Repeatability of measures of behavioral organization over two years in captive infant rhesus macaques, Macaca mulatta

• Published in: American journal of primatology 2024-04, Vol.86 (4), p.e23591-n/a
• Main Authors: Pritchard, Alexander J., Capitanio, John P., Del Rosso, Laura, McCowan, Brenda, Vandeleest, Jessica J.
• Format: Article
• Language: English
• Subjects: Age; Age differences; Assessments; Behavior; Behavioral responses; Biobehavioral Assessment; Consistency; development; Emotional behavior; Emotionality; Gender differences; Health status; Hospitalization; Individual differences; Infants; infants and juveniles; Insight; Locomotion; Macaca mulatta; Mixed gender; Personality; Personality development; Personality traits; Primates; Public housing; Relocation; Reproducibility; Research facilities; Sex differences; Stimulus; Temperament; Time use
• ISSN: 0275-2565; 1098-2345
• DOI: 10.1002/ajp.23591

Individual differences of infant temperament have been associated with future health outcomes that provide explanatory power beyond adult personality. Despite the importance of such a metric, our developmental understanding of personality‐like traits is poor. Therefore, we examined whether young primates show consistency in personality traits throughout development. We replicated a Biobehavioral Assessment (BBA) at three time periods: 3–4 months, 1 year, and 2 years of age in 47 rhesus macaque (Macaca mulatta) subjects from large mixed‐sex outdoor social housing units at the California National Primate Research Center. We report results for tests focused on responses and adaptation to the temporary separation and relocation, responses to a threatening stimulus, and ratings of overall temperament. We found consistently repeatable associations in measures of Emotionality; these associations were stronger in males, but also present in females, and broadly consistent between Years 1 and 2. We also explored whether behavioral responses to this experimental relocation might be influenced by their experience being relocated for other reasons (i.e., hospitalizations) as individuals' responses might be influenced by similar experiences to the BBA procedure. Only locomotion, during one of the assessments, was associated with past hospitalization events. Overall, repeatability in Emotionality‐associated behaviors was evident across the 2 years, in both sexes. We did, however, find evidence of the emergence of sex differences via differentiated expression of behavioral responses during the BBA. We emphasize that there is likely contextual nuance in the use of these BBA factor‐associated behaviors. Further research is required to determine whether and how shifts occur in underlying factor structure and the expression of associated behaviors. We examined whether young rhesus macaques showed consistency in personality traits throughout development. This graphical visualizes and describes the sampling in the center image and text panel, respectively. We also summarize the results in the right text panel. Highlights We ran BioBehavioral Assessments (BBA) on 47 subjects, replicating BBA at ~3.4 months‐, 1 year‐, and 2 years of age to provide insight on the development of individual differences and the design of relevant assessments over time. Results supported that Emotionality‐associated behaviors exhibited rank consistency over time, more so than for activity and other BB