Behavioral measurement of temperament in male nursery-raised infant macaques and baboons

We define temperament as an individual's set of characteristic behavioral r esponses to novel or challenging stimuli. This study adapted a temperament scale used with rhesus macaques by Schneider and colleagues [American Journ al of Primatology 25:137-155, 1991] for use with male pigtailed macaque (Ma caca nemestrina, n = 7), longtailed macaque (M. fascicularis, n = 3), and b aboon infants (Papio cynocephalus anubis, n = 4). Subjects were evaluated t wice weekly for the first 5 months of age during routine removal from their cages for weighing. Behavioral measures were based on the subject's intera ctions with a familiar human caretaker and included predominant state befor e capture, response to capture, contact latency, resistance to tester's hol d, degree of clinging, attention to environment, defecation/urination, cons olability, facial expression, vocalizations, and irritability. Species diff erences indicated that baboons were more active than macaques in establishi ng or terminating contact with the tester. Temperament scores decreased ove r time for the variables Response to Capture and Contact Latency, indicatin g that as they grew older, subjects became less reactive and more bold in t heir interactions with the tester. Temperament scores changed slowly with a ge, with greater change occurring at younger ages. The retention of variabi lity in reactivity between and within species may be advantageous for prima tes, reflecting the flexibility necessary to survive in a changing environm ent. (C) 1999 Wiley-Liss, Inc.