Why are animal rhythms important? Cross-species work can help isolate what is unique in the human capacity for rhythm. In addition, cross-species work can provide inference on the origins and evolution of human rhythmic capacities. Neural tissue and cognitive capacities do not fossilize: by pinpointing shared biological mechanisms between humans and other animals, cross-species research can help reconstruct the evolution of rhythmic capacities in humans. This symposium will unify multiple comparative approaches to the evolution of musical rhythm. Specifically, we aim at (1) providing a platform for multiple fields to compare theoretical frameworks and methodologies across species, (2) integrating findings from behaviour, neuroscience, modelling, and cognition, (3) actively spurring cross-fertilization between musical rhythm and animal timing research, (4) drawing inferences on the evolution of human rhythm.

Communicating species identity is a key component of many animal signals. However, whether selection for species recognition systematically increases signal diversity during clade radiation remains debated. Here we show that in woodpecker drumming, a rhythmic signal used during mating and territorial defense, the amount of species identity information encoded remained stable during woodpeckers' radiation. Acoustic analyses and evolutionary reconstructions show interchange among six main drumming types despite strong phylogenetic contingencies, suggesting evolutionary tinkering of drumming structure within a constrained acoustic space. Playback experiments and quantification of species discriminability demonstrate sufficient signal differentiation to support species recognition in local communities. Finally, we only find character displacement in the rare cases where sympatric species are also closely related. Overall, our results illustrate how historical contingencies and ecological interactions can promote conservatism in signals during a clade radiation without impairing the effectiveness of information transfer relevant to inter-specific discrimination.