Perceiving and Participating in Synchrony

QUESTION. Why does music make us want to move? The link between music and movement is observed across cultures, develops early in life, and is exceptionally rare in other animals. BACKGROUND. Key to answering this question is musics capacity to induce synchronized motor behavior among one or more individuals. Research has shown that synchronized motor behavior leads to increased prosocial behavior between synchronizers. These observations have led to the synchrony and sociality hypothesis of music evolution, which explains our tendency to move to music as the signature of an evolutionary process in which the prosocial consequences of synchronous behavior conferred a fitness advantage on individuals in groups that practiced music. GOAL. To rigorously and empirically evaluate predictions of the synchrony and sociality hypothesis using physiological and behavioral data. METHODOLOGY. Manipulate the degree of synchrony between elements in visual and auditory stimuli, as well as between participants in real and simulated interactions, while measuring eye movements, pupillary, cardiac, and respiratory activity, levels of oxytocin, cortisol, and endogenous opioids, and affiliation and cooperation among participants. INNOVATION. The experiments in this proposal outline a state-of-the-art empirical methodology to evaluate a leading hypothesis for the biological origins of music, i.e., the synchrony and sociality hypothesis. It combines new experimental paradigms with rigorous physiological methods previously unexploited in this field. SIGNIFICANCE. The synchrony and sociality hypothesis is well-defined and makes testable predictions, providing a unique opportunity to make an empirical contribution to a biological account of music and its evolution, and thus shed light on a fundamental component of human experience.

Why is music so important for our species? Music is a human universal, and yet our understanding of its biological origins remains largely the same today as when Darwin considered the problem some 150 years ago. This project aimed to address the human obsession with music by focusing its capacity to make us move. In response to a musical beat, many humans are struck by a spontaneous urge to move in synchrony with it, e.g., by tapping, swaying, bobbing our heads or more complex dancing. This behavior is biologically bizarre. Only a small handful of species appear to be capable of synchronizing their movements to a beat, and as far as we know none do so. The aim of this project was to discover the biological foundations of the link between music and movement in our species, or more simply to understand, why music makes us want to move?On a mechanistic level, the results demonstrate that music that is particular good at stimulating movement (called high groove music) generates physiological arousal in listeners. Focusing on pupil dilation, which reflects general cortical arousal, we found larger responses to high compared to low groove music. Furthermore, in a series of carefully controlled experiments we established that the pupillary responses is driven in part by fundamental acoustical properties (e.g., the amount of high frequency energy), and key structural aspects of musical rhythm (e.g., the amount of syncopation). Together these results imply that music makes us want to move in part because it arouses us. On an evolutionary level, the results demonstrate that participation in group musical activities results in the down regulation of cortisol, a key hormone in the bodys stress response. This implies that one of the ways in which group music making may have benefited our ancestors is through the reduction of stress, which might otherwise block affiliate interaction and decrease the strength of important social bonds. Together, these results demonstrate the connection between movement and music in our species on a physiological level. The methods developed here can be extended to comparative contexts, looking across species to determine the extent to which the physiological responses observed here are specific to humans, and are thus likely to have evolved uniquely in our lineage. This is relevant for not only for understanding the evolution of music, but also the biology of social communication. A final point on the societal relevance of this work, is that with further research, synchronized musical activities on stress and pain offer promising pathways to reduce pain and stress, thus leading to improved mental and physical health.