The phenomenon of animal personality has received increased attention by scientists in recent years. Our study on male crested macaques revealed that their personalities are formed through five factors: Anxiety, Sociability, Connectedness, Aggressiveness and Boldness. Interestingly, Connectedness has no obvious homologue in other macaque species and thus seems to be a derived feature that most likely evolved in relation to the species’ tolerant social style. Our results also open up an alternative scenario for the evolution of personality factors in hominids: in contrast to what has been suggested so far, the hominid Extraversion factor may have evolved from a single factor that we labelled Anxiety.

Original Publication
Neumann, C.; Agil, M., Widdig, A.; Engelhardt, A. (2013): Personality of wild male crested macaques (Macaca nigra). PLoS One. DOI 10.1371/journal.pone.0069383