The Similarity Principle Underlying Social Bonding among Female Rhesus Monkeys

Abstract

Twenty adult female rhesus monkeys (Macaca mulatta) were observed over a three-year period. They lived in a mixed captive group with kinship relations known for three generations. The study’s aim was to test Seyfarth’s [J. theor. Biol. 65: 671–698, 1977] model of rank-related grooming and to investigate two other possible determinants of social bonding, i.e. relative age and the group’s stratification into two social classes. Data on affiliation, coalitions, and social competition were collected by means of both focal observation and instantaneous time sampling. Whereas certain elements of the existing model were confirmed, its explanatory principles were not. Social competition did not result in more contact among close-ranking females (the opposite effect was found), and the relation between affiliative behavior and coalitions was more complex than predicted. Based on multivariate analyses and a comparison of theoretical models, we propose a simpler, more encompassing principle underlying interfemale attraction. According to this ‘similarity principle’, rhesus females establish bonds with females whom they most resemble. The similarity may concern (l)genetical and social background, (2) age, (3) hierarchical position and (4) social class. Effects of these four factors were independently demonstrated. The most successful model assumed that similarity factors influence female bonding in a cumulative fashion.

Dominance hierarchy and social grooming in female lion- tailed macaques (Macaca silenus) in the Western Ghats, India

“…The view that more grooming occurs between closely ranked dyads than between distant dyads (Parr et al 1997) was true in the case of the high-ranking and the middle-ranking lion-tailed macaque females where the low-ranking females largely groomed distant ranks. The view that grooming is reciprocal in macaques (de Waal and Luttrell 1986;de Waal 1991) was true only for high-ranking females as the middle-and the low-ranking females were observed to groom more unidirectionally than reciprocally. The grooming patterns of the lion-tailed macaque females, therefore, point to a more despotic than a relaxed system.…”

“…In the egalitarian society of Tonkean macaques, grooming is not dominance-related (Thierry et al 1990). On the other hand, grooming is signifi cantly dominancerelated in the despotic rhesus (Sade 1972;de Waal and Luttrell 1986) and Japanese (Mehlman and Chapais 1988) macaques. In lion-tailed macaques, grooming was upward in the hierarchy.…”

Factors influencing male affiliation and coalitions in a species with male dispersal and intense male–male competition, Colobus vellerosus

“…We have observed affiliation among subadult males more often than between adults so we predicted that we would see an effect of age on male affiliation. Male dyads were predicted to be most affiliative when they were kin, of similar age, had been co-resident for a long period of time, or had participated in parallel transfer (e.g., the similarity principle; de Waal & Lutrell, 1986). Dyads that were the least aggressive, which may have been an indi-cation of a good relationship, were also predicted to have higher affiliation rates.…”

Behaviourally specific preferred associations in bottlenose dolphins, Tursiops spp.

“…We suggest that associates are chosen to maximize efficiency or benefits when carrying out specific behaviours. In a study population which exhibits at least 13 different foraging techniques (Smolker et al 1997;Connor et al 2000b;Mann and Sargeant 2003;Krützen et al 2005), it is likely that individuals would maximize foraging efficiency by associating preferentially with individuals that forage in a similar manner (de Waal and Luttrell 1986). In turn, these foraging associates may not provide equivalent benefits while performing social or resting behaviours.…”