J.-M.; Halloy, J.; Rivault, C.; Detrain, C.; Deneubourg, J.L. |
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Title |
Collegial decision making based on social amplification leads to optimal group formation |
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Journal Article |
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2006 |
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Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
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103 |
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15 |
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5835-5840 |
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Animals; Blattellidae/*physiology; Choice Behavior; Decision Making; Leadership; *Social Behavior |
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Group-living animals are often faced with choosing between one or more alternative resource sites. A central question in such collective decision making includes determining which individuals induce the decision and when. This experimental and theoretical study of shelter selection by cockroach groups demonstrates that choices can emerge through nonlinear interaction dynamics between equal individuals without perfect knowledge or leadership. We identify a simple mechanism whereby a decision is taken on the move with limited information and signaling and without comparison of available opportunities. This mechanism leads to optimal mean benefit for group individuals. Our model points to a generic self-organized collective decision-making process independent of animal species. |
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Service d'Ecologie Sociale CP231, Universite Libre de Bruxelles, Avenue F. D. Roosevelt 50, B-1050 Brussels, Belgium |
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0027-8424 |
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PMID:16581903 |
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Equine Behaviour @ team @ |
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2042 |
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Ballew, R.M.; Sabelko, J.; Gruebele, M. |
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Title |
Direct observation of fast protein folding: the initial collapse of apomyoglobin |
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Journal Article |
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1996 |
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Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
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93 |
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12 |
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5759-5764 |
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Animals; Apoproteins/*chemistry; Circular Dichroism; Horses; Kinetics; Muscle, Skeletal/chemistry; Myoglobin/*chemistry; *Protein Folding; Spectrometry, Fluorescence; Spectrophotometry, Infrared; Temperature |
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The rapid refolding dynamics of apomyoglobin are followed by a new temperature-jump fluorescence technique on a 15-ns to 0.5-ms time scale in vitro. The apparatus measures the protein-folding history in a single sweep in standard aqueous buffers. The earliest steps during folding to a compact state are observed and are complete in under 20 micros. Experiments on mutants and consideration of steady-state CD and fluorescence spectra indicate that the observed microsecond phase monitors assembly of an A x (H x G) helix subunit. Measurements at different viscosities indicate diffusive behavior even at low viscosities, in agreement with motions of a solvent-exposed protein during the initial collapse. |
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School of Chemical Sciences and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, 61801, USA |
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0027-8424 |
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PMID:8650166 |
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Equine Behaviour @ team @ |
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3798 |
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Begall, S.; Cervený, J.; Neef, J.; Vojtech, O.; Burda, H. |
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Magnetic alignment in grazing and resting cattle and deer |
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Journal Article |
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2008 |
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Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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105 |
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36 |
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13451-13455 |
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We demonstrate by means of simple, noninvasive methods (analysis of satellite images, field observations, and measuring “deer beds” in snow) that domestic cattle (n = 8,510 in 308 pastures) across the globe, and grazing and resting red and roe deer (n = 2,974 at 241 localities), align their body axes in roughly a north–south direction. Direct observations of roe deer revealed that animals orient their heads northward when grazing or resting. Amazingly, this ubiquitous phenomenon does not seem to have been noticed by herdsmen, ranchers, or hunters. Because wind and light conditions could be excluded as a common denominator determining the body axis orientation, magnetic alignment is the most parsimonious explanation. To test the hypothesis that cattle orient their body axes along the field lines of the Earth's magnetic field, we analyzed the body orientation of cattle from localities with high magnetic declination. Here, magnetic north was a better predictor than geographic north. This study reveals the magnetic alignment in large mammals based on statistically sufficient sample sizes. Our findings open horizons for the study of magnetoreception in general and are of potential significance for applied ethology (husbandry, animal welfare). They challenge neuroscientists and biophysics to explain the proximate mechanisms. |
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10.1073/pnas.0803650105 |
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Equine Behaviour @ team @ |
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5316 |
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Author |
Bergstrom, C.T.; Lachmann, M. |
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Title |
Signaling among relatives. III. Talk is cheap |
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Journal Article |
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Year |
1998 |
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Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
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95 |
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9 |
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5100-5105 |
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Animal Communication; Animals; Costs and Cost Analysis; *Evolution; Interpersonal Relations; Models, Biological |
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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. |
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Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA. carl@charles.stanford.edu |
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0027-8424 |
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PMID:9560235 |
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refbase @ user @ |
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561 |
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Bergstrom,C. T.; Lachmann, M. |
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Title |
Signalling among relatives. I. Is costly signalling too costly? |
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Journal Article |
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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. |
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Volume |
352(1353) |
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609-617 |
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Keywords |
Signalling |
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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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refbase @ user @ |
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559 |
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Author |
Biegler, R.; McGregor, A.; Krebs, J.R.; Healy, S.D. |
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Title |
A larger hippocampus is associated with longer-lasting spatial memory |
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Journal Article |
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2001 |
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Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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Volume |
98 |
Issue |
12 |
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6941-6944 |
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Volumetric studies in a range of animals (London taxi-drivers, polygynous male voles, nest-parasitic female cowbirds, and a number of food-storing birds) have shown that the size of the hippocampus, a brain region essential to learning and memory, is correlated with tasks involving an extra demand for spatial learning and memory. In this paper, we report the quantitative advantage that food storers gain from such an enlargement. Coal tits () a food-storing species, performed better than great tits (), a nonstoring species, on a task that assessed memory persistence but not on a task that assessed memory resolution or on one that tested memory capacity. These results show that the advantage to the food-storing species associated with an enlarged hippocampus is one of memory persistence. |
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10.1073/pnas.121034798 |
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Equine Behaviour @ team @ |
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4743 |
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Cameron, E.Z.; Setsaas, T.H.; Linklater, W.L. |
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Social bonds between unrelated females increase reproductive success in feral horses |
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Journal Article |
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2009 |
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Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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106 |
Issue |
33 |
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13850-13853 |
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In many mammals, females form close social bonds with members of their group, usually between kin. Studies of social bonds and their fitness benefits have not been investigated outside primates, and are confounded by the relatedness between individuals in primate groups. Bonds may arise from kin selection and inclusive fitness rather than through direct benefits of association. However, female equids live in long-term social groups with unrelated members. We present 4 years of behavioral data, which demonstrate that social integration between unrelated females increases both foal birth rates and survival, independent of maternal habitat quality, social group type, dominance status, and age. Also, we show that such social integration reduces harassment by males. Consequently, social integration has strong direct fitness consequences between nonrelatives, suggesting that social bonds can evolve based on these direct benefits alone. Our results support recent studies highlighting the importance of direct benefits in maintaining cooperative behavior, while controlling for the confounding influence of kinship. |
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10.1073/pnas.0900639106 |
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Equine Behaviour @ team @ |
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5152 |
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Chase, I.D.; Tovey, C.; Spangler-Martin, D.; Manfredonia, M. |
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Individual differences versus social dynamics in the formation of animal dominance hierarchies |
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2002 |
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Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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99 |
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8 |
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5744-5749 |
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Animals; *Behavior, Animal; Fishes; Humans; *Social Behavior; *Social Dominance |
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Linear hierarchies, the classical pecking-order structures, are formed readily in both nature and the laboratory in a great range of species including humans. However, the probability of getting linear structures by chance alone is quite low. In this paper we investigate the two hypotheses that are proposed most often to explain linear hierarchies: they are predetermined by differences in the attributes of animals, or they are produced by the dynamics of social interaction, i.e., they are self-organizing. We evaluate these hypotheses using cichlid fish as model animals, and although differences in attributes play a significant part, we find that social interaction is necessary for high proportions of groups with linear hierarchies. Our results suggest that dominance hierarchy formation is a much richer and more complex phenomenon than previously thought, and we explore the implications of these results for evolutionary biology, the social sciences, and the use of animal models in understanding human social organization. |
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Department of Sociology, State University of New York, Stony Brook, NY 11794-4356, USA. Ichase@notes.cc.sunysb.edu |
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0027-8424 |
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PMID:11960030 |
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refbase @ user @ |
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442 |
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de Waal, F.B.M.; Dindo, M.; Freeman, C.A.; Hall, M.J. |
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Title |
The monkey in the mirror: hardly a stranger |
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Journal Article |
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2005 |
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Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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102 |
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32 |
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11140-11147 |
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Analysis of Variance; Animals; Cebus/*physiology; *Discrimination (Psychology); Empathy; Female; Male; Observation; *Recognition (Psychology); *Self Concept; Sex Factors |
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It is widely assumed that monkeys see a stranger in the mirror, whereas apes and humans recognize themselves. In this study, we question the former assumption by using a detailed comparison of how monkeys respond to mirrors versus live individuals. Eight adult female and six adult male brown capuchin monkeys (Cebus apella) were exposed twice to three conditions: (i) a familiar same-sex partner, (ii) an unfamiliar same-sex partner, and (iii) a mirror. Females showed more eye contact and friendly behavior and fewer signs of anxiety in front of a mirror than they did when exposed to an unfamiliar partner. Males showed greater ambiguity, but they too reacted differently to mirrors and strangers. Discrimination between conditions was immediate, and blind coders were able to tell the difference between monkeys under the three conditions. Capuchins thus seem to recognize their reflection in the mirror as special, and they may not confuse it with an actual conspecific. Possibly, they reach a level of self-other distinction intermediate between seeing their mirror image as other and recognizing it as self. |
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Living Links Center, Emory University, Atlanta, GA 30322, USA. dewaal@emory.edu |
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0027-8424 |
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PMID:16055557 |
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refbase @ user @ |
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164 |
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Drea, C.M.; Wallen, K. |
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Low-status monkeys “play dumb” when learning in mixed social groups |
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1999 |
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Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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96 |
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22 |
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12965-12969 |
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Many primates, including humans, live in complex hierarchical societies where social context and status affect daily life. Nevertheless, primate learning studies typically test single animals in limited laboratory settings where the important effects of social interactions and relationships cannot be studied. To investigate the impact of sociality on associative learning, we compared the individual performances of group-tested rhesus monkeys (Macaca mulatta) across various social contexts. We used a traditional discrimination paradigm that measures an animal's ability to form associations between cues and the obtaining of food in choice situations; but we adapted the task for group testing. After training a 55-member colony to separate on command into two subgroups, composed of either high- or low-status families, we exposed animals to two color discrimination problems, one with all monkeys present (combined condition), the other in their “dominant” and “subordinate” cohorts (split condition). Next, we manipulated learning history by testing animals on the same problems, but with the social contexts reversed. Monkeys from dominant families excelled in all conditions, but subordinates performed well in the split condition only, regardless of learning history. Subordinate animals had learned the associations, but expressed their knowledge only when segregated from higher-ranking animals. Because aggressive behavior was rare, performance deficits probably reflected voluntary inhibition. This experimental evidence of rank-related, social modulation of performance calls for greater consideration of social factors when assessing learning and may also have relevance for the evaluation of human scholastic achievement. |
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10.1073/pnas.96.22.12965 |
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2093 |
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