There is increasing evidence for cultural variations in behaviour among non-human species, but human societies additionally
display elaborate cumulative cultural evolution, with successive generations building on earlier achievements. Evidence for
cumulative culture in non-human species remains minimal and controversial. Relevant experiments are also lacking. Here we
present a first experiment designed to examine chimpanzees’ capacity for cumulative social learning. Eleven young chimpanzees
were presented with a foraging device, which afforded both a relatively simple and a more complex tool-use technique for extracting
honey. The more complex ‘probing’ technique incorporated the core actions of the simpler ‘dipping’ one and was also much more
productive. In a baseline, exploration condition only two subjects discovered the dipping technique and a solitary instance
of probing occurred. Demonstrations of dipping by a familiar human were followed by acquisition of this technique by the five
subjects aged three years or above, whilst younger subjects showed a significant increase only in the elements of the dipping
technique. By contrast, subsequent demonstrations of the probing task were not followed by acquisition of this more productive
technique. Subjects stuck to their habitual dipping method despite an escalating series of demonstrations eventually exceeding
200. Supplementary tests showed this technique is within the capability of chimpanzees of this age. We therefore tentatively
conclude that young chimpanzees exhibit a tendency to become ‘stuck’ on a technique they initially learn, inhibiting cumulative
social learning and possibly constraining the species’ capacity for cumulative cultural evolution.
Keywords Social learning - Chimpanzees - Tool-use - Ratchet effect - Cumulative culture