Data from: How chimpanzees solve collective action problems

We presented small groups of chimpanzees with two collective action situations, in which action was necessary for reward but there was a disincentive for individuals to act due to the possibility of free-riding on the efforts of others. We found that in simpler scenarios (Experiment 1) in which group size was small, there was a positive relationship between rank and action with more dominant individuals volunteering to act more often, particularly when the reward was less dispersed. Social tolerance also seemed to mediate action whereby higher tolerance levels within a group resulted in individuals of lower ranks sometimes acting and appropriating more of the reward. In more complex scenarios when group size was larger and cooperation was necessary (Experiment 2), overcoming the problem was more challenging. There was highly significant variability in the action rates of different individuals as well as between dyads suggesting success was more greatly influenced by the individual personalities and personal relationships present in the group.我们向多组小型黑猩猩设置了两类集体行动（collective action）情境。在这类情境中，个体需采取行动才能获取奖励，但由于存在搭便车（free-riding）的可能，即个体可利用他人努力坐享其成，个体行动会面临负向激励。我们发现，在群体规模较小的简易情境（实验1）中，个体的社会等级与行动参与呈正相关关系：优势等级更高的个体更常主动参与行动，尤其当奖励分配较为集中时。社会容忍度似乎也对行动起到中介作用：群体内容忍度越高，低等级个体有时会更主动地参与行动，并获取更多的奖励份额。而在群体规模更大、且合作不可或缺的复杂情境（实验2）中，克服该集体行动困境的难度更高。不同个体间以及个体两两配对（dyads）间的行动参与率存在极显著差异，这表明任务的成功与否更大程度上受群体内个体性格与人际互动关系的影响。