Propagation of handclasp grooming among captive chimpanzees

Abstract

A grooming posture previously reported for two wild chimpanzee (Pan troglodytes) communities developed spontaneously in a captive group of the same species. This offered a unique opportunity to follow the propagation of a new social custom. The posture consists of two partners grasping hands—either both right hands or both left hands—and raising the arms in an A‐frame above their heads while mutually grooming with their free hands. The propagation of this pattern was followed over a 5 year period. In the beginning, handclasps were always initiated by the same adult female. This female initiated the posture mainly with her adult female kin. In subsequent years, these relatives became frequent participants in the posture with each other as well as with nonrelatives. Over the years the posture increased in frequency and duration and spread to the majority of adults and also to a few adolescents and older juveniles. The pattern persisted after removal of the apparent originator. Am. J. Primatol. 43:339–346, 1997. © 1997 Wiley‐Liss, Inc.

Traditions in wild white-faced capuchin monkeys

“…Some noteworthy exceptions include unique grooming styles in Japanese macaques (Tanaka, 1995(Tanaka, , 1998 and chimpanzees (Boesch, 1996a,b;de Waal and Seres, 1997;McGrew and Tutin, 1978;Nakamura, McGrew, Marchant, and Nishida, 2000;Whiten et al, 1999), such as social scratching, hand-clasp grooming, and leaf grooming, which are found only in particular social networks or sites. Some social conventions, such as leaf-clipping (Boesch, 1996a,b) are exhibited at multiple sites in identical form, but are used to convey different meanings at different sites.…”

Distribution of a Chimpanzee Social Custom Is Explained by Matrilineal Relationship Rather Than Conformity

“…In three of eleven wild populations high-arm grooming is absent, suggesting that elsewhere it is socially learned [7] (see SI). In support of social learning, the western and eastern subspecies each include at least one population in which the pattern is present, and at least one in which it is absent [7]; high-arm grooming has been observed to be socially propagated in captivity [8]; and wild mothers sometimes mold their young offspring's high-arm grooming behavior [9].…”

Ape gestures and language evolution

“…The cross-group differences in the context of gestures, especially in bonobos, may be caused by both individual learning (53) and a particular sensitivity of gestures to ''cultural'' variation (8). The latter sensitivity is supported by the capacity of apes to imitate gestures (54,55) as well as the population specificity of many gestures, such as the so-called grooming hand clasp (56)(57)(58), hand clapping (11), and the leaf-clip display and social scratching (59,60). Far more than facial expressions and vocalizations, gestures seem subject to modification, conventionalization, and social transmission.…”