| Records |
| Author |
Barton, R.A. |
| Title |
Neocortex size and behavioural ecology in primates |
Type |
Journal Article |
| Year |
1996 |
Publication |
Proceedings of the Royal Society B |
Abbreviated Journal |
Proc. R. Soc. Lond. B |
Volume  |
263 |
Issue |
1367 |
Pages |
173-177 |
| Keywords |
Animals; *Behavior, Animal; Brain/*anatomy & histology; Cerebral Cortex/*anatomy & histology/*physiology; *Ecology; Evolution; Primates/anatomy & histology/*physiology/psychology; Regression Analysis; Species Specificity |
| Abstract |
The neocortex is widely held to have been the focus of mammalian brain evolution, but what selection pressures explain the observed diversity in its size and structure? Among primates, comparative studies suggest that neocortical evolution is related to the cognitive demands of sociality, and here I confirm that neocortex size and social group size are positively correlated once phylogenetic associations and overall brain size are taken into account. This association holds within haplorhine but not strepsirhine primates. In addition, the neocortex is larger in diurnal than in nocturnal primates, and among diurnal haplorhines its size is positively correlated with the degree of frugivory. These ecological correlates reflect the diverse sensory-cognitive functions of the neocortex. |
| Address |
Department of Anthropology, University of Durham |
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English |
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0962-8452 |
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| Notes |
PMID:8728982 |
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| Call Number |
Equine Behaviour @ team @ |
Serial |
4783 |
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| Author |
Swaddle, J.P.; Witter, M.S. |
| Title |
Chest Plumage, Dominance and Fluctuating Asymmetry in Female Starlings |
Type |
Journal Article |
| Year |
1995 |
Publication |
Proceedings of the Royal Society B: Biological Sciences |
Abbreviated Journal |
Proc. Roy. Soc. Lond. B Biol. Sci. |
| Volume |
260 |
Issue |
1358 |
Pages |
219-223 |
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| Abstract |
It has been proposed that levels of fluctuating asymmetry (FA) may be used in establishing and maintaining dominance hierarchies, as asymmetry reflects aspects of individual quality. However, previous manipulations of FA have failed to reveal that the level or outcome of agonistic intra-sexual interactions are affected by levels of FA. In female European starlings (Sturnus vulgaris), correlational data suggest that FA of the speckled chest plumage may be related to dominance status. These data are confounded, however, by total number of spots on the chest and the proportion of the chest that is white, both of which positively covary with chest asymmetry. Thus, we deconfounded the effects of these plumage traits on dominance by experimentally manipulating the number of spots and spot number asymmetry in a factorial design. The results indicated that dominance is influenced by the number of spots on the chest, but not by spot asymmetry. Birds with spottier chests were dominant over birds with experimentally decreased spot number. We suggest that female starlings' chests are exposed to extensive abrasion throughout the breeding season and so are susceptible to damage asymmetries that may mask the `true' fluctuating asymmetry of the trait. This may devalue the use of chest asymmetry as a quality indicator. Spottier chests may be costly to maintain, in part because of increased susceptibility to abrasion, and so may be a better indicator of quality than asymmetry. |
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Equine Behaviour @ team @ |
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2202 |
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| Author |
Witter, M.S.; Swaddle, J.P. |
| Title |
Fluctuating Asymmetries, Competition and Dominance |
Type |
Journal Article |
| Year |
1994 |
Publication |
Proceedings of the Royal Society B: Biological Sciences |
Abbreviated Journal |
Proc. Roy. Soc. Lond. B Biol. Sci. |
| Volume |
256 |
Issue |
1347 |
Pages |
299-303 |
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| Abstract |
Levels of fluctuating asymmetry (FA) in the primary feathers of European starlings, Sturnus vulgaris, have been shown to be sensitive to nutritional and energetic stress. Furthermore, between-individual variation in plumage FA has been found to be related to social dominance, even without social interactions during feather growth, with dominant birds exhibiting the highest levels of FA. Here we examine whether the relation between dominance and FA differs when birds are housed in social groups, under different degrees of competition for food, during moult. We reason that dominants should derive a greater benefit from their social status as competition for food increases. Our results support this proposition. The relation between dominance and FA differed significantly according to the degree of competition for food. However, in no cases did the dominants exhibit lower levels of FA than subdominants. When competition for food was low, dominants had higher levels of FA than subdominants. When competition for food was high, there was no systematic relation between dominance and FA. These results suggest that dominants may only derive a net benefit from their social status, under the circumstances of our experiment, during severe conditions of competition. |
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Equine Behaviour @ team @ |
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2203 |
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| Author |
Schneider, A.-C.; Melis, A.P.; Tomasello, M. |
| Title |
How chimpanzees solve collective action problems |
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Journal Article |
| Year |
2012 |
Publication |
Proceedings of the Royal Society B: Biological Sciences |
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We presented small groups of chimpanzees with two collective action situations, in which action was necessary for reward but there was a disincentive for individuals to act owing to the possibility of free-riding on the efforts of others. We found that in simpler scenarios (experiment 1) in which group size was small, there was a positive relationship between rank and action with more dominant individuals volunteering to act more often, particularly when the reward was less dispersed. Social tolerance also seemed to mediate action whereby higher tolerance levels within a group resulted in individuals of lower ranks sometimes acting and appropriating more of the reward. In more complex scenarios, when group size was larger and cooperation was necessary (experiment 2), overcoming the problem was more challenging. There was highly significant variability in the action rates of different individuals as well as between dyads, suggesting success was more greatly influenced by the individual personalities and personal relationships present in the group. |
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Equine Behaviour @ team @ |
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5629 |
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