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Seyfarth, R. M., & Cheney, D. L. (2003). Signalers and receivers in animal communication. Annu Rev Psychol, 54, 145–173.
Abstract: In animal communication natural selection favors callers who vocalize to affect the behavior of listeners and listeners who acquire information from vocalizations, using this information to represent their environment. The acquisition of information in the wild is similar to the learning that occurs in laboratory conditioning experiments. It also has some parallels with language. The dichotomous view that animal signals must be either referential or emotional is false, because they can easily be both: The mechanisms that cause a signaler to vocalize do not limit a listener's ability to extract information from the call. The inability of most animals to recognize the mental states of others distinguishes animal communication most clearly from human language. Whereas signalers may vocalize to change a listener's behavior, they do not call to inform others. Listeners acquire information from signalers who do not, in the human sense, intend to provide it.
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Cheney, D. l., & Seyfarth, R. M. (2004). Social complexity and the information acquired during eavesdropping by primates and other animals. In P. K. McGregor (Ed.), Animal Communication networks. Cambridge, Massachusetts: Cambridge University Press.
Abstract: In many of the studies reviewed in this book, eavesdropping takes the
following form: a subject has the opportunity to monitor, or eavesdrop upon, an
interaction between two other animals,Aand B. The subject then uses the information
obtained through these observations to assess A`s and B`s relative dominance
or attractiveness as a mate (e.g. Mennill et al., 2002; Ch. 2). For example, Oliveira
et al. (1998) found that male fighting fish Betta splendens that had witnessed two
other males involved in an aggressive interaction subsequently responded more
strongly to the loser of that interaction than the winner. Subjects-behaviour could
not have been influenced by any inherent differences between the two males, because
subjects responded equally strongly to the winner and the loser of competitive
interactions they had not observed. Similarly, Peake et al. (2001) presented
male great tits Parus major with the opportunity to monitor an apparent competitive
interaction between two strangers by simulating a singing contest using two
loudspeakers. The relative timing of the singing bouts (as measured by the degree
of overlap between the two songs) provided information about each “contestants”
relative status. Following the singing interaction, one of the “contestants” was
introduced into the male`s territory. Males responded significantly less strongly
to singers that had apparently just “lost” the interaction (see also McGregor &
Dabelsteen, 1996; Naguib et al., 1999; Ch. 2).
What information does an individual acquire when it eavesdrops on others?
In theory, an eavesdropper could acquire information of many different sorts:
about A, about B, about the relationship between A and B, or about the place of
Animal Communication Networks, ed. Peter K. McGregor. Published by Cambridge University Press.
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A`s and B`s relationship in a larger social framework. The exact information acquired
will probably reflect the particular species social structure. For example,
songbirds like great tits live in communities in which six or seven neighbours
surround each territory-holding male. Males appear to benefit from the knowledge
that certain individuals occupy specific areas (e.g. Brooks & Falls, 1975), that
competitive interactions between two different neighbours have particular outcomes,
and that these outcomes are stable over time. We would, therefore, expect
an eavesdropping great tit not only to learn that neighbour A was dominant to
neighbour B, for example, but also to form the expectation that A was likely to
defeat B in all future encounters. More speculatively, because the outcome of territorial
interactions are often site specific (reviewed by Bradbury & Vehrencamp,
1998), we would expect eavesdropping tits to learn further that A dominates B
in some areas but B dominates A in others. In contrast, the information gained
from monitoring neighbours interactions would unlikely be sufficient to allow
the eavesdropper to rank all of its neighbours in a linear dominance hierarchy,
because not all neighbouring males would come into contact with one another.
Such information would be difficult if not impossible to acquire; it might also be
of little functional value.
In contrast, species that live in large, permanent social groups have a much
greater opportunity to monitor the social interactions of many different individuals
simultaneously. Monkey species such as baboons Papio cynocephalus, for
example, typically live in groups of 80 or more individuals, which include several
matrilineal families arranged in a stable, linear dominance rank order (Silk et al.,
1999). Offspring assume ranks similar to those of their mothers, and females maintain
close bonds with their matrilineal kin throughout their lives. Cutting across
these stable long-term relationships based on rank and kinship are more transient
bonds: for example, the temporary associations formed between unrelated
females whose infants are of similar ages, and the “friendships” formed between
adult males and lactating females as an apparent adaptation against infanticide
(Palombit et al., 1997, 2001). In order to compete successfully within such groups, it
would seem advantageous for individuals to recognize who outranks whom, who
is closely bonded to whom, and who is likely to be allied to whom (Harcourt, 1988,
1992; Cheney & Seyfarth, 1990; see below). The ability to adopt a third party`s perspective
and discriminate among the social relationships that exist among others
would seem to be of great selective benefit.
In this chapter, we review evidence for eavesdropping in selected primate
species and we consider what sort of information is acquired when one individual
observes or listens in on the interactions of others. We then compare eavesdropping
by primates with eavesdropping in other animal species, focusing on both
potential differences and directions for further research
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Wittig, R. M., Crockford, C., Wikberg, E., Seyfarth, R. M., & Cheney, D. L. (2007). Kin-mediated reconciliation substitutes for direct reconciliation in female baboons. Proc Biol Sci, 274(1613), 1109–1115.
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.
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Palombit, R. A., Seyfarth, R. M., & Cheney, D. L. (1997). The adaptive value of 'friendships' to female baboons: experimental and observational evidence. Anim. Behav., 54(3), 599–614.
Abstract: Lactating female baboons, Papio cynocephalusoften maintain close associations with particular males. There are at least three proposed benefits of 'friendships' to females: (1) male protection against potentially infanticidal males; (2) male protection against harassment by dominant females; (3) male attachment to an infant that develops into future care of juveniles. These hypotheses were examined in a population of chacma baboons, P. c. ursinusin which male infanticide accounted for at least 38% of infant mortality. Almost all mothers of young infants formed strong bonds with one or two males with whom they had copulated during the cycle in which they conceived their infants. Females were primarily responsible for maintaining friendships during lactation, but they terminated these relationships if their infants died. In playbacks of females' screams, male friends responded more strongly than control males. They also responded more strongly to the screams of female friends than to the screams of control females. Following an infant's death, however, male friends responded less strongly than control males to the same females' screams. Finally, male friends responded more strongly than control males to playback sequences in which female screams were combined with the threat vocalizations of a potentially infanticidal alpha male, but not when female screams were combined with the threat calls of a non-infanticidal male or the alpha female. Both observations and experiments suggest that the benefits of friendships to females derive from the protection of their infants against infanticide.1997The Association for the Study of Animal Behaviour
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Kitchen, D. M., Cheney, D. L., & Seyfarth, R. M. (2005). Male chacma baboons (Papio hamadryas ursinus) discriminate loud call contests between rivals of different relative ranks. Anim. Cogn., 8(1), 1–6.
Abstract: Males in multi-male groups of chacma baboons (Papio hamadryas ursinus) in Botswana compete for positions in a linear dominance hierarchy. Previous research suggests that males treat different categories of rivals differently; competitive displays between males of similar rank are more frequent and intense than those between disparately ranked males. Here we test whether males also respond differently to male-male interactions in which they are not directly involved, using playbacks of the loud 'wahoo' calls exchanged between competing males in aggressive displays. We played paired sequences of vocal contests between two adjacently ranked and two disparately ranked males to ten subjects, half ranking below the signalers in the call sequences and half above. Subjects who ranked above the two signalers showed stronger responses than lower-ranking subjects. Higher-ranking subjects also responded more strongly to sequences involving disparately ranked, as opposed to adjacently ranked opponents, suggesting that they recognized those individuals' relative ranks. Strong responses to sequences between disparately ranked opponents might have occurred either because such contests typically involve resources of high fitness value (defense of meat, estrous females or infants vulnerable to infanticide) or because they indicate a sudden change in one contestant's condition. In contrast, subjects who ranked lower than the signalers responded equally strongly to both types of sequences. These subjects may have been able to distinguish between the two categories of opponents but did not respond differently to them because they had little to lose or gain by a rank reversal between males that already ranked higher than they did.
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Crockford, C., Wittig, R. M., Seyfarth, R. M., & Cheney, D. L. (2007). Baboons eavesdrop to deduce mating opportunities. Anim. Behav., 73(5), 885–890.
Abstract: Many animals appear to monitor changes in other individuals' dominance ranks and social relationships and to track changes in them. However, it is not known whether they also track changes in very transient relationships. Rapid recognition of a temporary separation between a dominant male and a sexually receptive female, for example, should be adaptive in species where subordinate males use opportunistic strategies to achieve mating success. Dominant male baboons (Papio hamadryas ursinus) form sexual consortships with oestrous females that are characterized by mate guarding and close proximity. To assess whether subordinate males track temporary changes in the status of other males' consortships, we conducted playback experiments using a two-speaker paradigm. In the test condition, subjects heard the consort male's grunts played from one speaker and his consort female's copulation call played from a speaker approximately 40 m away. This sequence suggested that the male and female had temporarily separated and that the female was mating with another male. In a control trial, subjects heard another dominant male's grunts played from one speaker and the female's copulation call played from the other. In a second control trial, conducted within 24 h after the consortship had ended, subjects again heard the consort male's grunt and the female's copulation call played from separate speakers. As predicted, subjects responded strongly only in the test condition. Eavesdropping upon the temporal and spatial juxtaposition of other individuals' vocalizations may be one strategy by which male baboons achieve sneaky matings.
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Cheney, D. L., & Seyfarth, R. M. (1990). The representation of social relations by monkeys. Cognition, 37(1-2), 167–196.
Abstract: Monkeys recognize the social relations that exist among others in their group. They know who associates with whom, for example, and other animals' relative dominance ranks. In addition, monkeys appear to compare types of social relations and make same/different judgments about them. In captivity, longtailed macaques (Macaca fascicularis) trained to recognize the relation between one adult female and her offspring can identify the same relation among other mother-offspring pairs, and distinguish this relation from bonds between individuals who are related in a different way. In the wild, if a vervet monkey (Cercopithecus aethiops) has seen a fight between a member of its own family and a member of Family X, this increases the likelihood that it will act aggressively toward another member of Family X. Vervets act as if they recognize some similarity between their own close associates and the close associates of others. To make such comparisons the monkeys must have some way of representing the properties of social relationships. We discuss the adaptive value of such representations, the information they contain, their structure, and their limitations.
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Seyfarth, R. M., & Cheney, D. L. (1984). Grooming, alliances and reciprocal altruism in vervet monkeys. Nature, 308(5959), 541–543.
Abstract: Reciprocal altruism refers to the exchange of beneficial acts between individuals, in which the benefits to the recipient exceed the cost to the altruist. Theory predicts that cooperation among unrelated animals can occur whenever individuals encounter each other regularly and are capable of adjusting their cooperative behaviour according to experience. Although the potential for reciprocal altruism exists in many animal societies, most interactions occur between closely related individuals, and examples of reciprocity among non-kin are rare. The field experiments on vervet monkeys which we present here demonstrate that grooming between unrelated individuals increases the probability that they will subsequently attend to each others' solicitations for aid. Vervets appear to be more willing to aid unrelated individuals if those individuals have behaved affinitively toward them in the recent past. In contrast, recent grooming between close genetic relatives appears to have no effect on their willingness to respond to each other's solicitations for aid.
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Seyfarth, R. M., & Cheney, D. L. (2000). Social Awareness in Monkeys. Amer. Zool., 40(6), 902–909.
Abstract: Tests of self-awareness in nonhuman primates have to date been concerned almost entirely with the recognition of an animal's reflection in a mirror. By contrast, we know much less about non-human primates' perception of their place within a social network, or of their understanding of themselves as individuals with unique sets of social relationships. Here we review evidence that monkeys who fail the mirror test may nonetheless behave as if they recognize themselves as distinct individuals, each of whom occupies a unique place in society and has a specific set of relations with others. A free-ranging vervet monkey, baboon, or macaque recognizes other members of his group as individuals. He also recognizes matrilineal kin groups, linear dominance rank orders, and behaves as if he recognizes his own unique place within them. This sense of “social self” in monkeys, however, is markedly different from self-awareness in humans. Although monkeys may behave in ways that accurately place themselves within a social network, they are unaware of the knowledge that allows them to do so: they do not know what they know, cannot reflect on what they know, and cannot become the object of their own attention.
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Owren, M. J., Seyfarth, R. M., & Cheney, D. L. (1997). The acoustic features of vowel-like grunt calls in chacma baboons (Papio cyncephalus ursinus): implications for production processes and functions. J Acoust Soc Am, 101(5 Pt 1), 2951–2963.
Abstract: The acoustic features of 216 baboon grunts were investigated through analysis of field-recorded calls produced by identified females in known contexts. Analyses addressed two distinct questions: whether the acoustic features of these tonal sounds could be characterized using a source-filter approach and whether the acoustic features of grunts varied by individual caller and social context. Converging evidence indicated that grunts were produced through a combination of periodic laryngeal vibration and a stable vocal tract filter. Their acoustic properties closely resembled those of prototypical human vowel sounds. In general, variation in the acoustic features of the grunts was more strongly related to caller identity than to the social contexts of calling. However, two acoustic parameters, second formant frequency and overall spectral tilt, did vary consistently depending on whether the caller was interacting with an infant or participating in a group move. Nonetheless, in accordance with the general view that identity cueing is a compelling function in animal communication, it can be concluded that much of the observed variability in grunt acoustics is likely to be related to this aspect of signaling. Further, cues related to vocal tract filtering appear particularly likely to play an important role in identifying individual calling animals.
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