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Comparative analyses of the role of postnatal development on the expression of play fighting
Author(s) -
Pellis Sergio M.,
Iwaniuk Andrew N.
Publication year - 2000
Publication title -
developmental psychobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 93
eISSN - 1098-2302
pISSN - 0012-1630
DOI - 10.1002/(sici)1098-2302(200003)36:2<136::aid-dev5>3.0.co;2-v
Subject(s) - psychology , degree (music) , prenatal development , ontogeny , brain development , developmental psychology , body weight , analysis of variance , physiology , biology , fetus , zoology , pregnancy , demography , endocrinology , neuroscience , medicine , genetics , physics , acoustics , sociology
Abstract 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. © 2000 John Wiley & Sons, Inc. Dev Psychobiol 36: 136–147, 2000