Periodic Reporting for period 1 - TOHR (The Origins of Human Rhythm)
Okres sprawozdawczy: 2023-06-01 do 2025-11-30
Humans are particularly rhythmic animals. Why did the human sense of rhythm develop? Many hypotheses try to explain the origins of our acoustic rhythm capacities, but few are empirically tested, compared, and comparatively investigated. This project searches for the evolutionary roots of human rhythmicity, breaking new ground through three concerted approaches. First, it zooms in on core, measurable rhythmic properties, such as isochrony. Second, it compares hypotheses on the origin of human rhythm, selecting the most relevant ones to music and speech and testing them against each other. Third, it targets rhythm precursors in other species as predicted by these alternative hypotheses. The four hypotheses, tested against each other, propose that 1) gait or 2) breathing control, and the ability to 3) learn new sounds or 4) sing as part of a coordinated chorus are evolutionary precursors to rhythm, in human evolution and potentially in other species. We analyze behavioral, electrophysiological and physiological measures, to test whether the four features above predict rhythmic capacities, and combine them to inform computational models of the evolution of rhythmic abilities. Comparative animal work is key to test whether similar evolutionary pressures lead to similar rhythmic traits. We aim to collect data from humans and other key mammalian species. These species, chosen among primates and aquatic mammals, exhibit—each to varying degrees—the previously mentioned traits hypothesized to be precursors of rhythm: capacity to learn new sounds, developed breathing control, rhythmic locomotion, and propensity to sing in choruses. Finding rhythmic abilities and their potential precursors across species will provide a test bench to reconstruct the origins of human rhythm. The project moves the state of the art on rhythm processing abilities in new challenging directions. By connecting fields from the social sciences (experimental psychology and cognitive neuroscience), humanities (speech sciences, music theory and bio-musicology), and the “hard sciences” (bioacoustics, primatology and marine biology), we aim at showing which species have rhythm, and why humans evolved to be such chatty, rhythmic creatures.
The team has worked along 3 main lines: theoretical, methodological and empirical.
Theoretical contributions
Activities performed:
- We summarized and critically examined the existing literature on rhythmic behaviours across species, including humans.
Main achievements:
- We highlighted key species and behaviours one may want to target to better understand the evolution of rhythm;
- We developed testable hypotheses for cross-species rhythm research.
Methodological contributions
Activities performed:
- We developed closed-form mathematical equations and computer simulations to measure structural rhythmicity in time series;
- We developed Python packages and toolkits to both generate rhythmic stimuli in experiments and measure rhythmic regularities in behaviours.
Main achievements:
- We developed and shared several methodological approaches to investigate and measure rhythm;
- We showed the usefulness of formalizing and classifying the many ways to study and quantify rhythm across species (including humans).
Empirical contributions
Activities performed:
- We recorded behavioural data from several non-human mammalian species;
- We performed acoustic analyses of sounds and motor behaviour in 8 mammalian species;
- We applied and showcased novel statistical techniques to the analysis of rhythmic behaviour.
Main achievements:
- We showed how multiple, although specific, species show behaviours with structural similarities to human rhythmic behaviours;
- Our data prompts to reappraise and perhaps scale down human uniqueness when it comes to rhythmic capacities.
Theoretical contributions
Activities performed:
- We summarized and critically examined the existing literature on rhythmic behaviours across species, including humans.
Main achievements:
- We highlighted key species and behaviours one may want to target to better understand the evolution of rhythm;
- We developed testable hypotheses for cross-species rhythm research.
Methodological contributions
Activities performed:
- We developed closed-form mathematical equations and computer simulations to measure structural rhythmicity in time series;
- We developed Python packages and toolkits to both generate rhythmic stimuli in experiments and measure rhythmic regularities in behaviours.
Main achievements:
- We developed and shared several methodological approaches to investigate and measure rhythm;
- We showed the usefulness of formalizing and classifying the many ways to study and quantify rhythm across species (including humans).
Empirical contributions
Activities performed:
- We recorded behavioural data from several non-human mammalian species;
- We performed acoustic analyses of sounds and motor behaviour in 8 mammalian species;
- We applied and showcased novel statistical techniques to the analysis of rhythmic behaviour.
Main achievements:
- We showed how multiple, although specific, species show behaviours with structural similarities to human rhythmic behaviours;
- Our data prompts to reappraise and perhaps scale down human uniqueness when it comes to rhythmic capacities.
Our results beyond the state of the art are:
- We provided a tentative roadmap for comparative animal rhythm research; this will be useful not only to the ERC project, but hopefully also helpful for other laboratories in the world with similar interests;
- We developed and shared tools to quantify and adjudicate what it means for a behaviour or animal sound to be rhythmic;
- We showed that rhythmic traits are more common than previously surmised across mammalian species.
Challenges for future research will be:
- To reconcile different theoretical hypotheses which sometimes target different explanatory levels of a particular phenomenon, in our case the origins and evolution of rhythmic capacities;
- To ensure that quantitative measures can be applied similarly across species, while taking individual differences and species differences into account;
- To find out and target the most fruitful taxonomic groups and behaviours.
- We provided a tentative roadmap for comparative animal rhythm research; this will be useful not only to the ERC project, but hopefully also helpful for other laboratories in the world with similar interests;
- We developed and shared tools to quantify and adjudicate what it means for a behaviour or animal sound to be rhythmic;
- We showed that rhythmic traits are more common than previously surmised across mammalian species.
Challenges for future research will be:
- To reconcile different theoretical hypotheses which sometimes target different explanatory levels of a particular phenomenon, in our case the origins and evolution of rhythmic capacities;
- To ensure that quantitative measures can be applied similarly across species, while taking individual differences and species differences into account;
- To find out and target the most fruitful taxonomic groups and behaviours.