| 要旨トップ | 目次 | | 日本生態学会第73回全国大会 (2026年3月、京都) 講演要旨 ESJ73 Abstract

一般講演（ポスター発表） P1-349 （Poster presentation）

#### Testing Prestige Strategies in Chimpanzees: Effects of Novel Skill Acquisition on Social Networks【A】

*Mayu SHIMADA, Yige PIAO, Shinya YAMAMOTO（Kyoto Univ.）

In animal societies, high social status provides advantages for reproduction and survival. In human societies, social status is thought to be attained through two main strategies: dominance and prestige. In dominance strategies, individuals who coercively acquire status through aggressive interactions tend to be feared and avoided by subordinates. In contrast, in prestige strategies, individuals with knowledge or skills gain status by receiving respect from others. Such prestigious individuals are likely to be approached and provided with services by others seeking opportunities for observational learning. Despite its importance, the prestige-based social status in non-human animals and its evolution has been paid less attention, as nonhuman animals have traditionally been assumed to acquire status solely through dominance. In this study, we tested the hypothesis that chimpanzees utilize prestige strategies by examining whether individuals that acquired and demonstrated a novel foraging skill would gain prestige. The subjects were a group of 13 captive male chimpanzees, including two “model” individuals who learned the novel foraging skill. The experiment consisted of three phases: a pre-demonstration phase; a demonstration phase during which the models performed the skill in front of the group; and a post-demonstration phase. During each phase, we recorded inter-individual proximity and allogrooming interactions through behavioral observations. Through the experiment, non-model individuals did not socially learn the skill from the model individuals. We calculated each individual’s centrality in both proximity and grooming networks based on proximity data and the amount of grooming each individual received from others. Our analyses revealed that changes in centrality from the pre-phase to the demonstration and post phases were not significantly associated with whether individuals possessed the skill. In a previous study using the same model individuals, the centrality of the skilled individuals increased after they demonstrated the skill. In contrast, such an increase was not observed in the present experiment. These results suggest that chimpanzees may acquire prestige-based social status through the demonstration of a novel skill, however, when the skill does not provide benefits to the group, the effect may not be maintained over time. To better understand prestige in chimpanzees, future studies should employ skills that can be socially learned by other group members or group-rewarding skills. Such approaches will help clarify the conditions under which skill demonstration leads to stable changes in prestige-based social status. This study is expected to shed light on the evolutionary factors underlying the development of intelligence.

日本生態学会