Personality in Barbary macaques (Macaca sylvanus): Temporal stability and social rank

Tracing the evolutionary origins of species-specific personality structures requires comparative personality research. We used a 51 item questionnaire to examine the personality structure of 26 semi-free-ranging Barbary macaques assessed at two time points. Principal-components analysis revealed four dimensions: Friendliness, Activity/Excitability, Confidence, and Opportunism. These dimensions were reliable across raters, stable over time, and both similar to and different from the personality dimensions of free-ranging rhesus macaques and male Hanuman langurs. We modeled the relationships between Confidence and a behavioral measure of rank at both time points. The stability of rank over time could be explained by Confidence but not vice versa. These findings highlight how interspecies differences in personality structure reflect personality evolution and how rank is related to personality.