Personality dimensions capturing individual differences in behavior, cognition, and affect have been described in several species, including humans, chimpanzees, and orangutans. However, comparisons between species are limited by the use of different questionnaires. We asked raters to assess free-ranging rhesus macaques at two time points on personality and subjective well-being questionnaires used earlier to rate chimpanzees and orangutans. Principal-components analysis yielded domains we labeled Confidence, Friendliness, Dominance, Anxiety, Openness, and Activity. The presence of Openness in rhesus macaques suggests it is an ancestral characteristic. The absence of Conscientiousness suggests it is a derived characteristic in African apes. Higher Confidence and Friendliness, and lower Anxiety were prospectively related to subjective well-being, indicating that the connection between personality and subjective well-being in humans, chimpanzees, and orangutans is ancestral in catarrhine primates. As demonstrated here, each additional species studied adds another fold to the rich, historical story of primate personality evolution.

International audienceWhy regularities in personality can be described with particular dimensions is a basicquestion in differential psychology. Nonhuman primates can also be characterized in terms ofpersonality structure. Comparative approaches can help reveal phylogenetic constraints andsocial and ecological patterns associated with the presence or absence of specific personalitydimensions. We sought to determine how different personality structures are related tointerspecific variation in social style. Specifically, we examined this question in six differentspecies of macaques, as macaque social style is well characterized and can be categorized ona spectrum of despotic (grade 1) versus tolerant (grade 4) social styles. We derivedpersonality structures from adjectival ratings of Japanese (Macaca fuscata; grade 1),Assamese (M. assamensis; grade 2), Barbary (M. sylvanus; grade 3), Tonkean (M. tonkeana;grade 4), and crested (M. nigra; grade 4) macaques and compared these species to rhesusmacaques (M. mulatta; grade 1) whose personality has previously been characterized. Using anon-parametric method, fuzzy set analysis, to identify commonalities in personalitydimensions across species, we found that all but one species exhibited consistently definedFriendliness and Openness dimensions, but that similarities in personality dimensionscapturing aggression and social competence reflect similarities in social styles. Thesefindings suggest that social and phylogenetic relationships contribute to the origin,maintenance, and diversification of personality

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Pink-to-red anogenital and facial sexual skin occurs in females of many primate species. Since female sexual skin color varies with reproductive state, it has long been assumed that color acts to stimulate male sexual interest. Although there is supportive evidence for this as regards anogenital skin, it is unclear whether this is also the case for facial sexual skin. In this study we experimentally manipulated digital facial and hindquarter images of female rhesus macaques (Macaca mulatta) for color within the natural range of variation. The images were presented to adult male conspecifics to assess whether the males exhibited visual preferences for red vs. non-red female coloration, and whether preferences varied with anatomical region. The males displayed significantly longer gaze durations in response to reddened versions of female hindquarters, but not to reddened versions of faces. This suggests that female facial coloration may serve an alternative purpose to that of attracting males, and that the signal function of sexual skin and the intended recipients may vary across anatomical regions.