R. Adriana Hernández-Aguilar
Serra Húnter Lecturer in the Department of Social Psychology and Quantitative Psychology at the University of Barcelona and co-director of Research at the Jane Goodall Institute Spain and Senegal
The excellent study by Edwin van Leeuwen et al. is definitely timely. The evolution of cultural transmission is a topic that is receiving a lot of attention from researchers and has generated intense debate (see, for example, Whiten 2022, special issue in Physics of Life Reviews 2023, vol. 45). Currently, there is disagreement among researchers as to whether great apes (and other species) possess cumulative culture; that is, whether they are capable of socially learning a behaviour (which they cannot innovate individually) and improving it through successive changes over time. Thus, researchers have opposing views on the forms of social learning present in great apes. Some researchers consider that great apes are incapable of copying knowledge about how to perform a task (or know-how) by observing other individuals and assume that each individual re-innovates the task over time, independently. The latter view assumes that, as a consequence, great apes are not capable of producing a cumulative culture. Other researchers, however, believe that the complex social learning mechanisms of great apes do include the process of copying knowledge about how to perform a task, but this assumption has been poorly tested.
The study by van Leeuwen et al. aims to contribute to this debate by testing both views experimentally. The study was conducted with two groups of chimpanzees living in a semi-freedom sanctuary in Zambia, with a total of 66 individuals, an adequate sample size for primate studies. Twenty-one percent of the chimpanzees participating in the study were able to learn a task (composed of a sequence of actions), which they were unable to innovate individually, after observing knowledgeable individuals. These results suggest that chimpanzees could indeed copy knowledge of how to do a task by observing experienced individuals and support the hypothesis that they are capable of producing cumulative culture.
The results of this study have important implications not only for the evolution of human cognition, but specifically for the evolution of cumulative culture. The evidence in this study challenges the assumption that cumulative culture is a uniquely human trait and reminds us that the list of uniquely human behaviours is getting shorter and shorter as we move forward in the study of our close relatives.