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Objectives: Chimpanzees (Pan troglodytes) are notable for exhibiting high levels of male-to-female aggression. Much of this aggression from adult males serves sexually coercive functions. Despite being smaller and lower-ranking than adult males, adolescent males also engage in regular aggression against adult females. Here, we test whether the primary function of this aggression is sexual coercion, as in adult males, or, alternatively, whether adolescent males use aggression to establish social dominance over females., Materials and Methods: We analyzed 1771 copulations and 1812 instances of male-initiated aggression between adolescent males (aged nine through 14 years) and adult females across 21 years of observation of the Kanyawara chimpanzee community in Kibale National Park, Uganda., Results: Our test of the sexual coercion hypothesis revealed that adolescent males did not selectively target cycling females for aggression, nor did aggression against cycling females predict rates of copulation with those females. Our test of the social dominance hypothesis showed that males succeeded in dominating all adult females before, or soon after, dominating their first adult male. Additionally, we found that adolescent males dominated females approximately in the order of the females' own ranks, from the bottom to the top of the female hierarchy., Discussion: Our data illustrate that the establishment of social dominance was more important than sexual coercion in explaining patterns of adolescent male aggression toward females. In comparison, evidence for sexual coercion was clear and compelling in adult males. These findings highlight that the primary function of male-to-female aggression differs between adolescent and adult males., (© 2021 Wiley Periodicals LLC.)

Many nonhuman primates live in complex social groups in which they regularly encounter both social stressors such as aggression and social support such as that provided by long-term affiliative relationships. Repeated exposure to social stressors may result in chronically elevated cortisol levels that can have deleterious physical effects such as impaired immune function, cardiovascular disease, and reduced brain function. In contrast, affiliative social relationships may act as a buffer, dampening the release of cortisol in response to acute and chronic stressors. Understanding how social stressors and social support predict cortisol levels is therefore essential to understanding how social situations relate to health and welfare. We studied this relationship in 16 socially housed captive brown capuchin monkeys (Cebus [Sapajus] apella) by comparing long-term hair cortisol levels with behavioral measures of social stress (dominance rank, rank certainty, and amount of aggression received) and social support (amount of affiliation and centrality in the affiliative social network of the group). Dominance rank, rank certainty, amount of affiliation, and age were not significant predictors of long-term cortisol levels in this population. Instead, long-term cortisol levels were positively related to the amount of aggression received and negatively related to centrality in the affiliative social network of the group. This pattern may be attributed to the species' socially tolerant dominance system and to the availability of social support across the dominance hierarchy., (© 2019 Wiley Periodicals, Inc.)

Objectives: Cercopithicine primates tend to have nepotistic hierarchies characterized by predictable, kinship-based dominance. Although aggression is typically directed down the hierarchy, insubordinate aggression does occur. Insubordination is important to understand because it can precipitate social upheaval and undermine group stability; however, the factors underlying it are not well understood. We test whether key social and demographic variables predict insubordination among captive female rhesus macaques., Materials and Methods: To identify factors influencing insubordination, multivariate analyses of 10,821 dyadic conflicts among rhesus macaque females were conducted, using data from six captive groups. A segmented regression analysis was used to identify dyads with insubordination. Negative binomial regression analyses and an information theoretic approach were used to assess predictors of insubordination among dyads., Results: In the best models, weight difference (w = 1.0; IRR = 0.930), age (dominant: w = 1.0, IRR = 0.681; subordinate: w = 1.0, IRR = 1.069), the subordinate's total number of allies (w = 0.727, IRR = 1.060) or non-kin allies (w = 0.273, IRR = 1.165), the interaction of the dominant's kin allies and weight difference (w = 0.938, IRR = 1.046), violation of youngest ascendancy (w = 1.0; IRR = 2.727), and the subordinate's maternal support (w = 1.0; IRR = 2.928), are important predictors of insubordination., Discussion: These results show that both intrinsic and social factors influence insubordinate behavior. This adds to evidence of the importance of intrinsic factors and flexibility in a social structure thought to be rigid and predetermined by external factors. Further, because insubordination can precipitate social overthrow, determining predictors of insubordination will shed light on mechanisms underlying stability in nepotistic societies., (© 2017 Wiley Periodicals, Inc.)

Intense intolerance among males is considered to be an important mechanism maintaining the uni-male organization traditionally attributed to socially monogamous gibbons. Long-term field work, however, has revealed the existence of stable, socially polyandrous groups in at least two populations, raising questions about the mechanism that allows two adult males to co-reside in the same group. I collected 21 months of behavioral data on 7 two-male groups of wild siamangs (Symphalangus syndactylus) in southern Sumatra (Indonesia) to test the hypothesis that dominance relationships regulate the interactions of adult male siamangs and ultimately facilitate multi-male social groups. A dominant male could clearly be identified in each dyad, based on a consistent direction of agonistic interactions, displacements and the maintenance of an advantageous position in the canopy. Males identified as dominant enjoyed greater social access to the resident female and monopolized copulations. These results suggest that gibbons possess the psycho-social flexibility to regulate intra-sexual aggression and live in multi-male social units under certain social conditions. I discuss the effects that relatedness between males and female choice have in determining this grouping pattern, and the role of male intolerance in the maintenance of primate mating systems., (© 2015 Wiley Periodicals, Inc.)

GrooFiWorld is an individual-based, computational model of social interactions that can be used to examine factors underlying reciprocation and interchange of social behavior in primate societies. Individuals within GrooFiWorld are programed to maintain spatial proximity and thereby form a group. When an individual encounters another individual in its proximity, the individual attacks the other if the risk of losing is low. Otherwise, the individual considers grooming the other. Patterns of social behavior that emerge in the model resemble empirical data from primates. Triadic aggression emerges when an individual attacks one of the former combatants by chance immediately after an aggressive interaction, and reciprocation and interchange of grooming and support emerge even though individuals have no intention to help others or pay back services. The model generates predictions for patterns of contra-intervention that are counterintuitive within a framework of interchange of social services, such as that individuals receive more contra-intervention from those whom they groom more frequently. Here we tested these predictions in data collected on social interactions in a group of bonnet macaques (Macaca radiata). We confirmed the predictions of the model in the sense that contra-intervention was strongly correlated with dyadic aggression which suggests that contra-intervention is a subset of dyadic aggression. Adult females directed more contra-intervention to those individuals from whom they received more grooming. Further, contra-intervention was directed down the dominance hierarchy such that adult females received more contra-intervention from higher ranking females. Because these findings are consistent with the predictions from the GrooFiWorld model, they suggest that the distribution of interventions in fights is regulated by factors such as dominance rank and spatial structure rather than a motivation to help others and interchange social services., (© 2015 Wiley Periodicals, Inc.)

Objectives: Digit ratio (2D:4D)-a putative marker of prenatal androgen activity-has been shown to correlate with self-reported physical aggression and dominance behavior, especially in male children and adolescents. This evidence is derived primarily from the study of Western samples., Methods: Digit ratios, self-reported aggression, and dominance behavior were collected from men and women in two traditional, small-scale societies, i.e., the Hadza and the Datoga of Tanzania., Results: We found significant differences in physical and verbal aggression, anger, and hostility between the two societies with the Datoga reporting higher scores on all four measures. Moreover, self-reported dominance in the Datoga was higher than in the Hadza. The Datoga showed lower left and right hand 2D:4D ratios than the Hadza. Men reported higher physical and verbal aggression and dominance, and had lower 2D:4D ratios than women. A significant negative association between 2D:4D and dominance was found in Hadza women., Conclusions: We discuss our findings with reference to differences in mating systems between the two small-scale societies and previous findings of Western and other small-scale societies., (© 2015 Wiley Periodicals, Inc.)

Matrilineal overthrows in macaque societies are rare but devastating events, often resulting in severe morbidity, mortality, and loss of individual and group fitness. The handful of documented macaque overthrows provides scant evidence to reveal the severity or longevity of reproductive consequences resulting from such violent events. We analyzed archival records from semi-free ranging rhesus monkeys, Macaca mulatta, across 6 years (55 ≤ N ≤ 107, from 2007 to 2012) during which time a matrilineal overthrow occurred (in 2009) to test the hypothesis that extremely violent interactions such as a matrilineal overthrow would significantly reduce reproductive fitness for the involved matrilines and for the troop collectively. The matrilineal overthrow resulted in a significant increase in infant loss for the population from the previous year (χ(2)  = 8.117, df = 1, P = 0.004), as evidenced by the fact that in 2009, but not in other years, the proportion of infants lost was greater than the proportion of viable infants (χ(2)  = 4.55, df = 1, P = 0.03). Moreover, the deposed matriline suffered 100% infant loss in 2009, a significant change from the previous year (χ(2)  = 7.87, df = 1, P = 0.005) while the attacking matriline suffered 50% infant loss (also a significant change from the previous year; χ(2)  = 4.44, df = 1, P = 0.035), with the uninvolved, lowest-ranking matriline showing no change in infant loss from the previous year (χ(2)  = 0.008, df = 1, P = 0.93). The deposed matriline did not produce viable offspring again until 3 years later. We further found that rates of severe fighting (as indicated by the number of fight wounds requiring medical treatment) were positively correlated with infant loss across the 6 years of the study (r[s]  = 0.943, P = 0.005). Our data indicate that extreme periods of intra-group conflict, such as the matrilineal overthrow, have marked short-term consequences for individual fitness, and may be extreme examples of the long-term influences that group violence exerts on the mean fitness within a primate troop., (Published 2014. This article is a U.S. Government work and is in the public domain in the USA.)

Nearly all species engage in a variety of intraspecific social interactions, and there is evidence that these interactions are rewarding. Less is known, however, about the factors that influence social reward. Using the conditioned place preference paradigm, we tested whether social interactions are rewarding for male Syrian hamsters. We also tested whether social stimuli increase neural activation in the ventral tegmental area (VTA), a component of the mesolimbic reward system, and how individual differences in social behavior and experience influence neural activation. In the present study, we found that hamsters developed a conditioned place preference for social interactions, but the effects were significantly stronger in dominant animals compared with subordinates. The number of Fos-immunoreactive cells in the VTA was significantly higher in hamsters that had engaged in a direct social encounter compared with hamsters exposed to a caged stimulus hamster or controls. Interestingly, socially experienced males had more Fos-immunoreactive cells in the VTA than socially naive males after exposure to a social stimulus. Surprisingly, the amount of Fos immunoreactivity in the VTA induced by a social stimulus was correlated with the amount of aggressive/dominance behaviors that had been observed during interactions that had occurred 2 months earlier. Our results indicate that social interactions between males are rewarding, and that social dominance increases the reward value. Social interactions stimulate the mesolimbic reward system, and social experience enhances its response to novel social stimuli and may produce long-term changes in the neural mechanisms that mediate the maintenance of dominance over long periods of time., (© 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Nonhuman primates show remarkable variation in several aspects of social structure. One way to characterize this variation in the genus Macaca is through the concept of social style, which is based on the observation that several social traits appear to covary with one another in a linear or at least continuous manner. In practice, macaques are more simply characterized as fitting a four-grade scale in which species range from extremely despotic (grade 1) to extremely tolerant (grade 4). Here, we examine the fit of three core measures of social style-two measures of dominance gradients (hierarchical steepness) and another closely related measure (counter-aggression)-to this scale, controlling for phylogenetic relationships. Although raw scores for both steepness and counter-aggression correlated with social scale in predicted directions, the distributions appeared to vary by measure. Counter-aggression appeared to vary dichotomously with scale, with grade 4 species being distinct from all other grades. Steepness measures appeared more continuous. Species in grades 1 and 4 were distinct from one another on all measures, but those in the intermediate grades varied inconsistently. This confirms previous indications that covariation is more readily observable when comparing species at the extreme ends of the scale than those in intermediate positions. When behavioral measures were mapped onto phylogenetic trees, independent contrasts showed no significant consistent directional changes at nodes below which there were evolutionary changes in scale. Further, contrasts were no greater at these nodes than at neutral nodes. This suggests that correlations with the scale can be attributed largely to species' phylogenetic relationships. This could be due in turn to a structural linkage of social traits based on adaptation to similar ecological conditions in the distant past, or simply to unlinked phylogenetic closeness., (© 2012 Wiley Periodicals, Inc.)

In conflicts between primate groups, the resource-holding potential (RHP) of competitors is frequently related to group size or male group size, which can remain relatively constant for long periods of time, promoting stable intergroup dominance relationships. Demographic changes in neighboring groups, however, could introduce uncertainty into existing relationships. Among tufted capuchin monkeys (Cebus apella nigritus), dominant male replacement is a relatively infrequent demographic event that can have a profound effect on both the composition and size of the social group. Here, we report such a case and the consequences for home range use and intergroup aggression. Between June 2008 and August 2010, we periodically followed two neighboring groups (Macuco and Rita) in Iguazú National Park, recording daily paths (N = 143) and encounters between the groups (N = 28). We describe the events leading to a change in the male dominance hierarchy in the larger group (Macuco), which resulted in the death or dispersal of all adult males, followed by the succession of a young adult male to the dominant position. This takeover event reduced the numerical advantage in number of males between the two groups, although the ratio of total group sizes remained nearly constant. Following this shift in numerical asymmetry, the degree of escalation of intergroup aggression increased, and we observed reversals in the former intergroup dominance relationship. These changes in behavior during intergroup encounters were associated with changes in the use of overlapping areas. In the 6 months following the takeover, the area of home range overlap doubled, and the formerly dominant group's area of exclusive access was reduced by half. These results suggest that RHPin tufted capuchin monkeys is related to male group size. Furthermore, they highlight the importance of considering rare demographic events in attempts to understand the dynamics of aggression between primate groups., (© 2012 Wiley Periodicals, Inc.)

Affiliation/agonism and social dominance are central factors determining social organization in primates. The aim of our study is to investigate and describe, for the first time, the intersexual relations in a nocturnal and cohesive pair-living prosimian primate, the western woolly lemur (Avahi occidentalis), and to determine to what extent phylogeny, activity mode, or the cohesiveness of pair partners shape the quality of social interactions. Six pairs of western woolly lemurs were radio-collared in the dry deciduous forest of northwestern Madagascar. More than 874 hr of focal animal sampling were conducted. All occurrences of social interactions involving a focal animal were recorded. The rate of affiliation between pair partners was significantly higher than the rate of agonism. Western woolly lemur pairs' interactions were extremely peaceful. All decided agonistic conflicts (N = 15) were exclusively initiated and won by the female. No female showed spontaneous submission toward her male partner. These results are in line with those of diurnal cohesive pair-living anthropoid primates. Findings support the hypothesis that social relations in pair-living primates are linked to the cohesiveness of pair partners in time and space irrespective of phylogeny and activity mode., (© 2011 Wiley Periodicals, Inc.)

Captive groups of primates often exhibit higher rates of aggression than wild, free-ranging groups. It is important to determine which factors influence aggression in captivity because aggression, particularly intense aggression, can be harmful to animal health and well-being. In this study, we investigated the effect of ground substrate as well as season, rank, age, and group size on rates of agonistic interactions per female in seven captive groups of rhesus macaques (n = 70 females, 1,723 focal samples) at the California National Primate Research Center. Agonistic interactions were divided into three categories: displacements, mild aggression, and intense aggression. Females living in enclosures with gravel substrate were 1.7 times more likely to be involved in intense aggression (e.g. chases and physical contact) than females living in enclosures with grass (Poisson regression model: P < 0.001). High-ranking females were at least 1.3 times more likely to be involved in mild (e.g. threats and lunges) aggression than lower-ranking females (low rank: P = 0.03; mid rank: P = 0.001). Females of all ranks were 1.5-1.9 times more likely to be involved in both intense and mild aggression during the breeding season than other seasons. Age and group size did not affect rates of mild or intense aggression. These findings indicate that although some aggression appears to be natural and unavoidable, i.e. aggression during the breeding season, the well-being of captive macaques can be improved by developing grass substrate in outdoor enclosures., (© 2011 Wiley Periodicals, Inc.)

In the wild, male rhesus macaques disperse at sexual maturity. In captivity, however, males cannot disperse from their natal groups. Thus, the presence of natal males in captive rhesus social groups is unnatural and has the potential to negatively influence group dynamics and stability. A primary difference between natal males and non-natal (immigrant) males is that natal males have the opportunity to form long-term alliances with their maternal kin as well as nonkin. We investigated the factors associated with natal males' kin alliances and the impact of these alliances on measures of natal male behavior, group dynamics, and group stability. We found that natal males more frequently formed alliances with maternal kin when they were from high-ranking matrilines, had more siblings, and were younger. More frequent kin alliances were associated with more frequent use of intense aggression, higher individual rank, and higher degree of integration within the male displacement network. Thus, it seems that natal males use their alliances to be more active and influential in the social group, which may affect group stability. It appears that juvenile natal males from high-ranking matrilines, in particular, have the largest impact on group stability. Younger natal males from high-ranking matrilines formed alliances with kin more frequently and used intense aggression more frequently than older or lower ranking males. Furthermore, groups with a higher proportion of juvenile males from high-ranking matrilines also had higher rates of wounding. We suggest that the presence of natal males in rhesus groups may act in opposition to group stability., (© 2010 Wiley-Liss, Inc.)

Several patterns of polyadic aggressive interactions have been previously reported. Here, we describe another pattern of polyadic interactions in a captive group of Japanese macaques (Macaca fuscata fuscata) that we designate as "successive aggression". We defined successive aggression as aggression by the original actor toward a second recipient within a very short time interval after the initial aggression toward the first recipient. We compared the patterns and characteristics of successive aggression to those of redirection. Among 2,698 recorded aggressive interactions, 80 involved successive aggressions and 75 were classified as redirections. Females, especially adult females, performed and received more successive aggression, whereas males, especially adult males, performed and received more redirection. Successive aggression often occurred when the first recipient exhibited counter-aggression. Successive aggression was then directed toward an individual related to the first recipient, such as the mother, offspring or sibling. The targets of redirection were not relatives of the first recipient in most cases, but were clearly subordinate individuals. The dominance relationships among the aggressor, the first recipient and the second recipients were usually non-linear for successive aggression, but were linear for most cases of redirection. These results suggest that monkeys can anticipate possible opponents who may intervene in ongoing aggressive interactions and suppress them, even though they are not yet hostile toward these individuals. Successive aggression may function to establish and maintain dominance relationships among matrilineal groups through repeated confirmations.

In primate species exhibiting seasonal reproduction, patterns of testosterone excretion in adult males are variable: in some species, peaks correlate with female receptivity periods and heightened male-male aggression over access to estrous females, in others, neither heightened aggression nor marked elevations in testosterone have been noted. In this study, we examined mean fecal testosterone ( f T) levels and intermale aggression in wild adult male ring-tailed lemurs residing in three groups at Beza Mahafaly Reserve, Madagascar. Results obtained from mating and post-mating season 2003 were compared to test Wingfield et al. [1990. Am Nat 136:829-846] "challenge hypothesis", which predicts a strong positive relationship between male testosterone levels and male-male competition for access to receptive females during breeding season. f T levels and rates of intermale aggression were significantly higher during mating season compared to the post-mating period. Mean f T levels and aggression rates were also higher in the first half of the mating season compared with the second half. Number of males in a group affected rates of intermale agonism, but not mean f T levels. The highest-ranking males in two of the groups exhibited higher mean f T levels than did lower-ranking males, and young males exhibited lower f T levels compared to prime-aged and old males. In the post-mating period, mean male f T levels did not differ between groups, nor were there rank or age effects. Thus, although male testosterone levels rose in relation to mating and heightened male-male aggression, f T levels fell to baseline breeding levels shortly after the early mating period, and to baseline non-breeding levels immediately after mating season had ended, offsetting the high cost of maintaining both high testosterone and high levels of male-male aggression in the early breeding period., ((c) 2007 Wiley-Liss, Inc.)

Testosterone is a steroid hormone with diverse effects on male reproductive function and behavior. The relationship between testosterone and social behavior such as mating and aggression has been investigated in a variety of primate species, but few such studies have been conducted on chimpanzees, and even fewer on primates during the juvenile and adolescent periods. This study explores the relationship between baseline urinary testosterone and behavioral variables including dominance rank, rates of aggression toward peers, and behavioral style in 16 juvenile and adolescent male chimpanzees (Pan troglodytes) living at the New Iberia Research Center in Louisiana. Behavioral observations and urine collection occurred during four research periods, each a year apart. After correcting for the positive association between testosterone and age, testosterone was positively associated with both dominance rank and rates of aggression directed at others. It was negatively associated with rates of aggression received. Individuals scoring highest in the "mellow" behavioral style component showed higher levels of testosterone than individuals scoring lowest in this component, an effect that may be partially due to the confounding effect of rank. The results of this study suggest that hormonal changes during the period preceding adulthood are not simply programmed physiological processes tied primarily to age-related change, but that important age-independent relationships with behavior also exist.

Female contact aggression against males is relatively rare in species in which the adult males are larger than the females, but it has the potential to influence group structure, male group membership, tenure, and dominance rank. We report an incident in which female mandrills living in a semi-free-ranging group in Franceville, Gabon, attacked a male that was apparently incapacitated after a fight with another male and was unable to escape. The attack involved the alpha male and did not occur in a sexual or infanticidal context. Other adult and adolescent males observed the attack, but when one adult male attempted to participate he was chased away by the females. This observation adds to reports of female coalitions excluding unwanted males from primate groups, or even killing them. The fact that this can also occur in mandrills suggests that females have a degree of control over male group membership, despite the large degree of sexual dimorphism in this species, and highlights the importance of coalitions in primate social organization., (Copyright (c) 2006 Wiley-Liss, Inc.)

An orphaned infant ring-tailed lemur (Lemur catta) was attacked persistently by immigrant males and disappeared with severe wounds at Berenty Reserve, Madagascar. Prior to the attacks, two troop members disappeared. On 20 November 1998, the only resident male in Troop C2B disappeared suddenly. After the disappearance, nine males from three neighboring troops approached, but only six males continued to shadow the troop. Of the females, the one lactating female attacked the males the most frequently. On 21 January 1999, the lactating female disappeared and her infant was orphaned. Subsequently, five attacks on the infant by immigrant males were observed for five consecutive days from January 23 to 27. The aggression was persistent and specifically targeted the infant, suggesting that the attacks were purposeful aggression, rather than redirected or accidental aggression. The primary attacker was the most dominant of the immigrant males, and mated with females in the next mating season., (Copyright 2005 Wiley-Liss, Inc.)

Studies on the relationship between female testosterone (T) measures and behavior, particularly in free-ranging primate populations, remain scant. In this study we used fecal steroid analysis to examine the effects of seasonal, reproductive, and social factors on female T in a group of free-ranging hybrid baboons (Papio sp.) in the Awash National Park of Ethiopia. We collected behavioral and hormonal data from 25 adult females across an 11-month period. Solid phase extraction and radioimmunoassay (RIA) techniques were used to quantify T in 776 fecal samples collected weekly from each female. The results indicate that 1) the females had elevated T during pregnancy and during the wet season relative to other periods, 2) female dominance rank was positively related to T measures, and 3) female T and aggression were positively related within subjects but not across subjects. Higher T concentrations during pregnancy are consistent with other published profiles of pregnancy in primates. In combination with data on foraging, wet season increases in T may indicate contest competition for females. The rank-T relationship may be mediated by supplants or aggression. Finally, we discuss the different interpretations of the hormone-behavior relationship based on within- and across-subject analyses.

Patterns of aggressive and affiliative behavior, such as counter aggression and reconciliation, are said to covary in the genus Macaca; this is referred to as the systematic variation hypothesis. These behavior patterns constitute a species dominance style. Van Schaik's [1989] socioecological model explains dominance style in macaques in terms of within- and between-group contest competition. Dominance style is also said to correlate with phylogeny in macaques. The present study was undertaken to examine phylogenetic and socioecological explanations of dominance style, as well as the systematic variation hypothesis. We collected data on counter aggression and reconciliation from a habituated group of Assamese macaques (Macaca assamensis) at the Tukeswari Temple in Assam, India. The proportion of agonistic episodes that involved counter aggression was relatively low. Counter aggression, however, occurred more often among males than among females, and it was most common when females initiated aggression against males. The conciliatory tendency for this group of Assamese macaques was 11.2%. The frequency of reconciliation was low for fights among males and for fights among females, but reconciliation was particularly rare for opposite-sexed opponents. Female social relationships were consistent with the systematic variation hypothesis, and suggest a despotic dominance style. A despotic dominance style in Assamese macaques weakens the correlation between dominance style and phylogeny in macaques, but it is not inconsistent with the socioecological model. Male-female relationships were not well explained by the despotic-egalitarian framework, and males may well have more tolerant social relationships than do females. Sex differences need to be considered when categorizing species according to dominance style., (Copyright 2002 Wiley-Liss, Inc.)

Dominance relationships of female sooty mangabeys have thus far been studied exclusively in captive groups. In captivity, adult females form a stable linear hierarchy as would be expected in species exhibiting strong contest competition. However, the same individuals do not exhibit other aspects of behavior that would be expected where contest competition occurs. For example, they show no kin-based alliances leading to hierarchies in which the members of each matriline occupy adjacent ranks. The goal of this study was to provide the first data on dominance relationships of sooty mangabey females in their natural environment in the Taï National Park, Ivory Coast. In our study group, adult females formed a linear dominance hierarchy. Aggression over food increased in food patches, as would be expected for species that experience contest competition. Moreover, females formed highly differentiated social relationships, showing particular affinities with females of adjacent rank., (Copyright 2002 Wiley-Liss, Inc.)

Female dominance or female feeding priority seem to be characteristic for many lemur species, but are rare traits in other primates and mammals in general. The nocturnal lemur species, however, are underrepresented in the quantitative studies on social dominance. The aim of this study is to investigate the pattern of intersexual dominance relationships in the gray mouse lemur (Microcebus murinus), a species that is generally thought to possess a number of ancestral lemur traits. The context, distribution, and outcome of intersexual conflicts are analyzed in four captive groups of gray mouse lemurs. Intersexual conflicts occurred in the study groups in different behavioral contexts and were mostly spatial interactions (chasing/fleeing, approach/avoidance). The majority of conflicts were decided, and were in all but one case won by females. This is the first evidence suggesting unconditional female dominance in a cheirogaleid primate. The existence of female dominance in most families of the Lemuriformes suggests it is an ancient trait that evolved in their common ancestor., (Copyright 2001 Wiley-Liss, Inc.)

In contrast to the usual pattern of higher male aggression, girls have been shown to exceed boys on frequency measures of indirect aggression. Women also tend to view aggression in terms of an expressive social representation whereby it is seen to result from loss of self-control, in contrast to men who tend to describe it as an instrumental act aimed at exerting control over others. Sixteen items measuring different forms of aggressive behaviour were given to 105 undergraduates together with Expagg, a psychometric measure of social representation of aggression. Factor analysis of the aggression items revealed three scales: direct (verbal and physical), indirect instrumental and indirect expressive aggression. The only aggression scale showing a significant sex difference was indirect expressive aggression on which women scored higher than men. There was also a significant sex difference on Expagg with women showing a more expressive representation of aggression. However the point biserial correlation between sex and indirect expressive aggression was not diminished when expressive representation of aggression was partialled out. It is argued that indirect expressive aggression (involving bitching and avoiding) fails to show a relationship with social representation because it lacks the formal requirements of intentional harm and consequently is not an act of 'aggression'.

We have previously studied the relationship between social subordinance (by approach-avoidance criteria) and physiology among male olive baboons (Papio anubis) living freely in a national park in Africa. In stable hierarchies, subordinate individuals have elevated basal glucocorticoid concentrations and a blunted glucocorticoid response to stress, as well as a prompt suppression of testosterone concentrations during stress. These facets have been interpreted as reflecting the chronic stress of social subordinance. In the present report, we find these endocrine features do not mark all subordinate individuals. Instead, endocrine profiles differed among subordinate males as a function of particular stylistic traits of social behavior. A subset of subordinate males was identified who had significantly high rates of consortships, a behavior usually shown only by high-ranking males. Such behavior predicted the beginning transition to dominance, as these males were significantly more likely than other subordinates to have moved to the dominant half of the hierarchy over the subsequent 3 years. In keeping with this theme of emerging from subordinance, these individuals had also significantly larger glucocorticoid stress-responses, another feature typical of dominant males. However, these subordinate males also had significantly elevated basal glucocorticoid concentrations; it is suggested that this reflects the stressfulness of their overt and precocious strategy of reproductive competition. In support of this, subordinate males with high rates of covert "stolen copulations" did not show elevated basal glucocorticoid concentrations. A second subset of subordinate males were the most likely to initiate fights are to displace aggression onto a third party after losing a fight. these males had significantly or near-significantly elevated testosterone concentrations, compared to the remaining subordinate cohort. Moreover, these males had significantly lower basal glucocorticoid concentrations; this echoes an extensive literature showing that the availability of a displacement behavior (whether aggressive or otherwise) after a stressor decreases glucocorticoid secretion. In support of this interpretation suggesting that it was the initiation of these aggressive acts which attenuated glucocorticoid secretion, there was no association between glucocorticoid concentrations and participation (independent of initiation) in aggressive interactions. Thus, these findings suggest that variables other than rank alone may be associated with distinctive endocrine profiles, and that even in the face of a social stressor (such as subordinance), particular behavioral styles may attenuate the endocrine indices of stress.

The purpose of this study was to develop an animal model for behavioral features of type II, early-onset alcohol abuse. To perform this research, cerebrospinal fluid (CSF) monoamine metabolite concentrations and home-cage social behaviors of 29 rhesus macaque subjects were examined in a 4-year longitudinal study. Half of the monkeys were reared for their first 6 months with their mothers, and the other half were reared without adults, instead with access only to monkeys of similar age. When the subjects were 6 months old, and again when they were 50 months old, they underwent a series of four, 4-day social separations. We obtained cisternal CSF before and during the first and last separation of each series to quantify 5-hydroxyindoleacetic acid (5-HIAA), 3-methoxy-4-hydroxyphenylgycol (MHPG), and homovanillic acid concentrations. After the 6-month separations, subjects were placed into social groups, and social dominance rankings were assessed. Before and after the 50-month separations, social dominance rankings were evaluated again, and home-cage aggression and social behavior data were collected. Over the 3 1/2 years between CSF samplings, records were maintained of subjects' removal from their social groups for excessive aggression or treatment for wounding. Our results showed that among infants, reduced CSF 5-HIAA was correlated with low social dominance. As young adults, subjects from both rearing groups with low CSF 5-HIAA and MHPG concentrations exhibited reduced rates of social interaction and low social dominance rankings. In addition, peer-reared subjects with low CSF 5-HIAA concentrations exhibited inept social behaviors, and were frequently removed from their social groups for excessive aggression and deviant social behaviors. From these results, we conclude that the peer-rearing paradigm aggravates the untoward social consequences associated with low CSF 5-HIAA concentrations over and beyond reducing CSF 5-HIAA concentrations, suggesting that early experiences may contribute to CNS serotonin changes that increase the disposition to type II-related behaviors.

An ingrained technique in primatological analysis is to rank individual animals in a hierarchical system that is usually but not always based on the outcome of agonist encounters. An explication of group structure and function is then sought by correlating these rankings with aspects of behavior. When the behavior of the adult males in a free-ranging troop of olive baboons is examined, ranking is found to be inadequate to represent the behavioral variability existing between individuals. The relationships maintained by these animals is analyzed, emphasizing amounts of time devoted to specific activities, and it is recommended that affiliative rather than agonistic behavior be stressed in future studies.

Social hierarchies are often found in group‐living animals and can be formed through pairwise aggressive interactions. The dominance rank can influence reproductive success (RS) with a skew towards high‐ranking individuals.Using game theory, we investigate how the opportunity for differently ranked individuals to achieve RS influences the costs of hierarchy formation and the strength of winner and loser effects.In our model, individuals adjust their aggressive and submissive behaviour towards others through reinforcement learning. The learning is based on rewards and penalties, which depend on relative fighting ability. From individual‐based simulations, we determine evolutionary equilibria of traits such as learning rates. We examine situations that differ in the extent of monopolisation of contested RS by dominants and in the proportion of total RS that is contested.The model implements two kinds of fighting costs: a decrease in effective fighting ability from damage (loss of condition) and a risk of mortality that increases with the total accumulated damage. Either of these costs can limit the amount of fighting.We find that individuals form stable dominance hierarchies, with a positive correlation between dominance position and fighting ability. The accumulated costs differ between dominance positions, with the highest costs paid by low or intermediately ranked individuals. Costs tend to be higher in high‐skew situations.We identify a 'stay‐in, opt‐out' syndrome, comprising a range from weaker (stay‐in) to stronger (opt‐out) winner–loser effects. We interpret the opt‐out phenotype to be favoured by selection on lower ranked individuals to opt out of contests over social dominance, because it is more pronounced when more of the total RS is uncontested.We discuss our results in relation to field and experimental observations and argue that there is a need for empirical investigation of the behaviour and reproductive success of lower ranked individuals. [ABSTRACT FROM AUTHOR]

Strong, stable social bonds in primates are characterized by high levels of social affiliation, low levels of aggression, minimal stress, and affiliative reciprocity within the dyad. In relatively well‐studied catarrhine monkeys, these bonds tend to form most frequently between kin, animals close in age, and animals close in rank. This results in patterns of affiliation in which kin, similarly aged animals, and like‐ranked animals tend to affiliate and patterns of aggression and submission where animals tend to aggress more toward nonkin and closely ranked animals, and submit more toward distantly ranked animals. However, literature on how affiliative and agonistic relationships are organized in platyrrhine primate species like brown capuchin monkeys is limited and conflicting. In this study, we used social network analyses to characterize how age, sex, maternal kinship, and dominance rank relate to the patterns of submissive, aggressive, contact, and grooming interactions in a group of captive brown capuchin monkeys. Like catarrhine monkeys, brown capuchin monkeys showed a steep linear dominance hierarchy, tended to affiliate with kin, similarly aged animals, and like‐ranked animals, and tended to aggress more toward nonkin. However, our monkeys showed a pattern of affiliation and grooming down the hierarchy that is inconsistent with grooming up the hierarchy patterns often seen in catarrhine monkey groups, suggesting that brown capuchins do not compete for access to higher ranking social partners. Higher ranking monkeys were most central to the aggression network, and lower ranking monkeys were most central to the submission network. Mid‐ranking monkeys were the most central to the contact network, suggesting that they may play an important role in the affiliative cohesion of the group. These results inform our understanding of brown capuchin social behavior specifically, and of how demographic factors relate to social organization in platyrrhine primates generally. Highlights: Captive brown capuchins show a steep linear dominance hierarchy.Rank differentially predicts who is the most central across networks: High‐rankers for aggression, low‐rankers for submission, & mid‐rankers for contact.They affiliate with kin, similarly aged and like‐ranked animals, & aggress to nonkin. [ABSTRACT FROM AUTHOR]

A major challenge in the study of animal communication is distinguishing whether signals convey honest or dishonest information. Biologists infer the honesty of a signal from its correlation with the information being signalled (e.g. fecundity or fighting ability)—the better the correlation, the more honest the signal.However, this view of signalling potentially conflates unreliable indicators with dishonest signals. Just because a trait conveys unreliable information does not mean that the structure serves as a dishonest signal; developmental noise, genetic drift and environmental constraints can reduce the covariation between a putative signal and an organism's quality. Moreover, a trait must influence the behaviour of other organisms to qualify as a signal.We studied how a putative signal, claw size, affects physical performance and social dominance in three species of stream‐dwelling crayfish, which fight routinely over resources. For comparison, we measured the relationship between claw size and claw strength in three species of burrowing crayfish, which do not fight.In all species, crayfish with larger claws were not necessarily stronger, indicating that claw size poorly indicates claw strength. However, claw size is unlikely to function as a dishonest signal of fighting ability in these species for two reasons. First, claw size unreliably indicates claw strength in both the stream‐dwelling species and the burrowing species. Second, relative claw size poorly predicted whether stream‐dwelling crayfish would escalate aggression, questioning whether claw size serves as a signal. Instead, stream‐dwelling crayfish escalated aggression based on their relative body size.Our results highlight the importance of observing behaviour when determining the honesty of a signal. As such, future studies must distinguish between phenotypes that are unreliable indicators (or reliable indicators) from phenotypes that have been selected for dishonest (or honest) signalling. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Research has consistently demonstrated that faces manipulated to appear more masculine are perceived as more dominant. These studies, however, have used forced‐choice paradigms, in which a pair of masculinized and feminized faces was presented side by side. These studies are susceptible to demand characteristics, because participants may be able to draw the conclusion that faces which appear more masculine should be rated as more dominant. To prevent this, we tested if dominance could be perceived when masculinized or feminized faces were presented individually for only 100 ms. We predicted higher dominance ratings to masculinized faces and better memory of them in a surprise recognition memory test. In the experiment, 96 men rated the physical dominance of 40 facial photographs (masculinized = 20, feminized = 20), which were randomly drawn from a larger set of faces. This was followed by a surprise recognition memory test. Half of the participants were assigned to a condition in which the contours of the facial photographs were set to an oval to control for sexual dimorphism in face shape. Overall, men assigned higher dominance ratings to masculinized faces, suggesting that they can appraise differences in facial sexual dimorphism following very brief exposure. This effect occurred regardless of whether the outline of the face was set to an oval, suggesting that masculinized internal facial features were sufficient to affect dominance ratings. However, participants' recognition memory did not differ for masculinized and feminized faces, which could be due to a floor effect. [ABSTRACT FROM AUTHOR]

Research from a variety of disciplines suggests a positive relationship between Western cultural sexualization and women's likelihood of suffering harm. In the current experiment, 157 young men were romantically rejected by a sexualized or non-sexualized woman then given the opportunity to blast the woman with loud bursts of white noise. We tested whether the activation of sexual goals in men would mediate the relationship between sexualization and aggressive behavior after romantic rejection. We also tested whether behaving aggressively toward a woman after romantic rejection would increase men's feelings of sexual dominance. Results showed that interacting with a sexualized woman increased men's sex goals. Heightened sex goal activation, in turn, predicted increased aggression after romantic rejection. This result remained significant despite controlling for the effects of trait aggressiveness and negative affect. The findings suggest that heightened sex goal activation may lead men to perpetrate aggression against sexualized women who reject them. [ABSTRACT FROM AUTHOR]

Based on a social dominance approach, aggression is conceptualized as a strategy used to gain position, power, and influence within the peer network. However, aggression may only be beneficial when targeted against particular peers; both victims' social standing and the number of victims targeted may impact aggressors' social standing. The current study examined associations between aggressors' targeting tendencies (victims' social standing and number of victims) and aggressors' own social standing, both concurrently and over time. Analyses were conducted using three analytic samples of seventh and eighth grade aggressors (Ns ranged from 161 to 383, 49% girls; 50% Latina/o). Participants nominated their friends; nominations were used to calculate social network prestige. Peer nominations were used to identify aggressors and their victim(s). For each aggressor, number of victims and victims' social network prestige were assessed. Aggressors with more victims and with highly prestigious victims had higher social network prestige themselves, and they increased more in prestige over time than aggressors with fewer victims and less prestigious victims (though there were some differences across analytic samples). Findings have implications for the need to extend the social dominance approach to better address the links between aggressors and victims. Aggr. Behav. 43:364-374, 2017. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The relevance of interpersonal hostile-dominance (HD) to post-discharge aggression in mental health patients is unclear. This study assessed whether (1) HD is stable over time; (2) the relationship between HD and positive, negative, disorganized, and excited symptoms is consistent over time; and (3) HD is related to aggression post-discharge. Two hundred psychiatric inpatients were recruited on admission to hospital; 41 were available for follow-up at 6 months post-discharge, including 29 men and 12 women, with an age range of 19-63 (M = 39.63 years, SD = 12.69 years). Psychiatric symptomatology and interpersonal style were assessed at recruitment and follow-up; aggression in the community post-discharge was measured at follow-up. Results showed that (1) HD was stable over time despite an overall reduction in psychiatric symptoms, (2) HD was positively correlated with symptom severity at both time points, and (3) higher HD, excited symptoms, and positive symptoms measured in the community, and more severe positive symptoms measured in hospital, were associated with aggressive behavior post-discharge. These results suggest that HD is a risk factor for more severe psychopathology. Furthermore, HD, positive symptoms, and excited symptoms measured in the community act as risk factors for aggressive behavior post-discharge. As such, treatment planning and risk assessment should consider HD. Aggr. Behav. 42:324-332, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

This longitudinal, naturalistic study addressed behavioral and social cognitive processes implicated in preschool children's social dominance. In the first objective, we examined the degree to which peer aggression, affiliation, and postaggression reconciliation predicted social dominance across a school year. Consistent with predictions, all three predicted dominance early in the year while only affiliation predicted dominance later in the year, suggesting that aggression, affiliation, and reconciliation were used to establish social dominance where affiliation was used to maintain it. In the second, exploratory, objective we tested the relative importance of social dominance and reconciliation (the Machiavellian and Vygotskian intelligence hypotheses, respectively) in predicting theory of mind/false belief. Results indicated that social dominance accounted for significant variance, beyond that related to reconciliation and affiliation, in predicting theory of mind/false belief status. Results are discussed in terms of specific behavioral and social cognitive processes employed in establishing and maintaining social dominance. Aggr. Behav. Aggr. Behav. 37:248-257, 2011. © 2011 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Hormones seem to play important roles in the regulation of human aggression. Multiple studies have confirmed that testosterone (T) levels exhibit complex relationships with aggression, dominance, and/or risk-taking behavior. Some evidence suggests that cortisol (CORT) interacts with T and may also be associated with aspects of mood and aggression. However, almost no research to date has investigated the possibility that these neuroendocrine factors are associated with variations in political attitudes or with political aggression. During the second intifada, we tested the hypothesis that morning salivary T and/or salivary CORT levels might be associated with self-rated aggression or with support for religio-political aggression (RPA) among 14-year-old Palestinian boys living in Gaza. We obtained and averaged weekly 09:00 hr salivary measures of T and CORT for more than 1 month. Averaged morning T levels did not correlate with self-rated aggression, but were positively associated with agreement with the statement 'religious ends justify any means,' ( r = .355, P = .014) and marginally associated with a composite measure of support for RPA ( r = .247, P = .094). Average CORT levels were inversely correlated with self-rated aggression ( r = −.328, P = .037) and with anger ( r = −.373, P = .016), but CORT levels were not associated with support for RPA or with the statement 'religious ends justify any means.' Acknowledging that a modest sample size and methodological issues necessarily limit confidence in our conclusions, these results may represent the first findings regarding neurobiological correlates of support for political aggression. Aggr. Behav. 37:121-132, 2011. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

1. Static animal colour patches may function among competitors to minimize conflict escalation over resources, by serving as a signal of resource holding potential or aggressiveness. Empirical evidence for the use of colour patches in conflict resolution is largely restricted to pigment-based colours (melanins and carotenoids) and rarely defines the context in which the signals are used. 2. Here we test whether structural-based ultraviolet (UV) crown colouration functions in conflict resolution among dyads of first-year male blue tits Cyanistes caeruleus in captivity, in a context that is known to favour aggressive individuals. 3. We found that on first encounter in a pairwise context, experimentally UV-reduced males were significantly more likely to lose to control-treated opponents than expected by chance. However, this disparity was less pronounced when conflicts were settled with physical fighting or when the opponent was considerably smaller in size. 4. When the same dyads were tested again several weeks later, but with the UV treatment reversed among opponents, none of the effects remained significant, but instead the winner was most likely to be the individual that won at their first encounter. 5. Our results suggest that structural-based UV colouration can affect the outcome of an interaction, but that size differences and the outcome of initial interactions between opponents can override the influence of this signal in conflict resolution. Whether there is a functional basis to maintain a link between aggressiveness and colouration may thus be highly dependent on the general context under which individuals compete in the wild. [ABSTRACT FROM AUTHOR]

The literature suggests that status goals are one of the driving motivations behind bullying behavior, yet this conjecture has rarely if ever been examined empirically. This study assessed status goals in three ways, using dyadic network analysis to analyze the relations and goals among 10–11 and 14–15 year olds in 22 school classes (N boys=225; N girls=277). As a validation bullies were contrasted with victims. Bullies had direct status goals (measured with the Interpersonal Goal Inventory for Children) and showed dominance as measured with proactive aggression. Moreover, as predicted from a goal perspective, bullying behavior was related to prestige in terms of perceived popularity. In contrast, victims lacked status goals, were only reactively aggressive, and low on prestige. That being popular is not the same as being liked could be shown by the fact that bullies were just as rejected as victims by their classmates. Eighth-grade bullies had more direct status goals than fourth-grade bullies, possibly indicating that striving for the popularity component of status increases in early adolescence. Aggr. Behav. 35:57–67, 2009. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Social dominance theory has generally posited that terror and intergroup violence can be explained in terms of social dominance struggles. Social dominance theorists have described terror mostly as a tool for maintaining intergroup hierarchies in society (Sidanius & Pratto, 1999). Although implications of the theory suggest that terror may also be used by lower status groups as a tool for the resistance of domination by higher status groups, this prediction heretofore has not been empirically demonstrated. Data from two samples, one in the United States and one in Lebanon, were collected regarding attitudes toward terrorism and intergroup violence. The results show that the American sample demonstrates the typical patterns of social dominance such that those who are higher in social dominance orientation tend to support greater violence toward the Middle East. However, the Lebanese sample shows the opposite pattern, such that those who are lower in social dominance orientation tend to support violence toward the West. These results suggest that (1) support for terrorism among Middle East citizens is a project of counterdominance, and, more broadly, that (2) the relationship between social dominance orientation and support for violence depends on the dynamics of the conflict and the status of the perpetrators. [ABSTRACT FROM AUTHOR]

Principles of conspecific defense have been analyzed for rodents, in which specific target sites for biting by attackers on defenders serve as an important determinant of the actions involved in both attacker and defender behavior. In an effort to determine the generality of these principles, attack and defensive behaviors and target sites for biting attack were evaluated in a nonrodent species, the tree shrew (Tupaia belangeri ). Brief daily and repeated conspecific dyadic encounters between adult, socially experienced males (dominants, attackers), and adult, socially naive males (subordinates, defenders) that had been transferred into the territory of the dominants, produced a polarization of attack and defense. The dominant males showed chase, chase attack, jump attack, and biting behaviors, while the subordinates displayed flight and freezing. The vast majority of bites, as well as wounds and bruises, were on the subordinates’ backs. These patterns are very similar to those previously found in rats and mice and suggest that the organization of fighting, with targets of biting (or other painful) attack serving as an important determinant of both attacker (dominant) and defender (subordinate) behavior, may show considerable generality across nonrodent as well as rodent species. Although relatively few wounds were found after 28 days of repeated and daily encounters, the subordinate tree shrews show a variety of behavioral, neuroendocrine, and central nervous changes, indicating that they are stressed by these encounters per se. Aggr. Behav. 27:139–148, 2001. © 2001 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Previous evidence indicates that the correlates of dominance vary over studies. We hypothesized that one source of this variability is that dominance shifts with age from being associated with aggression to being more associated with prosocial behavior and sociometric status. To test this, we examined 10 vs. 13 year-old boys' perceptions of dominance, using a measure that assessed the perceived outcomes of dyadic agonism. In a sample consisting predominantly of lower- and middle-SES boys from public schools attending a racially integrated summer program for youths with behavior problems, we examined the relation between perceived dominance, sociometric status, and measures of social behavior, including physical and verbal aggression. Perceived dominance was associated with hitting and bullying among 10 year-olds, whereas among 13 year-olds it was more closely associated with sociometric status. The measure of perceived dominance we present produced rigidity scores comparable to those found using behavioral measures of dominance. [ABSTRACT FROM AUTHOR]

Factors influencing the tendency to be aggressive were investigated in male house mice using a series of paired encounters. Body size, body length, body temperature, age, and anogenital distance were measure on all males. Paired encounters were conducted using a standard mouse cage as an arena. Across 64 males involved in 224 encounters, the tendency to be dominant and win encounters was significantly correlated only with anogenital distance (r=0.383). These findings suggest that there are significant behavioral effects that have been elucidated in female house mice and other rodents. [ABSTRACT FROM AUTHOR]

A 3 day long cohabitation in pairs of previously isolated adult male Betta splendens was studied. The first two mornings started with intense fighting, the frequency of which decreased during the day. The bursts of aggression noticed in the mornings were associated with a significant carbohydrate metabolism activation, while daytime activity resulted in a reduction of muscle proteins in the evenings. These changes were more pronounced in submissives than in dominants. The third day marked a shift in the behavior of the pairs: burst of attack activity were not noticed, while the threatening display frequency increased. During this day a similar reduction in lipids was observed in dominants and submissives. While during the first 2 days the dominant position offered some metabolic advantage, this advantage disappeared during the third day when both members of the dyad seemed to do equally less well than their isolated counterparts. Combined with previous findings obtained in this series of experiments, the present results support the assumption that in this species the presence of one opponent is less well tolerated than the presence of four conspecifics. [ABSTRACT FROM AUTHOR]

The resident-intruder paradigm was used to examine the effects of social dominance and individual recognition on odor preferences and urine-marking in male rats. Resident males were significantly more aggressive than intruders and spent more time investigating the odors of familiar intruders. Resident males urine-marked most over the odors of females and familiar intruders while intruders marked least over the odor of the familiar resident. Intruders did not avoid investigating nor marking over the odors of familiar resident males or other conspecifics. These results suggest thin Individual odors of male rats may be more salient than a general odor of dominance, and that the dominant males increase their investigation and marking over the odors of familiar sub-ordinates but not unfamiliar subordinates. The importance of olfactory learning during aggressive interactions is discussed. [ABSTRACT FROM AUTHOR]

Captive studies can make a unique contribution to primate socioecology by documenting species-typical social dispositions under controlled conditions. Recent theories seek to connect the dominance relationships, group cohesiveness, and feeding ecology of primates. The present study explores the first to aspects by comparing the social organization of rhesus (Macaca mulatta) and stumptail monkeys (M. arctoides). Data were collected over a period of eight years, with five different methods, on three well-established captive groups in identical environments. The groups were found to share one characteristic: a clear-cut, linear formal dominance hierarchy as expressed in teeth-bearing displays. The two main study groups (one of each species) differed significantly, however, with respect to nine of eleven behavioral measures. In addition to a previously reported higher frequency of reconciliation in the stumptail group, this group showed 1) more frequent but less severe aggressive behavior, 2) greater symmetry of contests, 3) greater social tolerance, 4) more nonagonistic approaches, and 5) more allogrooming. The differences can be summarized as a contrast in dominance "style," with the stumptails having a more relaxed style and placing greater emphasis on social cohesion than the rhesus monkeys. An egalitarian attitude was also reflected in approach behavior: contacts in the rhesus group were initiated dominants, whereas contacts in the stumptail group were initiated independent of rank. Comparisons with a second rhesus group, and with published reports, suggest that while some of the observed differences are probably representative of the two species, considerably intraspecific variation does exist, and a more comprehensive program of comparative studies is needed. [ABSTRACT FROM AUTHOR]

Social dominance rank in red grouse has a large inherited component. The relative contributions of mothers and fathers to the dominance ranks of their sons and daughters were studied by breeding a dominant and a subordinate strain and crossing them. Both parents contributed equally to the dominance ranks of both sons and daughters. Cocks from the dominant strain were more aggressive and had bigger combs than cocks from the subordinate strain. Dominant cocks and hens, however, did not weigh more than subordinates. [ABSTRACT FROM AUTHOR]

The diallel cross genetic design was employed to determine the pattern of inheritance of male--male agonistic behavior in laboratory mice. The results indicated strong strain differences in agonistic behaviors and strain ranks that replicated previous findings. The genetic analysis showed the presence of additive and nondirectional dominance effects on the behaviors measured. This pattern has been characterized as indicating the action of stabilizing selection and indicates that the trait has not been under directional selection. [ABSTRACT FROM AUTHOR]

Sibling red grouse resembled each other and their parents in social dominance rank and in an aggressiveness score. This was shown by comparisons of variance within and among clutches, correlations between parents and offspring, and experiments involving selection. Both dominance and aggressiveness scores were inherited. There was weak evidence that a laying hen's nutrition and crowding might also influence the dominance of her offspring. These results indicate mechanisms that may underlie fluctuations in the numbers of wild red grouse. [ABSTRACT FROM AUTHOR]

The social relations of three adult males in a captive chimpanzee group were evaluated for 12 months. The observations encompassed a period of transition in the dominance hierarchy providing an opportunity to assess behavioral patterns involved in the initiation of status changes. This study shows that dominance in the chimpanzee is expressed primarily through ritualized and non-contact behavior rather than by overt aggression. In particular, display behavior is important for indicating dominance rank, in communicating aggressive intent, and as a prelude to status struggles. The functional relationships between status, displays and other socio-sexual behavior patterns are presented. [ABSTRACT FROM AUTHOR]

Following an initial intruder aggression test, 10 pairs of adult male rats matched on aggressiveness were formed. The first 20 mm of paired cohabitation were used to determine dominance and subordinance between pair members. Residents judged to be dominant from this observation session gained significantly more weight during cohabitation and exhibited significantly more aggression on the second aggression test than their subordinate counterparts. Significant correlations among various measures of aggression were found, but open field performance did not correlate with the measures of aggression nor did changes in open field scores reflect changes in aggression. [ABSTRACT FROM AUTHOR]