Evolving building blocks of rhythm: How human cognition creates music via cultural transmission
Musical rhythm, in all its cross-cultural diversity, exhibits several commonalities across world cultures. Traditionally, music research has been split in two fields. Some scientists focused on musicality, namely the human biocognitive predispositions for music, with an emphasis on cross-cultural similarities. Other scholars investigated music, seen as cultural product, focusing on the large variation in world musical cultures. Recent experiments found deep connections between music and musicality, reconciling these opposing views. Here we address the question of how individual cognitive biases affect the process of cultural evolution of music. Data from two experiments is analyzed using two different, complementary techniques. In the experiments, participants hear drumming patterns and imitate them. These patterns are then given to the same or another participant to imitate. The structure of these - initially random - patterns is tracked down to later experimental generations. Frequentist statistics show how participants biases are amplified by cultural transmission, making drumming patterns more structured. Structure is achieved faster than in transmission within, rather than between, participants. A Bayesian model approximates the motif structures participants learned and created. Overall, our data and model show that individual biases for musicality play a central role in shaping cultural transmission of musical rhythm.