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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/50419 |
| Date | 04 1900 |
| Creators | Sharpe, Lynda L. |
| Contributors | Cherry, M. I., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 210 p. : ill. |
| Rights | Stellenbosch University |
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