The relationship of agonistic and affiliative behavior patterns to cellular immune function among cynomolgus monkeys (Macaca fascicularis) living in unstable social groups

Considerable recent interest has focused on the possibility that behavioral factors may influence immune competence, and hence, potentially, patterns of disease. We report here the relationship between the aggressive and affiliative behavior and the cellular immune responses of 30 adult male cynomolgus monkeys (Macaca fascicularis) living in small (n = 5) social groups whose members were periodically redistributed over 26 months. Animals also were subjected to behavioral observation, allowing them to be categorized as either high or low in aggressiveness and affiliation. At the end of the 26 months, lymphocyte proliferation tests were performed on blood samples from all monkeys, using both concanavalin A (ConA) and phytohemagglutinin (PHA) in concentrations of 1, 5, and 10 ug/ml. Two-by-two (Aggressiveness [high, low] X Affiliation [high, low]) analyses of variance performed on these data showed lymphocyte proliferation in response to both ConA and PHA to be greatest (at 1 ug/ml) among highly affiliative animals, albeit only if they were also low in aggressiveness (ConA: Affiliation x Aggression, P < 0.02; PHA: Affiliation x Aggression, P < 0.03). An additional finding was that natural killer cell activity (at an effector to target ratio of 100:1) was highest among highly affiliative animals, regardless of their aggressiveness (P < 0.05). These results indicate that immune competence may be enhanced among monkeys which, in response to a disrupted social environment, spend large amounts of time in affiliation with other animals. Social status, a phenomenon known to influence many aspects of nonhuman primate physiology, was unassociated with nonspecific lymphocyte blastogenesis or natural killer cell activity in this experiment.     

Dyadic and triadic reconciliation in pigtail macaques (Macaca nemestrina)

The tendency in primates for former antagonists to approach and affiliate following aggression has been termed reconciliation because the response is thought to resolve social conflicts produced by aggression. In primate societies, however, an aggressive interaction between two individuals often spreads to include other group members, especially the kin of the combatants. If post conflict affiliation resolves aggressive conflicts in a group, then affiliative increases might occur between combatants and the kin of their opponents following aggression as well as between former opponents. This hypothesis was tested in a captive group of 39 pigtail macaques (Macaca nemestrina) by comparing affiliative response frequencies of combatants during the 5 minute period following aggression to affiliative response frequencies during 5 minute baseline periods not preceded by aggressive activity. Following aggression, affiliation rates increased between combatants and their opponents, aggressors and the kin of their opponents, and aggressors and their own kin. Additional analyses showed that aggression among kin was reconciled more often than aggression among nonkin. Recipients of aggression reconciled with their attackers more often than aggressors reconciled with their victims. Animals with similar dominance ranks reconciled proportionately more often than those with large rank disparities and aggressive infractions of a calculated dominance hierarchy were reconciled more often than attacks consistent with the hierarchy. Results suggest that both dyadic and triadic reconciliations occur in M. nemestrina and that compared to other primate species M. nemestrina exhibit a moderate-to-high conciliatory tendency.     

Social facilitation of agonistic responses to strangers in pairs of saddle back tamarins (Saguinus fuscicollis)

The effect of the presence of a familiar social partner on the interactions of saddle back tamarins with unfamiliar conspecifics was studied. Fifteen adult male-female pairs, of which six were composed of a castrated male and an intact female, served as subjects. All subject pairs were given two social encounters during which both mates met a strange male and two encounters during which they met a strange female. In addition, all subjects were given four encounters during which they met the same strangers while their own pair mates were absent. As a group, the subjects showed higher intensities of injurious aggression and of agonistic displays when they met strangers in the presence of their own pair mates. Females and castrated males, as subgroups, showed significant increases in most agonistic responses when they met strangers in the presence of their pair mates. Intact males, however, did not.     

Differences in background and outcome of three behavior problems of dogs

In order to characterize the three major behavior problems, aggression toward owners, aggression toward strangers and separation anxiety, backgrounds of dogs and general outcomes of the behavioral treatments were analyzed retrospectively. There were 169 cases of aggression toward owners, 84 cases of aggression toward strangers and 78 cases of separation anxiety which did not overlap each other during the 5 years from 1993 to 1997 at Cornell University Animal Behavior Clinic. Based on the case records, including discharge instructions, follow-up information, and pre-presentation questionnaires, several variables were compared among these three groups. The sexual status of these groups was not statistically different, although dogs with aggression toward owners had the highest proportion of males and there were more males in all behavior groups than in the hospital population. Also, breed types were different among three groups with a significantly higher proportion of mixed breed dogs among dogs with separation anxiety and aggression to strangers as compared to dogs with aggression to owners and to the hospital population. A higher percentage of dogs in the separation anxiety group tended to live in apartments and to be disciplined only verbally by the owner than in the other two groups. Age differences were apparent among the three groups in relation to when the dogs were obtained, and the separation anxiety group was different from at least one of the other groups in the age when first obtained, the age the owners first noticed the problem, and the age of behavioral examination. Regarding the general outcome of the behavioral treatment, there were no significant differences among the behavioral groups with regards to the proportion of dogs reported improved. These results provide new characterizations of these three major behavior problems.     

An approach to canine behavioural genetics employing guide dogs for the blind

The purpose of this study was to attempt to find related variables of the canine genome with behavioural traits of dogs maintained and tested in a guide dog facility which provided a relatively uniform environment. The study involved 81 Labrador Retrievers that were being trained as guide dogs. Each dog was taken on walk-out sessions in which the trainer weekly recorded observations that were related to behavioural traits. The records were subjected to key-word analysis of 14 behaviour-related words. A factor analysis on the appearance rate of the 14 key words or phrases resulted in the extraction of six factors that accounted for 67.4% of the variance. Factor 1, referred to as aggressiveness, was significantly related to the success or failure of the dog in qualifying as a guide dog, and was also related to the variable of litter identification. Factor 2, referred to as distraction, was related to the variable of trainer. Factor 3, activity level, was related to the variable of sex, and was significantly related to the polymorphisms of c.471T>C in the solute carrier family 1 ( neuronal/epithelial high affinity glutamate transporter ) member 2 gene and c.216G>A in the catechol-O-methyltransferase gene. The involvement of polymorphisms c.471T>C and c.216G>A in behavioural patterns related to activity level is similar to comparable genetic studies in other mammalian species. These results contribute to a greater understanding of the role of these genes in behaviour.     

Personality influences the neural responses to viewing facial expressions of emotion

Cognitive research has long been aware of the relationship between individual differences in personality and performance on behavioural tasks. However, within the field of cognitive neuroscience, the way in which such differences manifest at a neural level has received relatively little attention. We review recent research addressing the relationship between personality traits and the neural response to viewing facial signals of emotion. In one section, we discuss work demonstrating the relationship between anxiety and the amygdala response to facial signals of threat. A second section considers research showing that individual differences in reward drive (behavioural activation system), a trait linked to aggression, influence the neural responsivity and connectivity between brain regions implicated in aggression when viewing facial signals of anger. Finally, we address recent criticisms of the correlational approach to fMRI analyses and conclude that when used appropriately, analyses examining the relationship between personality and brain activity provide a useful tool for understanding the neural basis of facial expression processing and emotion processing in general.     

Pair bonding prevents reinforcing effects of testosterone in male California mice in an unfamiliar environment

Testosterone (T) can be released by stimuli such as social interactions, and thereby influence future social behaviours. Because the reinforcing effects of T can induce preferences for specific environmental locations, T has the potential to alter behaviour through space use. In a monogamous species, this T pulse may contribute differently to space use in sexually naive (SN) and pair-bonded (PB) males: SN males may be more likely to explore new areas to set up a territory than PB males, which are more likely to defend an existing, established territory. In this study, we test for variation in T-driven space use by examining variation in the formation of conditioned place preferences (CPPs) in SN and PB male California mice. In the three-chambered CPP apparatus, subcutaneous administrations of physiological levels of T were used to repeatedly condition SN and PB males to a side chamber, which is an unfamiliar/neutral environment. The final tests revealed that T-induced CPPs in the side chamber are developed in SN, but not PB males. This study fills a gap in our knowledge about plasticity in the rewarding nature of T pulses, based on past social experience.     

Introduction and integration of strangers into captive groups of tufted capuchins (Cebus apella)

We introduced two to four unfamiliar animals into three established groups (N = 6–9 per group) of tufted capuchins (Cebus apella).We present findings on the behavioral consequences of introductions as a function of age, sex, and residency status and long-term consequences for health and reproduction. No morbidity from aggression occurred at the time of introductions or during several months following, and reproduction was not compromised. Activity budgets and patterns of social spacing and interaction were little changed following the introductions except for increases in vigilance behavior, especially by newly introduced adult females. Adult females exhibited the strongest and longest-lasting response to changes in group composition. The results indicate that in this species (1) introductions of adult females can be carried out with acceptable risk to the newcomers provided that careful monitoring occurs, so that the onset of severe aggression instigated by resident females toward new females can be avoided, (2) juveniles can be introduced with minimal risk, and (3) adult males can be introduced into groups lacking resident adult males with minimal risk. Capuchins differ in important ways from the better-studied Old World monkeys in their response to introductions of strangers. The differences are instructive with regard to processes supporting species-typical social structure, which is less overtly hierarchical in capuchins than in macaques.