Thesis (M.S. in animal science)--Washington State University, August 2009. / Title from PDF title page (viewed on July 27, 2009). "Department of Animal Science." Includes bibliographical references (p. 89-119).

Thesis (M.A.)--University of Nevada, Reno, 2006. / "May, 2006." Includes bibliographical references (leaves 33-35). Online version available on the World Wide Web.

Thesis (PhD)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Despite more than three decades of research, and the postulation of more than 30 hypotheses of function, the adaptive significance of play remains unknown. This study quantitatively evaluated a selection of hypotheses of function, using data collected from a wild population of small, social carnivore, the meerkat, Suricata suricatta. The study found that although play in meerkats carried an energetic cost, with individuals modulating their frequency of play in response to their energy intake, none of the hypotheses evaluated by the study could identify the adaptive benefits that meerkats derived from play. Play did not increase 'social harmony' by reducing aggression between playmates, nor did it strengthen an individual's bonds to its social group, such that it remained in the group for longer, or contributed more to the group's cooperative activities. There was no evidence that meerkats used play to strengthen alliances between individuals, and young meerkats played no more frequently with their future dispersal partners than with matched controls with which they did not disperse. Play fighting experience did not improve a meerkat's subsequent fighting skills, and individuals that ultimately won the dominant breeding position within a group (through serious fighting) played no more frequently, and no more successfully, as youngsters, than the littermates that they defeated in combat. Although play was inhibited by aggression, meerkats did not use play to contest, assert or establish dominance status, and there was little evidence to suggest that the preference young meerkats showed for play partners that were well matched in age, size and ability arose from their use of play for self-assessment. This study assessed only those hypotheses of function that predicted benefits that were of importance to the inclusive fitness of the study species. For example, the enhancement of social harmony and group cohesion should be invaluable to a species whose survival is dependent upon social cooperation; and the high reproductive skew exhibited by this species places huge value upon fighting skill and the ability to win social dominance. As a consequence, this study's negative findings suggest strongly that play is not capable of providing these benefits, and that play behaviour is unlikely to be used for these purposes in any mammal species. I conclude that the most likely function of play (based on play's ubiquitous characteristics, and the findings of neurological research on rats) is the promotion of growth of the cerebral cortex. / AFRIKAANSE OPSOMMING: Ten spyte van meer as drie dekades van navorsing en die voorstelling van meer as 30 hipoteses oor funksie, bly die aanpassingswaarde van spelonbekend. Hierdie studie is 'n kwantitatiewe evaluasie van verskeie hipoteses oor funksie, en gebruik data versamel vanuit 'n wilde bevolking van 'n klein sosiale karnivoor, die meerkat, Suricata suricatta. Die studie het bevind dat hoewel spel in meerkaaie 'n energetiese koste beloop, met individue wat hul spelfrekwensie aanpas by energie-inname, geen-een van die hipoteses onder beskouing die aanpassingswaarde van spel vir meerkaaie kon verduidelik nie. Spel het nie "sosiale harmonie" bevorder deur die afuame in aggressie tussen speelmaats nie, en het ook nie 'n individu se verbintenis tot sy sosiale groep versterk sodat hy langer in die groep sou bly of meer sou bydra tot samewerkingsaktiwiteite nie. Daar was geen bewyse vir die gebruik van spel in die versterking van bondgenootskappe tussen individue nie, en jong meerkaaie het nie meer gereeld met toekomstige verspreidings-venote gespeel as met gepaarde kontroles saam met wie hulle nie uiteengegaan het nie. Speelse gevegte het nie 'n meerkat se daaropvolgende gevegsvermoëns verbeter nie, en die individue wat uiteindelik die dominante voortplantingsposisie in 'n groep gewen het (deur ernstige stryd) het nie meer gereeld ofmeer suksesvol as jongelinge gespeel in vergelyking met die werpselmaats wat hulle in die stryd oorwin het nie. Hoewel spel deur aggressie onderdruk is, het meerkaaie spel nie gebruik om dominante range te beveg, bevestig of tot stand te bring nie. Daar was min bewyse ter ondersteuning van die voorstel dat jong meerkaaie se voorkeur vir speelmaats wat hul gelyke is in ouderdom, grootte en vermoë, onstaan het in die gebruik van spel vir selfondersoek. Hierdie studie het slegs die hipoteses van funksie beskou wat voorspellings gemaak het oor die voordele wat belangrik is in die inklusiewe fiksheid van die studie-species. Byvoorbeeld, die verbetering van sosiale harmonie en groepsamehang behoort van onskatbare waarde te wees vir 'n species wat afhanklik is van sosiale samewerking vir oorlewing; en die hoë graad van voorkeuraanwas duidelik in hierdie species plaas groot waarde op gevegsvaardighede en die vermoë om sosiale dominansie te wen. Gevolglik dui hierdie ondersoek se negatiewe bevindinge daarop dat spel nie hierdie voordele kan bied nie, en dat speelgedrag heel waarskynlik nie vir hierdie doeleindes in enige soogdier-species gebruik word nie. Ek kom tot die gevolgtrekking dat die heel waarskynlikste funksie van spel (gebaseer op spel se alomteenwoordige kenmerke en die bevindinge van neurologiese navorsing op rotte) die bevordering van groei in die serebrale korteks is.

Playing is a common behavior among juveniles of many mammalian species, including rats (Rattus norvegicus). The mechanisms underlying the change that occurs in the play fighting of male rats at puberty were the focus of this thesis. It was found that castration at weaning disrupted the formation of male-typical dominance relationships, but did not alter the pubertal changes in play fighting, whereas neonatal castration prevented the shift from juvenile- to adult-typical behaviour at puberty. This transistion is male specific and cannot be induced in females by exposing htme to more extreme social contexts, involving interactions with unfamiliar males. The change in play by males at puberty is not, then, a byproduct of other sex differences, but results from a highly specific mechanism in early infancy. The significance of this sex difference is explored with respect to the functions of play fighting in rats and other species. / xii, 137 leaves : ill. ; 28 cm.

Play fighting in kindling-prone (FAST) and kindling-resistant (SLOW) rats: Potential genetic controls over the components of play. Even though the behavioral components of play fighting have been well characterized in the rat, little is known about the underlying neurobehavioral mechanisms that control them. FAST and SLOW lines of selectively-bred rats were used to determine whether the components of play fighting were dissociable. Differences in their respective play profiles suggest tht there are genetic differences in the expression of differnt components of play. The effects of gene-environment interactions on the components of play suggest that playful attack and playful defense may be differentially labile, and that socially-relevant envionmental manipulations may have a greater impact on social interactions in adulthood than in the juvenile phase. Furthermore, these findings suggest that the genetic constraints on each of the components of play fighting give each component a unique pattern of context-dependent change. Future experiments using FAST and SLOW, as well as other selectively-bred lines of rats may provide insight into the proximate mechanisms regulating play fighting. / viii, 125 leaves ; 28 cm.

Thesis (Ph. D.)--Psychology, Georgia Institute of Technology, 2006. / Terry Maple, Committee Chair ; M. Jackson Marr, Committee Member ; Rebecca Snyder, Committee Member ; Marc Weissburg, Committee Member ; Paul Corballis, Committee Member ; Roger Bakeman, Committee Member.

The role of social play in juvenile behavioral development was examined in the punare (<u>Thrichomys apereoides</u>). Three proposed functions of social play were evaluated: 1. play serves to develop agonistic skills, 2. play has a role in the onset of weaning and 3. play establishes dominance relationships among participants. Eight litters consisting of three juveniles and both parents were observed from birth until eight weeks of age, and the content, sequence and duration of parental and play behaviors were recorded. Adult agonism was characterized in paired encounters between. unfamiliar adults. Encounters between unfamiliar juvenile dyads were conducted and compared to litter mate play. Sex specific differences in social play were concordant with observed differences in adult agonistic interactions. Play bouts between male juveniles were more frequent, of greater duration and incorporated more dominance reinforcement behaviors than bouts between females. Mothers tended to avoid playing with offspring, while paternal play was frequent. Self-handicapping was observed during father-daughter play. Dominance relationships were evident during play, with strong, stable hierarchies established among male juveniles. Adult males dominated all offspring and juvenile males dominated female littermates. Unfamiliar juvenile play bouts were shorter in duration and more frequently resulted in avoidance than bouts among litter mates. These results suggest that punare social play functions to develop agonistic skills while concurrently establishing dominance relationships. The early establishment of dominance relationships may serve as a non-injurous means of precipitating male-biased post-weaning dispersal. / Master of Science

The influence of play behavior on the brain was investigated through plasticity and metaplasticity methodology. Regions in both cortical and sub-cortical areas were investigated. Animals in both studies either experienced play with juvenile partners or did not experience play by being paired with an adult. Play experience alone was shown to affect the plasticity in the prefrontal cortex, although it did not show structural changes to sub-cortical regions. If animals were given nicotine after play experiences, the affects of play in the prefrontal cortex were abolished. In addition, playful behaviors appear to prime some sub-cortical regions of the brain for expression of later plasticity. Thus, play appears to alter the structure of multiple brain areas, but do so in different ways. / ix, 67 leaves ; 29 cm

Thesis (Ph. D.)--University of California, San Diego, 2002. / Vita. Includes bibliographical references (leaves 244-258).

Stress is thought to be antithetical to play. However, this thesis shows that mild stress (e.g., social deprivation) enhances rough-and-tumble play, as opposed to other social behaviors, in adolescent rats. Social deprivation results in both higher levels of corticosterone (a stress hormone) and higher levels of play. When non-socially deprived rats were injected with ACTH (a precursor to corticosterone), the frequency of play was elevated to levels comparable to that seen when juveniles were socially deprived. Moreover, corticosterone was reduced by the opportunity to play, but not when given social contact (but no play) or solitary exercise (i.e. a running wheel). Therefore, this thesis provides evidence that play is not only enhanced by mild stress, but that it is used by animals to reduce stress. / vi, 70 leaves ; 29 cm.