LONG-TERM EFFECTS OF INFANT REARING CONDITION ON THE ACQUISITION OF DOMINANCE RANK IN JUVENILE AND ADULT RHESUS MACAQUES (MACACA MULATTA) |
M. Bastian1; A. Sponberg1; S. Suomi2 and J. Higley1
1Laboratory of Clinical Studies, NIAAA, NIH Animal Center, Bldg.112/Rm.205, P.O.Box 529 Fisher Ave., Poolesville, Maryland, 20837, USA, 2Laboratory of Comparative Ethology, NICHD |
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| Previous research has linked maternal deprivation in infant monkeys to subsequent social deficits. Little is known, however, about the development of social competence in monkeys reared with limited peer interactions as compared to mother- and peer-reared monkeys. In two studies, we examined the effects of early rearing experience on the development of dominance status in juvenile (N=53) and then in adult (N=38) rhesus monkeys. We predicted that both as juveniles and through adulthood, mother-reared (MR) monkeys would outrank both their peer-reared (PR) and surrogate-peer-reared (SPR) counterparts and PR monkeys would rank higher than SPR subjects. Agonistic dyadic interactions were recorded and summarized into a win/lose matrix to produce dominance ranks. Juvenile MR and PR subjects did not differ in ranks, but monkeys from both rearing backgrounds outranked SPR cage-mates. At age 3, males outranked females. Although animals who eventually obtained high or low rank were identical in weight prior to group formation, subjects who ranked highest by age 3 gained the most weight between yrs 1-3 of life regardless of rearing condition, suggesting that low dominance status may lead to inhibited developmental growth. Adult MR subjects outranked both PR and SPR subjects, with PR animals occupying intermediate ranks. These findings indicate that impoverished early rearing experiences, such as adult absence and varying degrees of social isolation, are useful predictors of future social success in rhesus monkeys. |
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