Friendship is the single most important factor influencing our health, well-being, and happiness. Creating and maintaining friendships is, however, extremely costly, in terms of both the time that has to be invested and the cognitive mechanisms that underpin them. Nonetheless, personal social networks exhibit many constancies, notably in their size and their hierarchical structuring. Understanding the processes that give rise to these patterns and their evolutionary origins requires a multidisciplinary approach that combines social and neuropsychology as well as evolutionary biology.

中文翻译：

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友谊的剖析

友谊是影响我们健康、幸福和幸福的最重要的因素。然而，就必须投入的时间和支撑友谊的认知机制而言，建立和维持友谊的成本极其高昂。尽管如此，个人社交网络表现出许多不变性，特别是在它们的规模和层次结构方面。了解产生这些模式的过程及其进化起源需要一种结合社会和神经心理学以及进化生物学的多学科方法。