| Records |
| Author |
Bergstrom,C. T.; Lachmann, M. |
| Title |
Signalling among relatives. I. Is costly signalling too costly? |
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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 |
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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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559 |
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| Author |
Bergstrom, C.T.; Lachmann, M. |
| Title |
Signaling among relatives. III. Talk is cheap |
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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. |
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Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA. carl@charles.stanford.edu |
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English |
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0027-8424 |
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PMID:9560235 |
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561 |
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Dusek, J.A.; Eichenbaum, H. |
| Title |
The hippocampus and memory for orderly stimulus relations |
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 |
94 |
Issue |
13 |
Pages |
7109-7114 |
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Animals; Attention; Discrimination (Psychology)/physiology; Hippocampus/anatomy & histology/*physiology; Male; Memory/*physiology; Rats |
| Abstract |
Human declarative memory involves a systematic organization of information that supports generalizations and inferences from acquired knowledge. This kind of memory depends on the hippocampal region in humans, but the extent to which animals also have declarative memory, and whether inferential expression of memory depends on the hippocampus in animals, remains a major challenge in cognitive neuroscience. To examine these issues, we used a test of transitive inference pioneered by Piaget to assess capacities for systematic organization of knowledge and logical inference in children. In our adaptation of the test, rats were trained on a set of four overlapping odor discrimination problems that could be encoded either separately or as a single representation of orderly relations among the odor stimuli. Normal rats learned the problems and demonstrated the relational memory organization through appropriate transitive inferences about items not presented together during training. By contrast, after disconnection of the hippocampus from either its cortical or subcortical pathway, rats succeeded in acquiring the separate discrimination problems but did not demonstrate transitive inference, indicating that they had failed to develop or could not inferentially express the orderly organization of the stimulus elements. These findings strongly support the view that the hippocampus mediates a general declarative memory capacity in animals, as it does in humans. |
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Department of Psychology, Boston University, 64 Cummington Street, Boston, MA 02215, USA |
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0027-8424 |
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PMID:9192700 |
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no |
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607 |
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Seyfarth, R.M.; Cheney, D.L. |
| Title |
What are big brains for? |
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Journal Article |
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2002 |
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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. |
| Volume |
99 |
Issue |
7 |
Pages |
4141-4142 |
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Animals; Brain/*anatomy & histology; *Intelligence; Learning; Primates/*anatomy & histology/*psychology; Social Behavior |
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Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA. seyfarth@psych.upenn.edu |
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0027-8424 |
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PMID:11929989 |
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refbase @ user @ |
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692 |
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Jansen, T.; Forster, P.; Levine, M.A.; Oelke, H.; Hurles, M.; Renfrew, C.; Weber, J.; Olek, K. |
| Title |
Mitochondrial DNA and the origins of the domestic horse |
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Journal Article |
| Year |
2002 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
99 |
Issue |
16 |
Pages |
10905-10910 |
| Keywords |
Animals; Animals, Domestic/classification/*genetics; Base Sequence; DNA, Complementary; *DNA, Mitochondrial; *Evolution, Molecular; Horses/classification/*genetics; Molecular Sequence Data; Phylogeny |
| Abstract |
The place and date of the domestication of the horse has long been a matter for debate among archaeologists. To determine whether horses were domesticated from one or several ancestral horse populations, we sequenced the mitochondrial D-loop for 318 horses from 25 oriental and European breeds, including American mustangs. Adding these sequences to previously published data, the total comes to 652, the largest currently available database. From these sequences, a phylogenetic network was constructed that showed that most of the 93 different mitochondrial (mt)DNA types grouped into 17 distinct phylogenetic clusters. Several of the clusters correspond to breeds and/or geographic areas, notably cluster A2, which is specific to Przewalski's horses, cluster C1, which is distinctive for northern European ponies, and cluster D1, which is well represented in Iberian and northwest African breeds. A consideration of the horse mtDNA mutation rate together with the archaeological timeframe for domestication requires at least 77 successfully breeding mares recruited from the wild. The extensive genetic diversity of these 77 ancestral mares leads us to conclude that several distinct horse populations were involved in the domestication of the horse. |
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Biopsytec Analytik GmbH, Marie-Curie-Strasse 1, 53359 Rheinbach, Germany. jansen@biopsytec.com |
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0027-8424 |
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PMID:12130666 |
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772 |
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