The Origins of Human Rhythm

Introduction

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.

Key Rhythmic Properties

First, I zoom in on key rhythmic properties:

• Isochrony: an even occurrence of events in time.
• Meter: a relative accentuation of events.

Comparison of Hypotheses

Second, I compare hypotheses on rhythm origins, selecting the most relevant ones to music and speech and testing them against each other.

Rhythm Precursors in Other Species

Third, I target rhythm precursors in other species as predicted by these alternative hypotheses. I test four hypotheses, which propose that:

1. Gait
2. Breathing control
3. The ability to learn new sounds
4. Singing in a chorus

These are considered evolutionary precursors to human rhythm.

Methodology

I will use different measures including:

• Behavior
• Electrophysiology
• Gait tracking
• Breathing
• Computational modeling

to test whether the four features above predict rhythmic capacities. Comparative animal work is needed to test whether similar evolutionary pressures lead to similar rhythmic traits.

Data Collection

I will collect data from humans and four more species. I will test:

• Seals: displaying vocal learning
• Porpoises: both mammals have developed breathing control
• Siamangs: displaying rhythmic locomotion
• Indris: both primates naturally sing in choruses, a rare trait in non-human mammals

Finding rhythm in other species will provide a test bench to reconstruct the origins of human rhythm.

Project Expansion

Resting on my background in bioacoustics and mathematics, the project expands in new challenging directions, such as:

• Neurophysiology of marine mammals
• Automated gait analyses
• Biomusicology

Conclusion

In brief, I will show which species have rhythm, and why humans evolved to be such chatty, rhythmic creatures.