Gruber investigated whether chimpanzees from Sonso and Kanyawara approached a novel task — extracting liquid honey from a log with an artificially provided leafy stick — in community-specific ways. Kanyawara chimpanzees, who sometimes use sticks for food acquisition, tended to use the stick as a dipping tool to remove the honey. Sonso chimpanzees, who have never been observed using sticks in a foraging context, found the leaves to be the most salient part of the tool. Some produced leaf-sponges, but none used the stick to obtain honey.
In a second experiment, Gruber exposed Sonso chimpanzees to the preferred Kanyawara approach to the task by placing leafy stick tools in the honey, prompting them to retrieve the leafy stick directly from the hole. Although some of the chimpanzees touched or manipulated the stick, none of them used it as a tool to obtain honey.
Further research is needed to understand the learning mechanisms chimpanzees use in the wild, but these results suggest that cultural bias constrains how individuals from different communities perceive and evaluate their environment. They also suggest that in some contexts, social learning may be more important to chimpanzees than individual trial- and-error learning. The article appears here in the journal Scientific Reports.