Group-living animals can develop social bonds. Social bonds can be considered a type of social relationship characterized by frequent and consistent affiliative (non-reproductive) interactions. Social bonds with conspecifics bring many advantages, also in terms of direct fitness. A characteristic of social bonds is that they need time to develop. Several studies on humans have emphasized the fact that sharing experiences can affect the strength of social bonds. A similar trend can be spotted in non-human species. For example, a recent experiment showed that if chimpanzees watched a video together with a conspecific, they spent more time in proximity compared to conspecifics with whom they did not actively watch a video. Another experiment on fish showed that individuals who experienced a situation of high predation risk together, showed preference for each other compared to those who did not. As the link between shared experiences and social bonds is not explicitly recognized in non-human animals, the main goal of this work is to propose the exploration of this novel research path. This exploration would contribute to shed light on the evolutionary mechanisms of social bond (or friendship) development and maintenance between individuals in different vertebrate species, from fish to non-human primates.

集体生活的动物可以发展社会纽带。社会纽带可以被认为是一种社会关系，其特征是频繁且持续的亲属（非生殖）互动。具有特定关系的社会纽带在直接适应性方面也带来许多优势。社会纽带的一个特点是它们需要时间来发展。关于人类的几项研究强调了这样一个事实，即分享经验会影响社会纽带的力量。在非人类物种中也可以发现类似的趋势。例如，最近的一项实验表明，如果黑猩猩与同伴一起观看视频，与没有主动观看视频的同伴相比，他们在附近花费的时间更多。另一项关于鱼类的实验表明，一起经历高捕食风险的人，与没有的人相比，他们表现出彼此的偏爱。由于在非人类动物中没有明确认识到共享经验和社会纽带之间的联系，因此这项工作的主要目的是提出探索这一新颖研究路径的建议。这项探索将有助于阐明从鱼类到非人类灵长类动物不同脊椎动物物种之间的社会纽带（或友谊）发展和维持的进化机制。