Received: 13 February 2017
Revised: 8 November 2017
Accepted: 17 November 2017
The influence of age on wild rhesus macaques' affiliative
School of Life Sciences, Sun Yat-sen
University, GuangZhou, China
School of Sociology and Anthropology, Sun
Yat-sen University, GuangZhou, China
Peng Zhang, School of Sociology and
Anthropology, Sun Yat-sen University,
GuangZhou, 510275 China.
National Natural Science Foundation of China,
Grant number: 31470456; Young Top-notch
Talent for Ten Thousand Talent Program,
Grant number: (2014-17); JSPSNSFC Joint
Program, Grant number: NSFC3161101409
The social relationships that individuals experience at different life stages have a non-
negligible influence on their lives, and this is particularly true for group living animals. The
long lifespan of many primates makes it likely that these animals have various tactics of
social interaction to adapt to complex changes in environmental or physical conditions.
The different strategies used in social interaction by individuals at different life stages,
and whether the position (central or peripheral) or role (initiator or recipient) of an
individual in the group social network changes with age, are intriguing questions that
remain to be investigated. We used social network analysis to examine age-related
differences in social interaction patterns, social roles, and social positions in three
affiliative social networks (approach, allogrooming, and social play) in a group of wild
rhesus macaques (Macaca mulatta). Our results showed that social interaction patterns
of rhesus macaques differbetween age classes in the following ways: i) young individuals
tend to allocate social time to a high number of groupmates, older individuals prefer to
focus on fewer, specific partners; ii) as they grow older, individuals tend to be recipients
in approach interactions and initiators in grooming interactions; and iii) regardless of the
different social interaction strategies, individuals of all ages occupy a central position in
the group. These results reveal a possible key role played by immature individuals in
group social communication, a little-explored issue which deserves closer investigation
in future research.
affiliative behaviors, age-related differences, rhesus macaque, Social network analysis, social
Societies are complex systems in which animals have to make a trade-
off in their time investment on different partners in order to optimize
their fitness (Lehmann, Majolo, & McFarland, 2016; Massen et al.,
2012; Rommeck, Capitanio, Strand, & McCowan, 2011; Silk, 2007).
Moreover, the long-life expectancy of many primates exposes them to
continual changes in physical condition and environment throughout
their lives, obliging animals to face various selective pressures at
different life stages namely infancy, juvenility, and adulthood. To attain
a better survival rate or higher reproductive efficiency, individuals may
modulate patterns of social interaction according to their current
needs and situation (Henzi, Lusseau, Weingrill, van Schaik, & Barrett,
2009; Silk, 2007; Silk et al., 2009).
The small body size, low locomotivity, and limited experience of
juveniles make them vulnerable and easy prey for predators. From this
perspective, juveniles could benefit from staying at the center of the
group to reduce the probability of being prey, thus increasing their
chances of survival(Stanton & Mann, 2012).Some studies using the social
network analysis method have shown that the high social activity of
Zhijie Liao and Sebastian Sosa contributed equally to this work.
Am J Primatol. 2018;80:e22733. wileyonlinelibrary.com/journal/ajp © 2017 Wiley Periodicals, Inc.