Exploring cultural techniques in non-human animals: how are flexibility and rigidity expressed at the individual, group, and population level?

Non-human animal (henceforth animal) culture has been demonstrated across a variety of species and, for some, includes technical traditions. Like human culture, animal culture must strike a balance between flexible and rigid behaviour. On one hand, culture must allow for the creation, acquisition, or application of cultural behaviours. On the other hand, culture must ensure a high degree of similarity between individual performances, leading to stable traditions that persist across generations despite disruptive influences. The dominant argument for understanding the rigidity of cultural transmission within animals has focused on social learning, with mechanisms such as imitation leading to the highest fidelity of transmission. Thereby animal culture has often been limited to examples explained by social learning alone and has historically excluded behaviours that could be explained by genetic or ecological factors. In this chapter we argue that these factors, rather than be excluded, may assist social learning in explaining cultural differences. To explore these concepts, we will examine and define flexible and rigid behaviour at the individual level, then expand to the group and population level. We then describe the current perspectives from social learning theory as well as cultural attraction theory in understanding animal cultural behaviour, highlighting the objectives and limitations of each. Further, we propose a framework that combines social learning and cultural attraction theory to understand the origin and stability of chimpanzee cultural techniques. We argue that cultural traits are the product of three classes of factors of attraction: individual predispositions, social influences, and ecological contexts. This new framework can contribute to better understanding the origins, persistence, and eventual demise of cultural techniques.