The Evolutionary Origins of Rhythm: A Top-down/bottom-up Approach to Temporal Patterning in Music and Language

Abstract

Music and language are two of the most prominent human features. Both systems rely, among others, on the human cognitive ability for rhythm (Kotz & Schwartze, 2010; Patel, 2003, 2006), intended as patterning over time (McAuley, 2010). It is however unclear: (i) when and how humans evolved rhythmic abilities, (ii) whether these were direct results of pressures for language or music, or simply by-products of other evolutionary processes (Patel, 2010), and (iii) the degree of overlap between rhythm in language and music cognition (Cason & Schön, 2012). At the same time, rhythm and synchronization are truly cross-disciplinary concepts, broadly employed not only in musicology and linguistics, but also in cognitive psychology, biology, and physics (Cummins, 2012; Greenfield & Roizen, 1993; Patel & Daniele, 2003; Pikovsky, Rosenblum, & Kurths, 2003; Strogatz & Stewart, 1993; Winfree, 1986). This often creates conflicts between definitions and assumptions from different disciplines (Cummins, 2012). In this talk, I present my ongoing work, trying to unveil the evolutionary bases of time patterning, and to build a unifying, theoretical framework for rhythm, transcending specific disciplines. I argue how a broad comparative approach, comparing different animal species (including humans), can inform us on the evolutionary origins of the cognitive ability to process rhythm (Fitch, 2012; Honing et al., 2012; Ravignani et al., 2013). I describe three parallel and complementary lines of research to understand the origins of rhythm. First, I introduce a theoretical framework providing a common platform for the interdisciplinary study of rhythm in music and language (Ravignani, Bowling, & Kirby, in press). The framework I propose, the “hierarchy of coupled oscillations”, attempts to connect human music, dance and phonology on one side, to occurrences of synchronization and chorusing in non-human animals (as in fireflies or crickets) on the other side (Hagen & Bryant, 2003; Hagen & Hammerstein, 2009). Second, I present some preliminary results on group synchronization in an agent-based model of chorusing, aimed at investigating rhythmic abilities in pre-musical hominids (Merker, Madison, & Eckerdal, 2009). In particular, I suggest how rhythmic complexity can emerge from simple, local interactions. This bottom-up approach is particularly useful in finding out which rhythmic features can in principle exist without centralized processing (Ravignani, 2014). In parallel, using a top-down approach, I describe some experimental pilot work investigating the cognitive abilities for rhythm in our closest living relatives: the chimpanzees. Chimpanzees naturally “drum” in the wild (Arcadi, Robert, & Boesch, 1998). Building on this natural predisposition, I describe the development and pilot testing of a new tool to sonify apes’ movements (Ravignani et al., 2013). Ongoing experiments with this “Prima-Drum” will serve to: (i) investigate the temporal nature of drumming patterns in chimpanzees, (ii) compare them to those found in music and language, and (iii) ascertain chimpanzees’ abilities in discriminating and copying human-produced rhythms (as described in phonology and music theory research).