Graduate School of Human Sciences, Osaka University, Osaka, Japan.
Primates. 2020 Jul;61(4):593-602. doi: 10.1007/s10329-020-00808-3. Epub 2020 Feb 28.
This study aimed to quantitatively describe triadic grooming bouts in a free-ranging group of Japanese macaques (Macaca fuscata). Two types of triadic grooming bouts occurred less frequently and for a shorter duration than dyadic grooming bouts: straight-line type (SL), where individual A grooms B, who then grooms C; and two-to-one type (TO), where individuals X1 and X2 groom Y. TO-type grooming was recorded more often than SL-type grooming. As in the dyadic grooming bouts, two females who had direct grooming interactions in both SL-type (i.e., between A and B or between B and C) and TO-type groomings (i.e., between X1 and Y and between X2 and Y) and two groomers who did not have direct grooming interactions in TO-type grooming were closely related to each other in more than the half of the pairs recorded. Groomers were more likely to be subordinate to groomees in triadic grooming. Almost all of the observed pairs in SL- and TO-type groomings were also recorded in dyadic grooming bouts. These findings indicate that like dyadic grooming, triadic grooming bouts are largely influenced by blood relatedness through maternal lines and dominance relationships between participants. Based on affiliative relationships maintained through dyadic grooming, triadic grooming could be influenced by such affiliative relationships and then function to strengthen bonds between participants. Possible relationships between triadic grooming and the level of social tolerance among individuals are discussed from the viewpoints of interspecies differences among macaque species and regional differences in Japanese macaques.
本研究旨在定量描述自由放养的日本猕猴（Macaca fuscata）群体中的三元梳理行为。两种类型的三元梳理行为比二元梳理行为发生的频率更低，持续时间更短：直线型（SL），其中个体 A 梳理 B，然后 B 梳理 C；以及二对一型（TO），其中个体 X1 和 X2 梳理 Y。TO 型梳理比 SL 型梳理记录更频繁。与二元梳理行为一样，在 SL 型（即 A 与 B 或 B 与 C 之间）和 TO 型梳理（即 X1 与 Y 和 X2 与 Y 之间）中直接进行梳理互动的两个雌性，以及在 TO 型梳理中没有直接梳理互动的两个梳理者，在超过一半的记录对中彼此之间存在密切的亲缘关系。在三元梳理中，梳理者比被梳理者更有可能处于从属地位。几乎所有在 SL 和 TO 型梳理中观察到的对都也记录在二元梳理行为中。这些发现表明，与二元梳理一样，三元梳理行为主要受到通过母系遗传的血缘关系和参与者之间的支配关系的影响。基于通过二元梳理保持的亲和关系，三元梳理可能受到这种亲和关系的影响，然后起到加强参与者之间联系的作用。从猕猴种间差异和日本猕猴的区域差异的角度讨论了三元梳理与个体之间社会容忍度水平之间的可能关系。
