Ramana Academy, San Jose, California.
Am J Primatol. 2011 Nov;73(11):1107-13. doi: 10.1002/ajp.20987. Epub 2011 Sep 8.
In captivity, male bonnet macaques (Macaca radiata) frequently express "friendship" toward one another, including affiliative behavior such as huddling, grooming, coalitionary support, and sitting in close proximity. The purpose of this study was to determine whether wild adult male bonnet macaques also express "friendship" by investigating whether or not (1) adult male bonnet macaques have affiliative social relationships with other males, (2) the strength of social relationships varies among dyads, (3) there is time-matched reciprocity in allogrooming among dyads, and if so, whether the level of reciprocity occurs within a bout of grooming, a day, or over 2 months (the limit of this study), and (4) a correlation exists between the strength of social relationships and dominance ranks among adult males. Focal samples totaling 150 hr on all seven adult males in one study group were conducted to record both agonistic and affiliative interactions. Agonistic interactions were used to construct a dominance hierarchy, whereas affiliative interactions (sitting in proximity to within 1 m with and without grooming) were used to quantify the existence and strength of social bonds within dyads. Results show that adult male bonnet macaques had differentiated affiliative relationships with other males in their group. There was little reciprocity of grooming within a bout of grooming or within a day, but greater reciprocity over the study period of 2 months. There was no correlation between dominance ranking distance and the strength of affiliative relationship within dyads; however, within dyads lower-ranking males groomed higher-ranking males more than vice versa. This study suggests that friendships in male bonnet macaques are characterized not by immediate tit-for-tat reciprocal altruism, but by reciprocity over a longer time span, and that affiliative social relationships may be less constrained by agonistic relationships than is the case in more despotic species of macaques.
在圈养环境下，雄性冕狐猴（Macaca radiata）之间经常表现出“友谊”，包括亲昵行为，如拥抱、梳理毛发、联合支持和近距离坐在一起。本研究的目的是确定野生成年雄性冕狐猴是否也通过以下方式表达“友谊”：（1）成年雄性冕狐猴是否与其他雄性存在亲昵的社交关系；（2）社交关系的强弱是否在对偶中有所不同；（3）对偶之间的理毛是否存在时间匹配的互惠性，如果有，这种互惠性是在一次梳理、一天还是在 2 个月（本研究的限制）内发生的；（4）成年雄性之间的社会关系强弱与支配等级之间是否存在相关性。在一个研究组中，对 7 只成年雄性中的每一只进行了总计 150 小时的焦点样本观察，以记录所有的攻击和亲昵互动。攻击互动用于构建支配等级，而亲昵互动（在 1 米内近距离坐在一起，有或没有梳理毛发）则用于量化对偶中社会关系的存在和强弱。结果表明，成年雄性冕狐猴与群体中的其他雄性存在分化的亲昵关系。在一次梳理或一天内，理毛的互惠性很小，但在 2 个月的研究期间，互惠性更大。支配等级距离与对偶内亲昵关系的强弱之间没有相关性；然而，在对偶中，低等级的雄性给高等级的雄性梳理毛发的次数多于相反的情况。本研究表明，雄性冕狐猴的友谊特征不是即时的、以牙还牙的互惠利他主义，而是在较长时间跨度内的互惠性，并且亲昵的社会关系可能不像在更专制的猕猴物种中那样受到攻击关系的限制。
