Abstract # 188:

Scheduled for Friday, August 19, 2005 07:00 PM-09:00 PM: (Cambridge/Oxford Room) Poster Presentation

Individual differences in temperament predict affiliative partner preferences in yearling rhesus macaques (Macaca mulatta)

T. Weinstein1,2 and J. P. Capitanio1,2
1Department of Psychology, University of California - Davis, One Shields Ave, Davis, California 95616, USA, 2California National Primate Research Center
     We previously presented pilot data demonstrating the importance of temperament in the formation of yearling rhesus macaque peer affiliative relationships. The current report adds data from a new cohort of 23 yearlings living in two naturalistic half-acre field enclosures, increasing our total sample to 48 animals across two cohorts and 4 independent living-groups. We conducted fifteen 10-minute focal observations on each animal during a 10-week period and derived the following social network variables: number of proximity and play preferences displayed, received, and reciprocated. Temperament ratings had been conducted during a colony-wide biobehavioral assessment when subjects were 3-4 months old. Across both cohorts, yearlings displayed preferences toward an average of 2.85 animals for proximity and 2.00 animals for play. We used Chi Square tests (α = 0.05) to determine whether subjects spent more time with particular peers than would be expected by chance. Males had larger play networks than females (P < 0.01). Monkeys rated higher in Calmness, Curiosity, Flexibility, and Gentleness displayed fewer proximity preferences (P < 0.01). The relationship between these traits and partner preference was related to cohort differences in social networks. Animals in the second cohort displayed fewer proximity preferences than those in the first (t = 2.38, P < 0.05), and were rated higher on the four abovementioned traits (P < 0.01). Despite significant differences in the two cohorts’ social behavior, the consistent relationship between these specific temperament traits and affiliative network size across cohorts established temperament as a proximate psychological mechanism underlying affiliative preferences.