Overview
- The PNAS paper, published Monday, analyzed 91 chimpanzees from four wild Taï communities in Côte d’Ivoire and four orphan, peer‑raised groups at Tacugama Sanctuary in Sierra Leone.
- Wild Taï chimpanzees used the unvoiced 'raspberry' almost exclusively during grooming, whereas sanctuary juveniles used the same sound across many different social situations.
- When an adult was introduced into a Tacugama group the juveniles' raspberry use gradually converged on the adult's pattern, showing young chimps learn call function from older role models.
- Authors report limits to chimp vocal learning because chimps struggle to learn wholly new sounds and offer an alternative explanation that grooming‑related lip movements could cause independent convergence on the same call.
- The team calls for wider, long‑term field comparisons and stronger protection for wild populations to map how widespread learned vocal conventions are and how they are passed between generations.