Chimps Learn 'Culture' From One Another

Researchers who were in the right place at the right time have witnessed the spread of two tool-use behaviors among a band of wild chimpanzees, which they believe sheds light on human cultural evolution.

Scientists have long been intrigued by the differences in behavior between chimp communities, in which some use tools while others do not. These variations are described as "cultural," in that one individual learns from another, but most of the time they are established so it is difficult to determine where the behavior originally came from.

It has long been argued that studies conducted among chimps in captivity, as is often the case, cannot definitely confirm the cultural exchange of tools without first documenting such behavior in the wild.

Published in the journal PLOS Biology, an international team of researchers set out to observe the Sonso chimp community in Uganda's Budongo Forest.

They investigated the use of leaf-sponges - tools used to dip into water to drink from, usually made from moss - as well as leaf sponge re-use, in which chimps leave the leaf in a particular spot to be used again later.

Among the Sonso community, the alpha male made a moss sponge while being watched by the dominant adult female. Six days later, seven other chimps crafted moss sponges, with one also re-using a discarded sponge.

The research team also recorded an adult male retrieving and using a discarded leaf sponge, which was followed by eight more chimps re-using the sponges even though only four had observed the re-use technique.

They estimated that chimps that observed moss-sponging were 15 times more likely to develop the behavior than those that did not.

"This study tells us that chimpanzee culture changes over time, little by little, by building on previous knowledge found within the community," Thibaud Gruber, Marie Curie Fellow at the University of Neuchatel, explained in a statement.

"This is probably how our early ancestors' cultures also changed over time," he added. "In this respect, this is a great example of how studying chimpanzee culture can help us model the evolution of human culture."