Although they are widely regarded as the most “cultural” non-human animals on Earth, evidence for the social diffusion of new behaviors in wild chimpanzees is lacking as most studies have been conducted on animals in captivity. But now, a team of scientists have finally managed to capture the social spread of novel tool-use behaviors in a group of wild chimps. According to the researchers, this is the first time that social learning has been directly observed in the wild. The work has been published in PLOS Biology.
The team, which included researchers from the University of St Andrews, the University of Neuchâtel, Anglia Ruskin University and Université du Quebec, made their extremely rare observations whilst studying a group of chimps living in Uganda’s Budongo Forest. It’s been known for some time that chimpanzees make and use tools, such as leaf-sponges which are used to collect and drink water. Leaf-sponging is thought to be a universal behavior in chimp communities, but how the animals manufacture these tools varies considerably between different groups. Members of this particular community, for example, usually make the sponges by folding and chewing leaves. The apes then dip these tools into ponds and drink the collected water.
During their observations, the scientists were lucky enough to record two new variants of this tool use behavior. The first involved a 29-year-old alpha male called Nick, who made a new type of sponge out of moss instead of a leaf. He made his new tool while being watched by a dominant adult female called Namibi. Within the next six days, seven more chimps made and used this type of sponge. Six of these individuals had seen another chimp make a moss sponge before making one themselves, whereas the other picked up and used a discarded sponge, which is probably how the behavior was learned.
The second behavior involved chimps picking up old-leaf sponges made by other members of the community and re-using them. This sometimes involved chimps picking up discarded sponges, but more often it involved infants begging or scrounging from older relatives. “It might sound trivial, but the chimps [we study] just don’t do that,” lead author Dr. Catherine Hobaiter told BBC News.
According to the researchers, this new evidence of social learning in wild chimps strongly supports the idea that this prerequisite for culture has its origins in a common ancestor of great apes and humans.
“This study tells us that chimpanzee culture changes over time, little by little, by building on previous knowledge found within the community,” lead researcher Dr. Thibaud Gruber said in a news release. “This is probably how our early ancestors’ cultures changed over time.”