Mom, mom, look at the leaf! Chimpanzees also use gestures to draw attention
Researchers have recorded a female chimpanzee showing a leaf to her mother. If the gesture seems quite innocent to us – and even rather banal in humans – it is a fact rarely observed in great apes. This scene filmed in a forest in Uganda is a discovery of great importance for studying the evolution of human social cognition and understanding the emergence of language.
In the Kibale forest in Uganda, Fiona and her mother Sutherland, two adult female chimpanzees, go about their daily business. While Fiona is in the middle of grooming leaves (a common practice in this species, which consists of tearing off a leaf, observing it and caressing it), she holds the leaf out to her mother next to her to show it to her… and only to show it to her. A gesture that may seem insignificant for humans, but is rarely observed in other species.
“Wild great apes seldom use referential gestures, and when they do, it seems to be exclusively for imperative purposes, like when they want to direct grooming,” explains Simon W. Townsend, PI for the NCCR Evolving Language and one of the authors of the study.
The researchers therefore wondered whether Fiona really intended to share attention for sharing’s shake or whether her gesture had been misinterpreted. To do this, they compared 84 videos of leaf grooming scenes and analysed the chimpanzees’ gestures. According to their analysis, it appears that Fiona’s gesture had no other intention than to draw her mother’s attention to the leaf. Future studies will confirm how often and in what context (here, the mother-daughter bond suggests strong social affiliation) apes communicate with each other simply to share attention.
Why is this interesting for the study of language evolution?
We can’t find traces of the language of the past in archaeological excavations. However, we can compare our communication with that of other species. “Studying chimpanzees can give us a glimpse into the communication our last common ancestor, living 6 million years ago, was capable of. Our work suggests they too were already potentially using referential declarative signals “, concludes Simon W. Townsend.
Wilke, Claudia, Nicole J. Lahiff, Kris H. Sabbi, David P. Watts, Simon W. Townsend, and Katie E. Slocombe. 2022. “Declarative Referential Gesturing in a Wild Chimpanzee (Pan Troglodytes).” Proceedings of the National Academy of Sciences 119(47):e2206486119. doi: 10.1073/pnas.2206486119.