In the first recorded occurrence of social learning among wildlife, researchers looked at how chimpanzee behaviour is transmitted from individual to individual.
The researchers happened to be in the "right place at the right time" to notice and document the social spread of the use of two tool-used behaviors among a chimpanzee community, PLOS reported.
"Researchers have been fascinated for decades by the differences in [behavior] between chimpanzee communities; some use tools some don't, some use different tools for the same job. These [behavioral] variations have been described as 'cultural', which in human terms would mean they spread when one individual learns from another; but in most cases they're long established and it's hard to know how they originally spread within a group," said Catherine Hobaiter, lecturer in psychology at the University of St Andrews.
The researchers looked at how the Sonso chimpanzees used "leaf sponges" as a drinking tool to scoop up water. Different individuals in the group were found to develop two behaviors, moss-sponging (using a combination of moss and other materials to create the sponge) or leaf-sponge reuse (using a sponge left behind from a previous visit). These behaviors had not been observed in chimpanzees over the previous 20 years of observation.
"Our results provide strong evidence for social transmission along the chimpanzees' social network, demonstrating that wild chimpanzees learn novel tool-use from each other and support the claim that some of the observed [behavioral] diversity in wild chimpanzees should be interpreted as 'cultural'," said William Hoppitt, senior lecturer in zoology at Anglia Ruskin University.
The analysis began when the 29-year-old alpha male chimpanzee, Nick, made a moss sponge, causing seven others in the social group to copy the behavior. One of these individuals was observed reusing its moss sponge. Another eight individuals adopted the reuse technique but only four of them had observed others practicing the behavior.
The study's findings suggest chimpanzees' culture changes slowly over time based on behaviors learned within the community. Researcher believe this is how early human culture evolved.
"Nevertheless, something must have subsequently happened in our evolution that caused a qualitative shift in what we could transmit, rendering our culture much more complex than anything found in wild apes. Understanding this qualitative jump in our evolutionary history is what we need to investigate now," said Thibaud Gruber, Marie Curie Fellow at the University of Neuchâtel.
The findings were published Sept. 30 in the journal PLOS Biology.
WATCH:
