The fourth dimension of tool use: temporally enduring artefacts aid primates learning to use tools

All investigated cases of habitual tool use in wild chimpanzees and capuchin monkeys include youngsters encountering durable artefacts, most often in a supportive social context. We propose that enduring artefacts associated with tool use, such as previously used tools, partly processed food items and residual material from previous activity, aid non-human primates to learn to use tools, and to develop expertise in their use, thus contributing to traditional technologies in non-humans. Therefore, social contributions to tool use can be considered as situated in the three dimensions of Euclidean space, and in the fourth dimension of time. This notion expands the contribution of social context to learning a skill beyond the immediate presence of a model nearby. We provide examples supporting this hypothesis from wild bearded capuchin monkeys and chimpanzees, and suggest avenues for future research.所有经研究观测的野生黑猩猩与卷尾猴习惯性工具使用案例中，均包含幼崽接触耐用人工制品（artefacts）的场景，且这类场景大多发生在具有支持性的社会环境中。本研究提出，与工具使用相关的耐用人工制品——如已被使用过的工具、半加工的食物残渣，以及此前活动遗留的残留物质——可帮助非人灵长类动物学习工具使用方法，并提升其工具使用熟练度，进而推动非人动物传统技术的传承与发展。因此，社会环境对工具使用的促进作用，可被认为存在于欧几里得空间（Euclidean space）的三维维度与时间的第四维度之中。这一观点将社会环境对技能学习的促进作用，拓展至不限于"示范者近距离在场"的范畴。本研究结合野生白喉卷尾猴与黑猩猩的相关案例，为该假说提供了实证支持，并提出了未来的研究方向。