Vocal learning, chorusing seal pups, and the evolution of rhythm

The presence of vocal learning and rhythm capacities in only a few mammals drives a cross-species hypothesis in evolutionary neuroscience: vocal learning and rhythm perception and synchronization may be causally related. Harbor seals ( Phoca vitulina) are among these mammals, and their puppyhood is the most active vocal period in their lives. Building on both comparative psychology and animal behavior, this research integrates methods from human cognition with attention to species’ ecological sensory niches. We present data from seal pups in four different setups: recordings of semi-natural vocal interactions in (1) individual and (2) group settings, (3) playback experiments to elicit vocal responses, and (4) perceptual listening experiments to measure behavioral responses. We complement empirical data with agent-based computational modeling aimed at reverse-engineering the putative mechanisms underlying rhythmic vocal interactions. Our data suggest that seal pups have developed capacities to produce and perceive rhythmic patterns. Seals’ vocal exchanges show rhythmic interactivity and antisynchronous coordination. Evidence for antisynchrony, rather than synchrony, in seals suggests that the rhythm-vocal learning link across species is more complex than previously surmised.