Chimps grasp at social identities
By Bruce Bower
In a group of chimpanzees now living in Tanzania’s Mihale Mountains National Park, grooming partners sometimes both raise their right (or left) arms above their heads and grasp each others’ wrists as they take turns cleaning one another. In a nearby Mihale chimp community studied about 20 years ago, grooming duos preferred to raise arms and clasp hands, palm-to-palm, as they tidied up one another.
This is the first evidence that chimps employ a social custom in which different communities arbitrarily modify a common behavior to identify fellow group members and foster social solidarity, proposes a team led by anthropologist William C. McGrew of Miami University in Oxford, Ohio.