Play Fighting Research Articles

Comparative analyses of the role of postnatal development on the expression of play fighting

Whether it is that animals are young so that they can play, or whether it is that they play because they are young, play should be more prevalent in species that have a greater degree of postnatal development. This hypothesis is tested by comparative analyses within two mammalian orders (primates and muroid rodents) using independent contrasts. This technique can account for the relative degree of relatedness among the species. For both orders, the complexity or prevalence of play fighting is compared to the degree of prenatal development (neonatal weight/adult weight). In addition, the prevalence of play in primates is compared to prenatal brain development (neonatal brain weight/adult brain weight). Significant negative regressions show that 30% of the variance in the distribution of play in the rodents is accounted for by the degree of prenatal development of body size, and 60% of the variance in play in the primates is accounted for by prenatal brain growth. The findings are thus consistent with the prediction. Species with a greater proportion of their growth occurring postnatally play more and have more complex play than do species with more of their growth occurring prenatally.

Comparative analyses of the role of postnatal development on the expression of play fighting

Comparative analyses of the role of postnatal development on the expression of play fighting

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.

Play fighting of juvenile golden hamsters ( Mesocricetus auratus): effects of two types of social deprivation and days of testing

The effects of social deprivation schedules and days of testing on the play-fighting of juvenile golden hamsters were investigated. In Experiment 1, subjects totally (individually housed) or partially isolated (individually housed, but separated by a wire mesh 2 cm from another animal) for a period of 48 h spent significantly increased peer-peer bodily contact, play fighting, and play-fighting relative time (% of bodily contact time spent in play fighting), but exhibited decreased locomotor activity on the 1st day of testing. In Experiment 2, subjects reared since the 10th postnatal day with their mothers alone (chronically deprived of peer-peer social interactions) exhibited similar performances, except that locomotor activity was not affected. All dyads exhibited increased pinning turbulence (number of pinnings divided by time spent in play fighting) on the 1st day of testing, and the interactions between variables (deprivation schedules and days of testing) were statistically significant in most cases, suggesting that unfamiliarity between interactors also affect the performances of animals. We conclude that golden hamsters are sensitive to social deprivation, mothers do not substitute peer companions, animals reared in single-infant litters basically behave like socially-isolated animals, and the effects of induced social deprivation are reversible and disappear on days following testing.

Endocrine and Energetic Mediation of Play Behavior in Free-Living Belding's Ground Squirrels

Many juvenile mammals play, and rates and patterns of play behavior often differ between young males and females. The sexual dimorphisms typical of mammalian play suggest that it might be influenced by gonadal hormones. Moreover, because play competes with growth, physical development, and acquisition of fat reserves for available energy, play behavior should theoretically be influenced by energetic variables. We examined patterns of social play behavior and endocrine and energetic mediation of social play in free-living juvenile Belding's ground squirrels (Spermophilus beldingi). Bouts of social play in young S. beldingi resembled adult copulation and fighting, and young males initiated sexual play but not play fighting at much higher rates than did young females. To elucidate the proximal causes of play, we altered early androgen exposure by treating females with testosterone (T) at birth and used females treated with oil vehicle as controls. We concurrently manipulated energy availability by provisioning with extra food and used unprovisioned squirrels as controls. Hourly rates of play behavior were highest near the time of weaning and declined thereafter among both experimental and control groups of juveniles. Thus, we observed no influence of either T treatment or food provisioning on the temporal patterning of play behavior. Perinatal T treatment had no effect on play fighting, but caused rates of sexual play behavior initiated by young females to increase to near those observed for young males, suggesting that T organizes a masculine tendency to initiate sexual play behavior but not play fighting. Food provisioning increased rates of play among males and females from both T-treated and control litters, suggesting that energy availability limits play behavior.

The Problem of Adult Play Fighting: A Comparative Analysis of Play and Courtship in Primates

Although play fighting, like play generally, is predominantly a feature of the juvenile phase, such behavior persists in the adults of many species. There are two major contexts in which adults engage in play fighting – with juveniles and with other adults. The least attention has been given to adult–adult play. However, one pattern that has been noted by several authors is that the most commonly occurring context of adult–adult play fighting is during courtship, and that this is more likely to occur in solitary species. Supposedly, such play could function to overcome the aggressiveness of potential pairmates unfamiliar with one another, or as a means of evaluating mate quality by one or both partners. By contrasting the presence and degree of play fighting during courtship with the degree of male–female familiarity, the hypothesis that the former is influenced by the latter is tested. Data on 35 species of primates, from 15 families, were compiled from the literature and compared using a method of independent contrasts that incorporates information on phylogenetic relationships. A significant regression was found, with the degree of male–female familiarity accounting for 40% of the variance in courtship play. Therefore, our data support the hypothesis that play fighting in courtship is influenced by male–female patterns of association. However, the data also indicate that other factors must influence the occurrence of play fighting amongst adults, not only during courtship, but also in nonsexual contexts. The broader context of adult–adult play in mammals is discussed.

Distinguishing Serious and Playful Fighting by Children with Learning Disabilities and Nondisabled Children

The ability to distinguish serious from playful fighting by two groups of children with learning disabilities (LD) (mean age = 9.3 and 11.8 years) and non-LD children (mean age = 10.1 years) was examined. Children with LD were generally able to make this distinction, with older children being more accurate. However, the performance of children with LD was not as high as that of non-LD children: they used a smaller range of criteria; some criteria were used significantly less; and they were much more likely not to give any reason for the judgements made. On the other hand, the order in frequency of those criteria cited was similar for both non-LD children and children with LD. Physical actions of the participants, and inference about actions and/or intent were the most frequently cited criteria. These findings indicate that although children with LD use fewer social cues, and are less accurate in making judgements about the nature of behavioural episodes, the acquisition of the meaning of particular cues may follow the same sequence as for non-LD children. Possible delays in the social cognitive development of children with LD, and their implications for the social adjustment of these children, are discussed.

The roles of phylogeny and sociality in the evolution of social play in muroid rodents

A composite index incorporating the frequency and structure (target, type of defence, etc.) of play fighting was used to compare the complexity of such play in 13 species of muroid rodents whose behaviour has been previously described. A phylogenetic comparison of the distribution of the complexity of play fighting revealed that relatedness did not predict complexity. The most likely pattern for the ancestral rodent was moderate levels of complexity, from which increases or decreases in complexity then appeared to have evolved independently, at the level of subfamily and genus. Given that phylogeny did not predict the distribution of the pattern of play fighting, an alternative hypothesis was tested. That is, that instead, the distribution was produced by species differences in sociality, as reflected by the degrees of male–female association amongst adults. The analysis revealed that play complexity was unrelated to species differences in sociality, with both highly social and relatively asocial species being equally likely to have high or low levels of play complexity. The implications of these results for the evolution of mammalian play are considered.

The developmental onset of a rudimentary form of play fighting in C57 mice

Play fighting in its most elaborate form involves nonagonistic wrestling between pairmates, where one partner grabs, holds, bites, or otherwise contacts the other. Such play occurs in the absence of the functional consequences associated with serious fighting (e.g., resource acquisition or protection). Typically, the biting, nosing, or grooming contact during play fighting is directed at specific body targets. House mice have been classified as a species that lacks such play, even though play fighting is present in closely related species such as the rat. In this study, six litters of C57 mice were observed daily from the week before weaning until the week after weaning (15-30 days postnatally). Thirty-min videotaped records were collected daily for each litter. Consistent with other studies, over 85% of all play involved locomotor play, and most of the social play involved noncontact locomotion (86%). However, a rudimentary pattern of the "attack and defense" typical of play fighting was found to occur, albeit at a low frequency (2% of all play). Most playful attacks involved snout contact with the partner's rump, but evidence is provided that suggests that this rump contact may be transitory, with the nape area being the primary target for play. Most of the playful attacks elicited playful defense (97%), which in all cases involved the defender evading such contact by leaping or running away, or by dodging laterally away from the attacker. Therefore, there appears to be directed playful attacks in this species, with defense limited to evasion. Defensive tactics leading to wrestling were never observed. That is, play fighting in mice involves only a small subset of what other species, such as rats, exhibit. Nonetheless, the basic components of attack and defense are present in mice.

The developmental onset of a rudimentary form of play fighting in C57 mice

Play fighting in its most elaborate form involves nonagonistic wrestling between pairmates, where one partner grabs, holds, bites, or otherwise contacts the other. Such play occurs in the absence of the functional consequences associated with serious fighting (e.g., resource acquisition or protection). Typically, the biting, nosing, or grooming contact during play fighting is directed at specific body targets. House mice have been classified as a species that lacks such play, even though play fighting is present in closely related species such as the rat. In this study, six litters of C57 mice were observed daily from the week before weaning until the week after weaning (15–30 days postnatally). Thirty-min videotaped records were collected daily for each litter. Consistent with other studies, over 85% of all play involved locomotor play, and most of the social play involved noncontact locomotion (86%). However, a rudimentary pattern of the “attack and defense” typical of play fighting was found to occur, albeit at a low frequency (2% of all play). Most playful attacks involved snout contact with the partner's rump, but evidence is provided that suggests that this rump contact may be transitory, with the nape area being the primary target for play. Most of the playful attacks elicited playful defense (97%), which in all cases involved the defender evading such contact by leaping or running away, or by dodging laterally away from the attacker. Therefore, there appears to be directed playful attacks in this species, with defense limited to evasion. Defensive tactics leading to wrestling were never observed. That is, play fighting in mice involves only a small subset of what other species, such as rats, exhibit. Nonetheless, the basic components of attack and defense are present in mice. © 1999 John Wiley & Sons, Inc. Dev Psychobiol 34: 175–182, 1999

The developmental onset of a rudimentary form of play fighting in C57 mice

The developmental onset of a rudimentary form of play fighting in C57 mice

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.

Play fighting of rats in comparative perspective: a schema for neurobehavioral analyses

Play fighting is a commonly reported form of play in the young of many mammals. Most of the studies on the neurobehavioral mechanisms regulating this behavior have focused on the laboratory rat. The rationale for doing so has been primarily on practical grounds. This paper seeks to answer the question, “How good is the rat as a model of mammalian play fighting?” A review of the detailed structure of play fighting in rats and other mammals reveals that play fighting is not a unitary activity, but rather has distinct components with each having distinct regulatory mechanisms. The rat is typical of many other mammals for some features of play fighting, but not others. Therefore, two conclusions are drawn from this review. First, given that play fighting is a composite category of behavior, questions regarding its underlying neurobehavioral mechanisms need to be narrowly constructed, so as to deal with highly specific mechanisms. For example, what mechanism regulates the pubertal decline in play fighting? Second, the rat is shown to be a good model species for the study of some features of play fighting, but it cannot be assumed to represent an “average” mammal for all features.

Mechanisms underlying the absence of the pubertal shift in the playful defense of female rats

Due to the action of testicular hormones in the perinatal period, juvenile male rats engage in more play fighting than juvenile females. Also, following puberty, males, but not females, switch to using adultlike defensive tactics more frequently during play. This change in play is also due to the action of testicular hormones perinatally. In this study, two experiments were conducted to determine if the pubertal transition in defense could be induced in females. For Experiment 1, male and female cagemates were tested before and after puberty with familiar and unfamiliar partners. Even when playfully interacting with subadult males, females did not increase the use of the adultlike defensive tactics. For Experiment 2, neonatal females were either injected with testosterone propionate (TP) or ovariectomized (OVX), and again tested before and after puberty. While the TP-treated females had higher frequencies of play fighting, they did not change their pattern of defense following puberty. The OVX females exhibited the lower frequency of play fighting typical of females, but changed their pattern of defense with increased age. Thus, it appears that the pattern of pubertal change in playful defense typical of males is inhibited by ovarian hormones. The mechanisms by which ovarian hormones could exert this effect on developing females are discussed.

Mechanisms underlying the absence of the pubertal shift in the playful defense of female rats

Due to the action of testicular hormones in the perinatal period, juvenile male rats engage in more play fighting than juvenile females. Also, following puberty, males, but not females, switch to using adultlike defensive tactics more frequently during play. This change in play is also due to the action of testicular hormones perinatally. In this study, two experiments were conducted to determine if the pubertal transition in defense could be induced in females. For Experiment 1, male and female cagemates were tested before and after puberty with familiar and unfamiliar partners. Even when playfully interacting with subadult males, females did not increase the use of the adultlike defensive tactics. For Experiment 2, neonatal females were either injected with testosterone propionate (TP) or ovariectomized (OVX), and again tested before and after puberty. While the TP-treated females had higher frequencies of play fighting, they did not change their pattern of defense following puberty. The OVX females exhibited the lower frequency of play fighting typical of females, but changed their pattern of defense with increased age. Thus, it appears that the pattern of pubertal change in playful defense typical of males is inhibited by ovarian hormones. The mechanisms by which ovarian hormones could exert this effect on developing females are discussed. © 1998 John Wiley & Sons, Inc. Dev Psychobiol 33: 147–156, 1998

Play fighting in juvenile golden hamsters ( Mesocricetus auratus): Effects of litter size and analysis of social interaction among males

Previous studies have shown that different social experiences, such as the interaction involving partners of different ages or among individuals of different sexes, significantly alter the play rate. In the present study, two experiments are described, the hamster being used as subject, to investigate the effects of litter size and to analyse the play fighting behavior among males. It was found that there was no significant difference in the time spent in play fighting by an animal when it was placed in groups of 2, 4 or 6 individuals (Exp. 1). Moreover, the majority of animals did not show preferences during play fighting when they were placed in groups formed by four males (Exp. 2). Through these data it has been noted that the hamster distributes the total time spent in play fighting among the available partners. This fact can be explained by the hamster's social organization, because it is a solitary animal, which does not develop a clear and durable interaction with its playmates. Also, through other results, a certain stability was found in most of the behavioral categories registered such that they were not significantly affected by the manipulated variables.

The Postpubertal Change in the Playful Defense of Male Rats Depends upon Neonatal Exposure to Gonadal Hormones

Smith, L. K., M. L. Forgie and S. M. Pellis. The postpubertal change in the playful defense of male rats depends upon neonatal exposure to gonadal hormones. Physiol Behav 63(1) 151–155, 1998.—The pattern of playful defense used during play fighting by male rats ( Rattus norvegicus) castrated at birth was compared to that of sham-operated and untreated controls during the juvenile phase and after puberty. The neonatal castrates failed to exhibit the age-related changes in playful defense present in intact male rats of the same age. Following puberty, control rats, but not neonatal castrates, switched from juvenile to more adult-typical defensive tactics. That the neonatal castrations were effective was independently shown by the animals’ failure to exhibit the asymmetries in weight and play behavior indicative of dominance–subordinance relationships present in normal adult males. A previous study found that castration following weaning did not prevent the pubertal change in playful defense, but did block the formation of dominance–subordinance relationships. Therefore, it appears that the age-related shift in playful defense is a feature of the development of play fighting in males that is likely preprogrammed by gonadal hormone exposure in the perinatal period.

The prejuvenile onset of play fighting in laboratory rats (Rattus norvegicus)

Play fighting in rats is most frequent in the juvenile phase (30-40 days) and then wanes following puberty. During the juvenile phase, the most commonly used defensive tactic to block access to the nape (i.e., the play target) is to rotate around the longitudinal axis to supine. From this position of lying on its back, the defender uses its limbs to hold off the attacking pup. With the onset of puberty males, but not females, switch to more adultlike patterns of defense. The adultlike pattern involves partially rotating around the longitudinal axis of the body, but retaining ground contact with the hindpaws. In this position, the defender is able to rear to a defensive upright posture, or can slam into the partner with its hip. In this study, the manner of onset of play fighting and its components was investigated by daily videotaped observations of six litters of Long Evans hooded rats, starting at 15 or 16 days and ending at 30 days postnatally. The predominant form of social interaction in the midteens was allogrooming, but by 20 days, playful attacks to the nape were the most common form of contact. Allogrooming was most often directed to the head, not the nape. With respect to playful defense, the more adultlike tactics matured first, with all tactics present in the repertoire by 20 days. The fully juvenile pattern of defense did not mature until 25-30 days with both males and females exhibiting the same developmental pattern. These data lead to several conclusions. First, play fighting is a separate category of behavior from the outset, and does not emerge from allogrooming. Second, the adultlike defense patterns do not emerge gradually from the juvenile ones at puberty, but rather, all are present in the repertoire from infancy; and third, both males and females have the same pattern of onset of play fighting. These conclusions are discussed with respect to the possible functions of juvenile play fighting.

War Toy Play and Aggression in Dutch Kindergarten Children

AbstractThe play behavior of 54 four to seven‐year‐old Dutch children in the presence of a standard set of war toys and neutral toys was related to five groups of variables, i.e., parental attitude, possession of war toys at home, the habitual aggressiveness of the child in daily life, the characteristics of the toys themselves, and the play situation. Real object‐ or person‐oriented aggression was rare and was not related to play with the war toys. Suppression of aggression by the experimental situation seemed unlikely. During play, the levels of involvement and fantasy were generally high. Regularly, playful fighting was observed, differentiated as Make‐Believe‐Aggression and Rough‐and‐Tumble. These two Play ‘Aggression’ factors, and Real Aggression, could be predicted from other variables, principally from gender, the influence of session partners, play involvement, type of war toy used and parental attitude.

Sex Differences and the Development of Social Behavior in a Marsupial, the Gray Short-Tailed Opossum ( Monodelphis Domestica)

Fadem, B. H. and A. Corbett. Sex differences and the development of social behavior in a marsupial, the gray short-tailed opossum (Monodelphis domestica). Physiol Behav 61(6) 857–861, 1997.—The effects of sex and age on social behavior were examined in gray short-tailed opossums ( Monodelphis domestica), small didelphid marsupials. Each animal received five behavior test batteries spanning prepubertal to postpubertal ages. Each test battery consisted of two tests with animals of the same age, one with a male and one with a female. Precopulatory behavior toward females, intermale fighting requiring test interruptions as well as scent marking behavior were seen at higher levels in males than in females and were seen more frequently around and after puberty than before puberty. Females showed more threat behavior than males in mixed-sex and in same-sex interactions. This sex difference was apparent after puberty in tests with male partners and prior to as well as around puberty in tests with female partners. Because climbing over and boxing with another animal were seen more frequently prior to than after puberty, these behaviors may be elements of play fighting (i.e. attack and defense without submission and threat). These findings are discussed with respect to the role of gonadal hormones in the organization and activation of behavior and with reference to their comparative significance in mammals.