Animal behaviour: Wild chimpanzees’ cultural bias

Wild chimpanzees’ previous experiences may affect the type of tools they use to solve novel tasks. The findings, published in Scientific Reports, support previous research suggesting that apes in captivity prefer to rely on previously acquired foraging techniques.

Thibaud Gruber and colleagues investigated whether wild chimpanzees from two distinct communities in Uganda (Sonso and Kanyawara) approached a novel task — extracting liquid honey from a rectangular hole with an artificially provided leafy stick — in community-specific ways. Kanyawara chimpanzees, which sometimes use sticks for food acquisition, tended to use the stick as a dipping tool to remove the honey. Sonso chimpanzees, which have never been observed using sticks in a foraging context, found the leaves to be the most salient part of the tool, some producing leaf-sponges, but no individual used the stick to obtain the honey.

In a second experiment, the authors exposed Sonso chimpanzees to the Kanyawara individuals’ preferred approach to the task by letting the animals encounter and retrieve the leafy stick directly from the hole. Although some of the chimpanzees picked up or touched the stick, none of them used it as a tool to obtain the honey.

Further research is needed to understand the learning mechanisms chimpanzees use in the wild but the authors suggest these results could be interpreted in terms of a cultural bias, which constrains how chimpanzees from different communities perceive and evaluate their environment.