There is growing evidence that behavioral tendencies, or “personalities,” in animals are an important aspect of their biology, yet their evolutionary basis is poorly understood. Specifically, how individual variation in personality arises and is subsequently maintained by selection remains unclear. To address this gap, studies of personality require explicit incorporation of genetic information. Here, we explored the genetic basis of personality in rhesus macaques by determining the heritability of personality components and by examining the fitness consequences of those components. We collected observational data for 108 adult females living in three social groups in a free-ranging population via focal animal sampling. We applied principal component analysis to nine spontaneously occurring behaviors and identified six putative personality components, which we named Meek, Bold, Aggressive, Passive, Loner, and Nervous. All components were repeatable and heritable, with heritability estimates ranging from 0.14 to 0.35. We found no evidence of an association with reproductive output, measured either by infant survival or by interbirth interval, for any of the personality components. This finding suggests either that personality does not have fitness-related consequences in this population or that selection has acted to reduce fitness-associated variation in personality.

中文翻译：

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恒河猴（Macaca mulatta）的性格特征是可遗传的，但不能预测繁殖能力

越来越多的证据表明，动物的行为倾向或“个性”是其生物学的一个重要方面，但人们对它们的进化基础知之甚少。具体来说，个性的个体差异是如何产生并随后通过选择维持的仍然不清楚。为了解决这一差距，人格研究需要明确纳入遗传信息。在这里，我们通过确定人格成分的遗传力并检查这些成分的适应性结果，探索了恒河猴人格的遗传基础。我们通过重点动物采样收集了自由放养种群中生活在三个社会群体中的 108 名成年女性的观察数据。我们将主成分分析应用于九种自发发生的行为，并确定了六种假定的人格成分，我们将其命名为温顺、大胆、好斗、被动、孤独和紧张。所有成分都是可重复和可遗传的，遗传力估计范围为 0.14 至 0.35。我们没有发现任何人格成分与生殖产出相关的证据，无论是通过婴儿存活率还是生育间隔来衡量。这一发现表明，人格在该人群中不会产生与健康相关的后果，或者选择可以减少与健康相关的人格变异。