Agonistic versus amicable targets of attack and defense: Consequences for the origin,function, and descriptive classification of play-fighting

Play-fighting appears to involve the behavior patterns of attack and defense otherwise seen in serious fighting. The degree of similarity, however, depends on the body targets attacked and defended during these forms of fighting. For many taxa, including diverse mammalian families and some birds, the same targets are attacked and defended during both play-fighting and serious fighting. However, for several species of muroid rodents, the targets of play-fighting are not the same as those of serious fighting. In these cases, the tactics of attack and defense are also different. It is argued that for these muroid species the playful targets have arisen from amicable behavior (e.g., social investigation, greeting, allogrooming) rather than, as appears to be the case in so many other taxa, from agonistic behavior. These data strongly suggest that “play-fighting” has evolved from different precursors in different taxa and thus has multiple origins. Furthermore, these data have an important bearing on the universal applicability of many of the suggested functions of play-fighting and also on how such behavior is to be described and classified.     

Targets and tactics of agonistic and precopulatory behavior in montane and prairie voles: Their relationship to juvenile play-fighting

Play-fighting by juvenile montane and prairie voles involves attack and defense of the head, neck and shoulders. Since during play animals typically borrow behavior patterns from other functional contexts, two adult behavioral contexts were compared to juvenile play-fighting. These were serious fighting and sexual encounters. During serious fighting in a resident-intruder paradigm, most bites are directed at the rump and lower flanks. During sexual encounters, especially in precopulatory behavior, the head, neck and shoulders are gently contacted. Therefore, play-fighting by juveniles would appear to involve attack and defense of areas of the body contacted in adult precopulatory behavior, not adult fighting. Furthermore, the species-specific differences in juvenile play-fighting were also found to be matched by species-specific differences in precopulatory behavior. In both playful and precopulatory encounters, montane voles contacted the head and used upright defensive behaviors more often than prairie voles. In contrast, prairie voles made mutual contact more often and were more likely to rotate to supine in defense of contact to the nape and head. These findings support our hypothesis that juvenile play-fighting in muroid rodents involves the precocial expression of precopulatory, not agonistic behavior.     

The organization of play fighting in the grasshopper mouse (Onychomys leucogaster): Mixing predatory and sociosexual targets and tactics

The body targets contacted, the type of contact made, and the patterns of defense and counterattack elicited by those attacks are examined in the play fighting of captive male and female pairs of grasshopper mice. The nape was the most frequently contacted body target, irrespective of the type of contact made, be it nosing, allogrooming, biting, or striking with a forepaw. The types of defense varied with both body area contacted and type of attack performed. Based on the topography and pattern of contact, it was concluded that grasshopper mice, as is the case for many other muroid rodents, primarily attack and defend targets otherwise contacted during precopulatory encounters. However, grasshopper mice, which are obligate carnivores, also attack and defend predatory targets, although less frequently than sociosexual targets. Surprisingly, predatory attacks were more likely to be counterattacked with predatory attacks, whereas sociosexual attacks were more likely to be counterattacked with sociosexual attacks. Conspecific aggression involves bites directed at the face, lower flanks, and dorsum. Neither the biting of these areas nor the tactics of attack and defense usually associated with such bites were observed during the juvenile interactions. There were no sex differences in either frequency or patterns of attack and defense in play fighting. The data presented for grasshopper mice shed light on the issue of mixing behavior patterns from multiple functional systems during play. Aggr. Behav. 26:319–334, 2000. © 2000 Wiley‐Liss, Inc.     

Play-fighting differs from serious fighting in both target of attack and tactics of fighting in the laboratory rat Rattus norvegicus

Play-fighting is often difficult to differentiate from inhibited or immature serious fighting because both may utilize many of the same behavior patterns. In the rat the two behaviors involve different targets of attack. During play-fighting, snout or oral contact is directed at the opponent's nape of the neck, whereas during serious fighting, male residents mostly direct their bites at the intruder's rump. Although similar to those used in serious fighting, the behavior patterns used during play-fighting are modified to achieve the different targets of attack. Even though the tactics of attack and defense appear more adult-like with increasing age, the playful targets persist well into adulthood.     

Identification of the possible origin of the body target that differentiates play fighting from serious fighting in syrian golden hamsters (Mesocricetus auratus)

Play fighting in the Syrian Golden hamster Mesocricetus auratus can be distinguished from serious fighting by the targets attacked in each case. In play fighting, the animals attack and defend the cheeks and cheek pouches, whereas in serious fighting they attack and defend the rump and lower flanks. Since play typically involves the use of behaviors borrowed from other functional contexts, this paper investigates the origin of the cheek target during play fighting. Comparison of resident-intruder serious fighting with awake and anesthetized intruders does not reveal the cheek to be an inhibited target for serious attack. Similarly, analysis of social investigation and allog-rooming, while revealing the ears to be important targets, do not show the cheeks to be targets in these behaviors. Sniffing, licking, and nibbling of the cheek area appear to occur mainly during sexual encounters by males. This area, seemingly a sexual target, may be the one utilized during play fighting.     

Analysis of the targets and tactics of conspecific attack and predatory attack in northern grasshopper mice onychomys leucogaster

Comparisons of tactics of fighting between species are often difficult to make since the body targets attacked may differ. Thus it becomes difficult to assess whether differences in fighting tactics are due to species-specific differences in the tactics themselves or due to the different targets attacked. A solution to this problem is to analyse the tactics of a species that attacks different targets under different circumstances. In this way, differences in tactics can be more readily attributed to differences in targets. In this study, resident male northern grasshopper mice (Onychomys leucogaster) were tested against intruding male conspecifics and against laboratory mice (Mus musculus domesticus). Conspecifics were mainly bitten on the lower dorsum, whereas prey were bitten and killed by bites to the nape of the neck. Therefore, it was possible to analyze the tactics of attack by grasshopper mice when attacking different body targets. For example, in order to defend the lower dorsum and the nape, both intruding conspecifics and prey adopted an upright defensive posture. Resident grasshopper mice used the lateral attack tactic to gain access to the lower flanks but not the nape. This illustrates that the lateral attack tactic is not merely a tactic suitable for overcoming the upright defense tactic, but is used in this context only when the target attacked is on the opponent's posterior dorsum. Such withinpecies comparison enables the identification of the contextual rules which govern the use of fighting tactics. © 1992 Wiley-Liss, Inc.     

The use of muroid rodents in the psychology laboratory

The rodent superfamily Muroidea represents a group of animals with much potential for comparative behavioral study as they are readily acquired, easy to maintain, and exist with sufficient ecological and behavioral diversity to enhance the likelihood of significant results. The superfamily includes Old World rodents, gerbils, hamsters, and a considerable variety of New World rats, mice, and voles which inhabit all 48 adjacent United States. Potential uses of muroid rodents, their taxonomy, and their husbandry are described with particular reference to the 28 species that have been maintained in the author’s laboratory. Although research on muroid behavior is just beginning, available data already support the proposed utility of these animals in behavioral research.     

Ultrasounds produced by rats accompany decreases in intraspecific fighting

Male intruder rats were placed individually into the cage of an established resident on 2 occasions separated by a 7–8 day interval. Residents readily attacked intruders and both animals lost weight during the first encounter. In contrast, no serious fighting occurred on the second encounter, and both intruders and residents maintained their body weight during the 24-hr test. Observation of the intruder's behavior during the first 30 min of each encounter indicated that defensive-submissive postures represent a response to an attack that only temporarily inhibits aggression whereas the emission of 22 kHz calls by the intruder is associated with a relatively permanent decrease in the resident animal's aggressive response.     

Attack and defense in conspecific fighting in tree shrews (Tupaia belangeri)

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.     

Motivational systems of agonistic behavior in muroid rodents: A comparative review and neural model

The data on agonistic behavior of muroid rodents that have been obtained from field observations and laboratory experiments are reviewed and compared in terms of a hypothetical model of the neural organization of these behaviors. The neural model has been presented elsewhere and is used here only as a way to organize the data. The data are organized in terms of four hypothetical motivational systems: Offense, defense, submission, and patrol/marking. The various behaviors are considered as motor patterns and are compared and analyzed in terms of the proposed motivating, releasing, and directing stimuli of the motivational systems. Interactions and overlaps between the motivational systems are also considered. It is concluded that the organization of agonistic behavior may be similar across all species of muroid rodents. Generalizations are complicated by the profound effects of ontogenetic factors. Four categories of behaviors differ from species to species: Scent-marking, submissive behaviors, threat behaviors, and alarm signals. The possible phylogenetic and ontogenetic factors in these differences are considered.     

Predictors of dominance in male Betta splendens

The formation of dominance/subordinancy relations in pairs of male Siamese fighting fish was examined in six experiments. Dominant animals typically were those fish that built the largest nests and that attacked an image of a live, displaying male most intensely prior to combat. However, pretest performance on an operant task and reaction to an animal's own mirror image were not useful predictors of subsequent dominance. These findings are consistent with the suggestion that domesticated Bettas have a territorial social strategy that includes both nest-building and fighting behaviors.     

Attack and defensive behaviors in the albino mouse

Attack by dominant male colony mice on intruders included chasing and lateral attack behaviors, while the corresponding intruder behaviors were flight, boxing, and checking. Both of these are similar to the attack and defensive behaviors of colony rats and intruders. However, mice did not show a significant constraint on bites to ventral areas, and the rat defensive behavior of lying on the back, which is effective because of this constraint, was rare; the corresponding “on-top” behavior of attackers was almost absent in mice. These findings strongly support the view that intraspecific attack and defensive behaviors, and target sites for bites, are interrelated factors facilitating effective but nonlethal agonistic interactions in muroid rodents.     

Playful defensive responses in adult male rats depend on the status of the unfamiliar opponent

Adult male rats reared as pairmates from weaning were tested in a neutral arena with both members of another pair (one at a time). The unfamiliar pairs were found to engage in play fighting, although they were more likely to escalate the encounter into serious fighting than were pairs of familiar rats. Based on their within‐home pair behavior, each pairmate was designated as a dominant or a subordinate. When the test encounters between unfamiliar males were analyzed with regard to whether the pairings consisted of two dominants, two subordinates, or a mixed pair, the pattern of play fighting was found to be attenuated. Both dominants and subordinates were more likely to initiate playful encounters, to respond defensively during these encounters, and to do so using adult‐typical tactics of defense when paired with an unfamiliar rat that was dominant in its home cage. The mechanisms by which the home status of unfamiliar male rats can be identified by another male are discussed, particularly with regard to the role that play fighting may serve for this function. It is concluded that the data support the hypothesis that play fighting can be used by adult rats for social testing, which in this case seems to involve ascertaining the opponent's fighting capability. Aggr. Behav. 25:141–152, 1999. © 1999 Wiley‐Liss, Inc.     

Interplay of Biomechanical Constraints and Kinematic Strategies in Selecting Arm Postures

In this study, the authors examined the interplay between biomechanics and control strategies in the resolution of excess degrees of freedom at the joint level. Seven participants made aimed arm movements from 30 starting points and several starting postures to targets. Final arm postures for movements to a target exhibited substantial joint angle variation. Through regression modeling and by comparing observed final arm postures with biomechanically plausible postures, the authors identified 3 kinematic strategies: (a) Maintain deviations from the average angle at the starting point to the joint's final posture; (b) make torso rotations that are a fixed proportion of shoulder rotations; and (c) adopt a characteristic combination of 4 wrist-positioning approaches. The results demonstrated that kinematic strategies can account for substantial variance in final arm postures, if one takes into account 2 types of individual differences—those that arise inevitably from biomechanical constraints and those that reflect choices in movement strategy.     

Dominance and age-related changes in the play fighting of intact and post-weaning castrated male rats (Rattus norvegicus)

The play fighting behaviour of male rats (Rattus norvegicus) castrated at weaning was compared to that of intact controls during the juvenile and post-pubertal phases of development. Following puberty, both the castrated and intact animals exhibited an age-related change in their play fighting; the frequency of initiating play fighting decreased and juvenile patterns of playful defense were replaced by more adult-like patterns. As these changes occurred even in the absence of the pubertal surge of gonadal hormones, they were more likely to result from the organizational effects of gonadal hormones in the perinatal period than the activational effects of these hormones at puberty. Although the castrated animals exhibited the age-related changes in behaviour, they did not exhibit the asymmetries in play associated with dominance relationships. As demonstrated in previous studies, in pairs of intact rats, the animal that attacks the most and uses more juvenile defenses during play fighting and weighs the least is typically the subordinate. In the castrates, asymmetries in weight and playful defense are not related to play frequency, indicating the absence of a dominance relationship. Although the characteristic changes in male play fighting at puberty are independent of the activational effects of gonadal hormones, dominance relationships and their associated changes in play fighting are dependent on these hormones. Therefore, in the perinatal period gonadal hormones most likely organize the age-related changes in play behaviour, whereas post-pubertally gonadal hormones activate dominance relationships and thus, indirectly modify play fighting by affecting dominance-associated assymetries in behaviour. © 1996 Wiley-Liss, Inc.     

Role reversal changes during the ontogeny of play fighting in male rats: Attack vs. defense

From weaning until sexual maturity, the rates at which young male rats hold each other supine during play fighting appear to become progressively asymmetrical. These changes have been previously thought to reflect an initial lack of dominance and a later development of dominance-subordinance relationships. In this paper it is shown that pairs of male rats exhibit asymmetries in playful attack and playful defense throughout development. The changes, resulting in greater asymmetry of pinning rates, are shown to result from age-dependent changes in defensive tactics; the relationship, therefore, remains constant while the form of the behavior changes. Furthermore, it is not the animals showing the highest rates of playful attack who become dominant in older ages.     

Reflexive fighting in response to aversive stimulation

Reflexive fighting was elicited between paired rats as a reflex reaction to electric shock prior to any specific conditioning. Such fighting was fairly stereotyped and easily differentiated from the rats' usual behavior. The strength of this reflex was not attributable to any apparent operant reinforcement. Elicitation of fighting was a direct function of the enclosed floor area and a nonmonotonic function of the shock intensity.

Failure to scramble the polarity of the electrified grid produced inconsistent fighting. Under optimal conditions fighting was consistently elicited by shock regardless of the rat's sex, strain, previous familiarity with each other, or the number present during shock. Repeated shock presentations did not produce an appreciable decrease in fighting until signs of physical debility appeared. Although shock did not cause a rat to attack inanimate objects, it did produce attack movements toward other small animals. Failure of guinea pigs to defend themselves revealed that the elicitation of fighting from the rat does not require reciprocal attack. Paired hamsters showed fighting reactions similar to those of the rats, whereas guinea pigs failed to fight. Electrode shock and a heated floor elicited fighting between the rats, but intense noise and a cooled floor did not.

     

Interplay of biomechanical constraints and kinematic strategies in selecting arm postures

In this study, the authors examined the interplay between biomechanics and control strategies in the resolution of excess degrees of freedom at the joint level. Seven participants made aimed arm movements from 30 starting points and several starting postures to targets. Final arm postures for movements to a target exhibited substantial joint angle variation. Through regression modeling and by comparing observed final arm postures with biomechanically plausible postures, the authors identified 3 kinematic strategies: (a) Maintain deviations from the average angle at the starting point to the joint's final posture; (b) make torso rotations that are a fixed proportion of shoulder rotations; and (c) adopt a characteristic combination of 4 wrist-positioning approaches. The results demonstrated that kinematic strategies can account for substantial variance in final arm postures, if one takes into account 2 types of individual differences-those that arise inevitably from biomechanical constraints and those that reflect choices in movement strategy.     

MISUNDERSTOOD IN THE DIASPORA: THE EXPERIENCE OF ORTHODOX SIKHS IN VANCOUVER

Heroism and martyrdom are central values in contemporary Sikh historiography and primary symbols in their collective memory. Both are replete with the stories of numerous heroes and martyrs who faced death, unflinchingly fighting in defense of the Sikh faith and its believers (constituting the Panth or community) against overwhelming odds. Conversely, it is considered shameful for Sikhs to become mere victims, succumbing to attacks against faith and community without fighting to the death. It is also insisted that true Sikhs do not themselves attack those who are weak or harmless; on the contrary true Sikhs come to the defense of such persons even if they are not of the same faith. However, during the last half century, Sikhs have many times become victims, as well as perpetrators of violence, being unable to act in a way consistent with their central values. The consequence has been an inability to integrate their modern history successfully into a narrative consistent with those values and to find appropriate ways of memorializing what has been done to many Sikhs and what many Sikhs have done to others.