Aggressive behavior in a confined troop of Japanese macaques: Effects of density,season, and gender

A troop of Japanese macaques (Macaca fuscata) confined in a 2-acre outdoor corral increased from 107 to 192 individuals during the 5-year tenure of a project that assessed the effects of density, season, and gender on the expression of adult aggressive behavior. Two statistical subgroups of 16 males and 28 females that were adults at the start of the project and that survived until its completion were studied intensively. There were significant season and sex differences in all groups: males were much more aggressive than females, and males were most aggressive during the fall and and winter mating season; females were most aggressive during the spring and summer birth season. Only the 16 adult males increased their frequency of aggressive behavior as the population density increased. This increase was due to the greater number of potential antagonists available each year.     

The introduction of a group of alien mice (Mus musculus L.) into hierarchically organized groups of five male mice

Groups of 3 male or female Mus musculus were introduced into hierarchically organized colonies of 5 male mice for a period of 8 days. The colonies were of 2 kinds; high-level aggressive (HLA), which had been set up 3 days prior to the introduction of the aliens, and low-level aggressive (LLA), which had been established for 21 days before strangers were introduced. Both males and anestrous females were attacked, but males were attacked 5 times more frequently than females. In HLA colonies most of the attacks on the aliens were by the dominant; in LLA colonies there was no difference in the behavior of dominant and subordinate mice toward strangers. Both aggression toward aliens and intracolony aggression declined over the 8 day experimental period. In HLA colonies the dominant mouse mounted females 5 times more frequently than did either his subordinates or male mice in the LLA colonies. In HLA colonies aliens huddled with subordinates to form a single colony with 1 dominant and 7 subordinates. In LLA colonies alien males remained as a discrete group spatially separated in the cage. Female aliens were incorporated into the main colony. In all cases dominant male mice made more attacks on aliens as compared with familiar mice.     

70-kHz vocalizations by male mice do not inhibit aggression in lactating mice

Two experiments investigated the relationship between adult male 70-kHz vocalizations and aggression by lactating female mice (Mus domesticus). Intact, vocalizing males, surgically devocalized males, and naturally nonvocalizing males were used to assess the effects of high frequency vocalizations on maternal aggression. The emission of high frequency vocalizations promoted aggressive behavior by the females. In both experiments, lactating females attacked the vocalizing males more rapidly and showed a higher incidence of aggressive behaviors toward these males than they did to the nonvocalizing male. We suggest that these vocalizations are only one of many situational cues that the female uses to determine her final behavioral response.     

Rare male aggression directed toward females in a female‐dominated society: Baiting behavior in the spotted hyena

Spotted hyenas (Crocuta crocuta) are gregarious carnivores. The females are socially dominant to males, and adult males rarely direct aggression toward adult females. This study analyzed all cases in which adult immigrant males behaved aggressively toward adult females in a large population of free‐living hyenas in Kenya, observed for 11 years. Our goals were to describe the conditions under which male attacks on females occur, and address possible adaptive functions. Most aggression directed by adult immigrant males against females occurred when coalitions of two or more males attacked a single adult female, who typically responded by defending herself and fighting back. Male aggression against females frequently occurred at sites of ungulate kills, but males never behaved aggressively toward females over food, and all male attacks on females were unprovoked. Although no mounting or other copulatory behaviors ever occurred during or immediately after an attack, the number of male attacks on females peaked around the time of conception. Daily rates at which males attacked females did not vary with female social rank. However, daily attack rates did vary significantly with female reproductive state, and the highest rates of male attack on females were observed during the two stages of the reproductive cycle during which females were most likely to conceive litters. The adaptive significance of male aggression against females in this species remains unknown, but a tight association between male attacks on females and a female's time of conception provides strong evidence of some role for male aggression in hyena sexual behavior. In particular, our data are consistent with hypotheses suggesting that male aggression toward females in this species either serves to inform females about male fitness or represents sexual harassment. Aggr. Behav. 29:457–474, 2003. © 2003 Wiley‐Liss, Inc.     

Aggressive behavior in the free-ranging rhesus monkeys of kathmandu,nepal

We present a composite sample of the aggressive behavior of free-ranging rhesus monkeys (Macaca mulatta), recorded at two temples in Kathmandu, Nepal. We analyze the total number and the rate per monkey of threats, chases, attacks, fights, and aggressive acts directed at other species (principally humans), in order to elucidate social dynamics of the troop as a whole. Our 1,506 hours of observation were divided among the four seasons; between a.m. and p.m.; and among a temple yard, two parklands, and a forested garden. We found seasonal patterns to be the most important correlates of aggressive behavior. Habitat was a modulating influence, and time of day was the least important factor. Rates of aggression were generally higher per male monkey than per female. In terms of total aggression recorded, however, females instigated significantly more than males, both in encounters between monkeys and in aggression against other species. This finding is consistent with the females' greater numbers in the troop and with their lifelong membership in the troop. Analysis of behavior by social groups, rather than by individual rates, points up the iomportance of adult females and their social stability in troop behavior.     

Continuity of aggression from childhood to early adulthood as a predictor of life outcomes: implications for the adolescent‐limited and life‐course‐persistent models

Using data from the Columbia County Longitudinal Study, a 40‐year longitudinal study following an entire county's population of third‐grade students from age 8 to 48, we examine questions about the long‐term consequences of aggressive and antisocial behavior in childhood, adolescence, and young adulthood. We found moderate levels of continuity of aggression from age 8 to 48 both for males and for females. Contrary to what some have proposed, we found that continuity of aggressiveness is owing to not only the high‐aggressive participants staying high but also owing to the low‐aggressive participants staying low. Compared with life‐course‐persistent low aggressives, we found that life‐course‐persistent high aggressives had consistently poorer outcomes across domains of life success, criminal behavior, and psychosocial functioning at age 48 (e.g., arrests, traffic violations, aggression toward spouse and divorces, depression, health, occupational and educational attainment). In contrast, adolescent‐limited and child‐limited aggressives did not differ from life‐course‐persistent low aggressives on the age 48 outcomes. Finally, the outcomes for late‐onset (early adulthood) aggressives were also problematic in some domains though not as problematic as those for life‐course‐persistent aggressives. Aggr. Behav. 35:136–149, 2009. © 2009 Wiley‐Liss, Inc.     

Behaviour of Young Growing Pigs in a Resident‐Intruder Test Designed to Measure Aggressiveness

A total of 125 growing pigs (47 days old) were tested for aggressive responses on two occasions using a resident‐intruder (R‐I) design. Our aims were twofold: (1) to attempt to replicate earlier work on pigs showing that resident aggression is a consistent individual characteristic, unaffected by weight or sex of the resident or intruder and (2) to develop behavioural measures to characterise the wide range of aggressive responses in the test. Resident pigs, housed since birth with littermates, were placed individually in a divided‐off portion of their home pen, and a smaller, unfamiliar intruder (approximately 66% of the resident's weight) was introduced. The test ended 5 min after the first investigation of the intruder by the resident or when one of the pigs began to attack the other (by delivering a sudden, rapid series of bites). On days 1 and 2, 33.6% and 43.2% of tests, respectively, ended in an attack by a resident. Intruder attacks were rare. Pigs were consistent in whether they attacked or not over the two tests, although attack latencies for pigs attacking in both tests were not correlated. Females were more likely to attack and attacked more quickly than males on the first test day but not in the second test or overall. Intruder sex had some effect on the test outcome (males were attacked more rapidly in the second test only). Resident and intruder weight had no effect. Aggressive pigs (meaning pigs that attacked vs. pigs that did not and fast‐attacking pigs vs. slow‐attacking pigs) showed a number of differences in behaviour during the R‐I test: (1) they took longer to make initial contact with the intruder in their first test; (2) they showed a higher frequency of aggressive acts (single head knocks, bites, and shoves); (3) they spent a greater proportion of the test engaging in social contact with the intruder rather than non‐social behaviours; (4) their social behaviour involved more postures directed toward the head as opposed to flank‐ or rear‐directed postures or re‐establishing social contact; and (5) they showed closer physical contact with intruders during social encounters, as characterised by their lower head positions. Some of these behavioural measures could be used to improve the measuring power of the test in the future. Improved behavioural measures would enable aggressiveness scoring among pigs that did not attack instead of classifying them all together as “non‐attacking.” Aggr. Behav. 28:401–415, 2002. © 2002 Wiley‐Liss, Inc.     

Avoidance of relatively aggressive male Japanese Quail (Coturnix japonica) by sexually experienced conspecific females

Sexually experienced female Japanese quail (Coturnix japonica) that are offered a choice between 2 conspecific males previously observed engaging in an aggressive encounter prefer to affiliate with the less aggressive male. The authors determined whether this apparent preference for less aggressive males results from females approaching less aggressive individuals or avoiding more aggressive individuals. The authors found that females that had seen 2 males fight before choosing, in counterbalanced order, between each of them and a neutral stimulus were indifferent to less aggressive males but avoided more aggressive males. The results are consistent with the view that in species in which male courtship and mating are potentially harmful to females, females keep away from relatively aggressive males in order to avoid the physical punishment that can result from contact with them.     

Why are there sex differences in risky driving? the relationship between sex and gender‐role on aggressive driving,traffic offences,and accident involvement among young turkish drivers

The aim of this study was to investigate how sex (male and female) and gender‐role (masculinity and femininity) and their interaction were associated with risky driving behaviors, traffic offences, and accident involvement among young Turkish drivers. Three‐hundred and fifty‐four young drivers (221 males and 133 females) filled in a form including the short form of Bem Sex‐Role Inventory (BSRI), the Driver Behaviour Questionnaire (DBQ), questions about a driver's accident history, and background information. The effects were tested on outcome variables by using hierarchical regression analysis. It was found that sex (being male) predicted only the ordinary violations. While masculinity score predicted positively the number of offences, and aggressive and ordinary (highway code) violations, femininity score predicted negatively the number of accidents and offences, aggressive and ordinary violations, and errors. The effect of interaction between masculinity and femininity was only found on the number of accidents and aggressive violations among young drivers. There was no significant interaction effect between sex and gender roles on criterion variables. Aggr. Behav. 00:1–12, 2005. © 2005 Wiley‐Liss, Inc.     

Interfemale aggression in adult bank voles (Clethrionomys glareolus)

Agonistic interaction may play a large role in shaping the social structure and spatial distribution of rodents such as Clethrionomys glareolus. Aggressive and non-aggressive behaviors of adult bank vole females were investigated with a home cage test during 10 min sessions. The number of attacks was significantly higher in virgin females kept with intact adult males than in singly reared females or those exposed to male urine. Bulbectomy of the tested females completely inhibited the male stimulating effect. This indicates that males influence the behavior of females by activating their olfactory systems. Aggressive behavior in pregnant or lactating females, which is linked to maternal behavior, was also tested. Female bank voles between 11 and 17 days of pregnancy or lactating at 3–4 days or 9–10 days attacked their partners significantly more frequently than virgins did. Females that had direct contact with males, even if they were not fertilized, appeared to be more successful in same-sex competition. Aggr. Behav. 24:53–61, 1998. © 1998 Wiley-Liss, Inc.     

Cross-generational transmission of aggressive parent behavior: a prospective,mediational examination

The intergenerational transmission of aggressive parenting behavior was examined within the context of a prospective longitudinal study of adolescent and young adult adjustment. Thirty-nine young adults (G2; 33 females, 6 males) who had participated in early phases of this study with their parents (G1) continued their involvement with their young children (G3; 17 females, 22 males, mean age = 2.6) several years later. Data included direct observation of parent–adolescent (G1–G2) and parent–child (G2–G3) interactions as well as self-reports. Analyses demonstrated directly observed cross-generational continuity in aggressive parenting from G1 to G2 some 6–7 years later. However, the results also showed that adolescent aggressive behavior served as the mediational link reducing the direct path from G1 to G2 aggressive parenting to nonsignificant levels. The results are consistent with a social interactional model of intergenerational continuity of parenting behavior.     

Stability and predictors of psychopathic traits from mid‐adolescence through early adulthood

High levels of psychopathic traits in youth are associated with multiple negative outcomes including substance misuse, aggressive behavior, and criminality. Evidence regarding stability of psychopathic traits is contradictory. No previous study has examined long‐term stability of psychopathic traits assessed with validated clinical measures. The present study examined the stability of psychopathic traits from mid‐adolescence to early adulthood and explored adolescent factors that predicted psychopathic traits five years later. The sample included 99 women and 81 men who had consulted a clinic for substance misuse in adolescence. At an average age of 16.8 years, the adolescents were assessed using the Psychopathy Checklist: Youth Version (PCL: YV) and five years later using the PCL‐Revised (PCL‐R). Additionally, extensive clinical assessments of the adolescents and their parents were completed in mid‐adolescence. Among both females and males, moderate to high rank‐order stability was observed for total PCL and facet scores. Among both females and males, there was a decrease in the mean total PCL score, interpersonal facet score, affective facet score, and lifestyle facet score. However, the great majority of females and males showed no change in psychopathy scores over the five‐year period as indicated by the Reliable Change Index. Despite the measures of multiple family and individual factors in adolescence, only aggressive behavior and male sex predicted PCL‐R total scores in early adulthood after taking account of PCL:YV scores. Taken together, these results from a sample who engaged in antisocial behavior in adolescence suggest that factors promoting high psychopathy scores act early in life.     

Male–male combats in a polymorphic lizard: residency and size,but not color,affect fighting rules and contest outcome

Theoretical models predict that the outcome of dyadic agonistic encounters between males is influenced by resource‐holding potential, resource value, and intrinsic aggressiveness of contestants. Moreover, in territorial disputes residents enjoy a further obvious competitive advantage from the residency itself, owing to the intimate familiarity with their territory. Costs of physical combats are, however, dramatically high in many instances. Thus, signals reliably reflecting fighting ability of the opponents could easily evolve in order to reduce these costs. For example, variation in color morph in polymorphic species has been associated with dominance in several case studies. In this study, we staged asymmetric resident‐intruder encounters in males of the common wall lizard Podarcis muralis, a species showing three discrete morphs (white, yellow, and red) to investigate the effects of asymmetries in color morph, residency, and size between contestants on the outcome of territorial contests. We collected aggression data by presenting each resident male with three intruders of different color morph, in three consecutive tests conducted in different days, and videotaping their interactions. The results showed that simple rules such as residency and body size differences could determine the outcome of agonistic interactions: residents were more aggressive than intruders, and larger males were competitively superior to smaller males. However, we did not find any effect of color on male aggression or fighting success, suggesting that color polymorphism in this species is not a signal of status or fighting ability in intermale conflicts. Aggr. Behav. 35:274–283, 2009. © 2009 Wiley‐Liss, Inc.     

Toward a refined view of aggressive fantasy as a risk factor for aggression: interaction effects involving cognitive and situational variables

Over three decades of research have established a positive connection between fantasizing about aggression and enacting aggression. Such findings have provided strong evidence against the catharsis view of aggressive fantasy. However, little attention has been paid to the potentially nuanced nature of the link between fantasy aggression and actual aggression. In the present article, we examined the influence of four variables in the aggressive fantasy–aggressive behavior link: gender, exposure to violence, fantasy absorption, and level of fantasy about harm befalling loved ones and the self (dysphoric fantasy). Using data from a diverse, community‐based sample of 7–14‐year olds and their mothers, we replicated the general finding that aggressive fantasy is positively associated with real‐world aggressive behavior. However, we also found that the interaction of aggressive fantasy and exposure to violence related significantly to aggression, as did the relation between aggressive fantasy and dysphoric fantasy. When exposure to violence was low, even high levels of aggressive fantasizing did not predict aggressive behavior, and, when aggressive fantasizing was low, even high levels of exposure to violence did not predict aggressive behavior. Similarly, when dysphoric fantasy was high, the connection between fantasy aggression and real aggression was markedly attenuated. The implications of these findings for intervention efforts and future research are considered. Aggr. Behav. 35:313–323, 2009. © 2009 Wiley‐Liss, Inc.     

Response of male and female Siberian hamsters towards pups

The influence of sex, reproductive maturity, and parental experience on the behavior of Siberian hamsters (Phodopus sungorus sungorus) toward strange pups was examined in this study. Immature, mature, or parentally experienced male and female Siberian hamsters were presented with 3- to 8-day-old pups. We recorded pup carrying during the initial 10 min, nesting with pups after 8 or 14 h, and attacking pups during the test period. Among inexperienced animals, more mature males attacked pups than did immature males or mature females. Parental experience significantly decreased pup attacks by males and increased nesting with pups by both males and females. Repeated testing did not modify the responses to pups. We conclude that in Siberian hamsters both caretaking and aggressive responses to pups may be shown by immature and mature animals of both sexes. Parental experience resulted in increased caretaking by males and females and decreased aggressive responses by males.     

Local erotic songs and chants among rural Nigerian adolescent males

This paper investigates local erotic songs and chants circulating among adolescent males in Nigeria. The purpose is to assess the critical themes which these erotic verses evoke and their potentials in the discursive construction of adolescent sexual identities and definition of the (erotic) spaces and meanings on the basis of which young Nigerian males constitute their sexual conducts. Data indicate high level of awareness and knowledge of local erotic songs and chants among adolescent males. The songs and chants were reportedly used to learn about gender and sex roles, the body, and sexuality, and for recreation. Themes in local boys’ erotic songs and chants are primarily male privileging and penis advantaging, and celebrate male sexual activity, desire, violence, ruthlessness, and risk-taking as well as male control and subordination of women and their body. The songs and chants depict feminity and female sexuality as inferior to masculinity and male sexuality and tend to objectify women’s body as a facility for male sexual pleasure. The paper argues that while erotic verses circulating among adolescent Nigerian males help relieve them of the difficulties caused by the cultural relegation of sex and sexuality to the realm of the unspoken, they contain very disturbing and potentially dangerous images that provide little space for male responsibility and respect for women. Local erotic verses circulating among adolescents present an under-explored resource in sexuality education and a critical entry point for current efforts to understand and help young people extricate themselves from the sea of half-truths, myths, and prejudices about sex and sexuality.     

Maternal aggression toward infanticidal males of different social status in wild house mice (Mus musculus domesticus)

Maternal aggression was examined in wild female mice (Mus musculus domesticus) derived from animals trapped in Alberta, Canada. Lactating females were tested for their behavior toward intruder males during the time of postpartum estrus while housed in a two-cage apparatus containing a defensible nest area. Prior to being used as intruders, sexually naive males were screened for their behavior toward a newborn pup (83% exhibited infanticide). Only infanticidal males were then housed in pairs and allowed to establish a dominance hierarchy. Dominance status was further verified by a urine marking test. The dominant and subordinate infanticidal males were then placed into a lactating female's cage and observed for 1 hr. The test was terminated immediately when a male began to attack the pups. Lactating females attacked the males in both groups, but subordinate males received more intense attacks than dominant males. Dominant males elicited significantly more fear/defense behavior than subordinate intruders. All of the dominant males and only one submissive male attacked the pups. Females were thus successful in blocking infanticide only by infanticidal subordinate males. Since females do not persist in attacking males with high fighting ability, one function of maternal aggression could be to assess the fighting, and resource holding, potential of a future mate. © 1994 Wiley-Liss, Inc.     

Female behavior in populations of mice in the presence and absence of male hierarchy

Female aggression may be the regulator of population size in small mammals. Freely growing populations of house mice showed several differences in aggressive female behavior in the presence and the absence of a male hierarchy. Territoriality in females and not in males appeared to maintain social order and regulate population density. Certain females were seen patrolling and guarding the territory and chasing and fighting with both male and female intruders. These females did not fight amongst themselves, suggesting that they were not fighting for rank (as do the males) but for territory. Although these aggressive females produced young, the pups were neglected, and few were weaned. The non-aggressive females were the successful breeders. Aggression by the females only occurred when there was reproduction and increased densities. Assembled females with no males present never show this aggression. The occurrence of “male-type” behavior became most apparent when the males were removed at peak population densities. The removed males were then castrated and injected with testosterone cyprionate. Doses were increased by population cage, and therefore all males returned to each freely growing population were given the same dose. The males given oil placebo injections showed no return of a male hierarchy and the females showed high levels of aggression toward them. Males injected with testosterone cyprionate showed return of male aggression and fighting and mounting of females. But the new “dominant” females continued their patrols and chased males away from their territories and did not permit these males to mount. Male-male fighting consisted primarily of frontal attacks to the face and roll and tumble fights. Female-male aggression consisted primarily of attacks to the posterior region targeted at the base of the tail and the genitals of the male. The males were rarely seen attacking females and then only during mating. Females only attacked each other in defense of their territories.     

Justification of interpersonal aggression in Japanese,American, and Spanish students

Six hundred and thirty‐two university students of both sexes—242 Japanese (137 males and 105 females), 190 Spanish (71 males and 119 females), and 200 American (100 males and 100 females)—completed a questionnaire that examined their attitudes toward various kinds of aggression directed at other people in different situations that ranged from self‐defense to a method of overcoming communication problems. Factor analysis revealed three factors: physical aggression (killing, torture, and hitting), direct verbal aggression (shouting and rage), and indirect verbal aggression (being ironic and hindering). The basic factor structure of the Japanese, the Spanish, and the USA samples was similar. In all samples, men showed a higher justification of physical aggressive acts in any situation and of indirect verbal aggression in nondefensive circumstances. Cultural differences were found in the degree of justification of the three factors: in all kinds of situations, Japanese students showed a lower justification of indirect verbal aggression but a higher justification of direct verbal aggression than USA and Spain samples. Physical aggression in defensive situations is justified more by Americans than by Japanese and Spanish students. These findings suggest the existence of a common basic moral code about physical aggressive acts, but there seems to be a cultural influence on moral codes concerning verbal aggressive acts. Oriental cultures, with an interdependent construal of self, seem to be more permissive of direct verbal aggression compared with Western cultures, but they have less tolerance for indirect verbal aggression. There were practically no significant differences between American and Spanish scores. Aggr. Behav. 25:185–195, 1999. © 1999 Wiley‐Liss, Inc.