Sex differences in longitudinal personality stability in chimpanzees

Personality factors analogous to the Big Five observed in humans are
present in the great apes. However, few studies have examined the
long-term stability of great ape personality, particularly using
factor-based personality instruments. Here, we assessed overall group, and
individual-level, stability of chimpanzee personality by collecting
ratings for chimpanzees (N = 50) and comparing them to ratings collected
approximately 10 years previously, using the same personality scale. The
overall mean ratings of three of the six factors differed across the two
time points. Sex differences in personality were also observed, with
overall sex differences found for three traits, and males and females
showing different trajectories for two further traits over the 10-year
period. Regardless of sex, rank-order stability analysis revealed strong
stability for dominance; individuals who were dominant at the first time
point were also dominant 10 years later. The other personality factors
exhibited moderate-to-weak rank-order stability indicating that
individuals were variable in their rank-position consistency over time. As
many studies assessing chimpanzee cognition rely on personality data
collected several years prior to testing, these data highlight the
importance of collecting current personality data when correlating them
with cognitive performance.

与人类观测到的大五人格（Big Five）类似的人格因子，存在于类人猿中。然而，鲜有研究探讨类人猿人格的长期稳定性，尤其是采用基于因子的人格测评工具的相关研究。本研究通过收集50只黑猩猩的人格评分，并与约10年前采用相同人格量表收集的评分进行对比，评估了黑猩猩人格的群体层面与个体层面稳定性。六个人格因子中，有三个因子的总体平均评分在两个时间点存在差异。本研究还观测到人格方面的性别差异：三个特质存在总体性别差异，另有两个特质在10年随访期内，雄性与雌性个体呈现出不同的变化轨迹。无论性别如何，等级顺序稳定性分析均显示支配性特质具有极强的稳定性——首次测评时处于支配地位的个体，在10年后仍保持该地位。其余人格因子则表现出中等至较弱的等级顺序稳定性，表明个体的等级位置一致性随时间推移存在差异。由于诸多评估黑猩猩认知能力的研究，均依赖于测试前数年收集的人格数据，本研究结果凸显了在将人格数据与认知表现进行关联时，采集当前人格数据的重要性。