Socially meaningful vocal plasticity in adult Campbell's monkeys (Cercopithecus campbelli)

Campbell's monkeys (Cercopithecus campbelli) frequently exchange vocalizations, the combined-harmonic calls, with individuals responding to one another's calls. Previous work has shown that these calls can be grouped into several structural variants. Adult females differ in their variant repertoires, which may change during their adult life, particularly after changes in the group composition. Playback of females' currently produced variants triggered vocal responses from other group members, whereas the same females' former, no longer used variants and those of stranger females never did. In contrast, former variants caused long-term cessation of vocal behavior, whereas stranger variants had no effect. Data showed that monkeys were able to distinguish between the different types of variants, indicating that these calls form part of a long-term social memory.     

Individual differences in response to a stranger: social impulsivity as a dimension of temperament in vervet monkeys (Cercopithecus aethiops sabaeus)

Social impulsivity in response to a stranger was assessed in male vervet monkeys (Cercopithecus aethiops sabaeus) using the Intruder Challenge Test. Vervets (N = 128, ages 3-18 years) were presented with an unfamiliar adult male at the periphery of the home enclosure. An index of impulsivity reflecting variation in the tendency to rapidly approach, engage, and challenge the intruder was derived from factor analysis of behavioral responses. Scale reliability (alpha = .84) and test-retest consistency (intraclass correlation = .83) were high, indicating that this index reliably and efficiently measures a stable aspect of temperament from impulsive to inhibited. Impulsivity scores peaked at age 4, when vervet males typically emigrate from the natal group. The highest ranking males in each group were more likely to score in the moderate range, whereas lower ranking males were more likely to score in the highest (impulsive) or lowest (inhibited) quartiles.     

Sexual segregation in squirrel monkeys (Saimiri sciureus): a transactional analysis of adult social dynamics.

Female agonism against males and male interventions in social transactions between the sexes are 2 explanations for the low rates of social engagement observed between male and female squirrel monkeys (Saimiri sciureus). These possibilities were evaluated by comparing the frequency, structure, and content of transactions between the sexes in 3 experimental social units: male-female pairs, single-male-multifemale groups, and multimale-multifemale groups. Affiliative transactions between the sexes occurred 3-5 times less often in multimale-multifemale groups than in male-female pairs and in single-male-multifemale groups. Intermale agonism in the multimale-multifemale groups often coincided with ongoing transactions between the sexes, whereas female agonism against males was rather uncommon in all social units. The results failed to support the female agonism hypothesis and indicate a need for more detailed studies of intermale social dynamics.     

Hand preferences in unimanual and bimanual feeding by wild vervet monkeys (Cercopithecus aethiops)

Lateral preference was examined in spontaneous feeding actions in 2 troops of wild vervet monkeys (Cercopithecus aethiops). Processing of 4 foods (termites, leaf shoots, sugarcane, and fruit) was studied. Actions included unimanual reaching to moving objects, operating from an unstable posture, and coordinated bimanual processing. Between 19 and 31 subjects were available, according to the task. In 2 tasks, laterality of 2 independent stages was measured separately, giving 6 measures in all. On 4 of these measures, most monkeys were ambipreferent, and only a few showed significant hand preferences. Only for termite feeding and detaching material from fruits did the majority show significant lateralization; no tasks elicited exclusive use of 1 hand. Preference appeared labile, because in 2 tasks, population trends reversed with increasing age. No population trends to left or right were found; instead, these monkeys showed ambilaterality, with lateralization associated with task complexity.     

Kinship and affiliative behavior patterns in a captive group of Celebes black apes (Macaca nigra)

The influence of matrilineal kinship on four socially affiliative behavior patterns--grooming, contact, proximity, and play--was studied in a little-known primate species, the Celebes black ape (Macaca nigra). Twenty group-living black apes, comprising four genealogical groups, were observed for more than 100 hr; data were collected by the instantaneous scan technique. Animals spent more time than was expected by chance grooming, in contact with, and in proximity to their matrilineal relatives, but they did not play with relatives more than was expected. The proximal mechanisms responsible for these results are unknown, and increased familiarity among matrilineal relatives may have influenced the interaction patterns in the group. The results obtained in this study are similar to those of many others that demonstrate differential behavior toward kin, and they are consistent with the theory that animals may increase their inclusive fitness by interacting preferentially with relatives.     

Effects of short-term crowding on aggression in captive groups of pigtail monkeys (macaca nemestrina)

Agonistic behaviors of 14 groups of pigtail monkeys were monitored under 2 spatial conditions, normal living space and half that amount of space. Aggression occurred less frequently in the crowded than in the relatively less crowded condition. The results of this study resemble those of some analogous research on human children, and they suggest that nonhuman primate models of crowding stress and aggression may be especially appropriate.     

Acoustic classification of alarm calls by vervet monkeys (Cercopithecus aethiops) and humans (Homo sapiens): II. Synthetic calls

In 2 experiments classification of synthetic versions of species-typical snake and eagle alarm calls by vervet monkeys (Cercopithecus aethiops) and human (Homo sapiens) control subjects was investigated. In a 2-choice, operant-conditioning-based procedure, this work followed up acoustic analyses that had used various digitally based algorithms (Owren & Bernacki, 1988). All subjects were first tested with alarm-call replicas that were based on analysis data. These models were classified in the same manner as natural stimuli, which verified the appropriateness of the acoustic characterizations. Synthetic stimuli were then presented to test the importance of specific acoustic cues. Spectral patterning was found to be the most salient cue for classification by the monkeys, whereas results from the human subjects were mixed. Implications for the study of nonhuman primate vocalizations and Lieberman's (1984) theory of speech evolution are discussed.     

Acoustic classification of alarm calls by vervet monkeys (Cercopithecus aethiops) and humans (Homo sapiens): I. Natural calls

A 2-choice, operant-conditioning-based classification procedure was developed in which vervet monkeys (Cercopithecus aethiops) categorized species-typical snake and eagle alarm calls recorded from individually identified free-ranging animals. After preliminary training with a pair of calls from a single animal, 2 vervets were tested with novel exemplars produced by a variety of callers. Experiment 1 combined testing with continued training in routine classification of 14 new calls. In Experiment 2, the subjects were tested with 48 novel calls in rapid succession. Human (Homo sapiens) control subjects participated in the first study without extended preliminary training. Monkey and human subjects both showed immediate transfer to classification of unfamiliar alarm calls, despite variations both in voice characteristics and reproduction quality.     

Return of juvenile rhesus monkeys (Macaca mulatta) to the natal social group following an 18 week separation

Return of 6 juvenile rhesus monkeys to their natal social group following an absence of 18 weeks resulted in changes in cortisol levels and absolute numbers of lymphocyte subsets 24 hours later which were related to behaviors received during the 2 hours immediately following the return. Baseline blood samples were collected 1 week prier to the return and then at 24 hours, 1 week, and 4 weeks thereafter and hermonal and immune measurements were made. Six subjects, matched for age, sex, weight, and rank, which had remained in the social group also were evaluated. In contrast to those subjects which remained in the group (“in-group”), test subjects showed significantly higher cortisol levels and significantly lower absolute numbers of T-helper and T-suppresser cells 24 hours following return when compared to baseline values. There was a significant correlation between percent decline from baseline in absolute numbers of total T cells and total frequency of bites received during the 2 hours following return to the group (r = −0.85). Additionally, mothers of the test subjects showed a significantly greater increase in cortisol levels 24 hours following return than mothers of the in-group subjects. Finally, for the test subjects, there was near perfect negative correlation between absolute numbers of total T cells and cortisol levels 24 hours following return (r = −0.95). These data demonstrate that return to a social group may be stressful and that the specific individual behavioral interactions may predict physiological responses. © 1993 Wiley-Liss, Inc.     

Interactive affective sharing versus non‐interactive affective sharing in work groups: Comparative effects of group affect on work group performance and dynamics

This study explores whether the dynamic path to group affect, which is characterized by interactive affective sharing processes, yields different effects on task performance and group dynamics than the static path to group affect, which arises from non‐interactive affective sharing. The results of our experiment with 70 three‐person work groups show that groups performed better on creative tasks than on analytical tasks when they were in a positive mood, and better on analytical tasks than on creative tasks when in a negative mood, but only when affect was interactively shared. Moreover, analysis of videotaped group member interactions during task performance showed similar results for work group dynamics, such that group affect influenced belongingness and information sharing only when affect was interactively shared and not when affect was non‐interactively shared. Results support the idea that affective sharing processes are fundamental for understanding the effects of group affect on behavior. Copyright © 2010 John Wiley & Sons, Ltd.     

The structure of social relationships among captive female giraffe (Giraffa camelopardalis)

Giraffe herds have been characterized as random associations of individuals, but recent evidence suggests giraffe have a more complex social structure. The authors formulated 3 hypotheses designed to evaluate whether a herd of captive giraffe (Giraffa camelopardalis) associated randomly or patterned their behavior and proximity in a manner indicative of social relationships. Affiliative interaction, proximity, and nearest neighbors for 6 captive female giraffe living in a large outdoor enclosure were analyzed, and all three measures were nonrandomly distributed, indicating female giraffe had social preferences. Furthermore, preferences were consistent across measures and time, suggesting that adult female giraffe maintain relationships. Mother-daughter pairs and pairs with large age differences between members interacted and associated most often. The social structure of this captive herd is influenced by social relationships between individual adult females, and the social behavior of individual females should be examined more closely in the wild.     

Note on social behavior of long-term captive female orangutans (Pongo pygmaeus abellii)

Some observations of social behavior of two aging female orangutans with a younger male son of one were made in an outdoor and in an indoor enclosure during the day. These included social distance, grooming, and locomotion plus wrestling and genital stimulation. As noted 15 years earlier, the two old females were never in contact with each other. Each showed contact and noncontact with the younger male. No clear social relation between the females was evident. Careful study of aging zoo populations could be useful.     

The mother-offspring relationship as a template in social development: reconciliation in captive brown capuchins (Cebus apella)

Mother-offspring (MO) relationship quality was investigated to determine its influence on the development of reconciliation--affiliation between opponents shortly after a fight--because it influenceswhat distressed youngsters learn about calming down. Data were longitudinal and cross-sectional observational samples of 38 MO pairs of monkeys across 24 months. An MO relationship quality index (RQI) classified each pair as secure or insecure. Reconciliation emerged in infancy.Secure youngsters had an appeasing conciliatory style, and insecure youngsters had an agitated conciliatory style. Conclusions are that reconciliation develops from the attachment behavior system and MO RQI is related to the particular conciliatory style youngsters develop by affecting how aroused they are by conflict and the subsequent socializing they seek to calm down.     

Patterns of social preference across different social contexts in golden lion tamarins (Leontopithecus rosalia)

We investigated the role of mutual and circumstantial factors in maintaining exclusive social relationships in a New World primate. Four breeding pairs of golden lion tamarins (Leontopithecus rosalia rosalia) were allowed to interact with their mate or an unfamiliar, opposite-sex adult in each of 4 different social contexts: in view of the mate, out of the mate's view, with only the mate present, and with only the unfamiliar animal present. Males and females were in proximity to, approached, and sniffed their mates significantly more often than they did unfamiliar tamarins. These behaviors suggest a preference for the familiar mate. However, when mates were absent, tamarins demonstrated significantly higher levels of approach and sniffs toward unfamiliar animals. These patterns of behavior indicate that circumstantial factors, such as social context, may regulate social interactions between paired tamarins and unfamiliar, opposite-sex conspecifics.     

Imitation recognition in a captive chimpanzee (Pan troglodytes)

This study investigated the ability of a captive chimpanzee (Pan troglodytes) to recognise when he is being imitated. In the experimental condition of test 1a, an experimenter imitated the postures and behaviours of the chimpanzee as they were being displayed. In three control conditions the same experimenter exhibited (1) actions that were contingent on, but different from, the actions of the chimpanzee, (2) actions that were not contingent on, and different from, the actions of the chimpanzee, or (3) no action at all. The chimpanzee showed more "testing" sequences (i.e., systematically varying his actions while oriented to the imitating experimenter) and more repetitive behaviour when he was being imitated, than when he was not. This finding was replicated 4 months later in test 1b. When the experimenter repeated the same actions she displayed in the experimental condition of test 1a back to the chimpanzee in test 2, these actions now did not elicit those same testing sequences or repetitive behaviours. However, a live imitation condition did. Together these results provide the first evidence of imitation recognition in a nonhuman animal.     

Cortical control of conditioned and spontaneous vocal behavior in rhesus monkeys

Rhesus monkeys were trained on a discriminative conditioning of vocalizations paradigm, a task that requires volitional vocal control. The monkeys' spontaneous vocal and other social behavior was also assessed. Each monkey then underwent ablation of anterior cingulate cortex, ablation of the homologus of Broca's and Wernicke's areas, or no lesion. The anterior cingulate lesions severely disrupted both conditioned and spontaneous vocal behavior, but had no effect on nonvocal social behavior or on a discriminative conditioning task requiring a nonvocal response. The lesions of the homologs of Broca's and Wernicke's areas had no effects on the behaviors studied. These findings have implications for the comparative neurology of primate vocalization and speech.     

High maternal aggression in dwarf hamsters (Phodopus campbelli and P. sungorus)

The defense of offspring, termed maternal aggression, is a highly conserved behavior in mammals, including rodents. This study examined relative levels of maternal aggression in two closely related dwarf hamster species, Phodopus campbelli and P. sungorus, that normally inhabit high latitude, boreal environments. When tested with first litters and with the breeder male remaining with the female (for P. campbelli the male is necessary for successful rearing of offspring), both species exhibited high levels of maternal aggression with average duration of aggressive behavior>80 sec for a 10 min test. For P. sungorus, males are not required to rear offspring. P. sungorus females with either one or multiple litters (singly housed after impregnation) exhibited significantly higher levels of aggression (>300 sec) relative to females co‐housed with the sires. In terms of species differences in attack style, P. campbelli exhibited a boxing or clawing strategy for ～50% of total attack time, but for P. sungorus, this form of attack occurred<5% of the time. For P. sungorus, attacks to the vulnerable belly and flank constituted>90% of all attacks, but these regions were attacked ～50% of the time for P. campbelli. A survey of levels of maternal aggression of rodents in other genera suggests that maternal aggression in Phodopus is at the high end of the spectrum. Results of this study suggest that the presence of the breeder male may actually suppress aggression in P. sungorus. This fact, as well as its high level of aggression and its distant relationship to mice and rats, suggest P. sungorus as a possible model for future studies on the neurobiological basis of maternal aggression. The relationship between the high rates of maternal aggression and life history strategy in Phodopus is discussed. Aggr. Behav. 00:000–000, 2005. © 2005 Wiley‐Liss, Inc.     

Rhesus monkeys (Macaca mulatta) and capuchin monkeys (Cebus apella) remember future responses in a computerized task

Planning is an important aspect of many daily activities for humans. Planning involves forming a strategy in anticipation of a future need. However, evidence that nonhuman animals can plan for future situations is limited, particularly in relation to the many other kinds of cognitive capacities that they appear to share with humans. One critical aspect of planning is the ability to remember future responses, or what is called prospective coding. Two monkey species (Macaca mulatta and Cebus apella) performed a series of computerized tasks that required encoding a future response at the outset of each trial. Monkeys of both species showed competence in all tests that were given, providing evidence that they anticipated future responses and that they appropriately engaged in those responses when the time was right for such responses. In addition, some tests demonstrated that monkeys even remembered future responses that were not as presently motivating as were other aspects of the task environment. These results indicated that monkeys could anticipate future responses and retain and implement those responses when appropriate.