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Predictors of social status in cynomolgus monkeys ( Macaca fascicularis ) after group formation
Author(s) -
Morgan Drake,
Grant Kathleen A.,
Prioleau Osric A.,
Nader Susan H.,
Kaplan Jay R.,
Nader Michael A.
Publication year - 2000
Publication title -
american journal of primatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.988
H-Index - 81
eISSN - 1098-2345
pISSN - 0275-2565
DOI - 10.1002/1098-2345(200011)52:3<115::aid-ajp1>3.0.co;2-z
Subject(s) - agonistic behaviour , primate , psychology , endocrinology , open field , medicine , testosterone (patch) , hormone , trait , social relation , hydrocortisone , physiology , biology , developmental psychology , aggression , social psychology , neuroscience , computer science , programming language
The purpose of the present study was to determine whether various behavioral and hormonal markers obtained in individually housed monkeys would be predictive of social rank following group housing. Body weight, serum cortisol and testosterone levels, and locomotor activity in an open‐field apparatus were examined in 20 experimentally naive male cynomolgus monkeys ( Macaca fascicularis ) while they were individually housed. It was hypothesized that eventual subordinate monkeys would have higher cortisol levels and increased locomotor activity scores. These monkeys were then placed in social groups of four (five pens of four monkeys), and social rank was determined based on outcomes of dyadic agonistic encounters. Body weight correlated significantly with eventual social rank. In general, the heavier the monkey the higher the social rank. Locomotor activity in an open‐field apparatus following administration of a low dose of cocaine (0.01 mg/kg, i.v.), which has been shown to increase CNS dopamine, correlated with eventual social rank such that individually housed monkeys with high levels of locomotion were more likely to become subordinate. Serum cortisol and testosterone levels failed to correlate with eventual social rank. Hypothalamic‐pituitary feedback sensitivity and adrenal responsiveness were examined by measuring cortisol levels after administration of dexamethasone and following ACTH challenge. Cortisol responses in these tests were not associated with eventual social rank. These results suggest that, in addition to body weight, the level of reactivity in a novel environment after administration of a low dose of cocaine is a potential trait marker for social rank. This trait is apparently not associated with hormone levels, but may involve other CNS mechanisms. Am. J. Primatol. 52:115–131, 2000. © 2000 Wiley‐Liss, Inc.