In the second case two adult males partially obscured by foliage performed GHC. In one case JL and KT formed a grooming clique with an estrous female but it was unclear if the two males performed GHC or if one performed it with the female. On both occasions grooming chimpanzees were observed in tree crowns from &ge 80 m distance and identity of participants, and the form of GHC, was unconfirmed. Two further instances of GHC were recorded. On this occasion JL rested his left hand/wrist on KT’s forearm. At 0904 they raised their left arms and performed wrist-to-wrist GHC for approximately 60 seconds.
At 0859 we observed JL, KT and MR in a Parkia filicoidea tree, 55 m distant. The second instance occurred on 31 July 2007. Adult males JL (left) and KT (right) performing handclasp grooming at Bulindi (May 2007) The bout lasted 49 seconds (Video 1, available online at /PAN/18_2/18(2)_03.html). Once extended, KT’s wrist appeared supported by JL’s wrist (Figure 2a). Video analysis indicated that JL initiated or facilitated the bout by momentarily taking hold of KT’s right forearm at elbow and wrist and gently pushing upwards (Figure 2b). At 0818 they raised their right arms overhead and performed the wrist-to-wrist variant of GHC (Figure 2a). When he sat JL began grooming him after several minutes they groomed mutually. At 0808 KT climbed on the log and stood glaring at us with erect hair. After approximately two minutes, JL and MR began self-grooming while monitoring us a third male (JK) was peeping from behind the log. However, on this occasion the males did not threaten us. Previous short-range encounters with chimpanzees generated alarm and agitation, usually accompanied by threats from adult males 7. Two males immediately climbed down behind the log while two (JL and MR) remained in view, staring with hair erect. Four adult males were seated on a rotting log, 27 m distant. At 0736 on we followed chimpanzee vocalizations to a clearing in heavily logged forest. Two instances of GHC were observed in which the identity of participants was confirmed.
An unknown number of small chimpanzee groups utilize forest patches to the north and west of Bulindi. The locations of the Sonso community in Budongo and nearby Kasokwa community (where grooming hand-clasp has not been seen) are also indicated. The approximate home range of Bulindi chimpanzees is encircled. Map showing the location of Bulindi (at bottom) in relation to Budongo Forest in western Uganda. Consequently, observations of social behavior including grooming and dominance interactions increased as the study progressed.įigure 1. Although chimpanzees were unhabituated to close observation, from mid-2007 the community’s six adult males showed signs of semi-habituation 7. I studied a community of &ge 25 chimpanzees for 18 months during 2006–2008. Here I report preliminary observations of GHC in chimpanzees at Bulindi, Uganda.īulindi is a forest–agriculture ecotone, 25-km south of Budongo Forest (Figure 1) 6,7. Records from new study sites are valuable because they increase our understanding of chimpanzee behavioral variation. It occurs in more study communities than not (whether present, habitual or customary), yet is notably absent at three long-term sites: Bossou (Guinea), Gombe (Tanzania), and Budongo (Uganda) 4,5. GHC has a patchy distribution across Africa. The behavior may originate from branch-clasp grooming-a universal behavior in chimpanzees 4-in which participants grasp an overhead branch whilst grooming socially 1. Variant forms include one participant grasping their partner’s hand or wrist, and ‘wrist-to-wrist’ in which participants rest their wrists against each other’s forearm, usually one partner supporting most of the weight of both 2,3.
The resulting configuration is strikingly symmetrical.
#Chimpanzee hand groom clasp free
It occurs when two chimpanzees seated opposite one another clasp hands overhead and groom each other’s underarm with their free hand. The grooming hand-clasp (GHC) was the first documented social custom in wild chimpanzees 1. Anthropology Centre for Conservation, Environment & Development, Oxford Brookes University, UK
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