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.